JP5160858B2 - A coil of a power transmission device, a power transmission device, a power transmission device of the power transmission device, and a power reception device of the power transmission device. - Google Patents

Description

The present invention comprises a separable power transmission unit and a power reception unit, and is provided in a power transmission device that transmits power by a mutual induction effect generated between a power transmission coil of the power transmission unit and a power reception coil of the power reception unit. The present invention relates to a coil of a device, a power transmission device, a power transmission device of the power transmission device, and a power reception device of the power transmission device .

  The power transmission device in which the power transmission coil and the power reception coil can be separated is in a separated state in which the distance between the coils is long when power transmission is not performed. For example, at the time of power transmission, as shown in FIG. 93, the power transmission coil 1 and the power reception coil 2 are configured to face each other. When an alternating current is passed from the power transmission control circuit 3 to the power transmission coil 1, an electromotive force is induced in the power receiving coil 2 by the mutual induction action, and the alternating current due to the electromotive force flows to the load RL through the power reception control circuit 4 to transmit power. Is done.

The power transmission coil 1 or the power reception coil 2 is formed by, for example, winding the conductor 1x shown in the plan view of FIG. 94A in a spiral shape, and is along the line 6B-6B in FIG. As shown in the cross-sectional view of FIG. Since facing two coils formed by winding the conductor 1x in a spiral shape is synonymous with inductively coupling both coils, the notation "opposing" It is assumed that both coils are in an inductively coupled state. When both coils are in an inductively coupled state, both coils constitute a transformer, and Non-Patent Document 1 describes an explanation of the transformer theory.

  In FIG. 94 (B), the same coil 1 for power transmission and coil 2 for power reception are used. This is because, in the conventional example cited below, the facing state indicating inductive coupling uses the same coil for the power transmission coil 1 and the power reception coil 2. Of course, a coil in which the power transmission coil 1 and the power reception coil 2 are different can be used. Hereinafter, when it is simply indicated as “coil” including the conventional example, it refers to the power transmission coil 1 or the power reception coil 2 or both coils. Moreover, in this application, since the vocabulary used differs with the literature referred, vocabulary is demonstrated. The portion including the power transmission control circuit 3 and the power transmission coil 1 in FIG. 93 is represented as a power transmission side, a primary side, an input side, etc., and the power transmission coil 1 is represented by a power transmission coil, a power transmission coil, a primary coil, and a primary. Indicated as side coil. 93, the portion including the power reception control circuit 4 and the power reception coil 2 is expressed as a power reception side, a secondary side, an output side, etc., and the power reception coil 2 is a power reception coil, a power reception coil, a secondary coil, Indicated as secondary coil. Next, a resistance component existing in series in an equivalent circuit of a coil or a capacitor is generally expressed as ESR, and is called Equivalent Series Resistance in Japanese. In this application, reference is made to “Effective Series Resistance” because the frequency characteristics of ESR are referred to.

  A power transmission device using a coil having a configuration as shown in FIG. 94 is described in Japanese Patent Laid-Open No. 8-148360 (Patent Document 1). Patent Document 1 describes a donut-shaped planar spiral coil as Comparative Example 1. That is, this coil is made by winding 5 turns of 100 copper wires with an insulation coating of 100 μm in diameter, and creating an outer diameter of 30 mm, an inner diameter of 15 mm, and a thickness of 1.5 mm. Not equipped with magnetic material. The side that is connected to the power supply with these facing each other is the primary side (input side), and the side that generates output by the mutual induction action is the secondary side (output side).

  Moreover, in the Example of patent document 1, the measurement data in which the power transmission frequency is 100 kHz is described, and it is described that the power transmission frequency is not limited to 100 kHz. That is, paragraph number 0040 of Patent Document 1 describes that the power transmission frequency can be arbitrarily selected.

  Another example of the coil having such a configuration is described in Japanese Patent Laid-Open No. 4-122007 (Patent Document 2). In this Patent Document 2, as a comparative example 1, there is a flat spiral coil, in which an enameled copper wire having a diameter of 1 mm is wound for 25 turns, an outer diameter is 80 mm, an inner diameter is 24 mm, and a magnetic core is not provided. Have been described. The one that is connected to the power supply with these facing each other is the primary side (input side), and the one that generates output by the mutual induction action is the secondary side (output side).

  In the air-core coil, the coil characteristics (inductance and effective series resistance) change due to the proximity of the metal. In order to prevent this influence, many inventions have been filed in which a coiled antenna is equipped with a combination of a magnetic material and a metal plate. However, the coiled antenna transmits energy by electromagnetic waves and does not use a mutual induction action. In a power transmission device using a mutual induction action, Japanese Patent Application Laid-Open No. 2006-42519 (Patent Document 3) is formed of a magnetic material on the opposite side of a plane spiral coil for the purpose of eliminating unnecessary radiation. The coil of the structure equipped with the sheet | seat and the coil of the structure which affixes a metal plate on the opposite surface side of the coil equipment surface of the sheet | seat formed with a magnetic material are described.

  Furthermore, Japanese Patent Laid-Open No. 2002-353050 (Patent Document 4) describes that a diamagnetic metal is used as a metal material that eliminates the influence of a metal material approaching the coil. Also in patent document 4, a coil is described as "magnetic field type antenna", and the coil used for a mutual induction effect and the antenna which transmits / receives electromagnetic waves are confused.

Further, in a power transmission device based on a mutual induction action, there are a method for preventing heat generation of a metal body close to a coil of a power transmission unit, and a method for controlling transmission power by providing a signal transmission method between a power transmission unit and a power reception unit. No. 10-271713: U.S. Pat. No. 5,896,278 (Patent Document 5).
JP-A-8-148360 (paragraph number 0027) JP-A-4-122007 (Tables 1 and 2) JP 2006-42519 A (paragraph numbers 0019, 0020, claim 1, claim 2, FIG. 2, FIG. 3) JP 2002-353050 A (paragraph numbers 0015, 0019, claim 5) JP-A-10-271713 (paragraph numbers 0005, 0009, etc.) University Course Electrical Circuit (1), by Katsuro Ohno and Tetsuo Nishi, published by Ohmsha (August 20, 2001: first edition Showa 45) ISBN: 9784274131660 Chapter 6 Mutual Inductance and Transformer (Transformer)

  A power transmission device in which a power transmission unit and a power reception unit can be separated can transmit electric power to an electric device or an electronic device without using an electric wire or a mechanical contact. There are various application uses and advantages when it is possible to send electric power necessary for the operation of electrical equipment and electronic equipment without using electric wires or mechanical contacts. However, in the conventional technology, the configuration and characteristics of the power transmission coil that transmits power using the mutual induction effect, and the function and effect are not clarified. Therefore, a power transmission device in which a power transmission coil and a power reception coil can be separated, and a conventional example regarding a coil of the power transmission device will be considered.

  First, Patent Document 1 describes that the power transmission frequency can be arbitrarily selected. However, the power transmission means is a transformer. Although the primary and secondary coils are inseparable, it is clear that a transformer designed for a 50 Hz to 60 Hz commercial power supply cannot be used at any frequency, for example, 5 Hz or 10 kHz. That is, the transformer which is a power transmission means has a lower limit and an upper limit of usable frequencies. However, there is no conventional technique that considers a frequency range that can be used as a power transmission coil.

  Further, in a transformer in which the primary coil and the secondary coil cannot be separated, the coupling coefficient between both the coils is in a tightly coupled state. On the other hand, a transformer capable of separating the primary coil and the secondary coil is in a loosely coupled state in which the coupling coefficient between the two coils is at most about 0.9. Therefore, the coil described as an Example in patent document 1 and patent document 2 equips the coil wound by plane spiral shape with a magnetic material, and ensures the coupling coefficient between both coils. That is, the coils described in Patent Document 1 and Patent Document 2 are both comparative examples, and when an air-core planar spiral coil is used, the performance cannot be improved unless a magnetic material is provided. Can be seen.

  However, the advantage of the planar spiral coil lies in its shape. In particular, the power receiving coil provided on the equipment side has a mounting problem unless it is thin. In particular, in a small portable device incorporating a secondary battery, the coil volume is required to be as small as possible due to space constraints. In order to improve the power transmission performance, for example, as described in Patent Document 1, a plate material made of a magnetic material must be provided on the opposite side of the opposing surface of the coil. However, in this case, there is a problem that the volume of the coil increases and it is difficult to incorporate the coil into the device.

  Both Patent Document 1 and Patent Document 2 compare the comparative example with the example, and describe that power cannot be transmitted efficiently with an air-core planar spiral coil. However, the reason is not specified.

  Therefore, the disclosure data regarding the air-core coil cited as Comparative Example 1 in Patent Document 1 will be examined. First, the inventor of the present application created the same coil as that disclosed in Patent Document 1, and measured the characteristics of the coil. The coil described as a comparative example in Patent Document 1 is merely winding five turns of a thick conducting wire having a wire diameter of 1.5 mm in which 100 insulation-coated copper wires having a diameter of 100 μm are bundled. For this reason, the self-inductance is as small as about 0.8 μH, and the mutual inductance is also reduced due to the coil shape. Therefore, a power factor falls and apparent power and reactive power become large. Further, since the wire diameter is large and the number of turns is small, there is a problem that the effective series resistance of the coil becomes too small at about 17 mΩ at a frequency of 100 kHz described in paragraph No. 0051 of Patent Document 1.

  FIG. 95 is an equivalent circuit diagram when the coil of Comparative Example 1 described in Patent Document 1 is used for the power transmission coil 1 and the power reception coil 2. As shown in FIG. 95, a transformer including a power transmission coil 1 and a power reception coil 2 is formed using two coils. In this case, at a frequency of 100 kHz, the impedance Z of the primary coil viewed from the AC power supply V side when the load resistance RL is 10Ω is a very small value, Z = approximately 0.6Ω. In FIG. 95 of the present application, the internal resistance of the AC power supply V indicated by R3 is usually 0.5Ω to several tens of Ω. Therefore, when the primary side coil is connected to the AC power source V, the AC power source V becomes close to a short-circuited state. For this reason, the internal resistance R3 of the AC power supply V consumes a considerable amount of power, and the power cannot be efficiently transmitted, and the transmittable power value is reduced.

  Originally, the coil described in Patent Document 1 is intended to secure a self-inductance by equipping a magnetic material on the opposite side of the coil facing surface, confine magnetic flux when the coils face each other, and increase the coupling coefficient. Created with. For this reason, it is not optimized as an air-core coil.

  Next, the reason why the coil of Comparative Example 1 disclosed in Patent Document 2 is inferior in performance with an air core will be described. In the coil configured as in Comparative Example 1 disclosed in Patent Document 2, when the frequency increases, the effective series resistance of the coil increases due to the skin effect and eddy current loss. It is known that this characteristic has a more significant effect as the wire diameter of the single conductor is thicker. The inventor of the present application tried to make a trial of a coil that is almost equivalent to the coil described as Comparative Example 1 in Patent Document 2. As a result, it has been found that at 50 kHz, the effective series resistance of the coil becomes 0.266Ω, which is about three times or more the direct current resistance of the coil of about 0.08Ω.

  The power transmission control circuit 3 in FIG. 93 is indicated by an AC power supply V in FIG. 95, and R3 is an internal resistance of the AC power supply V. R1 is an effective series resistance of the power transmission coil 1. R2 is an effective series resistance of the power receiving coil 2. RL is a load resistor connected to the power reception control circuit 4.

  When the coil described as Comparative Example 1 in Patent Document 2 is used for both the primary side and secondary side coils, the effective series resistance R1 is connected in series to the AC power supply V as shown in FIG. And by connecting the effective series resistance R2 in series with the load resistance RL, power loss occurs at least at two locations R1 and R2. The only way to avoid this is to lower the frequency and reduce the effects of the skin effect and eddy current loss. However, when the frequency is lowered, the reactance of the coil decreases. As a result, the impedance Z of the power transmission coil decreases, and excessive apparent power is input to the power transmission coil 1. Then, an excessive current due to the apparent power flows through the power transmission coil 1, and power loss occurs due to the effective series resistance R1 and the internal resistance R3 of the AC power supply. Therefore, in the Example of patent document 2, the magnetic material is equipped in order to ensure the inductance and reactance of a coil, and to reduce apparent power. In order to use a coil with an air core, a coil that can be operated at a high frequency must be realized so as to ensure reactance. That is, a coil having a high frequency and a low effective series resistance R1 may be realized.

  Contrary to patent document 1, although the coil of the comparative example 1 of patent document 2 has high inductance, the effective series resistance of a coil is also high. Therefore, it is not suitable for use with an air core as described above. That is, both the coil described in the comparative example of Patent Document 1 and the coil described in Comparative Example 1 of Patent Document 2 have a low Q in the high frequency region, as will be described later.

  On the other hand, although the coil configuration is different, many inventions for improving the frequency characteristics of the effective series resistance of the coil have been filed. This is intended to suppress the increase in effective series resistance due to the increase in frequency and increase the Q of the coil in a high frequency region where the reactance of the coil increases. However, in the conventional example, only the configuration of the coil is defined, and there is hardly any description about inductance, which is an important characteristic of the coil. Even if the configuration of the coil is defined and the increase in effective series resistance is suppressed, if the inductance decreases, the Q of the coil may decrease in some cases. It cannot be said that a coil with good performance could be realized with the configuration rule in which Q decreases. As will be described later, the Q of the coil varies depending on the frequency. Therefore, as described above, a frequency region where the coil can be used must be found and a coil suitable for power transmission must be selected.

  In Patent Document 1 and Patent Document 2, the method opposite to the above-described method for reducing the effective series resistance is adopted, and the effective series resistance due to the increase in the frequency is obtained by equipping the coil with a magnetic material having a high magnetic permeability. It is presumed that a method of increasing the Q of the coil by increasing the inductance rather than the increasing rate is used.

  In other words, in order to realize a coil with good power transmission performance, it is possible to secure self-inductance and mutual inductance (coupling coefficient) and to prevent the coil heat generation caused by power loss due to effective series resistance. Coil must be selected. Then, it is necessary to define the coil operating conditions by defining the coil characteristics, and it is not sufficient to simply improve the frequency characteristics of the effective series resistance of the coil.

  As described above, it is a conventional theory that an air-core power transmission coil in which a conducting wire is wound on a flat plate in a single layer spiral shape has poor power transmission performance. Therefore, the power transmission performance is improved by using a magnetic material or the like. There is no prior art that considers the relationship between the effective series resistance and the frequency of the above-described power transmission coil, which is one factor affecting the power transmission performance, together with the configuration of the power transmission coil. That is, the conventional technology cannot realize a power transmission coil wound in a spiral suitable for use in a power transmission device. Moreover, the operating condition of the coil for electric power transmission wound by the spiral is not prescribed | regulated. Therefore, a power transmission device with good power transmission performance cannot be realized. The first problem in this field is that an optimal power transmission coil used in the power transmission device described above cannot be realized.

  On the other hand, paragraph number 0021 of Patent Document 3 describes that the magnetic sheet eliminates unnecessary radiation due to the “magnetic field” generated by the coil. And it is described that a metal sheet excludes the unnecessary radiation by the "electric field" which a coil generates.

  As described above, when the mutual induction action is used, energy is transmitted not by electromagnetic waves but by “magnetic flux”. That is, the power transmission coil and the power reception coil that are inductively coupled constitute a transformer. The transformer is equipped with a core, so that the coupling coefficient can be approximately 1, and in this case, the power factor is approximately 1. On the other hand, in the power transmission device in which the power transmission coil and the power reception coil can be separated, the coupling coefficient between the two coils is in a loosely coupled state with a maximum of 0.9. Therefore, the power factor is reduced to about 0.2. When the coupling coefficient is smaller than 1, a leakage magnetic flux is generated. However, as will be described later, the presence of the leakage magnetic flux does not cause a loss of energy. Therefore, Patent Document 3 also confuses power transmission by mutual induction and power transmission by electromagnetic waves.

  The magnetic material sheet, like the transformer core, has the effect of confining magnetic flux and increasing the coupling coefficient. This is also specified in (Action) at the lower right of page 2 of Patent Document 2. As far as the present inventors have verified, it has been confirmed that when a magnetic material plate is mounted on a coil, the inductance of the coil increases and the effective series resistance also increases. A magnetic material plate formed by molding at least magnetic material powder changes the coil characteristics (inductance and effective series resistance) when a metal material comes close to the opposite surface of the coil. That is, another problem in this field is that when the metal plate comes close to the air-core coil, the coil characteristics change whether the coil operates as a transformer or as an antenna.

  Furthermore, paragraph number 0019 of Patent Document 4 describes that a metal plate is disposed between the primary coil and the secondary coil, but this is presumed to be an error on the opposite side of the coil facing surface. Paragraph No. 0020 of Patent Document 4 describes a problem with an air-core coil in which, when a metal body is close to a coil (magnetic field antenna), power transmission performance is affected. As the material of the metal plate used to solve the problem, Paragraph No. 0019 of Patent Literature 4 includes diamagnetic metals such as copper (Cu), zinc (Zn), lead (Pb), and bismuth (Bi). Have been described. However, bismuth of atomic number 57, which is a diamagnetic metal, is described, although bismuth, which is a rare earth element of atomic number 83 and all the isotopes except one are all radioactive elements and is not normally used. (La) and gold (Au), which is a generally known noble metal having atomic number 79, are not described.

  As a result of a further trial by the inventor of the present application, it has been found that it is not the magnetic properties of the metal, but the thickness of the metal plate, except for the ferromagnetic metal, that affects the coil characteristics. Although details will be described later, a high-performance power transmission device that has solved the above-described problems has not been realized yet. However, these problems cannot be solved unless a coil having a good power transmission performance with an air core, which is the first problem, cannot be realized. In that sense, it cannot be said that the solving means described in Patent Literature 1 and Patent Literature 2 realize a practical power transmission device.

  Further, as described in Paragraph No. 0005 of Patent Document 5, when an alternating current is flowing through the power transmission coil, if a metal body approaches the power transmission coil, the eddy current described in Paragraph No. 0019 of Patent Document 4 The metal body generates heat. This is the same principle as an electromagnetic cooker.

  In Patent Document 5, when the power transmission unit is in a standby state, power is intermittently supplied to the power transmission coil. When a regular power receiving unit is attached to the power transmitting unit, the power transmitting unit continuously supplies power to the power transmitting coil by a signal from the power receiving unit. However, in patent document 5, the core is equipped in the power transmission coil and the receiving coil. As will be described later, the coupling coefficient decreases in a power transmission coil equipped with a core. Therefore, a power factor will also fall. There is also a patent document that employs the same technique as Patent Document 5 in a power transmission device using a planar air-core coil. There is also a patent document including means for detecting a metal body by a single power transmission unit.

  As described above, another problem in this field is that the metal body generates heat due to overcurrent loss or hysteresis loss when the metal body is close to the power transmission coil. Furthermore, the power transmission unit must discriminate between when the metal body is close and when the regular power receiving coil to which the load is connected faces, which is another problem in this field. .

  However, the fundamental problem is that, as in Patent Documents 1 to 4, a coil having good power transmission performance cannot be realized simply by defining a specific configuration of the coil. In patent document 1 and patent document 2, the effect is claimed by showing an example in which a specific configuration of the coil is defined. However, an equivalent effect is not always obtained until a configuration factor other than the specific configuration of the coil changes. In other words, not only the specific configuration of the coil but also the characteristics of coils with various configurations are defined, and a coil and power transmission device with good power transmission performance are realized unless a coil with good power transmission performance is selected. I can't do it.

  For example, in the non-contact transformer described in Patent Document 2, it is obvious that the embodiment as in Patent Document 5 cannot be applied. That is, a power countermeasure such as Patent Document 5 can only be realized if a power transmission coil with good power transmission performance, a power transmission device with good power transmission performance, and a power transmission coil whose characteristics do not change due to the proximity of a metal body can be realized. There is a meaning. In other words, first, it is necessary to solve the first problem described above.

The present invention realizes a coil of a power transmission device with good power transmission performance by defining the characteristics and configuration of the coil of the power transmission device, and a power transmission device and power transmission device with good power transmission performance using this coil It is providing a power transmission device and a power reception device.

The coil of the power transmission device according to the present invention is configured such that the power transmission unit and the power reception unit are separable, and transmits power from the power transmission unit to the power reception unit with the power transmission coil of the power transmission unit and the power reception coil of the power reception unit facing each other. A coil of a power transmission device used in a power transmission device, wherein both the power transmission coil and the power reception coil are the same two air-core coils formed in an air-core shape by winding a conducting wire. The two coils are inductively coupled to each other to form a transformer, and one of the two identical air-core coils is used as one coil, and the other coil. The frequency characteristic of the effective series resistance of the coil is measured, and in order to detect a change in the effective series resistance of one coil, another coil identical to the one coil constituting the transformer is opposed to the one coil. The other coil, one coil alone If the effective series resistance is Rw (Ω), and the other coil with both ends short-circuited is opposed to one coil to form a transformer, the effective series resistance of one coil is Rs (Ω). Using a predetermined wire having a predetermined wire diameter, a predetermined number of windings and a predetermined number of windings, so that the maximum frequency f1 satisfying the relationship Rs> Rw is at least 100 kHz or more. It has a diameter and an inner diameter.

The frequency characteristic of the effective series resistance Rw of one coil unit is measured using two coils that can be inductively coupled between the same two air-core coils, and the other end short-circuited to one coil. A coil configured to measure the effective series resistance Rs frequency characteristic of one coil and to satisfy the relationship of Rs> Rw is 100 kHz or more. By selecting, a coil with good power transmission performance can be realized .

In a preferred embodiment, the conducting wire forming the coil is a single conducting wire provided with insulating clothing. When the maximum diameter of the single conducting wire is d2 (mm) and one coil outer diameter is D (mm), The coil outer diameter D is at least 25 times greater than the maximum diameter d2, the number of turns of the conducting wire is at least a predetermined number of turns, and the self-inductance of one coil is at least 2 μH .

Thus, by providing insulating coating to the conducting wire, oxidation of the conducting wire can be prevented and short circuit between adjacent conducting wires can be prevented. In addition, by defining the coil diameter D and the number of turns, it is possible to secure the necessary self-inductance and to secure the necessary coupling coefficient at a predetermined facing distance between the two coils .

In another preferred example, at least one of the opposing coils includes a plurality of conductors, and each conductor has an insulation coating on a collection of a plurality of bare single conductors having a maximum diameter of 0.3 mm or less. The at least one coil is formed by closely winding a single-layered or multi-layered spiral conductor with an assembly of a plurality of bare single conductors. When the maximum body diameter is d2 (mm) and at least one coil outer diameter is D (mm), at least one coil outer diameter D is at least 25 times the maximum diameter d2 and the number of turns of the conductor is The number of turns is not less than a predetermined number, and the self-inductance of at least one coil is not less than 2 μH .

In this example, while having the same effect as the above-mentioned invention, the eddy current loss due to the magnetic flux penetrating the conductor increases in proportion to the volume of the conductor. An increase in effective series resistance Rw (Ω) due to eddy current loss and skin effect can be suppressed by using a conductive wire forming at least one coil and increasing the surface area of the conductor .

In still another preferred embodiment, the conductor forming at least one of the opposing coils is provided with an insulator layer inside the conductor, and the cross-sectional area of the insulator layer is 11% of the cross-sectional area of the entire conductor. The at least one coil is formed by closely winding a conductor wire provided with an insulator layer in a single layer or a multilayer spiral, and the maximum diameter of the conductor wire provided with the insulator layer is d3 (mm). When at least one of the coil outer diameters is D (mm), at least one of the coil outer diameters D is at least 25 times the maximum diameter d3 and the number of turns of the conducting wire is at least a predetermined number of turns, The coil has a self-inductance of at least 2 μH .

In this example, the same effect as the above invention is achieved, and the eddy current loss due to the magnetic flux penetrating the conductor increases in proportion to the volume of the conductor. Therefore, an insulator is provided inside the conductor constituting the coil. By reducing the volume of the conductor existing in the magnetic flux path penetrating the inside and increasing the surface area of the conductor, it is possible to suppress an increase in the effective series resistance Rw (Ω) due to the eddy current loss and the skin effect. The insulating material provides an insulating layer inside the conducting wire, and makes the conducting wire flexible, thereby facilitating bending of the conducting wire .

In still another preferred example, the conducting wire is composed of an assembly of a plurality of single conducting wires each coated with an insulating coating, and when the maximum diameter of the conductor in the single conducting wire is d4, d4 is 0. The thickness t (mm) of the insulating coating is selected to be (d4) / 30 or more.

In this example, while having the same effect as the above-mentioned invention, the eddy current loss due to the magnetic flux penetrating the conductor increases in proportion to the volume of the conductor. An increase in effective series resistance Rw (Ω) due to eddy current loss and skin effect can be suppressed by using a conductive wire forming at least one coil and increasing the surface area of the conductor .

The coil having this configuration is composed of an assembly of a plurality of single conductor wires each provided with an insulation coating, and a gap is provided by insulation coating between each single conductor wire adjacent to each single conductor wire. In addition, the density of magnetic flux generated by the current flowing through each single conductor becomes 1 / plurality, and the volume of each single conductor is small, so that eddy current loss can be reduced. Needless to say, the influence of the skin effect can be reduced .

Furthermore, among the plurality of single conductors constituting the conductor of the previous invention, at least one single conductor is used as a coupling line, and the coupling line is electrically insulated from the power transmission conductor of the coil of the power transmission device. Electromagnetically, it is configured to be in a state equivalent to the power transmission conductor of the coil of the power transmission device and the honey-couple transformer .

In this example, if at least one of the plurality of single conductors forming the power transmission coil is a coupling line, the coupling line is electrically insulated from the power transmission conductor, but electromagnetically Since they are coupled, the coupled line can be used for signal transmission between the power transmission unit and the power reception unit .

Specifically, at least one of the opposing coils is formed by winding a conducting wire in a flat single layer spiral shape, and is adjacent when the maximum diameter d of the conducting wire is 0.4 mm or more. A gap of 0.2 mm or more is provided between the conductors of the conductor, and a gap of d / 2 (mm) or more is provided between the conductors of adjacent conductors when the maximum diameter d of the conductor is less than 0.4 mm .

When no air gap is provided, the magnetic flux generated by each conducting wire penetrates all adjacent conducting wires, and when the frequency rises due to the eddy current loss caused by the magnetic flux penetrating the neighboring conducting wires, the effective series resistance Rw (Ω) increases, but by providing the air gap, the eddy current loss caused by the magnetic flux penetrating through the adjacent conductor can be reduced. Therefore, when the frequency increases, the effective series resistance Rw (Ω ) Increase .

Further, in the case of a coil having the same outer diameter, the total extension of the winding is shortened, so that the effective series resistance can be kept low. However, since the eddy current loss due to the magnetic flux penetrating the conductor increases in proportion to the volume of the conductor, if the maximum diameter of the single conductor is not 0.2 mm or more, even if an air gap is provided between the conductors, the frequency increases. The rate of increase in effective series resistance cannot be improved much .

Preferably, among the opposing coils, at least one of the coils is formed by winding a conducting wire in a flat single layer spiral shape, and is provided between conductors of adjacent conducting wires in the outermost peripheral portion of at least one of the coils. When the width of the gap is t1, and the width of the gap provided between the conductors of the adjacent conductors in the innermost circumference of at least one coil is t2, t2>t1> 0, and the inner circumference from the outermost circumference The width of the gap increases as it goes to the periphery, and the width t2 of the gap provided between the conductors of the adjacent conductors in the innermost periphery is at least 0.2 mm .

Since the magnetic flux density generated by the coil is low near the outer periphery and high at the inner periphery, the magnetic flux density is kept as constant as possible on the coil facing surface by honey-rolling the outer periphery and loosely winding the inner periphery. Thus, it is possible to prevent a decrease in transmittable power when the relative position of the opposing coils varies. Since the inner periphery has a high magnetic flux density, eddy current loss can be prevented by providing a gap .

The coil having the above-described configuration has a low effective series resistance Rw (Ω) in a wide frequency range and a wide frequency range satisfying Rs> Rw, and thus has good power transmission characteristics .

Further, at least one of the coils has an insulating layer at the outer peripheral portion of the conducting wire, and the conductors of the adjacent conducting wires at the outermost peripheral portion of at least one coil are in close contact with each other through the insulating layer .

Since one turn provided in the outer peripheral portion has a longer wire length than one turn provided in the inner peripheral portion, the effect of increasing the inductance of the coil is great. Therefore, the inductance of the coil can be ensured. In addition, as described above, one turn provided in the inner peripheral part causes an increase in eddy current loss in the inner peripheral part having a high magnetic flux density, rather than contributing to an increase in inductance. Provided. The effect of the void is as described above .

Preferably, at least one of the power transmission coil and the power reception coil is on the insulating plate or not.
It is formed on at least one of the edge members .

By disposing the coil on the insulating plate or on one side of the insulating member, the insulating layer of the conductive wire constituting the coil can be protected. If an insulating material is provided between the opposing coils, the withstand voltage between the two coils can be increased. Even when both coils are used in a fixed manner, the withstand voltage between the two coils can be increased by providing an insulating member or an insulating member .

Preferably, the coil of the power transmission device is similar to the air core coil of the previous invention, at least one magnetic material plate having a size equal to or larger than that of the air core coil, and a size equal to or larger than that of the air core coil. And at least one of the at least one insulating plate .

In this example, the inductance of the coil can be increased by equipping a plane spiral air core coil with a magnetic material plate. In addition, radio wave interference due to unnecessary radiation can be reduced. By making the size of the magnetic material plate larger than the size of the coil, it is possible to further increase the inductance of the coil and reduce radio wave interference due to unnecessary radiation .

When a magnetic material plate in which magnetic material powder is fixed with a binder is used, when the metal body is close to the opposite side of the coil facing surface of the magnetic material plate, the inductance and effective series resistance, which are coil characteristics, change. By providing a metal plate made of a metal or alloy having a paramagnetic or diamagnetic magnetic property, it is possible to prevent changes in the coil characteristics even when a metal body approaches the coil. Particularly, when the case is equipped with a coil close to a secondary battery made of metal, it is possible to prevent fluctuations in the characteristics of the coil due to the distance between the case and the coil being different depending on the type of the secondary battery. In the case where a power factor improving capacitor is provided in either one of the power transmission coil and the power receiving coil, it is possible to prevent fluctuations in reactance as viewed from the AC power source and maintain a high power factor. By making the size of the metal plate equal to the size of the magnetic material plate, it is possible to prevent changes in the coil characteristics .

Preferably, the coil is equipped with a metal plate having a dimension equal to or larger than that of the air-core coil on the surface opposite to the air-core coil mounting surface of the magnetic material plate and the insulating material plate, and the two coils. In the case of including the above magnetic material plate, the metal plate is a metal plate having a thickness M (mm) of 0.01 mm or more and made of a metal or alloy having an arbitrary magnetic property, and the coil has one sheet. When a magnetic material plate is included, the metal plate is a metal plate having a thickness M (mm) of 0.1 mm or more and made of a metal or alloy having diamagnetic or paramagnetic magnetic properties .

By providing two magnetic material plates, the inductance of the coil can be increased and the Q of the coil can be increased. Further, by providing a metal plate, it is possible to prevent a change in inductance of the coil even if a metal body is close to the coil .

Further, preferably, the coil is equipped with at least one insulating plate having a dimension equal to or larger than that of the air-core coil and a metal plate having a dimension equal to or larger than that of the air-core coil. If the minimum outer diameter of the air-core coil is D2 (mm), the predetermined distance G (mm) of D2 / 10 or more is provided between the air-core coil and the metal plate by one or more insulating plates. The provided metal plate is a metal plate having a thickness M (mm) of 0.1 mm or more and made of a metal or alloy having diamagnetic or paramagnetic magnetic properties.

By providing the insulating plate, it is possible to suppress an increase in the effective series resistance of the coil when the frequency becomes high. Further, the Q of the coil when the frequency becomes high can be increased.

Preferably, a hole through which a conducting wire can be penetrated is provided in the central portion of the magnetic material plate and the insulating plate, the conducting wire end of the inner peripheral portion of the coil is connected to the metal plate, and the metal plate is used as a terminal of the coil .

By adopting such a configuration, it is not necessary to draw out a conducting wire from the inner periphery of the coil, so that the thickness of the coil can be reduced .

Preferably, when the coil includes a magnetic material plate, the maximum distance from the center of the winding surface of the air-core coil constituting one coil to the end of the winding surface is Da, and the other facing the one air-core coil When the minimum distance from the center of the winding surface of the conducting wire constituting the coil to the end of the winding surface is Db, and Db> Da, the center of the winding surface of the conducting wire constituting one coil is magnetic from the center. The minimum distance to the end of the material plate is set to at least Db + (Db−Da) × 2 .

By determining the coil shape under such conditions, it is possible to ensure characteristics as a transformer composed of coils .

More preferably, the coils of the same two power transmission devices according to any one of the preceding inventions, wherein the same two coils are inductively coupled when the conductive wire winding surfaces of both coils are opposed to each other. The frequency characteristics of the effective series resistance of one of the two coils are measured, and the effective frequency of one coil is measured. In order to detect a change in series resistance, another coil identical to the one coil constituting the transformer is opposed to one coil, the other coil, and the effective series resistance when one coil alone is Rw ( Ω), when the other coil whose both ends are short-circuited is opposed to the one coil to constitute a transformer, and when the effective series resistance of one coil is Rs (Ω), , Rs> Rw, which satisfies the relationship The air core coil is equipped with only a predetermined magnetic material plate, or at least two of the predetermined magnetic material plate, the insulating plate, and the metal plate so that the maximum frequency f1 is at least 100 kHz or more. Equipped with equipment .

In this example, it is possible to realize a coil having the same effect as the previous invention that defines the configuration and characteristics of the air-core coil and good power transmission performance .

Furthermore, another aspect of the present invention is a power transmission device in which a power transmission unit and a power reception unit are separable, and any one of the coils of the power transmission device of the previous invention is provided on either the power transmission unit or the power reception unit. Equipped with a coil .

By equipping the power transmission device with the coil of the power transmission device of the previous invention, a power transmission device with good power transmission performance can be realized .

Preferably, the power transmission unit includes an AC power source including power conversion means for converting DC power into AC power, and the power transmission coil is driven by the AC power source, and the coil of the power transmission device according to any of the preceding inventions is The frequency characteristic of the effective series resistance of one coil is measured, and the coil is configured to be inductively coupled to one coil, and in order to detect a change in the effective series resistance of one coil, When the coil facing the coil is the other coil and one coil is used as the power transmission coil, the power reception coil is the other coil. When the other coil is used as the power transmission coil, the power reception coil is When a transformer is configured with one coil, the effective series resistance of one coil alone being Rw (Ω) and the other coil short-circuited at both ends facing one coil If the effective series resistance of one coil is Rs (Ω), the one coil is Rs> Rw, the highest frequency satisfying the relationship of f1 (Hz), and the output frequency of the AC power supply is fa (Hz), The output frequency fa (fa = fd) of the AC power supply, which is the frequency fd that drives the power transmission coil, so that one coil can transmit power in a frequency region that satisfies the relationship Rs> Rw. Is set to a frequency less than f1, and power is transmitted from the power transmission unit to the power reception unit in a frequency region less than f1.

In this example, an electric power transmission device with good electric power transmission performance can be realized by transmitting electric power at the maximum frequency f1 or less satisfying the relationship of Rs> Rw, which is determined by the combination of the power transmitting coil and the power receiving coil .

More preferably, when the other coil having both ends opened is opposed to one coil, the effective series resistance of one coil is Rn (Ω), and one coil has a relationship of Rs> Rn ≧ Rw. When the highest frequency to satisfy is f2 (Hz), the power transmission coil is set so that one coil can transmit power in a frequency range that satisfies the relationship Rs> Rn ≧ Rw. Fa, which is the output frequency of the driving AC power supply, is set to a frequency less than f2, and power is transmitted at a frequency less than f2 .

In this example, one of the coils, which is determined by the combination of the power transmission coil and the power reception coil, transmits power at the maximum frequency f2 (Hz) or less that satisfies the relationship Rs> Rn ≧ Rw. A good power transmission device can be realized .

Preferably, the thermal resistance of one coil is θi (° C / W), the allowable operating temperature of one coil is Tw (° C), the ambient temperature of the place where one coil is installed is Ta (° C), and power is transmitted. When the alternating current flowing through one of the coils is Ia (A), when fa (Hz), Rw ≦ (Tw−Ta) / (Ia ² Xθi), power is transmitted from the power transmitting unit to the power receiving unit so that one coil satisfies the relationship.

In this way, by defining the thermal conditions based on the effective series resistance Rw (Ω) and the alternating current Ia (A), a turn that determines the upper limit of the alternating current Ia of at least one coil or the effective series resistance Rw of one coil. The upper limit of the number and the frequency region where the effective series resistance Rw (Ω) is small can be defined .

Still another aspect of the present invention is a power transmission unit of the power transmission device of the previous invention, wherein power is transmitted from the power transmission unit to the power reception unit .

In the power transmission device of the present invention, the power transmission unit and the power reception unit are separable, and the power transmission unit is adapted not only to the specific power reception unit but also to the power transmission unit by using the power transmission device having the above configuration. Power can be transmitted to the power receiving unit.

Still another aspect of the present invention is a power reception unit of the power transmission device according to the previous invention, wherein the power reception unit receives power from the power transmission unit .

By making the power reception unit a power transmission device that can be separated from the power transmission unit as described above, it is possible to receive power from the power transmission unit that matches the power reception unit.

According to the present invention, a coil of a power transmission device with good power transmission can be realized by selecting a coil having a maximum frequency f1 of 100 kHz or more satisfying Rs> Rw with the same two coils. By providing the magnetic material plate, the inductance of the coil can be increased. Furthermore, radio wave interference due to unnecessary radiation can be reduced. By making the size of the magnetic material plate larger than the size of the coil, it is possible to further increase the inductance of the coil and reduce radio wave interference due to unnecessary radiation. By using this coil and setting the frequency for driving the coil to a frequency lower than f1 (Hz), it is possible to realize a power transmission device capable of improving the power transmission performance as compared with the prior art.

(Description of power transmission equipment)
FIG. 1 is a block diagram of a power transmission device 100 according to an embodiment of the present invention. In FIG. 1, a power transmission device 100 includes a power transmission unit 30 that operates as a power transmission device and a power reception unit 40 that operates as a power reception device. The power transmission unit 30 includes a DC power source Vd, a power transmission control circuit 30a, and the power transmission coil 1. Power reception device 40 includes power reception coil 2, power reception control circuit 40a, and load RL. The power transmission coil 1 and the power reception coil 2 are disposed to face each other.

  The power transmission unit 30 and the power reception unit 40 are configured to be separable. When the power transmission unit 30 and the power reception unit 40 are coupled, the power transmission coil 1 and the power reception coil 2 are arranged to face each other, so that the power transmission coil 1 and the power reception coil 2 function as a transformer.

  The power transmission control circuit 30a of the power transmission unit 30 includes at least power conversion means 30b such as an inverter circuit that converts the DC power source Vd into AC power. The power transmission coil 1 is driven by AC power, preferably by an AC sine wave or a staircase wave close to an AC sine wave, at a frequency lower than a predetermined frequency described later, and the power is transmitted to the power receiving unit 40. The power reception unit 40 receives the power transmitted from the power transmission coil 1 by the power reception coil 2. The power reception control circuit 40a supplies the received power to the load RL. The power reception control circuit 40a includes a rectifier circuit that converts AC power into DC power. When the load RL operates with AC power such as an incandescent bulb or LED, the power reception control circuit 40a can be omitted and the load RL can be directly connected to the power receiving coil 2.

  In addition, alternating current means what can send an electric current through the coil connected to the output terminal to the forward direction and a reverse direction. Hereinafter, the power conversion means for converting the DC power source Vd into AC power is referred to as AC power source 30b. The output frequency of the AC power supply 30b is expressed as fa (Hz). Further, a frequency at which the power transmission coil 1 is driven by the AC power supply 30b is expressed as fd (Hz). In this case, naturally, fa = fd (Hz).

(Description of operation of power transmission device)
The opposing power transmission coil 1 and power reception coil 2 shown in FIG. 1 are air-core coils, and the effective series resistance of one of the coils alone is Rw (Ω). Let Rs (Ω) be the effective series resistance of one coil when the other coil facing one coil is short-circuited. In the power transmission device 100 according to the embodiment of the present invention, the output frequency of the AC power source included in the power transmission unit 30 is set when f1 (Hz) is set as the highest frequency at which one coil satisfies Rs> Rw. Fa (Hz) is set to a frequency region less than f1 (Hz), and power is transmitted to the power receiving unit 40. When fa (Hz) is set as described above, one coil or the other coil, which is a power transmission coil, is driven at a frequency fd = fa (Hz).

  Further, the effective series resistance of one coil when the other coil facing the one coil is opened is defined as Rn (Ω). A maximum frequency satisfying Rs> Rn ≧ Rw is defined as f2 (Hz). The power transmission device 100 sets the output frequency fa (Hz) of the AC power supply 30b included in the power transmission control circuit 30a to a frequency region less than f2 (Hz), and transmits power to the power receiving unit 40. When fa (Hz) is set as described above, one coil or the other coil, which is a power transmission coil, is driven at a frequency fd = fa (Hz).

(Description of specific example of coil)
Hereinafter, the specific structure of the coil used for the power transmission device in the embodiment of the present invention will be described. The coil of each embodiment described below is used as the power transmission coil 1 or the power reception coil 2 of the power transmission device 100.

  2A and 2B are diagrams illustrating an example of an air-core coil. FIG. 2A is a plan view, and FIG. 2B is an enlarged view taken along line 1B-1B in FIG. .

  As shown in FIG. 2A, the coil 1a according to one embodiment of the present invention is configured by winding a conductive wire 11 in a flat and air-core single layer spiral shape so that adjacent conductive wires 11 are in close contact with each other. The As shown in FIG. 2 (B), the conductor 11 has a circular cross section, and the maximum diameter d1 (mm) is not particularly limited. Preferably, for example, a single conductor 12 having a wire diameter of 0.2 mm or more is covered with an insulating coating. 13 is applied. The insulation coating 13 may be either a strong coating that is thin like a formal wire or a thick coating such as a vinyl wire.

  Furthermore, the self-inductance of the coil 1a is at least 2 μH or more. Furthermore, let Rw (Ω) be the effective series resistance of the coil 1a alone shown in FIG. Let Rs (Ω) be the effective series resistance of the coil 1a when the other coil facing the coil 1a is short-circuited. At this time, the highest frequency satisfying Rs> Rw is defined as f1 (Hz). The coil 1a, which is a power transmission coil, or the other coil is driven by the AC power supply 30b at fd (Hz), which is a frequency less than f1 (Hz). Preferably, when the coil 1a is used for both one coil and the other coil, Rs> Rw is satisfied at 100 kHz.

  The reason why the coil outer diameter D (mm) is selected to be 25 times or more of the maximum diameter d1 (mm) of the single conductor 12 is to ensure a necessary coupling coefficient. The reason why the number of turns of the conducting wire 11 is selected to be 8 or more is to obtain a self-inductance of 2 μH or more. Although not only in this embodiment but also in other embodiments, it is desirable to provide the coil with a predetermined inner diameter on which no conducting wire is wound. The inner diameter may be any dimension as long as the outer diameter D is satisfied.

  Furthermore, the effective series resistance of the coil 1d when the other opposing coil is opened is Rn (Ω). At this time, the highest frequency satisfying Rs> Rn ≧ Rw is defined as f2 (Hz). The coil 1a, which is a power transmission coil, or the other coil is driven at a frequency fd (Hz) less than f2 (Hz) by the AC power supply 30b.

Furthermore, when the thermal resistance of the coil 1a is θi (° C / W), the allowable operating temperature of the coil 1a is Tw (° C), the ambient temperature of the place where the coil 1a is installed is Ta (° C), and power is transmitted When the alternating current flowing in the coil 1a is Ia (A), the relationship Rw ≦ (Tw−Ta) / (Ia ² × θi) is satisfied when the coil 1a is transmitting power. .

  The coil 1a configured as described above can be used as the power transmission coil 1 or the power reception coil 2 of the power transmission device illustrated in FIG. 1 in which the power transmission unit 30 and the power reception unit 40 can be separated.

  In addition, in embodiment of FIG. 2 (A), conducting wire is wound circularly. However, the shape is not limited to a circle, but an oval shape shown in FIG. 3A, an oval shape shown in FIG. 3B, a square shape shown in FIG. 3C, a rectangle shape shown in FIG. 3D, and FIG. It can be wound in an arbitrary shape such as a polygon such as a hexagon shown in FIG. The same applies to other embodiments described later. However, when the shape of the coil is other than a circle, the coil outer diameter D defines the minimum outer dimension D ′ of the coil as shown in FIGS. 3 (A) to 3 (E).

Next, the relationship described above, Rs> Rw, Rs> Rn ≧ Rw, Rw ≦ (Tw−Ta) / (Ia ² × θi) will be described. In addition, since this description has the same effect also in embodiment of the other coil mentioned later, description is abbreviate | omitted in embodiment described below.

(Explanation of transformer made up of coils)
4 shows an equivalent circuit of the transformer, FIG. 5 shows an equivalent circuit of the single coil, and FIG. 6 shows an equivalent circuit of the single transformer configured as shown in FIG. 93 described in the conventional example. FIG. FIG. 7 is a diagram illustrating an equivalent circuit of the transformer when the secondary coil is short-circuited, and FIG. 8 illustrates an equivalent circuit of the transformer when the load resistor RL is connected to the secondary coil. FIG.

When the power transmission coil 1 and the power reception coil 2 are arranged to face each other, they act as a transformer. Here, in order to refer to circuit theory, the power transmission coil is referred to as a primary coil, and the power reception coil is referred to as a secondary coil. In order to obtain the theoretical relationship between Rw, Rn, and Rs, the impedance Z1 on the primary side of the transformer is obtained in advance. In FIG. 4, L1 (H) is the inductance of the primary side coil, L2 (H) is the inductance of the secondary side coil, M (H) is the mutual inductance between the primary side coil and the secondary side coil, and V1 (V ) Is the voltage across the primary coil, V2 (V) is the voltage across the secondary coil (load resistance RL), I1 (A) is the current flowing through the primary coil, and I2 (A) is the secondary coil. , RL represents a load resistance (pure resistance), and Z1 (Ω) represents a primary side input impedance (complex impedance). In FIG. 4, the following circuit equation is established, and the pure resistance component (effective series resistance) and reactance component (inductance) of Z1 can be obtained by solving the following simultaneous equations. The circuit equation of FIG. 4 is described below. Note that j ² = −1, ω is an angular frequency, and ω = 2πf (f is a frequency, Hz).

V1 = jωL1 · I1 + jωM · I2 (1)
V2 = jωM · I1 + jωL2 · I2 (2)
V2 = −RL · I2 (3)
Since it is desired to obtain Z1 = V1 / I1, V2 and I2 can be eliminated from the above three simultaneous equations. Substituting equation (3) of the above simultaneous equations into equation (2) and eliminating V2,
0 = jωM · I1 + (jωL2 + RL) I2
When the above equation is solved with respect to I2 and substituted into the above equation (1), and I2 is eliminated,
V1 = (jωL1 + ω ² M ² / (jωL2 + RL)) I1
Since Z1 = V1 / I1, from the above equation, Z1 is
Z1 = jωL1 + ω ² M ² / (jωL2 + RL)
It becomes. Since an actual transformer has an effective series resistance R1 in the primary coil and an effective series resistance R2 in the secondary coil, considering the circuit of FIG. 6 and assuming RL = R2,
Z1 = R1 + jωL1 + ω ² M ² / (jωL2 + R2)
It becomes. In the above equation, ω ² M ² / (jωL2 + R2),
Multiplying (−jωL2 + R2) / (− jωL2 + R2) = 1,
Z1 = R1 + jωL1 + ω ² M ² (−jωL2 + R2) / (ω ² L2 ² + R2 ² )
Then, when the real and imaginary terms are arranged,
Z1 = R1 + R2 · ω ² M ² / (ω ² L2 ² + R2 ² ) + jω (L1−L2 · ω ² M ² / (ω ² L2 ² + R2 ² ))
Assuming that A ² = ω ² M2 ² / (ω ² L2 ² + R2 ² ), Z1 is
Z1 = (R1 + A ² R2) + jω (L1−A ² L2) (4)
It becomes. Since ω ² > 0, M ² ≧ 0, L2 ² > 0, and R2 ² > 0, obviously, A ² ≧ 0. That is, in FIG. 6, the input impedance Z1 of the primary coil is
Z1 = R1 + jωL1 (5)
As can be seen from the comparison between the equations (5) and (4), as shown in FIG. 7, when the secondary coil of the transformer is short-circuited, the effective series resistance R1 of the primary coil is It can be seen that the inductance L1 increases and the inductance L1 decreases. These are known circuit theories.

  The above formulas (4) and (5) are basic formulas cited to explain the relationship of Rs> Rw and Rs> Rn ≧ Rw.

  Next, a specific example of the coil 1a shown in FIG. There are some overlaps, but the definition of the symbol is clear. Rw is the effective series resistance of the coil 1a alone (R1 in FIG. 5), and Rn is the effective series resistance of the coil 1a when another coil is opposed to the coil 1a and the opposed coil is opened (in FIG. 6). R1) and Rs are the effective series resistance of the coil 1a when the other coil is opposed to the coil 1a and the opposed coil is short-circuited (R1 in FIG. 7), and kr is approximately obtained from Rw and Rs. The coupling coefficient between the two coils.

  Further, when the inductance of the coil 1a alone is Lw, another coil is opposed to the coil 1a, and the inductance of the coil 1a when the opposed coil is short-circuited is Ls, it is approximately obtained from Lw and Ls. The coupling coefficient is expressed as ki. An approximate method for obtaining kr and ki will be described later.

  When L1 indicates the coil itself, L1 is a symbol, and when L1 is a numerical value of inductance, a unit is added as L1 (H). The same applies to resistors such as R1 and Rw. However, when Rs> Rw, etc. are described with equal signs or inequality signs, when Rw etc. are described before or after when Rw etc. is described in the formula or when there is a description indicating that it is used for calculation , “Rw is 2Ω”, etc. When the unit and the unit are described immediately after Rw, etc., when it is clear that it is a numerical value in the explanation of the characteristic diagram, etc., the unit addition is omitted. ing.

  In the following description, the primary side and the secondary side of the transformer with opposed coils are distinguished, but the transformer can invert the primary side and the secondary side, so that R1 in FIG. , L1 can be considered as R2 and L2 on the secondary side, and the same result can be obtained. That is, the power transmission coil in the embodiment of the present invention may be provided on at least one of the primary side and the secondary side. For example, the same configuration as the coil 1a can be used on the secondary side (device side), and a solenoid-like coil or a honeycomb-shaped multi-layer coil described later can be used on the primary side (power transmission side). Let Rw be the effective series resistance of the coil 1a alone. Let Rs (Ω) be the effective series resistance of the coil 1a when a solenoid-like or honeycomb-like multi-layer wound coil is short-circuited to the coil 1a. Even in this case, the solenoid-shaped or honeycomb-shaped multi-layer wound coil as the power transmission coil has an AC power supply 30b at a frequency less than the maximum frequency f1 (Hz) at which the coil 1a satisfies Rs> Rw, fd (Hz). Driven by.

  Hereinafter, a specific configuration example of the coil 1a will be described.

(Description of specific configuration example 1A of coil 1a)
FIG. 9 shows effective power transmission when a 10 Ω load resistance is connected to Rw, Rn, Rs of coil 1A and a coil 1A in which a formal wire having a copper wire diameter of 1 mm is closely wound for 25 turns (T) with an outer diameter of 70 mm. It is a figure showing the relationship between efficiency (eta) and a frequency.

  The inventor of the present application refers to a coil described in Patent Document 2 (hereinafter referred to as a conventional example) as the coil 1a shown in FIG. A formal wire was used, and the coil 1A was formed by winding so that adjacent conducting wires were in close contact with each other. As a result, it has been found that when the coil 1A is used for both the power transmission coil and the power reception coil, only predetermined power transmission performance can be achieved.

  Therefore, the inventor of the present application has found coils 1B to 1G shown in FIGS. 10 to 17 that have improved transmission performance as compared with the coil 1A. Each of the coils 1B to 1G is configured by using a formal wire in the form of a flat single-layer spiral with an air core like the coil 1a in FIG.

(Description of specific configuration example 1B of coil 1a)
FIG. 10 is a characteristic diagram for explaining the coil 1B.

  The coil 1B is obtained by closely winding a formal wire having a copper wire diameter of 0.6 mm with an outer diameter of 70 mm for 40 turns. FIG. 10 shows the relationship between Rw, Rn, Rs, kr, ki and the frequency of the coil 1B.

(Description of Specific Configuration Example 1C of Coil 1a)
FIG. 11 is a characteristic diagram for explaining the coil 1 </ b> C.

  The coil 1C is obtained by closely winding a formal wire having a copper wire diameter of 0.3 mm with a diameter of 70 mm for 70 turns. FIG. 11 shows the relationship between Rw, Rn, Rs of the coil 1C, the phase angle θ described later, and the frequency.

(Description of Specific Configuration Example 1D of Coil 1a)
FIG. 12 is a characteristic diagram for explaining the coil 1D.

  The coil 1D is obtained by closely winding a formal wire having a copper wire diameter of 0.3 mm for 31 turns with a diameter of 30 mm. FIG. 12 shows the relationship between Rw, Rn, Rs of the coil 1D and the frequency.

(Description of specific configuration example 1E of coil 1a)
FIG. 13 is a characteristic diagram for explaining the coil 1E.

  The coil 1E is formed by sparsely winding a formal wire having a copper wire diameter of 1 mm with an outer diameter of 70 mm and a gap of about 1 mm for 14 turns. The relationship between Rw, Rn, Rs, kr and the frequency of the coil 1E is shown in FIG.

(Description of Specific Configuration Example 1F of Coil 1a)
FIG. 14 is a characteristic diagram for explaining the coil 1F.

  The coil 1F is obtained by closely winding an electric wire (Litz wire) bundled with 75 formal wires having a copper wire diameter of 0.05 mm to an outer diameter of 70 mm for 30 turns. The relationship between Rw, Rn, Rs, kr, ki and frequency of the coil 1F is shown in FIG.

(Description of Specific Configuration Example 1G of Coil 1a)
FIG. 15 is a characteristic diagram for explaining the coil 1G.

  The coil 1G is obtained by closely winding an electric wire (Litz wire) bundled with 75 formal wires having a copper wire diameter of 0.05 mm to an outer diameter of 50 mm for 20 turns. FIG. 15 shows the relationship between Rw, Rn, Rs, kr, ki and the frequency of the coil 1G.

(Examination of each coil)
10 to 15 show the maximum frequency f1 (Hz) satisfying Rs> Rw and the maximum frequency satisfying Rs> Rn ≧ Rw for all of the coils 1B to 1G. f2 (Hz) is shown in common. However, the maximum frequencies f1 (Hz) and f2 (Hz) differ depending on each of the coils 1B to 1G.

  Moreover, the characteristic diagrams shown in FIGS. 10 to 15 are all measured by measuring the distance between the opposing coils at zero. Even if the facing distance between the coils is separated, Rs (Ω) and Rn (Ω) are slightly lower than when the facing distance is zero, but the facing distance is up to about 1/10 of the coil outer diameter D. Almost no change. Actually, when the facing distance increases, the coupling coefficient between the two coils decreases, the reactance of the primary coil increases, and the apparent power increases, so the power factor decreases.

The power loss due to the effective series resistance of the coil can be suppressed by the definition of Rw ≦ (Tw−Ta) / (Ia ² × θi) described later. As will be described later, the values of R1 and R2 in FIG. Since the unknown point and Tw (° C.) and Ta (° C.) differ depending on the use conditions of the coil, in the embodiment of the present invention, the aforementioned Rw, Rs, and Rn are set to zero or the actual facing distance. What is necessary is just to obtain the maximum frequency f2 (Hz) satisfying Rs> Rn ≧ Rw and the maximum frequency f1 (Hz) satisfying Rs> Rw by measuring at the opposing distance of the coil to be used.

  First, the difference between the case where Rs> Rw is satisfied and the case where Rs> Rw is not satisfied will be described. As described above, it is known that the effective series resistance Rw (Ω) of a single coil increases as the frequency increases, and the skin effect and eddy current loss are known as the cause.

Further, according to the above circuit theory, as shown in FIG. 7, it is known that when the secondary coil is short-circuited, the pure resistance value on the primary side increases to (R1 + A ² R2) Ω. R2 is an effective series resistance value of the secondary coil, M is a value of mutual inductance between the primary coil and the secondary coil, ω is an angular frequency (ω = 2πf, f is a frequency, Hz), and L2 is 2 When the value of the self-inductance of the secondary coil is A ² = ω ² M ² / (ω ² L2 ² + R2 ² ), ω ² > 0, M ² ≧ 0, L2 ² > 0, R2 ² > 0, Therefore, clearly, A ² ≧ 0. As for the primary side inductance, if L1 is the value of the self-inductance of the primary side coil, as shown in FIG. 7, when the secondary side coil is short-circuited, the primary side inductance is (L1-A ² L2) H, is known to decrease.

  However, referring to FIG. 9 to FIG. 11, it can be seen that Rs (Ω) is smaller than Rw (Ω) in the high frequency region. The frequency at which Rs <Rw is about 67 kHz or more in the coil 1A as a comparative example, whereas it is about 208 kHz or more in the coil 1B. In the coil 1C, it becomes about 820 kHz or more. In the coil in which the formal wire is wound in close contact with the flat spiral shape, the maximum frequency f1 (Hz) satisfying Rs> Rw becomes lower as the diameter of the formal wire becomes larger. Further, from FIG. 12, in the coil 1D that uses the same single conductor as the coil 1C and is wound 31 turns with an outer diameter of 30 mm, the maximum frequency f1 (Hz) that satisfies Rs> Rw is higher than that of the coil 1C. Yes.

(Explanation of fluctuations in frequency characteristics due to wire diameter)
FIG. 16 shows the frequency and effective series resistance Rw (Ω) of a coil in which each formal wire having a copper wire diameter of 0.2 mm, 0.4 mm, 0.8 mm, and 1 mm is closely wound in a flat plate shape for 25 turns. Showing the relationship.

  As is apparent from FIGS. 9 to 12, a coil having a low maximum frequency f1 (Hz) that satisfies Rs> Rw has a high increase rate of the effective series resistance Rw (Ω) as the frequency increases. From FIG. 16, this characteristic is the same even with coils having different outer diameters in which formal wires having different wire diameters of 0.2 mm, 0.4 mm, 0.8 mm, and 1.0 mm have the same number of turns of 25 times. . That is, it can be seen that as the diameter of the formal wire increases, the rate of increase in the effective series resistance Rw (Ω) accompanying an increase in frequency increases. Further, in a coil wound with the same wire diameter, the smaller the number of turns and the smaller the outer shape, the higher the maximum frequency f1 (Hz) that satisfies Rs> Rw, and the effective series resistance Rw (Ω) due to the increase in frequency. ) Increase rate is also small.

  That is, if the circuit theory is followed, the relationship of Rs> Rn = Rw must be satisfied. However, in the transformer using coils 1A to 1D and configured as shown in FIGS. Then, the relationship of Rs> Rw is not satisfied. For example, in the coil 1B, it can be seen from FIG. 10 that Rs <Rw at a frequency of 208 kHz or higher.

In a frequency region where the relationship between Rw and Rs is Rs <Rw, A ^{2 that} is not positive becomes negative. 9 to 12, the actual values of the effective series resistances R1 and R2 shown in FIG. 8 cannot be obtained in the frequency region where Rs <Rw. An example is shown below. Here, since the coupling coefficient is approximately obtained from the effective series resistance, the coupling coefficient is expressed as kr. As will be described later, the coupling coefficient obtained from the inductance is expressed as ki.

According to the known circuit theory, when the coupling coefficient is kr, the mutual inductance is M (H), the self-inductance of the primary side coil is L1 (H), and the self-inductance of the secondary side coil is L2 (H). Then, the relationship of M ² = kr ² · L1 · L2 is established. If the same coil is used for the primary side coil and the secondary side coil, R1 = R2 = Rw and L1 = L2 = Lw. Therefore, when ω ² L2 ² >> R2 ² is satisfied, A ² = ω ² M ² / (ω ² L ^{2 2} + R ^{2 2} ) ≈ω ² M ² / (ω ² L2 ² ) = kr ² · L1 / L2 = kr ² Therefore, the ^{(R1 + A 2 R2),} (Rw + kr 2 Rw) = Rs, ^{next, kr 2 ≒ (Rs-Rw} ) / Rw, approximately prompted kr ² as, kr = √ ((Rs- Rw) / Rw).

When both coils are the same, R1 = R2 = Rw and L1 = L2 = Lw. Therefore, whether ω ² L2 ² >> R2 ² is satisfied is calculated by calculating the value of ω ² Lw ² / Rw ² , and the value of the coupling coefficient obtained when this value is 50 or more has an error of about 2%. Judgment is as follows. 9 to 15, when 10 kHz to 30 kHz or more, ω ² Lw ² / Rw ² > 50. In the frequency region satisfying Rs> Rw, the coupling coefficient kr can be approximately obtained from Rw and Rs in this way.

However, in the frequency region where Rs <Rw, A ^{2 that} is not positive becomes negative, and kr ² that is the square of the coupling coefficient kr that should be positive also becomes negative. It cannot be obtained from the effective series resistances Rw and Rs. As is apparent from the equation (4), the actual values of R1 and R2 cannot be obtained in FIG. When Rs = Rw, the coupling coefficient kr becomes zero, and when Rs <Rw, the coupling coefficient kr is mathematically an imaginary number. Although two coils are actually facing each other and the mutual inductance M is M ≠ 0, it is theoretically impossible that the coupling coefficient between the two coils becomes zero or becomes an imaginary number. .

In the frequency region where the condition of Rs> Rw is not satisfied, the values of the effective series resistances R1 and R2 in FIG. 8 are unknown as described above. Furthermore, the effective series resistance Rw (Ω) of the coil increases, and even if the current I is passed through either the primary side or the secondary side coil, R1 × I ² (W), R2 × I ² (W), The power loss due to is excessive, and the coil generates heat. Due to the power loss, the effective power transmission efficiency η decreases. When the same coil is used on both the primary side and the secondary side, when 2 × Rw = Rs (Ω), the coupling coefficient kr is 1, so that Rs is 2 × Rw (Ω), The closer it is to the better.

(Description of combination of coil 1A and coil 1F)
FIG. 17 shows effective power transmission when a load resistance of 10Ω is connected to Rw, Rn, Rs of coil 1A and coil 1F when coil 1A is one coil and coil 1F described later is the other coil. It is a characteristic view which shows the relationship between efficiency and a frequency.

  In FIG. 9, it has been described that when the coil 1A is used for both the power transmission coil and the power reception coil, only a predetermined power transmission performance can be achieved. This will be described. When the coil 1A is used for both one coil and the other coil, the maximum frequency f1 at which the coil 1A satisfies Rs> Rw is about 67 kHz from FIG. That is, f1 of the coil 1A is less than 100 kHz. Therefore, when the coil 1A using a 1 mm formal wire is used for both the power transmission coil and the power reception coil, only the same power transmission performance as that of the conventional coil can be achieved.

  The coil 1A shown in FIG. 9 was used as one coil, and the coil 1F shown in FIG. 14 was used as the other coil. Then, in the coil 1A, the highest frequency f1 satisfying at least Rs> Rw increased from 67 kHz to 110 kHz. As a result, the power transmission performance could be improved. Therefore, even if it is the coil 1A of FIG. 9, by selecting the other coil which opposes, electric power transmission performance can be improved with an air core, without using a magnetic material etc.

According to actual measurements, the maximum frequency f1 satisfying the condition of Rs> Rw per coil 1A is about 67 kHz when the opposing coil is the coil 1A, as shown in FIG. 9, and when the opposing coil is the coil 1F. From FIG. 17, when the opposing coil is the coil 1G, it is 150 kHz although not shown. By selecting the other opposing coil, the coil 1A can increase the maximum frequency f1 (Hz) that satisfies the condition of Rs> Rw. When the coil 1A is opposed to the coil 1F, the maximum frequency f1 that satisfies the condition of Rs> Rw for the coil 1F is about 2 MHz. In such a frequency region, the effective series resistance Rw of the coil 1A alone is a high value of 10Ω or more. Therefore, the thermal condition defined by Rw, which will be described later, Rw ≦ (Tw−Ta) / (Ia ² × θi), Thus, the current that can be passed through the coil 1A as the secondary coil can be defined.

  Preferably, when the coil 1A and the coil 1F are used in combination, as described above, the output frequency fa (Hz) of the AC power supply is set to f1 (Hz) in order to transmit power in the frequency region below f1 = 110 kHz. Set to less than. Naturally, at fa (Hz), both the coil 1A and the coil 1F satisfy Rs> Rw. The maximum frequency f1 at which the coil 1A satisfies Rs> Rw is about 67 kHz. However, by using the coil 1A and the coil 1F in combination, it is possible to transmit power at 67 kHz or higher regardless of whether the coil 1A is used as a power transmission coil or a power reception coil.

  In the embodiment of the present invention, when f1 (Hz) of one coil is low, f1 (Hz) of one coil is set to a predetermined frequency as the other coil, and the margin of about 10% shown in FIG. And select a coil that is higher than 100 kHz. The power transmission device is configured by combining one coil selected in this way and the other coil. With such a configuration, the coil can be used at a high frequency. Then, the power transmission performance of the power transmission device can be improved.

  That is, first, one coil and the other coil are selected. In one coil, each frequency characteristic of Rw, Rs, Rn is measured. Based on the measurement data, one coil obtains the maximum frequency f1 (Hz) that satisfies Rs> Rw. It can be seen from FIG. 17 that the frequency characteristics of the power transmission performance are good in the combination of coils having a high f1 (Hz), compared with FIG. And the output frequency fa (Hz) of AC power supply 30b is set to less than f1 (Hz). In this way, a power transmission device with good power transmission performance can be realized.

(Description of combination of coil 1B to coil 1D)
In each of the coils 1B to 1D using the single conducting wire, the maximum frequency f1 satisfying Rs> Rw exceeds 100 kHz. The coils 1B to 1D are set as one coil, and the other coil is set as any one of the coils 1B to 1D. In one coil, a maximum frequency f1 (Hz) satisfying Rs> Rw is obtained. The output frequency fa (Hz) of the AC power supply 30b included in the power transmission device is set to be less than f1 (Hz). In this way, a power transmission device with good power transmission performance can be realized.

(Explanation when Rs> Rn ≧ Rw is satisfied)
Next, the difference between when Rs> Rn ≧ Rw is satisfied and when it is not satisfied will be described. As described above, in the single coil, this effective series resistance Rw can be obtained accurately by measurement. However, in the transformer configured as shown in FIG. 6, as shown in FIGS. R1 rises from Rw to Rn in the high frequency region just by facing the side coils. R1 is the effective series resistance of the primary coil, but the frequency characteristic of R1 (same as Rw) in FIG. 5 is different from the frequency characteristic of R1 (same as Rn) in FIG. It can be seen from the frequency characteristic chart of Rw and Rn plotted in FIG.

Furthermore, as described above, the coupling coefficient kr can be obtained approximately by obtaining A ² from Rw and Rs and taking the square root of A ² .

  FIG. 13 plots the coupling coefficient kr obtained from Rw and Rs of the coil 1E and FIG. 14 of the coil 1F. In the coil 1E, as shown in FIG. 13, the rate at which Rn (Ω) increases with increasing frequency is low, and Rs> Rn ≧ Rw is satisfied up to about 3.7 MHz. In the coil 1F, as shown in FIG. 14, Rn (Ω) increases rapidly with increasing frequency, and Rs <Rn when the frequency region is 780 kHz or higher.

  Looking at the relationship between the coupling coefficient kr and the frequency between the two coils obtained approximately from Rw and Rs, the coil 1E has a value of the coupling coefficient kr of approximately 0.8 or more up to about 2 MHz. On the other hand, in the coil 1F, it can be seen that the coupling coefficient kr decreases from about 0.9 at 100 kHz as the frequency increases, and decreases to about 0.65 at 1 MHz. Therefore, the highest frequency f2 that satisfies Rs> Rn ≧ Rw is preferably as high as possible.

  By using the coil in the frequency region satisfying the condition of Rs> Rn ≧ Rw, both the coil alone of FIG. 5 and the transformer configured as shown in FIG. 6 are theoretically ideal characteristics. Therefore, the power transmission performance can be improved as compared with the conventional case.

(Explanation when Rs> Rn ≧ Rw is not satisfied)
However, depending on the frequency domain, Rn = Rw is not satisfied and Rn> Rw, and is affected by Rn. Therefore, the values of R1 and R2 cannot be accurately obtained in FIG. R1 and R2 vary depending on the value of RL shown in FIG. That is, R1 and R2 fluctuate due to currents flowing through R1 and R2, and naturally fluctuate depending on the frequency. Therefore, in FIG. 8, the actual accurate values of R1 and R2 at the time of power transmission cannot be obtained.

  In this embodiment, the measurement of whether two conditions of Rs> Rw and Rs> Rn ≧ Rw are satisfied describes a case where the same coil is opposed. However, as shown in FIG. 17, two arbitrary coils having different structures, configurations, outer diameters, and the like may be opposed to each other, and measurement may be performed using either the primary side coil or the secondary side coil. It is not necessary to measure it facing each other.

  Further, detailed operational effects regarding the relationship of Rs> Rn ≧ Rw will be described later with reference to the coils 1F and 1G.

(Description of thermal resistance θi (° C / W), temperature Tw (° C), ambient temperature Ta (° C))
Next, the relationship of Rw ≦ (Tw−Ta) / (Ia ² × θi) will be described. As described above, in FIG. 8, the values of the effective series resistances R1 and R2 of the coil when the power is actually transmitted to the load resistance RL are unknown, and in FIG. R1> Rw. In other words, the thermal condition of the coil cannot be defined except that Rw is used as a reference at the minimum. Therefore, it is necessary to define the thermal conditions of the coil based on Rw as a minimum.

  In implementing this invention, the thermal resistance θi (° C./W) of the coil is determined by the coil structure and installation conditions. For example, when the coil is a single air core, θi is high, and when the coil is fixed in a resin with low thermal resistance and installed in water, θi is low. The temperature Tw (° C.) at which the coil can operate is determined by the structure and application of the coil, and is 50, for example, in a case where it is incorporated in a case with good heat insulation or in a device such as a transformer. In a case where it is installed at a place where a human body, an animal, or the like touches, for example, about 80 ° C. to 80 ° C., the temperature is about 40 ° C. The ambient temperature Ta (° C.) of the place where the coil is installed is, for example, −20 ° C. to 40 ° C. outdoors, for example, 15 ° C. to 30 ° C. indoors, and 40 ° C. to 50 ° C. Become.

  Normally, the higher the temperature, the more heat is dissipated to the surroundings, so it is necessary to solve the heat diffusion equation accurately. However, since it is difficult to solve the thermal diffusion equation in consideration of thermal constants such as specific heat for coils having various structures, the thermal resistance θi (° C./W) is simply obtained by the following method.

  First, the coil temperature T1 (° C.) in the initial state is obtained at the place where the primary side or secondary side coil is installed. A DC constant current Id (A) is passed through the coil, the voltage Vd (V) across the coil is measured, and the power consumption of the coil is determined as Pd = Vd × Id (W). Since the resistance value of the metal wire increases as the temperature rises, the voltage Vd across the coil rises, so Vd is recorded with a pen recorder or the like to obtain an average value, or the Vd is monitored successively with an A / D converter or the like. It is desirable to take an average value. When the thermal equilibrium is reached, the coil temperature T2 (° C.) is measured. The thermal resistance θi (° C./W) is obtained as θi = (T2−T1) / Pd (° C./W). This measurement is preferably performed as an average value by measuring several times while changing the current value of Id.

The thus obtained thermal resistance θi (° C./W) is determined by an effective series resistance Rw (determined by an effective series resistance Rw (Ω) of the coil under actual use conditions and a current Ia (A) flowing through the coil. When the power consumed by Ω), Rw × Ia ² (W), is multiplied, the temperature rise value of the coil under actual use conditions, Tr (° C.), is obtained. Tr = θi × Rw × Ia ² (° C.) If the temperature at which the coil can be operated is Tw (° C.) and the ambient temperature of the place where the coil is installed is Ta (° C.), Tr = Tw−Ta. If (Tw−Ta) ≧ θi × Rw × Ia ² (° C.) is not satisfied, the usable temperature of the coil will be exceeded, making it difficult to implement the present invention.

The condition relating to the effective series resistance Rw (Ω), Rw ≦ (Tw−Ta) / (Ia ² × θi), transforms the inequality and defines the condition of Rw (Ω) or Ia (A). At the frequency at which power is transmitted, the effective series resistance Rw (Ω) is a variable obtained by actually measuring the primary side or secondary side coil alone, and the current Ia (A) flowing through the primary side or secondary side coil is also calculated. It is obtained by actual measurement or is determined by the power supply condition on the primary side and is determined by the load condition on the secondary side, and other Tw (° C), Ta (° C), and θi (° C / W) are known. Constant. Therefore, if Rw (Ω) is obtained, the upper limit value of Ia (A) is defined. Conversely, if Ia (A) is determined, the upper limit value of Rw (Ω) is defined.

  Rw (Ω) is the sum of DC resistance Rd (Ω) and AC resistance Ra (Ω), and Rd and Rw can be directly measured, so by determining Ia (A), it increases with the number of turns. The upper limit value of the effective series resistance Rw (Ω), which is the sum of Rd and Ra, can be defined, and the frequency range in which power can be transmitted can be defined from the relationship between the effective series resistance Rw (Ω) and the frequency.

  Both 1V × 10A and 10V × 1A have the same power of 10 W, but the power loss due to the effective series resistance of the coil is 100 times that of 1A in the case of 10A. Power transmission performance between two coils if the power loss due to the effective series resistance of the coil is not specified considering the current Ia (A) flowing through the coil, regardless of the primary side or the secondary side. Cannot be improved.

(Explanation of the relationship of Rs> Rn ≧ Rw)
Here, with reference to the coil 1F and the coil 1G, the detailed effect regarding the relationship of Rs>Rn> = Rw is demonstrated. The Litz wire is considered to have an equivalent circuit as shown in FIG. 18 in which the self-inductances of the respective strands constituting the Litz wire are connected in parallel and the mutual inductance is provided between the respective strands. Even if a litz wire is wound with a flat single-layer spiral, the frequency characteristics of the effective series resistance Rw (Ω) of the coil itself will not be improved, and the self-inductance of the coil itself will decrease. It is considered that the self-inductance when the wire is formed as a coil changes due to the mutual inductance between the formal wires and between the conducting wires. That is, the characteristics when formed as a coil vary depending on the twisting method, twisting pitch, winding method (close winding, loose winding, multilayer winding), number of turns, outer shape, and the like.

  The coil 1F shown in FIG. 14 and the conductor used in the coil 1G shown in FIG. 15 are the same, the conductor outer diameter is 0.05 mm, the insulation coating thickness is 5 μm, and the conductor outer diameter is 0.1 mm. A coil 1F is tightly wound 30 turns around an outer shape 70 mm, and the coil 1G is tightly wound 20 times around an outer diameter 50 mm.

  When the frequency characteristics of Rw, Rn, and Rs of the coil 1F and the coil 1G are compared in FIG. 14 and FIG. 15, the frequency region in which Rs <Rn exists in the coil 1F exists at 780 kHz or more. Then, the condition of Rs> Rn ≧ Rw is satisfied up to about 2.1 MHz. It cannot be determined whether this cause is related to the twisting method, the twisting pitch, or the number of turns, the outer diameter, and the winding method. However, if at least the frequency characteristics of Rw, Rn, and Rs of the coil are measured, it can be determined whether or not the coil is suitable for the power transmission device. The specific method is described below.

(Description of inductance and coupling factor)
Table 1 shows the inductance Ls when the single inductance Lw (μH) of the coil 1B, the coil 1F, and the coil 1G and the same short-circuited coil face each other at a distance of zero at frequencies of 5.0 kHz to 1.0 MHz. The value of (μH) and the coupling coefficient ki approximately obtained by the calculation method shown below are described. Each ki in this table is a ki plotted in FIG. 10, FIG. 14, and FIG.

First, a method for approximately obtaining the coupling coefficient ki from the coil inductance change will be described. As described above, when the self-inductance of the coil in FIG. 5 is Lw (H) and the inductance of the primary coil in FIG. 6 is Ln (H), L1 = Lw in FIGS. = Ln (H). Further, as shown in FIG. 7, when the primary side inductance when the secondary side coil facing the primary side coil is short-circuited is Ls (H), Ls = (L1−A ² L2 ) The relationship of H holds. Unlike the effective series resistances Rw (Ω) and Rn (Ω), L1 = Lw = Ln (H) in actual measurement. L1, L2, and A ² are as described above.

When the same coil is used for the primary side and the secondary side, since L1 = L2 = Lw and R1 = R2 = Rw, the relationship of Ls = (Lw−A ² Lw) is established. As described above, since the value of ω ² L2 ² / R2 ² = ω ² Lw ² / Rw ² is 50 or more at 10 kHz to 30 kHz or more, it can be regarded that A ² ≈ki ² . Therefore, the coupling coefficient ki is approximately obtained as ki ² = (Lw−Ls) / Lw and ki = √ ((Lw−Ls) / Lw). As described above, the coupling coefficient obtained from the inductance change, Lw, and Ls in this way is expressed as ki. Comparing kr and ki plotted in FIG. 14 and FIG. 15, it can be seen that kr and ki are almost the same in FIG.

  However, in FIG. 14, kr and ki do not match. Furthermore, in the coil 1B, kr and ki are plotted in FIG. 10, but in FIG. 10, it can be seen that kr sharply decreases at a frequency where Rn> Rs. Actually, when two coils 1G shown in FIG. 15 are used, Rs> Rn ≧ Rw is satisfied up to 2.1 MHz, and Rs> Rw is satisfied up to 10 MHz or higher. It can transmit power with high power factor and high effective power efficiency, and power transmission performance is very good.

  That is, the higher the maximum frequency f2 (Hz) that satisfies Rs> Rn ≧ Rw, and the higher the frequency, the closer the value of Rn / Rw is to 1, the better the coil performance, and the higher the frequency, Rw (Ω) There is little increase. As described above, the frequency characteristic of the coupling coefficient kr obtained from Rw and Rs is compared with the frequency characteristic of the coupling coefficient ki obtained from Lw and Ls by observing the relationship between the frequency and Rw, Rn, and Rs. As a result, it is possible to predict the performance as a transformer, which is a power transmission means with the coils facing each other, which cannot be determined only by the frequency characteristics of the effective series resistance of the single coil.

  Therefore, the proper twisting method, twisting pitch, and winding method of the Litz wire constituting the coil are to form a plurality of coils and measure the frequency characteristics of the coils Rw, Rn, Rs, and preferably the frequency of Lw, Ls By measuring the characteristics and comparing the frequency characteristics of kr and ki, it is possible to find the optimum coil. This technique is applicable not only to litz wires but also to copper wires, vinyl wires, and other electric wires of other embodiments described later, and a coil suitable for power transmission can be selected. In other words, by changing the wire material, wire diameter, dimensions, shape, winding method, etc., it is possible to determine the performance as a transformer that is a power transmission means facing the coil, which cannot be determined only by the frequency characteristics of the effective series resistance of the coil alone. Therefore, it is possible to provide a coil with good power transmission performance that could not be realized by the conventional technology.

  For example, a coil 1E wound with a 1 mm single conductor and provided with a gap has a maximum frequency f2 satisfying Rs> Rn ≧ Rw of 3.7 MHz and a maximum frequency f1 satisfying Rs> Rw. , 7.7 MHz, there is not much difference in the definition of Rs> Rn ≧ Rw compared to the coil 1G. However, the Rw of the coil 1E alone at 4 MHz is 0.87Ω, the Rw of the coil 1G alone is about 2Ω, the Rw of the coil 1E alone at 2.9MHz is 2.9Ω, and the Rw of the coil 1G alone is 17Ω. Thus, the coil 1E has better high-frequency characteristics of the effective series resistance Rw (Ω) of the coil alone than the coil 1G.

Therefore, according to the definition of Rw ≦ (Tw−Ta) / (Ia ² × θi), the coil 1E formed with a single conductor can be used at a higher frequency than the coil 1G formed with a litz wire. Thus, in the embodiment of the present invention, the highest frequency f1 (Hz) satisfying Rs> Rw, the highest frequency f2 (Hz) satisfying Rs> Rn ≧ Rw, and Rw ≦ (Tw−Ta) / ( Ia ² × θi), by realizing a coil that cannot be realized by the conventional technology, and by specifying an optimum frequency region for using the coil, power transmission performance compared to the conventional technology The present invention has an excellent effect that a good power transmission device can be realized.

  In the prior art including the above cited reference, only a specific configuration of the coil is defined. Then, by showing only one embodiment of a specific configuration, it is claimed that the characteristics of interest, for example, power transmission performance can be improved. However, as described above, even if the outer diameter and inner diameter are the same, the coil characteristics are completely different depending on the wire diameter and the number of turns. Even if the same conducting wire is used, if the configuration (outer diameter, number of turns, etc.) is different, the coil characteristics will be different. That is, even if a specific configuration such as a wire rod and a winding method is defined, coils actually produced have various configurations, and it is not guaranteed at all that they have the same effect.

  Therefore, it is impossible to realize a coil that satisfies the requirements as a coil of the power transmission device only by defining a specific configuration of the coil. Actually, a power transmission apparatus capable of transmitting 20 W of power with an effective power transmission efficiency of 80% as described in the prior art has not been implemented to date.

  As in the present application, a coil having good power transmission performance and a power transmission device having good power transmission performance are defined as long as the characteristics change when the configuration other than the specific configuration of the coil is changed, and the operating conditions of the coil are not defined. Cannot be realized. On the other hand, the embodiment of the present invention can realize a power transmission device with good power transmission performance by defining operating conditions of each coil in coils having various configurations capable of inductive coupling. As described above, the embodiment of the present invention exhibits extremely excellent effects that could not be realized by the conventional technology.

(Explanation of coil power factor)
In each embodiment of the present invention, a coil that is not equipped with a magnetic material transmits a large amount of power, which was conventionally difficult, between two coils in a loosely coupled state with a coupling coefficient of about 0.9 or less. The coil which can be realized is realized. As described above, although the power factor is 0.5 or more, the reactive power input to the primary coil may exceed the effective power in the loosely coupled state.

When the power factor decreases from 1 to 0.5, the current flowing in the primary coil due to the apparent power is doubled, and the power loss due to the effective series resistance Rw (Ω) of the primary coil is doubled. . In addition, when a current flows through the load resistance connected to the secondary coil, the magnetic flux generated by the current flowing through the secondary coil passes through the conducting wire forming the primary coil, generating eddy current loss and causing the primary The side coil generates heat. Therefore, the above inequality, Rw ≦ (Tw−Ta) / (Ia ² × θi), is preferably satisfied to implement the embodiment of the present invention, otherwise the implementation of the present invention is difficult. become.

When the frequency fd (Hz) at which one coil is driven satisfies Rs> Rn ≧ Rw, the value of the internal resistance R3 of the power supply shown in FIG. 95 is equal to or less than Rw (Ω). Since the secondary side coil viewed from the load resistance RL can be regarded as the primary side being short-circuited, R2 (Ω) is substantially equal to Rs (Ω). Therefore, it is more preferable that the secondary coil satisfies the relationship of Rs ≦ (Tw−Ta) / (Ia ² × θi). In FIG. 95, the value of R1 is unknown, but it is more preferable if the relationship of Rs ≦ (Tw−Ta) / (Ia ² × θi) is satisfied even in the primary side coil.

However, in a general transformer, the relationship between the linkage flux Φc, the leakage flux Φg, and the coupling coefficient k is k ² = Φc / (Φc + Φg), 1-k ² = Φg / (Φc + Φg), which is known. As shown, the flux linkage Φc transmits effective power. As is known, the leakage magnetic flux Φg provides reactive power that is the product of the voltage V applied to the reactive element and the flowing current I.

  In the coil, since the phase of I is 90 degrees behind the phase of V, multiplying the instantaneous value of V by the instantaneous value of I and integrating for one period makes the power zero, so that it is a reactive element. The coil does not consume power. In this field, there are many documents that specify that the magnetic flux leakage causes energy loss and specify the coil shape to increase the flux linkage ratio, but as mentioned above, the magnetic flux leakage does not consume power. .

  Therefore, if the effective series resistance Rw (Ω) is small enough to be ignored, large power can be transmitted regardless of the ratio of leakage magnetic flux. However, although the effective series resistance Rw (Ω) is small in the coil having the configuration disclosed in Patent Document 1, the power factor is remarkably small because the self-inductance and coupling coefficient of the coil are small. For this reason, a large apparent power must be supplied to the primary coil. To realize a coil suitable for power transmission, the coil configuration is determined, all parameters are set appropriately, and the effective series resistance is set. Rw (Ω) must be made as small as possible.

(Description of frequencies that can be used for power transmission)
The upper limit of the frequency at which the coil of the embodiment of the present invention can be used for power transmission is the highest frequency that satisfies fs (Hz) that satisfies Rs> Rw and Rs> Rn ≧ Rw. The lower limit of the frequency at which the coil can be used for power transmission can be determined by the regulation of f2 (Hz). The phase difference between the voltage V applied to the coil alone and the current I flowing through the coil alone is 80 degrees. It is obtained by defining the above.

  Although not shown, in the coil 1B having a low maximum frequency f1 (Hz) that satisfies Rs> Rw, the phase difference between V and I is 80 degrees or more up to less than 5 kHz, but Rs> Rw In the coil 1G having a maximum frequency f1 that satisfies 10 MHz exceeding 10 MHz, the phase difference between V and I is 80 degrees or less when it is less than 20 kHz.

  As described above, referring to FIG. 10, the highest frequency f1 at which the coil 1B satisfies Rs> Rw is about 210 kHz, and the maximum frequency f2 at which Rs> Rn ≧ Rw is about 75 kHz. The frequency range in which the coil 1B according to the definition of the maximum frequency f1 (Hz) satisfying Rs> Rw can be used is 5 to 210 kHz, and the coil according to the specification of the maximum frequency f2 (Hz) satisfying Rs> Rn ≧ Rw. The frequency region where 1B can be used is 5 to 75 kHz. In this manner, the coil according to the embodiment of the present invention can be used in a frequency region that is close to a theoretical ideal characteristic. In FIG. 11, the phase angle θ of the coil 1C is plotted. In the coil 1C having a higher f1 (Hz) than the f1 (Hz) of the coil 1B, the frequency at which the phase angle θ is 80 degrees is about 8 kHz, which is slightly higher than 5 kHz.

  As described above, according to this embodiment, the necessary self-inductance and coupling coefficient k can be ensured by defining the wire diameter of the conducting wire 11 of the coil 1a, the outer diameter of the coil, and the number of turns. In addition, the upper limit of the current value Ia of the coil 1a or the upper limit of the number of turns that determines the effective series resistance Rw (Ω) of the coil 1a can be defined, and the ratio of the reactance X to the pure resistance R when a load resistance is connected, X / By using the coil 1a in the vicinity of the frequency where R and the phase difference φ between the AC voltage applied to the coil and the AC current flowing through the coil are minimum, the power factor cos φ is maximum, and the effective series resistance Rw (Ω) is small. Reactive power and apparent power during power transmission can be reduced. Furthermore, the effective power efficiency can be increased to, for example, 85% or more.

(Description of comparison of frequency characteristics of coils 1A and 1E)
19 compares the frequency characteristics of the effective series resistance Rw (Ω) of the closely wound coil 1A shown in FIG. 9 and the effective series resistance Rw (Ω) of the loosely wound coil 1E shown in FIG. FIG. As shown in FIG. 19, when the frequency is increased, the loosely wound coil 1E can suppress an increase in the effective series resistance Rw (Ω) of the coil compared to the closely wound coil 1A. Further, in the case of a coil having the same outer diameter, the total extension of the winding is shortened, so that the direct current resistance can be kept low.

(Description of an example in which the frequency characteristics of the effective series resistance change depending on the width of the air gap)
FIG. 20 is a diagram showing how the frequency characteristic of the effective series resistance of the coil changes depending on the width of the gap when a 0.4 mm formal wire is wound for 25 turns. The width of the gap is set to 0 mm, 0.2 mm, and 0.4 mm, but it can be seen that a wider gap can suppress an increase in effective series resistance with an increase in frequency. Since the number of turns is the same, the outer diameter of the coil increases as the width of the gap increases, and the total length of the copper wire that constitutes the coil increases. However, the effective series resistance is low.

  However, since the eddy current loss is proportional to the volume of the conductor through which the magnetic flux penetrates, if the maximum diameter of the single conductor is not 0.2 mm or more, even if the gap t (mm) is provided between the conductors, The increase rate of the effective series resistance Rw does not decrease so much. In view of the relationship between the frequency of a single coil in which a single conducting wire having a wire diameter of 0.2 mm is closely wound and the effective series resistance Rw in FIG. 15, the increase rate of the effective series resistance due to the increase in the frequency is 0.2 mm. It can be seen that the frequency characteristic of the effective series resistance Rw cannot be improved much even with a single conductor having a wire diameter of 0.2 mm, even if a gap is provided.

  The self-inductance of the coil 1D shown in FIG. 12 is about 19 μH. The self-inductance of the coil in which the coil 1D is wound in two layers is about 76 μH, and a result almost equivalent to the theory that the self-inductance is proportional to the square of the number of turns is obtained. The frequency characteristic of the effective series resistance of the coil wound in two layers is worse than that in the single layer winding, and the maximum frequency f1 (Hz) that satisfies Rs> Rw is also low. However, in a low frequency region where the effective series resistance is low, reactance can be ensured, so it may be advantageous to use a two-layer winding and use at a low frequency.

  A coil in which the coil 1D is wound in two layers is used for one coil and the other coil. The maximum frequency f1 in which the coil 1D is wound in two layers satisfies Rs> Rw is 550 kHz, and the coil in which the coil 1D is wound in two layers has a high inductance. However, the required reactance can be secured.

In FIG. 16, the effective series resistance Rw at 5 kHz when a single conducting wire having a wire diameter of 0.2 mm is closely wound is 0.83Ω. The effective series resistance at 1 MHz is 2.16Ω, and the increase rate of the effective series resistance Rw is 2.16 / 0.83 = 2.60. The increase rate of the coil 1E provided and wound is smaller than 7.6. However, in a coil having a wire diameter of 0.2 mm, the absolute value of Rw (Ω) increases and the thermal resistance θi (° C./W) decreases, so that Rw ≦ (Tw−Ta) / (Ia ² × θi) In order to satisfy the relationship, it is necessary to select a wire diameter suitable for the power value to be transmitted.

(Explanation of coil turns and inductance)
Next, a description will be given of a coil having 8 turns and a minimum inductance value of 2 μH. The coil of the conventional example has 5 turns, and at 1 MHz, the coil Lw is 0.79 μH, Ls is 0.45 μH, Lw, and the coupling coefficient ki approximately calculated from Lw and Ls is 0.66. Power transmission performance is also very bad. A coil wound eight times in the same shape using the same wire as the coil has an Lw of about 2.1 μH, an Ls of about 0.7 μH, and an approximately calculated coupling coefficient ki of about 0.83. It has become.

  As described above, the coil in which the conductive wire of the conventional example is wound eight times is actually a high frequency that has an effective series resistance that is too low, a poor frequency characteristic of Rw (Ω), and a sufficient reactance. In the region, Rs> Rw is not satisfied. For this purpose, it is necessary to select an appropriate twisting and winding method for the conducting wire, but since the minimum inductance and coupling coefficient used in the high frequency region can be secured, a minimum number of windings of 8 is specified from the above measurement results. In addition, 2 μH is defined as the minimum value of inductance.

  And as mentioned above, the diameter of the conducting wire of the coil of the conventional example is 1.5 mm, and the conducting wire is further wound 3 times on the outermost peripheral part of the coil wound 5 times, and the number of turns is 8 times. The outer diameter is 3 times × 2 × 1.5 mm + 30 mm = 39 mm. Therefore, in a coil configured using the conventional coil conductor, in order to ensure the minimum inductance value of 2 μH and the coupling coefficient, the ratio of the coil outer diameter D to the wire diameter d3 is 39 / 1.5 = 26. The coil outer diameter D is required to be at least 25 times the wire diameter d3.

  However, as described above, the specific configuration that “D is required to be at least 25 times d3” can secure a minimum inductance value of 2 μH and a coupling coefficient by changing another configuration factor such as a wire and the number of turns. It can be lost. For example, it is conceivable that the diameter of the wire is reduced to provide a gap between the wires. Therefore, in order to secure the minimum value of 2 μH of inductance, there is a possibility that the number of turns of 8 times or more is required. The wire used and the number of turns are selected so as to ensure the minimum inductance value of 2 μH, and finally the frequency characteristics of Rw, Rs, and Rn are measured in the coil whose configuration is uniquely specified. It goes without saying that a coil whose configuration is uniquely specified means one actually created as a coil. Therefore, the frequency fa (Hz) of the AC power source, which is the aforementioned operating condition of the coil, derived from the characteristics obtained by measuring what is actually created as a coil is defined.

  To reiterate, a coil has a virtually infinite configuration by changing other components, for example, simply by defining a specific configuration. It has not been proved that a coil having a specific configuration exhibits an effect of always exhibiting an excellent power transmission performance as compared with an invention based on other specific configuration rules. It is virtually impossible to prove.

  Only by the embodiment of the present invention, the configuration is defined so as to ensure the above-described minimum inductance value of 2 μH and the coupling coefficient, and a coil suitable for power transmission can be selected from the coils satisfying those characteristic conditions. become able to. As described above, the embodiment of the present invention shows measured characteristic data in various embodiments, unlike the conventional coil. A coil having a configuration capable of inductive coupling has a variation that cannot be specified. Therefore, it is impossible to ensure power transmission performance in a coil having an arbitrary configuration. Further, in the conventional technique, it cannot be determined that the coil whose configuration is uniquely specified can ensure the power transmission performance.

  A power transmission device with good performance using the coils of the power transmission device having various configurations only by defining the operating condition based on the characteristic definition which is the gist of the embodiment of the present invention for the coil selected by the above-described method. Can be realized. This extremely excellent effect could not be realized with a conventional coil that defines only a specific configuration of the coil.

  Moreover, it is preferable that the maximum frequency f1 with which one coil satisfies Rs> Rw is 500 kHz or more. The same coil is used, and a coil having a high maximum frequency f1 (Hz) satisfying Rs> Rw is used at a frequency at which reactance can be secured. For example, it has been confirmed that power transmission performance can be ensured by driving at less than 250 kHz. Alternatively, it is more preferable that the maximum frequency f2 at which one coil satisfies Rs> Rn ≧ Rw is 500 kHz or more.

(Explanation regarding load resistance and power factor)
21 and 22 are diagrams showing the relationship between the power factor and the frequency when the load resistance RL is varied. Note that FIG. 9 described above also illustrates the relationship between the effective power transmission efficiency η and the frequency when the coil 1A is used for both the power transmission coil and the power reception coil. FIG. 17 also shows the relationship between the effective power transmission efficiency η and the frequency when the coil 1A is used as the power transmission coil and the coil 1F is used as the power reception coil. Both are frequency characteristics when the load resistance RL = 10Ω. The power factor is calculated from cos φ by measuring the impedance on the primary side to obtain the phase angle φ. cos 60 degrees = 0.5. In the frequency region where φ <60 degrees, the power factor is 50% or more.

  As can be seen from FIGS. 21 and 22, when the load resistance value is low, the frequency at which the power factor is highest is low. When the load resistance is high, the frequency at which the power factor is highest is high. Further, when the load resistance value is low, the maximum value of the power factor is large. When the load resistance value is high, the maximum value of the power factor is small. Below 5Ω, which is the minimum load resistance value that is generally used, the frequency at which the power factor is highest is less than f2 (Hz) of one coil.

  In FIG. 21, when two coils 1A are used, the load resistance value satisfying a power factor of 50% or more is 10Ω or less at the maximum frequency f1 = 67 kHz that satisfies Rs> Rw. In FIG. 22, when the coil 1A is used as the power transmission coil and the coil 1F is used as the power receiving coil, the load resistance value satisfying the power factor of 50% or more is less than 50Ω at the maximum frequency f1 = 110 kHz satisfying Rs> Rw. It corresponds. Further, as can be seen from a comparison between FIG. 21 and FIG. 22, in FIG. 22, the maximum value of the power factor increases as f1 (Hz) increases.

  Comparing the relationship between the power transmission efficiency η and the frequency in FIG. 17 with FIG. 9, it can be seen that f1 (Hz) increases and the power transmission performance is improved. In both FIG. 9 and FIG. 17, when the frequency is equal to or higher than f1 (Hz), the power transmission efficiency η is extremely deteriorated. Therefore, it can be seen that the power transmission performance η can be improved by making the coil 1F face the coil 1A.

  In the power transmission device in which an example of the specific configuration of the coil of the conventional example is described, only an example at a specific frequency of 100 kHz is described. And it is specified that the frequency is not limited to 100 kHz. However, as described above, the power factor and the effective series resistance Rw (Ω) of the coil change depending on the frequency. If the frequency is not set at the maximum power factor at the minimum value Rm (Ω) of the load resistance RL, power loss due to the effective series resistance Rw (Ω) occurs due to reactive power. As described above, the frequency characteristics of Rw, Rs, and Rn are measured, and f1 (Hz) and f2 (Hz) are obtained. The frequency fφ (Hz) at which the power factor is maximized is preferably smaller than f1 (Hz). However, as the resistance value of the load RL increases, the ratio of the effective series resistance Rw (Ω) to RL (Ω) of the coil, Rw / RL, decreases. Therefore, the power loss due to Rw (Ω) is relatively small compared to the power consumed by the load. Therefore, even when the load resistance value is large, the power factor is small, but power transmission can be performed at a frequency less than f1 (Hz).

(Explanation of frequency characteristics of effective power transmission efficiency η)
The frequency characteristics of the effective power transmission efficiency η in FIGS. 9 and 17 will be described. Connect a 10Ω non-inductive load resistor to the power receiving coil and measure the impedance on the power transmission side. The phase angle φ is obtained on the power transmission side by impedance measurement, and the power factor cos φ at each frequency is calculated. A voltage V (V) applied to the power transmission coil is set so that a constant current Ia of 0.2 A flows through the power transmission coil. The effective power Pr on the power transmission side is obtained as Pr = cos φ × V × Ia (W). The secondary effective power Ps (W) determines the effective value Ve of the voltage across the non-inductive load resistance ^{10Ω, Ps = Ve 2/10} (W), obtained as. The effective power transmission efficiency η at each frequency is obtained as η = Ps / Pr. This measurement method is different from the conventional example that does not take into consideration that the power factor varies depending on the load resistance value and frequency.

  Find the load resistance value from the power required by the actual electrical equipment. Since the power required by the electrical equipment is at the lower limit of voltage Vs = 5V, current Is = 0.5A, and power 2.5W, the minimum value of the load resistance value RL is about 10Ω. In an electric device that requires electric power of 10 W or more, the voltage Vs is increased and the current Is is decreased. Even if the actual circuit voltage is about 5V, a step-down PWM step-down converter is often used. For example, a personal computer or the like that requires about 30 W of power uses a 15V, 2A power source. In this case, the minimum value of the load resistance value RL is about 15/2 = 7.5Ω. Further, when the voltage Vs is increased and the current Is is decreased to about 30 V and 1 A, the minimum value of the load resistance value RL is about 30/1 = 30Ω. As a rough guide, the minimum value of the load resistance RL is about 2 to 50Ω. Therefore, in order to suppress the power loss due to the effective series resistance of the coil to about 20% or less of the received power, assuming that the minimum value of the load RL is Rm (Ω), the effective series resistance Rw of the receiving coil is Rw × 5 ≦ Rm (Ω) must be satisfied. In other words, at the output frequency fa (Hz) of the AC power supply, Rw of the power receiving coil is desirably 0.4 to 10Ω or less.

  According to actual measurement, the resistance component on the power transmission coil side is usually equal to or less than the load resistance value RL in the above-described embodiment, although it depends on the frequency. Therefore, when the minimum value of the load RL is Rm (Ω), it is desirable that the effective series resistance Rw is 0.4 to 10Ω or less for both the power transmission coil and the power reception coil.

  When the upper limit of the effective series resistance Rw (Ω) is determined, Rs (Ω) and Rn (Ω) are obtained by actual measurement. At f1 (Hz), the effective series resistance Rw is desirably 0.4 to 10Ω or less. Accordingly, it is desirable that both Rs and Rn be 10Ω or less at the frequency at which the coil is actually used.

As shown in FIG. 2 and described above, when power is actually transmitted, a loss due to eddy current loss due to the magnetic flux generated by the current flowing in the power transmission coil and the power reception coil passing through the other coil occurs, and the power loss is To increase. As described above, when power is actually transmitted, the values of R1 and R2 in FIG. 8 are unknown. Therefore, the actual effective series resistance value Rw (Ω) described above is determined by the use condition of the power receiving side device in the same manner as the definition of Rw ≦ (Tw−Ta) / (Ia ² × θi). Is.

(Explanation of conducting wire constituting coil)
FIG. 23A is a cross-sectional view of another conductor used in the coil shown in FIG. In FIG. 2 (A), a single conductor 12 having a circular cross section is used. However, as shown in FIG. 23 (A), the single conductor 12a having an elliptical cross section is provided with an insulating coating 13a. As shown in FIG. 23B, it is possible to use a single conductor wire 12b having a polygonal cross section and an insulating coating 13b. Also in this example, as the insulating coatings 13a and 13b, for example, either a strong coating such as a formal wire or a thick coating such as a vinyl wire may be used.

  However, in FIGS. 23A and 23B, the line indicating the maximum outer dimension d1 is preferably parallel to the surface on which the conducting wire is wound. The same applies to other embodiments of the present invention. Moreover, when adjacent conducting wires are in close contact, it is preferable to determine the direction of the conducting wire cross-section with respect to the winding surface so that the contact point of the conducting wire becomes a point.

(Description of an example of an umbrella-shaped coil in cross section)
FIG. 24 is a cross-sectional view of a coil in which a conducting wire is wound in an umbrella shape. The coil 1a shown in FIG. 2 (A) has a conducting wire 11 wound in a flat air core single layer spiral shape, whereas the coil 1b shown in FIG. 24 has an air core so that the cross section becomes an umbrella shape. It is formed in a single layer spiral.

  In this case, the winding width D1 and the inner diameter D2 in FIG. 24 are set, and 2 × D1 + D2 is 25 or more times the maximum outer shape d1 of the conducting wire. The angle θ formed by the lines indicating the two winding widths D1 is preferably set between 180 degrees and 90 degrees. However, in FIG. 23, when Rs> Rw is satisfied when the winding width D1 is approximately ¼ or less of the inner diameter D2 and the shorted coils face each other, θ is close to zero. It can also be a shape.

  25 (A) and 25 (B) compare the magnetic field strengths of the coil 1b wound in the cross-sectional umbrella shape shown in FIG. 24 and the cross-sectional planar type coil 1a shown in FIG. 2 (A). It is a figure for demonstrating. In the coil 1a shown in FIG. 2A, as shown in FIG. 25B, the magnetic field strength at the planar position becomes stronger at the central portion and becomes weaker toward the periphery. On the other hand, FIG. 25A shows the magnetic field strength at the planar position when the coil 1b wound in the cross-sectional umbrella shape shown in FIG. 24 is turned upside down. As shown in FIG. 25 (A), the coil 1b wound in an umbrella shape can obtain a substantially uniform magnetic field intensity on the entire surface on the coil facing surface.

  The coil 1b may be wound so that the cross section draws a wavy line.

(Description of an example of a coil in which a conductive wire is wound on an insulating material)
FIG. 26 is a cross-sectional view of a coil in which a conducting wire is wound on an insulating material. In this example, the coil 1a shown in FIG. 2A is arranged on the insulating material 5, and the insulating resin 6 is applied on the single conductor 11 of the coil 1a. In this example, since the insulating resin 6 as an insulating member enters and is fixed between the conductors 11, deformation of the coil 1a can be prevented. The coil 1a may be fixed on the insulating material 5 with an adhesive instead of the insulating resin 6. With such a configuration, the thermal resistance θi can be reduced, and the heat generation of the coil can be suppressed.

  Specifically, there is no problem even if there is a potential difference of about 10,000 V between the primary side and the secondary side by installing an insulating material 5 of about 5 mm between the coils. Further, since the heat resistance θi can be reduced and the heat generation of the coil can be reduced, large power can be transmitted.

(Description of another embodiment of the coil)
27 is a diagram showing a coil of a power transmission device according to another embodiment of the present invention. FIG. 27 (A) is a plan view, and FIG. 27 (B) is a line 2B-2B in FIG. 27 (A). The cross section along is enlarged and shown.

  In the embodiment shown in FIG. 27 (B), a conductor 11 in which an insulation coating 13 is applied to a single conductor 12 having a maximum diameter d1 of 0.4 mm or more is wound as a single conductor 12 in a flat plate air-core single layer spiral shape. As shown in FIG. 27 (B), a gap t of 0.2 mm or more is provided between the adjacent conductors 11 of the coil 1c so as to be loosely wound. Also in this example, the insulating coating 13 may be either a thin coating that is thin, such as a formal single conductor, or a thick coating, such as a vinyl wire. Moreover, since the space | interval t (mm) is provided between the adjacent conducting wires 11, you may use the bare conducting wire which has not provided the insulating coating 13. FIG. When the maximum outer diameter d1 is less than 0.4 mm, a gap of t = d1 / 2 (mm) is provided. In addition, this embodiment is the same also about the conducting wire of other embodiment mentioned later, and the largest outer diameter d1 (mm) is described with d.

  Also in this embodiment, the coil 1c has a coil outer diameter D of at least 25 times the maximum diameter d1 of the single conductor 12 and the number of turns of the conductor 11 is 8 or more, where D is the outer diameter of the coil. Configured as follows. Furthermore, the self-inductance of the coil 1c is required to satisfy at least 2 μH or more.

  Further, the effective series resistance of the coil 1c alone shown in FIG. 27A is Rw (Ω), and the effective series resistance of the coil 1c when the other coil facing the coil 1c is short-circuited is Rs ( Ω), and assuming that the maximum frequency satisfying Rs> Rw is f1 (Hz), the coil 1c, which is a power transmission coil, or the other coil has a frequency less than f1 (Hz), fd (Hz ). Preferably, when the coil 1c is used for both one coil and the other coil, Rs> Rw is satisfied at 100 kHz.

  Furthermore, when the effective series resistance of the coil 1c when the other opposing coil is opened is Rn (Ω), and the maximum frequency satisfying Rs> Rn ≧ Rw is f2 (Hz), The coil 1c, which is a power transmission coil, or the other coil is driven at fd (Hz), which is a frequency less than f2 (Hz).

Furthermore, when the thermal resistance of the coil 1c is θi (° C / W), the allowable operating temperature of the coil 1c is Tw (° C), the ambient temperature of the place where the coil 1c is installed is Ta (° C), and power is transmitted When the alternating current flowing through the coil 1c is Ia (A), the relationship of Rw ≦ (Tw−Ta) / (Ia ² × θi) is satisfied.

  As shown in FIG. 2B, when a single conducting wire is wound closely, the magnetic flux Φ generated by the current flowing through the conducting wire penetrates the neighboring conducting wire and generates an eddy current in the neighboring conducting wire. At the same time, the eddy current affects the current flowing in the conducting wire, and the effective series resistance Rw (Ω) increases. In this embodiment, by providing a gap, as shown in FIG. 27 (B), the magnetic flux Φ generated in the vicinity of the conducting wire by the current flowing through one of the neighboring conducting wires does not penetrate the neighboring conducting wire, The penetration of the magnetic flux Φ can suppress eddy current loss that occurs in the adjacent conductors.

  Since the eddy current loss increases in proportion to the frequency, an increase in the effective series resistance Rw (Ω) due to an increase in frequency can be prevented by providing a gap between adjacent conductors. Note that the magnetic flux Φ in the vicinity of the conductive wire 11 is strong, and the magnetic flux Φ suddenly weakens as soon as it is separated from the conductive wire 11, so that even a slight gap is effective, and the width of the gap can be expanded to an arbitrary dimension. If it is too wide, it may be impossible to secure the number of windings of eight times, or the self-inductance of the coil may be 2 μH or less.

(Description of other examples of coils)
FIG. 28 is a diagram showing a coil of a power transmission device according to still another embodiment of the present invention, FIG. 28 (A) shows a plan view, and FIG. 28 (B) shows a line 3B- in FIG. The cross section along 3B is enlarged and shown.

  In this embodiment, the adjacent conductors 11 in the outer peripheral part of the coil 1d are closely wound closely, and the adjacent conductors 11 in the inner peripheral part are loosely wound with a gap to be wound into a flat plate air-core single layer spiral. It has been turned. As a result, as shown in FIG. 28B, the width t1 of the gap between adjacent conductors provided on the outer periphery of the coil 1d is equal to the width t2 of the gap between adjacent conductors provided on the inner periphery of the coil 1d. It is narrower than.

  Also in this embodiment, in the coil 1d, when the coil outer diameter is D, the coil outer diameter D is at least 25 times the maximum diameter d1 of the single conductor 12, and the number of turns of the conductor 11 is 8 or more. Configured as follows. Furthermore, the self-inductance of the coil 1d is required to be at least 2 μH or more.

  Further, the effective series resistance of the coil 1d alone shown in FIG. 28A is Rw (Ω), and the effective series resistance of the coil 1d when the other coil facing the coil 1d is short-circuited is Rs ( Ω), and assuming that the maximum frequency satisfying Rs> Rw is f1 (Hz), the coil 1d as the power transmission coil or the other coil has a frequency less than f1 (Hz), fd (Hz ). Preferably, when the coil 1d is used for both one coil and the other coil, Rs> Rw is satisfied at 100 kHz.

  Furthermore, when the effective series resistance of the coil 1d when the other opposing coil is opened is Rn (Ω), and the maximum frequency satisfying Rs> Rn ≧ Rw is f2 (Hz), The coil 1d, which is a power transmission coil, or the other coil is driven at fd (Hz), which is a frequency less than f2 (Hz).

Furthermore, when the thermal resistance of the coil 1d is θi (° C / W), the allowable operating temperature of the coil 1d is Tw (° C), the ambient temperature of the place where the coil 1d is installed is Ta (° C), and power is transmitted When the alternating current flowing through the coil 1d is Ia (A), Rw ≦ (Tw−Ta) / (Ia ² × θi) is satisfied at fd (Hz).

  Since the effective series resistance Rw (Ω) is low over a wide frequency range and the maximum frequency f2 (Hz) that satisfies Rs> Rn ≧ Rw is high, the coil of the above embodiment has good power transmission characteristics.

  FIG. 29 is a computer simulation of the magnetic flux distribution generated by the outermost winding in FIG. The coil inner diameter is 5 mm, the conductor diameter is 1 mm, the number of turns is 25 turns, and the magnetic flux distribution generated by the coil having a conductor interval of 1.7 mm is shown. The conductor interval is the distance between the centers of the conductors.

  Referring to FIG. 29, the magnetic flux generated by the outermost winding is distorted in the inner periphery. Further, the windings that enter the inner circumference part from the outermost circumference also have the same magnetic flux distribution. At the inner periphery, the magnetic flux distribution has a substantially circular shape. Also from the result of this computer simulation, it can be seen that the magnetic flux density in the inner periphery is high and the magnetic flux density in the outer periphery is low. This is also shown in FIG.

  As is clear from the results of the computer simulation described above, the magnetic flux density generated by the coil closely wound in a plane spiral shape is low near the outer periphery and high at the inner periphery. Therefore, by configuring the coil 1d so that the outer peripheral portion is honey-wound and the inner peripheral portion is sparsely wound, the magnetic flux density on the coil facing surface is made as constant as possible, and relative to the coil facing the coil 1d. It is possible to reduce a decrease in transmittable power when the position changes. Since the inner periphery has a high magnetic flux density, eddy current loss can be prevented by providing a gap. The effect of the void is as described above.

  FIG. 30 is a cross-sectional view showing an assembly of bare single conductors used in a coil of a power transmission device according to still another embodiment of the present invention. In the above-described embodiment, the conductor 11 is a single conductor 12 having an insulating coating 13 applied thereto, whereas this embodiment has a maximum diameter d2 of 0.3 mm or less as shown in FIG. A conductive wire 11c called a so-called vinyl wire in which an assembly of bare single conductive wires 14 is covered with an insulating coating 13c is used. It is preferable that the conductive wire 11 which is an aggregate of the bare single conductive wires 14 is configured without being twisted. Note that the maximum diameter d2 of the bare single conductor wire 14 is selected to be 0.3 mm or less from the wire diameter of FIG. 16 showing the skin effect and the influence of overcurrent loss.

  An assembly of bare single conductors cannot maintain the shape of an electric wire unless it is twisted only by the collection of bare single conductors. The grounding wire of the lightning rod is called a demon stranded wire, and it is known that a plurality of bare single conductor wires are not twisted at a single direction pitch but are randomly twisted to lower the effective series resistance.

  Further, when a strong twist pitch is applied to the assembly of the plurality of bare single conductors 14, the bare single conductors 14 are in close contact with each other, and the conductor cross section in FIG. 28 is the same as the single conductor 12 in FIG. The skin effect and eddy current loss cannot be reduced. However, referring to the coil 1E formed using a single conductor of 1 mm, as will be described later, in the case of using a collection of bare single conductors as the conductor forming the coil and winding with a gap between the conductors In some cases, the characteristics at a high frequency are better when appropriate twisting is performed. In most cases, a coil actually wound with a vinyl wire satisfies the relationship Rs> Rn ≧ Rw in a frequency band of 1 MHz or higher.

  As a winding method, as shown in FIG. 2 (A), a method in which adjacent conductors 11 are brought into close contact with each other, or as shown in FIG. 27A, a gap is provided between adjacent conductors 11 for winding. The method of turning is applicable. In either case, the coil can be formed by winding it into a flat air core single layer spiral. When the conducting wire 11c is closely wound, a gap by the insulating coating 13c can be provided between the adjacent conducting wires. By providing the gap in the same manner as in the embodiment shown in FIG. As shown in FIG. 27 (B), the magnetic flux Φ generated in the vicinity of the conducting wire is prevented from passing through the adjacent conducting wire due to the current flowing through one of the neighboring conducting wires, and the magnetic flux Φ penetrates the neighboring conducting wire. In addition to suppressing eddy current loss occurring in the eddy current, it is possible to prevent the eddy current from affecting the current flowing in the conducting wire and to reduce the increase in effective series resistance. In addition, the influence of the skin effect can also be reduced.

  Since the effective series resistance Rw (Ω) is low over a wide frequency range and the maximum frequency f2 (Hz) that satisfies Rs> Rn ≧ Rw is high, the coil of the above embodiment has good power transmission characteristics.

(Description of an example of a coil having an insulating layer inside a conductor)
FIG. 31 is a view showing a coil of a power transmission device having an insulating layer inside a conductor forming a coil in still another embodiment of the present invention, FIG. 31 (A) is a plan view, and FIG. ) Is an enlarged cross-sectional view taken along line 4B-4B in FIG. FIG. 32 is a cross-sectional view of a conductive wire used in the coil shown in FIG.

  In this embodiment, a single conductor 15 shown in FIG. 32 (B) is made of a transparent resin such as polyurethane as an insulation coating 16, for example, an assembly conductor of conductor 8 having a cross-sectional structure shown in FIG. 32 (A). A certain 11d (also referred to as a litz wire) is used as a conductor forming a coil.

  In the conductor 11d shown in FIG. 32A, the ratio between the cross-sectional area of the conductor 15 and the cross-sectional area of the insulating coating 16 is determined by the diameter of the conductor, the number of conductor divisions inside the conductor, etc. The conducting wire 11d is composed of, for example, an assembly of seven single conducting wires 8 each provided with an insulating coating 16. For the single conductor 8, when the maximum diameter of the conductor 15 excluding the insulating coating 16 is d4 (mm), d4 is 0.3 mm or less, and the thickness α of the insulating coating is selected to be (d4) / 30 or more. Is preferred. In addition, since the air layer other than the insulating coating 16 is also an insulator layer, as shown in FIG. 30A, a minimum circle including seven single conductors 8 is drawn, and a regular hexagon inscribed in the circle is considered. When the total cross-sectional area of the regular hexagonal area and the seven conductors 15 having the wire diameter d4 is calculated, the ratio of the insulator layer in the conductor cross section is about 11% including the air layer. In addition, the maximum diameter d4 of the single conductor 8 is selected to be 0.3 mm or less from the wire diameter of FIG. 16 showing the skin effect and the influence of overcurrent loss.

  As shown in FIG. 31A, the coil 1e is formed by winding a conductive wire 11d around a bobbin 7 made of an insulating resin, as shown in FIG. 31B. The coil 1e is configured such that when the coil outer diameter is D, the coil outer diameter D is at least 25 times the maximum diameter d3 of the litz wire 11d, and the number of turns of the conducting wire 11d is eight or more. Furthermore, it is a condition that the self-inductance of the coil 1e satisfies at least 2 μH or more.

  Moreover, when the effective series resistance of the coil 1e alone at the frequency at which power is transmitted is Rw (Ω), two coils 1e shown in FIG. 31A are opposed to each other, and one of the opposed coils is short-circuited, When the effective series resistance of the other coil is Rs (Ω), and the highest frequency satisfying Rs> Rw is f1 (Hz), one coil or the other coil that is a power transmission coil is f1 ( Driven at a frequency fd (Hz) less than Hz.

  Furthermore, when the effective series resistance of the other coil when one of the opposing coils is opened is Rn (Ω) at the frequency at which power is transmitted, the maximum frequency satisfying Rs> Rn ≧ Rw is f2 Assuming (Hz), one coil or the other coil which is a power transmission coil is driven at a frequency fd (Hz) less than f2 (Hz).

Furthermore, when the thermal resistance of the coil 1e is θi (° C / W), the allowable operating temperature of the coil 1e is Tw (° C), the ambient temperature of the place where the coil 1e is installed is Ta (° C), and power is transmitted When the alternating current flowing through the coil 1e is Ia (A), Rw ≦ (Tw−Ta) / (Ia ² × θi) is satisfied at fd (Hz).

  In the embodiment shown in FIG. 31, the conductive wire 11 d composed of an assembly of a plurality of single conductive wires 8 shown in FIG. 32A is wound in multiple layers around the bobbin 7, but the present invention is not limited to this. The single-layer close winding shown in FIG. 27, the single-layer loose winding shown in FIG. 27A, and the adjacent conductors in the outer peripheral portion shown in FIG. The conducting wire may be loosely wound with a gap.

  Since the effective series resistance Rw (Ω) is low over a wide frequency range and the maximum frequency f2 (Hz) that satisfies Rs> Rn ≧ Rw is high, the coil of the above embodiment has good power transmission characteristics. In the present embodiment, several litz wires may be twisted to form one stranded wire, and several twisted wires may be twisted together to form a thick electric wire.

(Description of conductor structure)
33, FIG. 34, FIG. 35, FIG. 36, and FIG. 37 (A) to FIG. 37 (C) are diagrams showing the structure of the conductive wire that constitutes the coil of the power transmission device according to another embodiment of the present invention.

  In FIG. 33, when the pipe-shaped conductor 17 is filled with the insulating material 18, and the pipe is hollow, the pipe is prevented from being bent and cannot be bent. If the pipe itself has flexibility depending on the material of the pipe and the thickness of the pipe, the inside of the pipe may be hollow.

  FIG. 34 shows an example in which the conductor 20 is divided and formed on the insulating material 19.

  FIG. 35 shows an example in which the conductor 22 is divided and formed on the insulating material 21, and the conductor 23 is also formed inside the insulating material 21.

  FIG. 36 shows an example in which the conductor 27 is divided and formed on the insulating material 26 having a cross-shaped cross section.

  37 (A) to 37 (C) show a structure in which a foil-like conductor and an insulating material are overlapped, and a conductor is formed so that a cross-section is spiral and conductors and insulators are alternately present. That is, the foil conductor 24 and the insulating material 25 are laminated as shown in FIG. 37A, and the laminated foil conductor 24 and the insulating material are wound as shown in FIG. As shown in C), a conductive wire having a spiral cross section is formed.

  In FIGS. 33 to 36, the conductor layer is provided on the periphery of the single conductor constituting the conductor. However, the conductor layer may or may not be provided with an insulating coating as long as it conforms to the embodiment.

  As described above, FIGS. 33 to 36 are embodiments in which an insulating layer is provided inside a conductor forming a coil, and the insulating material is provided with an insulating layer inside the conducting wire, and the conducting wire is made flexible so that the bending of the conducting wire is possible. It facilitates processing.

  In addition, the air layer existing in the conductor formed by bundling the single conductor shown in FIG. 32 (A), and the conductor shown in FIG. 32 (A) and FIGS. The air layer can also be regarded as an insulating material.

  In the embodiment of FIG. 32A and FIGS. 33 to 37, the surface area of the conductor constituting the conductor can be increased, and the eddy current loss due to the magnetic flux penetrating the conductor increases in proportion to the volume of the conductor. . For this reason, since the volume of the conductor existing in the magnetic flux path passing through the conductor in the conductor can be reduced, the increase in the effective series resistance Rw (Ω) due to the skin effect and eddy current loss can be prevented.

  The embodiment shown in FIG. 32A and FIGS. 33 to 37 is merely an example in which the conductor constituting the conducting wire is divided and an insulating layer is provided inside the conducting wire, and it goes without saying that other embodiments exist.

  Each coil described above can be used not only as a power transmission coil and a power reception coil in a power device in which a primary side coil and a secondary side coil can be separated but also as a transformer (transformer) in which two coils cannot be separated. It is.

  The coil shown in each embodiment described above does not need to use the same coil as the primary side coil and the secondary side coil in each embodiment. For example, the coil 1a shown in the embodiment of FIG. Even if it exists, you may use the coil from which a turn number and an external shape differ as a primary side coil, a secondary side coil, or the coil 1a of embodiment of FIG. 2 (A), and the coil of embodiment of FIG. 27A 1c can also be combined. With such a configuration, the winding ratio can be arbitrarily set. In addition, it is possible to realize a power transmission means using a coil that can be stepped up and down.

  In such a case, Rw (Ω) is measured for each coil alone, and Rn (Ω) and Rs (Ω) are measured for each coil with Rs> Rw and Rs> Rn ≧ Rw. It is sufficient to check whether the relationship is satisfied. As described above, the power transmission performance when the two coils are combined can be predicted by observing the frequency characteristics of Rw, Rn, and Rs in each coil on the primary side and the secondary side.

  Alternatively, several different types of coils may be created, and in each coil, the same coil may be opposed, and the frequency characteristics of Rw, Rn, and Rs may be measured, and then coils having good characteristics may be used in combination. It is more preferable to measure the frequency characteristics of Rw, Rn, and Rs in the primary side coil and the secondary side coil after the combination.

(About the coil configuration to prevent unwanted radiation)
FIG. 38 is a diagram showing the structure of the coil 1 f that prevents unwanted radiation.

  In FIG. 38, at least one magnetic material plate 51 is provided on one side facing the coil 50. Thus, by providing at least one magnetic material plate 51 on one surface side of the coil 50, the coil 1f that prevents unnecessary radiation can be realized. In the conventional example, it is described that a coil having a configuration equivalent to that of the coil 1f has an effect of improving power transmission performance. However, the coil of the power transmission device of various configurations equipped with the magnetic material plate in the embodiment of the present invention to be described later improves the power transmission performance and reduces unnecessary radiation as compared with the conventional example. It has the effect of preventing fluctuations in coil characteristics when a metal body is close to the surface opposite to the coil equipment surface. Furthermore, the coils of the power transmission devices having various configurations according to the embodiments of the present invention to be described later have the same effects even when other structural factors such as the type of the conductive wire and the outer diameter change.

As described above, in the coil 1f, the coil 50 is short-circuited with the effective series resistance of one coil alone in the air-core state as Rw (Ω) and the other coil facing the one coil in the air-core state. When the effective series resistance of one coil is Rs (Ω), one coil satisfying Rs > Rw is used at 100 kHz. For example, as the coil 50, the coils 1B to 1G which are the embodiments of the present invention described above are used.

Furthermore, when the coil 1f to the coil 1t having the magnetic material plates 51 or 511 and 512, the metal plate 55, and the insulating plate 52 shown in FIGS. 38 to 49 are used as one coil, the coils 1f to 1t at 100 kHz are used. However, it is preferable that Rs > Rw is satisfied.

Furthermore, when the coil 1f equipped with the magnetic material plate 51 is one coil, the coil 1f preferably satisfies Rs > Rw at 100 kHz.

Assuming that the highest frequency satisfying Rs > Rw of the coil 1f is f1 (Hz), the power transmission device 100 equipped with the coil 1f transmits power at a frequency less than f1 (Hz).

  When the coil 1f is the power transmission coil 1 of the power transmission device 100, the coil 1f is driven at a frequency fa (Hz) less than f1 (Hz) by the AC power supply 30b shown in FIG.

  When the power transmission unit 30 of the power transmission device 100 includes the coil 1f, the power transmission unit 30 including the coil 1f is a power transmission device of the power transmission device of the present invention.

  When the power receiving unit of the power transmission device 100 includes 40 and the coil 1f, the power receiving unit 40 including the coil 1f is a power receiving device of the power transmission device of the present invention.

(Other coil configurations that prevent unwanted radiation)
FIG. 39 is a diagram showing a coil 1 g in which an insulating plate 52 is provided between the coil 50 and the magnetic material plate 51. In FIG. 39, the insulating plate 52 can suppress an increase in the effective series resistance Rwa (Ω) of the coil 1g when the frequency is increased. Further, it is possible to prevent the Q of the coil 1g from being lowered when the frequency is increased.

  FIG. 40 is a diagram showing a coil 1 h in which two layers of a magnetic material plate 511 and a magnetic material plate 512 are provided on one side of the coil 50. In FIG. 40, the coil 1h is provided with the magnetic material plate 511 and the magnetic material plate 512, so that the coil inductance can be increased and the coil Q can be increased as compared with the configuration of the coil 1f.

FIG. 41 is a view showing a coil 1j in which an insulating plate 52 having a thickness of I (mm) is provided between two magnetic material plates 511 and 512 constituting the coil 1h shown in FIG. In FIG. 41, the insulating plate 52 can suppress an increase in the effective series resistance Rw (Ω) of the coil 1j when the frequency is increased. Further, it is possible to prevent the Q of the coil 1j from being lowered when the frequency is increased. Such a configuration increases the thickness of the coil but is suitable for use in a power transmission coil. In particular, the power transmission coil converts electrical energy into magnetic energy, and it is preferable to use a power transmission coil to eliminate the cause of unnecessary radiation. The thickness I (mm) of the insulating plate 52 is preferably at least half of the thickness of the magnetic material plate 511 or 512. The effect of the insulating plate 52 is as described above.

(Regarding the coil configuration that prevents fluctuations in coil characteristics when a metal object is in close proximity)
FIG. 42 is a diagram showing the structure of the coil 1k that prevents fluctuations in coil characteristics when a metal body is close to the coil. 42, a metal plate 55 has a thickness M (mm), and an insulating plate 54 is provided on one surface side of the coil 50 so as to face the coil 50 through a predetermined distance G (mm). The dimension of the metal plate 55 is equal to or greater than the dimension of the coil 50 and is disposed so as to face the entire surface of the coil 50. For the coil 50, for example, the coil 1B to the coil 1G which are the embodiments of the present invention described above are used. The predetermined distance G (mm) is the same as the thickness of the insulating plate 54 and is selected to be 10% or more of the coil outer diameter D. Since the fluctuation of the characteristics of the coil 50 is small, the longer the predetermined distance G (mm) is, the better. When one metal is provided with a metal plate 55 as shown in FIG. 42, a coil capable of preventing characteristic variation when another metal body approaches the coil 50 can be realized.

  Note that the insulating material 5 shown in FIG. 26 described above may be used for the insulating plate 54, and the coil 1 a may be fixed to the insulating resin 6 as shown in FIG. 26. The insulating material 5 shown in FIG. 26 may be equipped with either a metal plate or a coil 1a. Therefore, not only the coil 1k shown in FIG. 42 but also the coil 1g shown in FIG. 39, the coil 1n shown in FIG. 44, the coil 1p shown in FIG. 45, the coil 1s shown in FIG. 48, and the coil 1t shown in FIG. 26 configurations can be applied.

(Concerning the configuration of the coil that prevents both the proximity effect of the metal body and unnecessary radiation)
FIG. 43 is a diagram showing a configuration of the coil 1m that prevents both the proximity effect of the metal body and unnecessary radiation. In FIG. 43, instead of the interval of a predetermined distance G (mm) provided between the metal plate 55 disposed on the opposite side of the surface of the insulating plate 54 facing the coil 50 in FIG. Is provided. For the coil 50, for example, the coil 1B to the coil 1G which are the embodiments of the present invention described above are used. The metal plate 55 is a metal or alloy having diamagnetic or paramagnetic magnetic properties and has a thickness of 0.1 mm or more. The metal plate 55 has the same dimensions as the magnetic material plate 51. As described in Patent Document 3, if the metal plate 55 is made larger than the dimension of the magnetic material plate 51, there is a problem when the wire winding outer diameter of the opposing coil is larger than the wire winding outer diameter of the coil 1 m. Arise. The coil configuration in the case where the outer diameter of the winding of the opposing coil is larger than the outer diameter of the winding of the coil 1m will be described later.

  FIG. 44 is a diagram showing a configuration of a coil 1n that prevents both the proximity effect of a metal body and unnecessary radiation according to another embodiment of the present invention. In FIG. 44, the insulating plate 52 is provided between the magnetic material plate 51 and the metal plate 55. The effect of the insulating plate 52 is as described above. The metal plate 55 is a metal or alloy having diamagnetic or paramagnetic magnetic properties and has a thickness of 0.1 mm or more.

  FIG. 45 is a diagram showing a configuration of a coil 1p that prevents both the proximity effect of a metal body and unnecessary radiation according to another embodiment of the present invention. In FIG. 45, the insulating plate 52 is provided between the coil 50 and the magnetic material plate 51. The effect of the insulating plate 52 is as described above. The metal plate 55 is a metal or alloy having diamagnetic or paramagnetic magnetic properties and has a thickness of 0.1 mm or more.

  FIG. 46 is a diagram showing a configuration of a coil 1q that prevents both the proximity effect of a metal body and unnecessary radiation according to another embodiment of the present invention. In FIG. 46, a magnetic material plate 511 and a magnetic material plate 512 are provided on one side of the coil 50. By providing the two magnetic material plates 511 and 512, the inductance of the coil 50 can be increased and the Q of the coil 50 can be increased. Also, by providing the two magnetic material plates 511 and 512, fluctuations in coil characteristics due to the type and thickness of the metal plate 55 provided on the magnetic material plate 512 side can be reduced. Therefore, unlike the coil 1k to the coil 1p described above, the metal plate 55 can have any magnetic property and thickness. It is more preferable to use a metal or alloy having a diamagnetic or paramagnetic magnetic property and having a thickness of 0.01 mm or more as the metal plate 55. For the coil 50, for example, the coil 1B to the coil 1G which are the embodiments of the present invention described above are used.

  FIG. 47 is a diagram showing a configuration of a coil 1r that prevents both the proximity effect of a metal body and unnecessary radiation according to another embodiment of the present invention. In FIG. 47, a magnetic material plate 511 is provided on one side of the coil 50. The insulating plate 52 is provided between the magnetic material plate 511 and the magnetic material plate 512, and the metal plate 55 is provided on the magnetic material plate 512 side. The effect of the insulating plate 52 is as described above. The metal plate 55 has the same dimensions as the magnetic material plates 511 and 512. The thickness I (mm) of the insulating plate 52 is selected similarly to the coil 1j.

  FIG. 48 is a diagram showing a configuration of a coil 1s that prevents both the proximity effect of the metal body and unnecessary radiation according to another embodiment of the present invention. In FIG. 48, the insulating plate 52 is provided between the magnetic material plate 512 and the metal plate 55. The effect of the insulating plate 52 is as described above. The metal plate 55 has the same dimensions as the magnetic material plate 512.

  FIG. 49 is a diagram showing a configuration of a coil 1t that prevents both the proximity effect of a metal body and unnecessary radiation according to another embodiment of the present invention. In FIG. 49, the insulating plate 52 is provided on one side of the coil 50. The insulating plate 52 is provided with magnetic material plates 511 and 512 and a metal plate 55. The effect of the insulating plate 52 is as described above. The metal plate 55 has the same dimensions as the magnetic material plates 511 and 512.

  Even when three or more magnetic material plates are used, the place where the insulating material is provided is between the plurality of magnetic material plates 511 and 512, between the coil 50 and the magnetic material plate 51, as shown in FIG. There are various embodiments, such as between the plate 51 and the metal plate 55. The effect of the insulating plate 52 is as described above.

As described above, in the coils 1g to 1t, the coil 50 includes the effective series resistance of one coil alone in the air-core state as Rwa (Ω), and the other coil facing the one coil in the air-core state. Assuming that the effective series resistance of one coil when R is short-circuited is Rsa (Ω), one coil that satisfies Rs > Rw at 100 kHz is used. For example, as the coil 50, the coils 1B to 1G which are the embodiments of the present invention described above are used.

Further, when the coil 1g to the coil 1t are provided with the magnetic material plate 51 or 511, 512 and the metal plate 55, the coil 1g to the coil 1t satisfy Rs > Rw at 100 kHz. Is preferred.

Assuming that the highest frequency satisfying Rs > Rw from coil 1g to coil 1t is f1 (Hz), power transmission device 100 equipped with coil 1t to coil 1t transmits power at a frequency less than f1 (Hz). .

  When the coils 1g to 1t are the power transmission coil 1 of the power transmission device 100, the coils 1g to 1t are driven at a frequency fa (Hz) less than f1 (Hz) by the AC power supply 30b.

  When the power transmission unit 30 of the power transmission device 100 includes the coil 1g to the coil 1t, the power transmission unit 30 including the coil 1g to the coil 1t is a power transmission device of the power transmission device of the present invention.

  When the power reception unit 40 of the power transmission device 100 includes the coil 1g to the coil 1t, the power reception unit 40 including the coil 1g to the coil 1t is a power reception device of the power transmission device of the present invention.

  Detailed actions and effects of the coils 1g to 1t, which are coils equipped with at least one of the metal plate 55 and the magnetic material plates 51, 511, and 512, will be described in detail later.

(When the opposing coil outer diameter is different)
FIG. 50 is a three-dimensional view of elements constituting both opposing coils. As shown in FIG. 50, the opposing coils 1ma and 1mb are equivalent to the coil 1m shown in FIG. 43, and the coils 50a and 50b, the magnetic material plates 51a and 51b, and the metal plates 55a. 55b.

  FIGS. 51 and 52 are diagrams showing an opposed state when the outer diameters of the coils 50a and 50b are different from each other and are configured in the same manner as the coil 1m shown in FIG. The coil 50b having a large conductor winding outer diameter is referred to as a power transmission coil, and the coil 50a having a small conductor winding outer diameter is referred to as a power receiving coil.

  FIG. 51 shows a case where the centers of the opposing power transmission coil 1mb and power reception coil 1ma coincide. In FIG. 51, Da is the maximum distance from the center of the winding surface of the power receiving coil conducting wire constituting one coil to the end of the winding surface, and the winding of the power transmitting coil conducting wire constituting the other coil facing one coil The minimum distance from the center of the winding surface to the end of the winding surface is Db, and when Db> Da, the minimum distance from the center of the winding surface of the receiving coil conducting wire to the end of the magnetic material plate 51b is at least , Db + (Db−Da) × 2.

  In FIG. 52, the conductive wire winding surface of the opposing power receiving coil 1 ma is in the conductive wire winding surface of the power transmission coil 1 mb indicated by a dotted line, and the end of the conductive wire winding surface of the power receiving coil 1 ma and the power transmission coil 1 mb The state which the end of conducting-wire winding surface exists in the same position is shown. As shown in FIG. 52, the relative positions of the opposing power transmission coil 1mb and power reception coil 1a are permissible until the end of the power reception coil conductor winding surface is within the end of the power transmission coil conductor winding surface. As described in Patent Document 3, if a magnetic material plate having the same dimensions as the conductive wire winding surface of the power receiving coil 1ma is equipped, and a metal plate larger than the magnetic material plate is equipped, in the case of FIG. The metal plate faces the conductive wire winding surface of the power transmission coil 1mb. When the metal plate faces the conductive wire winding surface of the power transmission coil 1mb, the characteristics of the power transmission coil 1mb naturally change. Furthermore, even if a magnetic material plate having the same dimensions as the conductive wire winding surface is provided, if a metal plate exists on the back surface of the magnetic material plate, depending on the relative position of the power transmission coil 1mb and the power reception coil 1ma, the power transmission coil 1mb The metal plate faces the conductive wire winding surface. Therefore, the shape and size of the magnetic material plate must be determined so that the magnetic material of the other coil faces the conductive wire winding surface.

  In the case of FIG. 52, if the outer diameter of the power transmission coil 1mb is D1, and the outer diameter of the power reception coil 1ma is D2, the outer diameter of the magnetic material plate of the power reception coil 1ma is Y = D1-D2, and D2 + 2 × Y The dimensions are required. Alternatively, the dimension of 2 (D1-D2) + D2 = 2 × D1-D2 is required.

  FIG. 53 is a diagram illustrating a relative positional relationship between the power transmission coil 1mb and the power reception coil 1ma when both the power transmission coil 1mb and the power reception coil 1ma are elliptical. In FIG. 53, the minimum outer diameter of the power transmission coil 1mb is D11, the maximum outer shape of the power transmission coil 1mb is D12, the minimum outer diameter of the power reception coil 1ma is D21, the maximum outer diameter of the power reception coil 1ma is D22, Y1 = D11-D22, Y2 = Assuming D12-D21, the magnetic plate must have a minimum outer shape that is at least 2 × Y1 larger than the minimum outer diameter of the coil 50. The magnetic material plate has a maximum outer diameter of 2 × Y2 or less than the maximum outer diameter of the coil 50, and the power receiving coil 1ma has a conductor winding surface within the conductor winding surface of the power transmission coil 1mb. The size and shape of the magnetic material plate 51a are selected so that the magnetic material plate 51a mounted on the coil 1ma always faces the conductive wire winding surface of the power transmission coil 1mb.

  The above can be generalized as follows. The “coil” refers to a conductive wire winding surface. When the size and shape of the opposing coils are different, the maximum distance from the center or center of gravity of the larger coil to the coil end surface is La, and the minimum dimension from the center or center of gravity of the smaller coil to the coil end surface is Lb. La and Lb correspond to radii with respect to the diameters of D1 and the like described above. Therefore, the smaller coil has a dimension of 4 (La−Lb) + 2 × Lb = 4 × La−2 × Lb or less, and the smaller coil facing surface enters the larger coil facing surface. The smaller coil must be equipped with a magnetic material plate having a size and shape so that the magnetic material plate faces the larger coil facing surface.

  FIG. 54 is a diagram illustrating an example of the power transmitting coil 1 and the power receiving coil 2 that face each other when the coil facing surface is not circular. For example, as shown in FIG. 54A, it is assumed that the power receiving coil 2 is a square having a side of 40 mm. The power receiving coil 1ma is completely in the plane of the power transmitting coil 1mb. In this case, the minimum outer diameter D2 of the power reception coil 1ma is 40 mm, and the maximum outer diameter D1 of the power transmission coil 1mb is 57 × √2≈80 mm. Therefore, the magnetic material plate 51 provided in the power receiving coil 1ma may be a square having a side of 80 mm as shown in FIG.

  When Y in FIG. 52 is applied to FIG. 54A, Y = D1−D2 = 80−40 = 40 mm. The power receiving coil 1ma is equipped with a magnetic material plate having an outer diameter of D2 + Y × 2. Therefore, in FIG. 52, the receiving coil 1ma is a square magnetic material plate whose diagonal is D2 + Y × 2 = 40 + 40 × 2 = 120 mm (maximum outer dimension) and whose one side is 120 / √2≈85 mm (minimum outer dimension). You must equip at least 51. However, even when the relative angle between the power receiving coil 1ma and the power transmitting coil 1mb is changed and the power receiving coil 1ma is completely within the plane of the power transmitting coil 1mb as shown in FIG. It can be seen that the material plates 51 are completely opposed.

  51 to 54, the area of the magnetic material plate 51 of the power transmission coil 1mb is equal to or larger than the area of the coil, and the coil is within the area of the magnetic material plate 51, and the magnetic material of the power receiving coil 1ma. The plate is within the area of the power transmission coil 1mb and is not related to the magnetic material plate on the power transmission coil 1mb side. Further, the outer diameters of the power transmission coil 1mb and the power reception coil 1ma are the same or the outer diameter of the power reception coil 1ma is smaller, and the conductive wire winding surface of the power reception coil 1ma does not protrude from the conductive wire winding surface of the power transmission coil 1mb. As long as these conditions are satisfied, the outer diameter shape of the coil and the magnetic material plate is not limited.

  However, when the smaller coil end is completely within the larger coil end, the magnetic plate is sized and shaped to face the larger coil as the magnetic plate to be equipped on the smaller coil. And the mounting position of the magnetic plate to be mounted on the smaller coil must be selected.

(Characteristics of coil 1f to coil 1t)
FIG. 55 shows the effectiveness of each coil when the coil 1G shown in FIG. 15 is used as the coil 1f shown in FIG. 38, the coil 1g shown in FIG. 39, the coil 1h shown in FIG. 40, and the coil 1j shown in FIG. It is a figure which shows the relationship with the frequency of series resistance Rw ((ohm)).

  FIG. 56 is a diagram showing a relationship with the frequency of Q of each coil when the coil 1G is used as each of the coils 1f, 1g, 1h, and 1j.

  As is clear from FIG. 55, when comparing the coil 1g and the coil 1f, in which the coil 50 is provided with the insulating plate 52 and the magnetic material plate 51, for example, the effective series resistance Rw (Ω) at 1 MHz is greater for the coil 1g. Low. As described above, by providing the coil 50 with the insulating plate 52, the effective series resistance Rw (Ω) of the coil in the high frequency region can be lowered. This tendency is the same even when the coil 1j in which the coil 50 is equipped with the magnetic material plate 511, the insulating plate 53, and the magnetic material plate 512 is compared with the coil 1h in which the coil 50 is equipped with the magnetic material plates 511 and 512. .

  As is clear from FIG. 56, the coil 1g equipped with the insulating plate 52 in the coil 50 has a higher Q of the coil at 1 MHz than the coil 1f equipped with only the magnetic material plate 51, for example. As apparent from FIGS. 55 and 56, even if the insulating plate 52 is provided in the coil 50, there is almost no difference in effective series resistance Rw (Ω) and Q at a frequency of 100 kHz. Thus, by providing the coil 50 with the insulating plate 52, the Q of the coil in the high frequency region can be increased. The effect of this insulating plate is the same in the coils 1m to 1t equipped with the magnetic material plates 51, 511, and 512 described above. Therefore, the description regarding an insulating board is abbreviate | omitted about the coil 1m to the coil 1t.

(Explanation when various metal plates face the coil)
FIG. 57 is a characteristic diagram showing the effective series resistance Rw (Ω) of the single coil 1G and the inductance Lw (μH) of the single coil 1G when various metal plates are brought close to each other using the coil 1G. .

  As shown in FIG. 57, the coil of the configuration (1) represents the effective series resistance Rw (Ω) and the inductance Lw (μH) of the coil 1G alone. The coil of the configuration (2) is left blank because it is used when a magnetic material plate described later is provided. The coil of the configuration (3) is in a state where an aluminum (Al) foil having a thickness of 12 μm is brought close to the coil 1G. The coil of the configuration (4) is in a state where an aluminum plate having a thickness of 0.1 mm is brought close to the coil 1G. The coil of the configuration (5) is in a state in which an aluminum plate having a thickness of 0.5 mm is brought close to the coil 1G. The coil of the configuration (6) is in a state in which an aluminum plate having a thickness of 3 mm is brought close to the coil 1G. The coil of the configuration (7) is in a state in which a copper foil (Cu) having a thickness of 35 μm is brought close to the coil 1G. The coil of the configuration (8) is in a state in which a copper plate having a thickness of 0.1 mm is brought close to the coil 1G. The coil of the configuration (9) is in a state in which a copper plate having a thickness of 0.5 mm is brought close to the coil 1G. The coil of the configuration (10) is in a state in which an iron plate (Fe) having a thickness of 0.5 mm is brought close to the coil 1G. FIG. 57 shows the effective series resistance Rw (Ω) and the inductance Lw (μH) at 100 kHz of the coils of the configurations (3) to (10) for comparison with the characteristics of the coil 1G alone of the configuration (1). It is shown as a bar graph.

(Construction and characteristics of the coil excluding the influence of proximity to the metal plate)
FIG. 58 is a characteristic diagram showing the effective series resistance Rw (Ω) of the single coil 1Ga and the inductance Lw (μH) of the single coil 1Ga when various metal plates are brought close to the coil 1G with a distance of 10 mm. It is. In other configurations, the metal plate provided in the coil 1Ga is the same as described above. Coil 1Ga is an embodiment of coil 1k shown in FIG.

  FIG. 59 shows the effective series resistance Rw (Ω) of the coil 1Gb alone and the inductance Lw (μH) of the coil 1Gb alone when various metal plates are brought close to the coil 1G provided with one magnetic material plate 51. FIG. The coil of the configuration (2) is in a state where the coil 1Gb is equipped with one magnetic material plate 51 and no metal plate is brought close to the coil 1Gb. In other configurations, the metal plate provided in the coil 1G is the same as described above. Coil 1Gb is an embodiment of coil 1f shown in FIG.

  FIG. 60 shows the effective series resistance Rw (Ω) of the coil 1Gc alone and the coil 1G alone when various metal plates are brought close to the coil 1Gc provided with the two magnetic material plates 511 and 512 in the coil 1G. It is a characteristic view which shows inductance Lw ((micro | micron | mu) H). The coil of the configuration (2) is in a state where the coil 1Gc is equipped with the two magnetic material plates 511 and 512 and the metal plates are not brought close to each other. In other configurations, the metal plate provided in the coil 1Gc is the same as described above. Coil 1Gc is an embodiment of coil 1q shown in FIG.

  FIG. 61 is a characteristic diagram showing the Q of each coil at 100 kHz of the coil 1Ga, the coil 1Gb, and the coil 1Gc described above.

  57 to 61, with reference to the frequency characteristic of the effective series resistance Rw (Ω) of the coil 1G alone shown in FIG. 15, measurement is performed by selecting 100 kHz where the effective series resistance Rw (Ω) is substantially equal to the DC resistance of the coil 1G. It is.

  First, the characteristic diagram shown in FIG. 57 will be examined. It can be seen from FIG. 57 that the effective series resistance Rw is about 0.2Ω and the inductance Lw is about 14 μH in the configuration of the coil 1G alone. In the coil 1G having the configuration (3) in which 12 μm aluminum foils are closely opposed to each other, the effective series resistance Rw is 3Ω or more, and the inductance Lw is reduced to about 5.5 μH. Looking at the characteristic diagrams of configurations (4) to (6) in which an aluminum plate of various thicknesses, which is a paramagnetic metal, is opposed to the coil 1G, when the aluminum thickness is 0.1 mm or more, the thickness is As the value increases, the effective series resistance Rw (Ω) of the coil decreases and the inductance Lw (μH) increases. This tendency is the same in the coils of configurations (8) and (9) in which copper, which is a diamagnetic metal, is opposed to the coil 1G. When the copper plate is thin, the effective series resistance Rw (Ω) of the coil decreases and the inductance Lw (μH) also decreases. When the thickness of the copper plate is about 0.5 mm, the effective series resistance Rw (Ω) of the coil has characteristics that are not significantly different from the 0.5 mm aluminum plate of the configuration (5). When a 0.5 mm iron plate, which is a ferromagnetic metal, is placed close to and opposed to the coil 1G, the effective series resistance Rw (Ω) is the same as when the aluminum foil in the configuration (3) is placed close to the coil 1G. Is 10 times or more, and the inductance Lw is reduced to about 8.5 μH. That is, the coil characteristics do not fluctuate due to the magnetic properties of the metal as described in Patent Document 4, but the coil thickness depends on the thickness of the metal plate that is in close proximity to the coil wound in a planar air-core spiral shape. Characteristics vary.

  Each coil of configurations (3) to (10) shown in FIG. 57 has an excessive effective series resistance Rw (Ω) and an inductance Lw (μH) that is too small compared to the air-core state. Therefore, the coils of configurations (3) to (10) shown in FIG. 57 cannot actually be used as coils of the power transmission device. FIG. 57 shows data to be compared with FIGS. 58 to 61 shown below. Incidentally, in the aluminum foil having a thickness of 12 μm, although the decrease rate of the inductance is small, the increase rate of the effective series resistance Rw (Ω) is 15 times or more that of the coil 1G alone. When the thickness of the aluminum plate of the configuration (4) is 0.1 mm, it can be inferred that some transition point exists between 10 μm and 100 μm (0.1 mm) when the inductance increases. . Looking at the data of the copper plates of the configuration (7) to the configuration (9), a tendency almost the same as that of the configuration (4) to the configuration (6) can be seen. Since copper is a diamagnetic metal, it cannot be determined, but with a thickness of about 30 μm as a boundary, a metal plate thinner than that has a reduced rate of decrease in inductance Lw (μH) and has an effective series resistance Rw (Ω). It is estimated that the rate of increase will rise rapidly. This is because the 0.1 mm thick aluminum plate and the copper plate in the configuration (4) and the configuration (8) are both close to the 0.5 mm thick aluminum plate and the copper plate in the configuration (5) and the configuration (9). It can be inferred from the fact that the characteristics are shown. The increase rate of the effective series resistance Rw (Ω) of the 35 μm-thick copper foil of the configuration (7) is smaller than the increase rate of the effective series resistance Rw (Ω) of the aluminum foil of the configuration (3) of 12 μm. Is presumed to be due to the thickness.

  FIG. 58 shows the characteristics of the coil 1Ga shown in FIG. 42 in which the various metal plates shown in FIG. 57 are opposed to the coil 1G via an insulator of 10 mm. As is clear from FIG. 57, in FIG. 58, the increase rate of the effective series resistance Rw (Ω) and the decrease rate of the inductance Lw (μH) are also small. It can be seen that the characteristics of the coil 1Ga are greatly improved by using an insulator of 10 mm. In particular, the value of the inductance Lw has decreased only to about 11.7 μH compared to about 13.7 μH in the air-core state. The value of Lw (μH) is almost the same in each configuration, and can be used for a power transmission device. However, when the 12 μm thick aluminum foil of the configuration (3), the 35 μm thick copper foil of the configuration (7), and the 0.5 mm iron plate as the ferromagnetic material of the configuration (10) face the coil 1G, the coil 1G Since the increase rate of the effective series resistance Rw (Ω) is large and power loss due to Rw (Ω) occurs, such a configuration is not suitable for use in a power transmission device.

  That is, referring to FIG. 58, a means for providing a predetermined distance G (mm) between the coil and the metal is equipped, and a metal plate having a diamagnetic or paramagnetic magnetic property of 0.1 mm or more. Alternatively, the use of an alloy can eliminate the influence of a metal body close to the air-core coil. In the configurations other than the configuration (1) and the configuration (2) shown in FIG. 58, various metals including a ferromagnetic metal such as iron are placed close to the opposite side of the metal plate to the coil facing surface. Neither change in μH) nor change in effective series resistance Rw (Ω) is observed. In addition, there is no change in power transmission performance.

  In paragraph No. 0022 of Patent Document 4, it is described that a metal plate having a size smaller than that of the magnetic field type antenna (coil) may be used. However, in order to eliminate the influence of the proximity of the metal body of the coil formed by winding the conducting wire in a plane spiral shape, the above-mentioned predetermined distance G (mm) is provided, and the thickness is 0. It must be equipped with a metal or alloy plate of the same size as the coil that is 1 mm or more.

  Note that paragraph number 0022 of Patent Document 4 describes that the metal plate is divided. The inventor of the present application measured the characteristics by dividing a 0.1 mm copper foil with the coil of the configuration (8) using the coil 1Ga, and Lw = 12.3 μH and Rw = 0.29Ω. This configuration has better characteristics than Lw = 11.7 μH and Rw = 0.23Ω when the copper plate is not divided. As described above, this is presumably because the eddy current loss that increases in proportion to the volume of the metal body decreases. This is also described in paragraph No. 0022 of Patent Document 4. However, in the configuration in which the 0.1 mm copper foil is divided and installed, when a 0.5 mm thick iron plate is brought close to the opposite surface of the copper plate coil, the Lw decreases to 12.3 μH and the Rw becomes 0.1. Increased to 38Ω. If the copper plate is not divided, the inductance Lw (μH) is smaller than the divided copper plate, but the effective series resistance Rw (Ω) is small. There was no change in both Lw (μH) and Rw (Ω) even when they were close to each other. Therefore, in an embodiment in which the metal plate described in paragraph No. 0022 of Patent Document 4 is divided and an embodiment in which the dimension of the metal plate is made smaller than the dimension of the coil, it is described in Paragraph No. 0022 of Patent Document 4. The effect of eliminating the fluctuation of the coil characteristics when the metal body is close to the coil is not expected.

  As described above, in the embodiment of the coil 1k shown in FIG. 42, by providing a means for making the distance between the coil and the metal plate constant between the coil and the metal plate, another metal body comes close to the back surface of the metal plate. However, fluctuations in the inductance Lw and effective series resistance Rw of the coil 1k can be eliminated. The coil 1k shown in FIG. 42 is suitable for a power transmission unit in which metal plates can be installed at regular intervals on the back surface of the coil. When the power transmission unit is placed on a steel desk, fluctuations in the inductance Lw and effective series resistance Rw of the coil 1k can be eliminated, and predetermined power transmission performance can be maintained. The predetermined distance G is 10 mm in the coil 1G, and good results are obtained. However, the predetermined distance G (mm) varies depending on the outer diameter D of the coil. Since the outer diameter D of the coil 1G is 50 mm, a predetermined distance G (mm) is determined by considering a margin, for example, G ≧ D / 10 = 5 mm.

  Next, consider FIG. 59, which is a characteristic diagram of the embodiment of the coil 1m shown in FIG. The configuration (2) in FIG. 59 shows the effective series resistance Rw (Ω) and the inductance Lw (μH) of the coil 1Gb alone in which a magnetic material plate having a thickness of 0.3 mm is attached to the coil 1G. In the coil 1Gb alone, the inductance Lw (μH) is increased and the effective series resistance Rw (Ω) is hardly changed compared to the coil 1G alone in the air-core state. The effective series resistance Rw (Ω) and the inductance Lw (μH) of each coil of the configuration (3) to the configuration (10) in which the same metal plate as that shown in FIGS. 57 and 58 is provided on the opposite surface of the coil 1Gb are shown. ing. In the configurations (3) to (10), the value of the inductance Lw is almost the same. However, as is apparent from FIG. 59, as in FIG. 58, a configuration (3) equipped with an aluminum foil having a thickness of 12 μm, a configuration (7) equipped with a copper foil having a thickness of 35 μm, 0 The coil of the configuration (10) equipped with a steel plate having a thickness of 0.5 mm has a high effective series resistance Rw (Ω).

  Furthermore, the characteristics of each component of the coil 1q having the configuration shown in FIG. 46, which is another embodiment of the present invention, will be examined with reference to FIG. The coil 1q having the configuration shown in FIG. 46 is equipped with two magnetic material plates 511 and 512. The two magnetic material plates 511 and 512 are preferably stacked with an insulating layer. Referring to FIG. 60, the characteristics of a single coil 1Gc in which two magnetic material plates are mounted on the coil 1G are shown in the configuration (2), and the inductance Lw is about 22.5 μH, which is about 14 μH in an air-core state. , About 1.6 times. Compared with FIG. 59, in all of the configurations (3) to (10), the inductance Lw exceeds 20 μH. Further, in all of the configurations (3) to (10), the value of the inductance Lw (μH) is substantially the same. Compared with FIG. 59, the 12 μm-thick aluminum foil of the configuration (3), the 35 μm-thick copper foil of the configuration (7), and the 0.5 mm iron plate as the ferromagnetic material of the configuration (10) are used as the coil 1Gc. Even when facing each other, there is a feature that there is almost no change in the effective series resistance Rw (Ω). That is, by mounting two magnetic material plates on top of each other, the coil is not affected by the magnetic properties or thickness of the metal provided on the opposite side of the coil facing surface of the magnetic material plate. By adopting a configuration like the coil 1q having the configuration shown in FIG. 46, the above-described proximity effect of the metal body can be eliminated with a thin metal such as an aluminum foil.

  In addition, as the magnetic material plate, a thickness of 0.01 mm to 1.5 mm and various configurations such as a magnetic material powder solidified with a binder, an amorphous type, and a ferrite type were tested. The characteristics due to the difference in the metal plates were the same as those shown in FIGS. Further, in the configuration of the coil 1f and the coil 1q, the increase in effective series resistance was large when the increase in inductance was large. At 100 kHz, the increase rate of the inductance and the increase rate of the effective series resistance were almost equal for any magnetic material plate. As will be described later, these actual measurement results indicate that this configuration rule has generality.

  The above results are summarized in FIG. First, the configurations (5) and (9) of the coil 1Ga that is an example of the coil 1k and the coil 1Gb that is an example of the coil 1f will be compared. The value of Q is almost the same when the coil 1Ga is equipped with a 0.5 mm-thick paramagnetic metal aluminum plate and when the coil 1Ga is equipped with a diamagnetic metal copper plate. Also in the coil 1Gb, when the coil 1Gb is equipped with a 0.5 mm-thick paramagnetic metal aluminum plate and when the coil 1Gb is equipped with a diamagnetic metal copper plate, the Q value is almost does not change. That is, as described in Patent Document 4, the diamagnetic metal is not suitable for eliminating the influence of the coil characteristics due to the metal body close to the coil. It can be seen from FIG. 61 that the metal mounted on the coil deteriorates the coil characteristics only in the thickness of the metal plate in the case of the ferromagnetic metal and the metal other than the ferromagnetic metal. Furthermore, in the coil 1Gc having the configuration of the coil 1q equipped with two or more magnetic material plates, the coil characteristics due to the metal body close to the opposite side of the opposing surface of the coil regardless of the magnetic properties of the metal and the thickness of the metal plate. It can be seen that the fluctuation of the can be prevented.

  As shown in FIG. 61, the Q of the coil 1G single core of the configuration (1) is about 42.5. The coils having the respective configurations described in FIG. 61 that are not suitable as the power transmission coil are the coil 1k and the coil 1m, which are the configuration (3), the configuration (7), and the configuration (10). This rule is based on the Q of the coil 1G air core alone, which is 70% of about 42.5, Q = 30, and a coil having a Q higher than the reference value is selected. Any coil having a Q higher than the line Q = 30 shown in FIG. However, FIG. 61 compares the Qs of the coils of each configuration. Actually, the frequency characteristics of the effective series resistance Rw (Ω) shown in FIG. 58 to FIG. 60 are measured, and the frequency characteristics of the coil having an excessive effective series resistance Rw (Ω) and the effective series resistance Rw (Ω) are poor. The coil must be excluded. It is preferable to judge from both the Q of the coil and the effective series resistance Rw (Ω). The reference value Q = 30 is defined as a condition having a power transmission performance of 90% or more compared to the case where power transmission is actually performed using the air-core coil 1G.

(Explanation that the power transmission coil configuration rules are general)
As described above, a coil with good performance cannot be realized simply by defining a specific configuration of the coil. However, the specific configuration of the coil in the present embodiment exhibits the same effects regardless of the coil type, winding method, outer diameter, and the like. That is, the specific configuration of the coil in the present embodiment has an effect of suppressing fluctuations in coil characteristics when a metal body is close to the back surface of the coil regardless of the wire type, winding method, outer diameter, and the like of the coil. An example is shown below.

  FIG. 62 is a characteristic diagram in which the effective series resistance Rw (Ω) and the inductance Lw (μH) are measured for the coil 1D shown in FIG. 12 in the same configuration as the coil 1k shown in FIG. . In FIG. 62, the distance between the coil 1D and the metal plate is set to 5 mm and measured.

  FIG. 63 is a characteristic diagram in which the effective series resistance Rw (Ω) and the inductance Lw (μH) are measured for the coil 1E shown in FIG. 13 in the same configuration as the coil 1k shown in FIG. . In FIG. 63, the distance between the coil 1E and the metal plate is set to 10 mm and measured.

  58, 62, and 63 are compared. In the coil 1k having the configuration shown in FIG. 42, the metal plate 55 is configured using an aluminum foil as an example (3), and is configured using a copper foil as an example (7). ), It can be seen that the effective series resistance Rw (Ω) of each of the coils of the example (10) configured using the iron plate is increased as compared with the coils of other configurations.

  This tendency is the same for both the coil 1D and the coil 1E in the configuration of the coil 1m shown in FIG. 43 and the configuration of the coil 1q shown in FIG. That is, when only a predetermined distance G (mm) is provided between the coil and the metal plate, or when one magnetic material plate is provided between the coil 50 and the metal plate 55, the metal plate 55 is configured using aluminum foil. In the coil of the example (3), the example (7) configured using the copper foil, and the example (10) configured using the iron plate, the effective series resistance Rw (Ω) is increased more than the coils of the other configurations. To do. When two or more magnetic plates are provided between the coil 50 and the metal plate 55, there is almost no increase rate of the effective series resistance Rw (Ω) as shown in FIG. 60 depending on the type and thickness of the metal plate 55.

  The effect of the coil 1k having the configuration shown in FIG. 42 is to prevent fluctuations in coil characteristics when a metal body is close to the opposite side of the coil facing surface as described in Patent Document 4. The effects of the coil 1m having the configuration shown in FIG. 43 and the coil 1q having the configuration shown in FIG. 46 also prevent fluctuations in coil characteristics when a metal body is close to the opposite side of the coil facing surface. Another effect of the coil 1m having the configuration shown in FIG. 43 and the coil 1q having the configuration shown in FIG. 46 is prevention of unnecessary radiation. In order to prevent unnecessary radiation, the configuration of the coil 1q shown in FIG. 46 is preferable. As described above, the coil 1q is hardly affected by the material and thickness of the metal plate. Therefore, even if it is the coil 1h shown in FIG. 38, the proximity | contact effect of a metal body can be excluded.

  58 to 60, the data of the coil 1n, the coil 1p, the coil 1r, the coil 1s, and the coil 1t that are formed of the metal plate, the magnetic material plate, and the insulating plate are omitted. This is because the effect of the metal plate 55 is the same as shown in FIGS. As shown in FIGS. 55 and 56, the coil having such a configuration has an effect of suppressing an increase in effective series resistance Rw (Ω) in a high frequency region and increasing Q. In actual measurement, in the high frequency region, the effective series resistance Rw (Ω) of each coil described above decreases compared to the coils 1n and 1q, and the Q of each coil increases compared to the coils 1n and 1q. Has been confirmed to do.

  As described above, the frequency characteristics of Rw, Rs, and Rn of the coil 1G2 set are extremely good. According to FIG. 15, the maximum frequency f1 satisfying Rs> Rw is 10 MHz or more, and the maximum frequency f2 satisfying Rs> Rn ≧ Rw is about 2.2 MHz. However, especially in the coil 1m and the coil 1q having the above-described configuration, f2 (Hz) is lowered. Consider this point below.

(Description of coil equipped with magnetic material plate)
FIG. 64 is a diagram illustrating an example of a coil 1 </ b> H in which a conducting wire 56 is wound around a core 53. FIG. 64A is a configuration diagram of a single coil 1H, and FIG. 64B is a diagram illustrating a state where two coils 1Ha and 1Hb are inductively coupled.

  In FIG. 64 (B), the cores 53a and 53b of the two coils 1Ha and 1Hb are not directly contacted but bonded via a double-sided tape or the like (not shown).

  FIG. 65 shows the effective series resistance Rw (Ω) of the single coil of the coil 1H having the configuration shown in FIG. 64 and two coils 1Ha and 1Hb inductively coupled, and the other coil is short-circuited at both ends. The relationship between Rw, Rs, Rn and frequency when the effective series resistance Rs (Ω) of the coil and the effective series resistance of one coil when the both ends of the other coil are opened are Rn (Ω). FIG.

  FIG. 66 shows that the inductance Lw (μH) of the coil 1H alone and the two coils 1Ha and 1Hb are inductively coupled, and the other coil is opened when the other coil is short-circuited. It is a figure which shows the relationship between Lw, Ls, Ln, and a frequency when the inductance of one coil at this time is set to Ln (microH).

  As far as FIG. 65 is referred to, the coil 1H has a small difference between Rw (Ω) and Rs (Ω). This is because the coupling coefficient between both coils is as small as about 0.3. The coupling coefficient kr approximately obtained by the method described above is also about 0.3. Furthermore, referring to FIG. 66, Ln> Ls> Lw is satisfied in the frequency region from 1 kHz to 10 MHz.

The above-described formula (4) is expressed by Z = (R1 + A ² R2) + jω (L1−A ² L2),
In the above equation (5), Z = R1 + jωL1 and A ² ≧ 0. Therefore, when the other coil inductively coupled to one coil is short-circuited, the inductance of one coil must be reduced. Don't be. That is, the relationship Lw = Ln> Ls must be satisfied.

  FIG. 67 is a diagram illustrating a relationship between Lw, Ls, Ln, and a coupling coefficient ki approximately obtained from Lw and Ls and a frequency measured when the coil 1G is in the air-core state.

  In FIG. 67, as described above, Lw at a frequency of 20 kHz or higher except for a frequency of 20 kHz or lower where the phase difference φ between the voltage V applied to the coil 1G and the current I flowing through the coil 1G is 80 degrees or lower. It can be seen that the circuit theoretical relationship of = Ln> Ls is satisfied up to at least 4 MHz. The difference between FIG. 66 and FIG. 67 is estimated as follows. In FIG. 66, when the same two coils are inductively coupled as shown in FIG. 64B, compared with the case of a single coil as shown in FIG. 64A, the core 61a having a high relative magnetic permeability in both coils. , 61b are magnetically coupled, so that Ln (μH) increases. However, when the other coil is short-circuited, Ls (μH) becomes lower than Ln (μH). In this case, it is considered that Ls> Lw is determined by the core material, the relative magnetic permeability of the core, the wire and diameter of the conductive wire, and the coil configuration. When the inventor of this application measured Lw, Ls, and Ln for various coils having the configuration as shown in FIG. 64B, there was a coil satisfying Ls <Lw. However, there is no coil that satisfies Ln = Lw, and Ln> Ls. From the configuration and circuit theory of the transformer described above, when a coil having the configuration shown in FIG. 64A is inductively coupled as shown in FIG. 64B, both coils are in the same state as a transformer that cannot be separated. It is believed that there is.

  68 is a diagram showing a configuration of a transformer 70 in which a primary coil 71 and a secondary coil 72 wound around a toroidal core 73 are inseparable from each other.

For confirmation, the inventor of the present invention uses a transformer 70 having the configuration shown in FIG. 68 to determine Rn (the transformer cannot measure Rw and Lw because both coils cannot be separated), Rs, Ln, and Ls. I measured at 100 kHz. Ln = 2.83 mH, Ls = 23.4 μH, Rn = 603Ω, Rs = 0.56Ω. Even in a transformer equipped with a core having a high relative permeability, a measurement result contrary to the circuit theory that Rn> Rs is obtained. When the coupling coefficient ki is approximately calculated from the above Ln and Ls, ki = √ ((Ln−Ls) / Ln), so ki = √ ((2830−0.0234) / 2830) = √ (0.99999)
= 0.999995 ≒ 1
It was almost tightly coupled. Thus, in the transformer of FIG. 68, the coupling coefficient ki may be obtained approximately from Ln and Ls. Therefore, in the coil 1m in FIG. 43 and the coil 1q in FIG. 46 described above, it is assumed that Ln> Lw even at a low frequency. It is also assumed that the maximum frequency f1 (Hz) satisfying Rs> Rw and the maximum frequency f2 (Hz) satisfying Rs> Rn ≧ Rw are also decreased.

  FIG. 69 is a diagram showing a relationship between Lw, Ls, Ln, ki, ki2 and frequency when two coils 1Gb are used in the coil 1Gb which is the coil 1f shown in FIG.

  In FIG. 69, ki2 is obtained from Ln and Ls instead of Lw and Ls.

  ki2 = √ ((Ln−Ls) / Ln). This is an approximate method for obtaining the same coupling coefficient ki as that of the transformer shown in FIG. Both the coupling coefficients ki and ki2 approximately obtained from the aforementioned Lw and Ls are plotted. Ln (μH) is close to twice Lw (μH), but since it takes a square root, there is no significant difference between ki and ki2, and both are 0.9 or more. This is a large value compared to the values of kr and ki plotted in FIG. Thus, the magnetic material plate has an effect of increasing the coupling coefficient between the two coils.

  In FIG. 69, unlike Ln> Ls> Lw in FIG. 66, the relationship is Ln> Lw> Ls. In the present application, various coil characteristics and configurations have been defined for coils having a configuration capable of inductive coupling, focusing on coils having good power transmission performance. However, as shown in FIG. 64, if the coil has a configuration capable of inductive coupling between two identical coils and satisfies the relationship of Rs> Rw at 100 kHz, Not only the power transmission device but also the performance as a coil which is a passive component is good. Furthermore, if the coil satisfies the relationship of Lw> Ls at 100 kHz, the performance as a coil that is a passive component is good. And since the coil of the structure shown in FIG. 64 is equipped with the core, it was conventionally considered that there is no proximity effect of a metal body.

  FIG. 70 is a coil having the configuration of FIG. 64, and various metal plates are brought close to the A surface of FIG. 64 (A), as shown in FIG. 59, to the coil 1H having the characteristics of FIGS. FIG. 6 is a characteristic diagram showing an effective series resistance Rw (Ω) at 100 kHz and an inductance Lw (μH).

  When FIG. 70 is compared with FIG. 59, the decrease rate of the inductance Lw (μH) is small, but the increase rate of the effective series resistance Rw (Ω) tends to be almost the same as that of FIG. That is, as described above, the coil having a configuration capable of inductive coupling is affected by the proximity of the metal body, and the effective series resistance Rw (Ω) increases. The coil of the configuration in which the aluminum foil having a thickness of 12 μm is close (3), the configuration in which the copper foil having a thickness of 35 μm is close (7), and the configuration in which the iron plate having a thickness of 0.5 mm is close (10) is effective. The series resistance Rw (Ω) is high as in FIG. Similarly to FIG. 59, the inductance Lw (μH) is reduced by the configuration. Alternatively, when two coils 1H configured to be inductively coupled are used and both coils are inductively coupled, Ln> Lw. Some configurations of the coil are contrary to the circuit theory of Ln> Lw> Ls.

  71 is a diagram showing the relationship between Rw, Rs, Rn and frequency when two coils 1Gb are used in a coil 1Gb having a magnetic material plate like the coil 1f shown in FIG. 38 in the coil 1G. is there.

  Looking at the frequency characteristics of Rw, Rs, and Rn shown in FIG. 71, it can be seen that the maximum frequency f1> 10 MHz that satisfies Rs> Rw shown in FIG. 15 has decreased to f1 = 1.35 MHz. . Furthermore, it can be seen that the maximum frequency f2 satisfying Rs> Rn ≧ Rw shown in FIG. 15 is reduced from 2.15 MHz to 150 kHz.

On the other hand, as shown in FIG. 65, the maximum frequency f2 of the coil 1H that satisfies Rs> Rn ≧ Rw is as high as 1.3 MHz. This is considered because the coupling coefficient between the two coils 1H is as low as about 0.3 and the coupling coefficient between the two coils 1Gb is as high as 0.9 or more. Therefore, the coupling coefficient between the two coils at 100 kHz is k, and the reference is 150 kHz, which is the highest frequency f2 in which two coils 1Gb satisfy Rs> Rn ≧ Rw. Then, the 150kHz, divided by ^{k 2.} In the case of the coil 1H with ki = 0.27, when the prescribed value of f2 (Hz) is calculated, f2 = 150 / 0.27 ² ≈2.05 MHz. From FIG. 65, the f2 of the coil 1H is about 1.3 Mz and does not satisfy f2 ≧ 2.05 MHz.

  The coil 1H has characteristics contrary to the circuit theory that Ln> Lw> Ls, and as shown in FIG. 66, the relationship of Ln> Lw> Ls is not satisfied. Further, referring to FIG. 70, when an arbitrary metal body is close to the A surface shown in FIG. 64 (A), the coil 1H has a decrease in inductance Lw (μH) exceeding 15%. In other words, the decrease rate of Lw (μH) is 85% or less. Further, under the same conditions, there is a configuration in which the increase in effective series resistance Rw (Ω) is five times or more that of a single unit.

  FIG. 72 shows one coil when the effective series resistance Rw (Ω) of the single coil and the two coils 1Ja and 1Jb are inductively coupled and the other coil is short-circuited in the coil 1J having the configuration of FIG. Is a graph showing the relationship between Rw, Rs, Rn and frequency when the effective series resistance of one coil is Rn (Ω) when the other coil is opened. is there.

  FIG. 73 shows the inductance Lw (μH) of the coil 1J alone, the inductance Ls (μH) of one coil when the two coils 1J are inductively coupled and the other coil is short-circuited, and one when the other coil is opened. It is a figure which shows the relationship between Lw, Ls, Ln, and a frequency when the inductance of the coil of this is set to Ln (microH).

  FIG. 74 shows an effective series resistance Rw (Ω) at 100 kHz and an inductance Lw (μH) when various metal plates are brought close to the A surface in FIG. FIG.

Referring to FIG. 72, the maximum frequency f2 that satisfies Rs> Rn ≧ Rw is 2 MHz or more. The coupling coefficient k between the two coils at 100 kHz is ki = 0.37. Therefore, 150 / ki ² = 150 / 0.372 ² = 1095 kHz. Therefore, the coil 1J satisfies f2> 1095 kHz. Referring to FIG. 73, Ln>Lw> Ls, and the relationship of Lw> Ls is also satisfied. Further, referring to FIG. 74, the coil 1J has an effective series resistance Rw (when an aluminum foil having a thickness of 12 μm or an iron plate having a thickness of 0.5 mm (in this case, any thickness) is brought close at 100 kHz. Ω) increase rate is 5 times or less. In addition, the coil 1J has an inductance Lw (μH) reduction rate of 85% or more when an arbitrary metal body approaches at 100 kHz. In addition to the coils having the configurations shown in FIGS. 2 and 38 to 49, if the coil has a configuration that can be inductively coupled between two identical coils, the above measurement is performed and the characteristics are defined. A coil with good performance can be specified, and a coil with good performance can be realized.

(Explanation of relationship between coil facing distance and coupling coefficient, f1 (Hz), f2 (Hz))
From the experimental results described above, the coil 1J has a good performance as a coil, but has a low coupling coefficient and a low power factor. In addition, as shown in FIG. 70, the effective series resistance Rw (Ω) increases when the high frequency region is reached. On the other hand, the maximum frequency f2 at which the coil 1J satisfies Rs> Rn ≧ Rw is 2 MHz or more, and the coil 1Gb is far from 150 kHz, which is the maximum frequency f2 at which Rs> Rn ≧ Rw. Very expensive. Therefore, in order to lower the coupling coefficient, the distance between the two coils 1Gb was 3 mm, and the frequency characteristics of Rw, Rs, and Rn were measured.

  FIG. 75 is a diagram showing the relationship between Rw, Rs, Rn and frequency when the distance TK between the two coils 1Gb is 3 mm.

  As can be seen by comparing FIG. 75 with FIG. 71, the maximum frequency f2 at which the coil 1Gb satisfies Rs> Rn ≧ Rw has increased to about 500 KHz. When two coils 1Gb are used and the facing distance TK is 3 mm, the coupling coefficient kr approximately calculated from Rs and Rw at 100 kHz is 0.89, and the coupling coefficient ki approximately calculated from Ln and Ls. Is 0.91. Thus, there is no significant difference in the coupling coefficient both when the opposing distance between the two coils 1Gb is zero and when the distance between the two coils 1Gb is 3 mm. However, the f2 is greatly increased to 500 kHz.

  FIG. 76 is a diagram showing the relationship between Rw, Rs, Rn and frequency when two coils 1Gd equipped with a 0.5 mm thick aluminum metal plate are used for the coil 1Gb and the opposing distance is zero. It is.

  The maximum frequency f2 at which the coil 1Gd satisfies Rs> Rn ≧ Rw is reduced to about 80 kHz.

  FIG. 77 is a diagram showing the relationship between Rw, Rs, Rn and frequency when two coils 1Gd are used and the facing distance TK is 3 mm.

  As can be seen from a comparison between FIG. 75 and FIG. 77, the maximum frequency f2 at which the coil 1Gd satisfies Rs> Rn ≧ Rw has increased to about 500 kHz. When two coils 1Gb not equipped with a metal plate are used and the opposing distance TK is set to 3 mm, or when two coils 1Gd are used and the opposing distance TK is set to 3 mm, f2 of both coils is the same.

  In the above-described embodiments from the coil 1A to the coil 1G, even if the facing distance TK between the coils changes, the highest frequency satisfying Rs> Rw and the highest frequency satisfying Rs> Rn ≧ Rw. As described above, there is not much change in f2 (Hz). However, in the coil 1Gb and the coil 1Gd, the maximum frequency f1 (Hz) satisfying Rs> Rw and the maximum frequency f2 (Hz) satisfying Rs> Rn ≧ Rw significantly change depending on the coil interval Z. Taking the coil 1Gb, the coil 1Gc, and the coil 1Gd as an example, it is preferable to provide a facing distance of at least 2 mm between the coils. Since the facing distance is a function of the coil outer diameter D, it is preferable that the coil outer diameter is D and the facing distance TK is TK ≧ D / 50. TK is shown in FIGS. 51 to 53, and is the distance between the conductor ends.

  The same applies to the coil 1q shown in FIG. 46 in which the two magnetic material plates 511 and 512 are overlapped and mounted on the coil 50, and the metal plate 55 is provided on the magnetic material plate 512 side. Further, in the coil 1q shown in FIG. 46, when the opposing distance TK becomes zero, a magnetic material plate having a high maximum frequency f2 (Hz) that satisfies Rs> Rn ≧ Rw is selected. In particular, in the coil 1q, the two magnetic material plates 511 and 512 are configured to have different thicknesses and materials, and magnetic material plates having different relative permeability are used so that f2 (Hz) is as high as possible. preferable. Since the magnetic material plates 511 and 512 are actually sheets obtained by solidifying magnetic material powder with a binder, it is difficult to actually measure the relative permeability. As long as the manufacturer's materials are referred to, f2 (Hz) decreases when the relative permeability of the magnetic material plate 511 near the coil 50 is lowered and the relative permeability of the magnetic material plate 512 away from the coil 50 is increased. The rate seems to be small. However, the magnetic material plates 511 and 512 have no established standards such as the relative dielectric constant of the insulator 52, and are only for reference. The configuration rules described in the embodiments of the present invention should be prioritized.

  Normally, a coil of a power transmission device configured by winding a conducting wire is not used when the opposing distance TK of both coils is zero, and requires a predetermined distance, for example, an interval of 3 mm as described above. . As described above, the coupling coefficient of the coil 1f shown in FIG. 38 to the coil 1t shown in FIG. 49 does not decrease even if the predetermined distance TK is provided. Therefore, it is possible to realize a power transmission coil that can maintain a high power factor and has good power transmission performance. By using this power transmission coil, a power transmission device with good power transmission performance can be realized. As described above, the coil 1f shown in FIG. 38 to the coil 1t shown in FIG. 49 can avoid characteristic fluctuation due to the proximity of the metal body. Moreover, unnecessary radiation can be reduced. Furthermore, even if the predetermined distance TK is provided between the two coils, there is an extremely excellent effect that the coupling coefficient does not decrease.

  Note that the coil 1Ga, which is an example of the coil 1k shown in FIG. 42, has a maximum frequency f1 satisfying Rs> Rw of 10 MHz or more and a maximum frequency f2 satisfying Rs> Rn ≧ Rw of 2 MHz or more. Since there is no influence of the magnetic plate and the effects other than the prevention of the change of the coil characteristics due to the proximity of the metal body are the same as those of the coils 1A to 1G, the description regarding the interval TK between the opposing coils is omitted.

  Needless to say, the coil 50 from the coil 1f to the coil 1t has an effective series resistance of one coil alone in the air-core state as Rw (Ω), and the other coil facing the one coil in the air-core state. Assuming that the effective series resistance of one coil when short-circuited is Rs (Ω), one coil that satisfies Rs> Rw at 100 kHz is used. For example, as the coil 50, the coils 1B to 1G which are the embodiments of the present invention described above are used.

  Further, when the coil 1f to the coil 1t equipped with the magnetic material plate 51 or 511, 512 are used as one coil, it is preferable that the coil 1f to the coil 1t satisfy Rs> Rw at 100 kHz.

  Assuming that the highest frequency satisfying Rs> Rw from the coil 1f to the coil 1t is f1 (Hz), the power transmission device 100 equipped with the coil 1t to the coil 1t transmits power at a frequency less than f1 (Hz). .

  When the coil 1f to the coil 1t are the power transmission coil 1 of the power transmission device 100, the coils 1f to 1t are driven by the AC power supply 30b at fd (Hz), which is a frequency less than f1 (Hz).

  Furthermore, when the coil 1m and the coil 1q of the above-described embodiment are one coil, the same coil is the other coil, the inductance of one coil is Lwa (H), and both coils are inductively coupled. If the inductance of one coil when the other coil is short-circuited is Lsa (H), the coil 1m and the coil 1q satisfy Lwa> Lsa at 100 kHz, and f1 ( It is preferable that Lwa> Lsa is satisfied in a frequency region less than (Hz) and a frequency used for power transmission.

The maximum frequency f2 satisfying Rn (Ω) and Rs > Rn ≧ Rw as the effective series resistance of each coil when the coil 1f to the coil 1t described above are set as one coil and the other opposing coil is opened. Assuming (Hz), one coil is preferably used in a frequency region below f2 (Hz).

  When the coil 1m and the coil 1q described above are set as one coil and the other coil facing each other is opened, the inductance of one coil is Ln, and at least the relationship of Ln> Lw> Ls is 100 kHz. In the frequency region below f1 (Hz), the coil 1m and the coil 1q satisfy the relationship Ln> Lw> Ls at the frequency fa (Hz) used for power transmission. It is preferable.

  More preferably, assuming that the maximum frequency f2 (Hz) satisfying Rs> Rn ≧ Rw from the coil 1f to the coil 1t, the coil 1f to the coil 1t are used in a frequency region less than f2 (Hz), and f2 ( In the frequency region below (Hz), the relationship of Ln> Lw> Ls is satisfied.

  The above-mentioned definition of the thermal condition can be satisfied by obtaining the thermal resistance θi by the same method as that described above.

  When the power transmission unit 30 of the power transmission device 100 includes the coil 1f to the coil 1t, the power transmission unit 30 including the coil 1f to the coil 1t is a power transmission device of the power transmission device of the present invention.

  When the power reception unit 40 of the power transmission device 100 includes the coil 1f to the coil 1t, the power reception unit 40 including the coil 1f to the coil 1t is a power reception device of the power transmission device of the present invention.

(Explanation when connecting the metal plate to the coil center wire)
FIG. 78 is a diagram in which a metal plate mounted on a coil is used as a wire to be taken out from the inner periphery of the coil in the coil 1k shown in FIG. 42 to the coil 1t shown in FIG.

  In the coil 50 having the configuration of the coil 1a to the coil 1j, the conducting wire taken out from the center of the coil 50 is thicker by the thickness of the conducting wire. In FIG. 78, a lead wire through hole is provided at the center of the insulating plate 54 of the coil 1 k shown in FIG. 42, and the lead wire 501 at the inner periphery of the coil is connected to the metal plate 55. The end portion 552 of the outer peripheral portion of the coil 50 is used as one terminal, and the end portion 551 of the metal plate 55 is used as the other terminal. Various methods such as soldering and welding can be used as a method of connecting the conductive wire 501 and the metal plate 55. This configuration is applicable not only to an insulating plate but also to a magnetic material plate.

(Example in which a coupling wire is provided in a coil)
In FIG. 79, a litz wire is used for the conductive wires used in the coils having the configurations shown in FIGS. 38 to 49, one end of the litz wire is connected to all strands, and the other end of the litz wire is connected to the litz wire. FIG. 5 is an equivalent circuit diagram when at least one of the constituent wires is taken out as a coupling line 10a.

  The coupling wire 10a shown in FIG. 79 can be used to detect the operating state of the coil. Alternatively, it can be used for signal transmission. In addition, self-excited oscillation can be performed by applying positive feedback using an inverting amplifier.

  The coupling line 10a is in a substantially tightly coupled state with the power transmission coil 1 or the power reception coil 2. The winding ratio is 1: 1. Therefore, an AC voltage having the same amplitude and phase as that of the power transmission coil 1 or the power reception coil 2 appears in the coupling line 10a. This coupling line 10a is a signal transmission function between a power transmission unit and a power reception unit in other embodiments of the present invention described later, detection when a metal body is close to a power transmission coil, and when a power reception coil to which a load is connected is close Can be used for discrimination.

  When the embodiment of FIG. 78 described above is applied to a litz wire, all the wires of the inner periphery are connected to the metal plate 55, and at least one of the wires taken out from the outer periphery is removed. The connecting line 10a is used. The coupling wire 10a may be taken out as a strand without being connected to the common line, and may be a four-terminal coil. In this case, since the power transmission coil and the coupling line are insulated, the degree of freedom in circuit configuration increases when used for signal detection, self-excited oscillation, and the like.

(Example of coil for power transmission)
The coil 1g shown in FIG. 38 to the coil 1t shown in FIG. 49 are also examples of the power transmission coil used in the power transmission device described above.

(Power transmission coil drive conditions)
Whether it is an air-core coil or a magnetic material plate, the above-described f1 (Hz) and f2 (Hz) are increased so that the power transmission coil is less than f1 (Hz) or f2 (Hz). A power transmission device with good performance cannot be realized unless the driving conditions of the coil to be driven are defined.

(Example of a single coil)
Furthermore, the coil used in the power transmission device according to the embodiment of the present invention in which the characteristic is defined as described above is also an invention of a coil having a configuration capable of inductively coupling between the same two coils. .

(Explanation regarding metals used in the present invention)
As described above, when a metal body is close to the air-core coil, the performance of the coil is deteriorated. Further, even when a magnetic material is brought close to the air-core coil, the magnetic material sometimes deteriorates the power transmission performance of the coil. For example, in the embodiment of FIG. 31A, there is a case where a magnetic material having a low magnetic permeability is provided in a bobbin-shaped inner diameter cavity. As described above, even if the coil is equipped with a magnetic material, the performance of the coil in the present invention cannot be improved regardless of the configuration regulations and characteristic regulations other than the embodiments of the present invention described above.

  Even when the coil is equipped with a magnetic material, the air core coil of the present invention must first be selected. In the embodiment described above, the coil 1G, which is the air core coil having the best performance, is selected and the magnetic material plate is provided. However, as described above, it has been explained that it is not easy to eliminate the proximity effect of the metal body while maintaining the power transmission performance of the coil 1G. In the coil shown in the example of Patent Document 2, the influence of proximity to the metal body cannot be eliminated, and operation at a high frequency is difficult. Due to unnecessary radiation, it is difficult to use a frequency of 250 kHz or higher. However, at a minimum, operation at 100 kHz must be realized. For this purpose, it is necessary to select an air-core coil with the best possible performance based on the above-mentioned regulations.

  In the embodiment of the present invention, the material of the conductor forming the conducting wire is not particularly limited, but all the coils described in this embodiment use copper as the conductor. Although copper having a small specific resistance is preferably used as the conductor, other metals or alloys having a small specific resistance can also be used as the conductor.

  In addition to diamagnetism, paramagnetism, and ferromagnetism, the magnetic properties of metals include antiferromagnetism. However, attention is focused on the magnetic property that increases the effective series resistance Rw (Ω) of the coil. The metal plate mounted on the coil may be anything other than a metal or alloy that is simply attracted to the permanent magnet.

  The inventor of the present application made measurements using various metals such as titanium, brass, and stainless steel. The 0.1 mm thick titanium plate showed the same characteristic variation as the 0.1 mm thick aluminum plate. A brass plate with a thickness of 0.5 mm showed the same characteristic variation as a copper plate with a thickness of 0.5 mm. The stainless steel plate adsorbed on the 0.5 mm thick permanent magnet caused characteristic deterioration more than the 0.5 mm thick iron plate. Thus, the metal plate may be selected depending on whether it is attracted to the permanent magnet or not.

(Measurement device used for measuring coil characteristics)
The effective series resistance and inductance of each coil described above were measured up to 1 MHz using an Agilent LCR meter, and 4284A, 1 to 10 MHz were measured using a Hewlett Packard LCR meter, 4275A. . In addition, since measurement of 1 to 10 MHz can be performed only at each point of 1, 2, 4, and 10 MHz, for example, when Rs> Rw is satisfied at 4 MHz and Rs> Rw is not satisfied at 10 MHz. Estimates the maximum frequency f1 (Hz) satisfying Rs> Rw by interpolation.

(Power transmission characteristics of power transmission equipment)
FIG. 80 shows the relationship between the load current of the secondary winding and the voltage at both ends of the secondary winding in a normal transformer (transformer) configured in a tightly coupled state, and the power transmission device 100 according to the embodiment of the present invention. It is a characteristic view which shows the relationship between the load current of the receiving coil 2 of this, and the both-ends voltage of a receiving coil. In FIG. 80, the characteristic of a general transformer is indicated by a solid line, and the characteristic of the power transmission device in the embodiment of the present invention is indicated by a broken line.

  In a normal transformer configured in a tightly coupled state, if the load current value of the secondary winding is equal to or less than the rated value Im (A) of the transformer, the voltage across the secondary winding is substantially constant. General electric devices and electronic devices operate at a constant voltage. Therefore, the transformer is used in a constant voltage region below the rated value Im (A) of the transformer shown in FIG. However, unlike a transformer used for a commercial power source, a transformer used for a general electric device or electronic device has a slightly higher rated value Im (A) than the maximum current consumed by the device. Things are used. This is because if an excessive margin is provided, the volume of the transformer increases and the cost also increases.

  On the other hand, when looking at the relationship between the load current of the receiving coil of the power transmission device and the voltage across the secondary winding in the embodiment of the present invention, the voltage across the secondary winding drops as the load current increases. I can see that This characteristic diagram is calculated by reading numerical values from FIG. 8 of Patent Document 2 and performing normalization after slight correction. In the follow-up test by the inventor of the present application, the voltage drop rate across the secondary winding due to the increase in the load current is larger than that of Patent Document 2.

  In the power transmission device according to the embodiment of the present invention having such characteristics, when the load is set to the maximum current required by the device, the power supply voltage decreases. When the current consumed by the device decreases, the power supply voltage increases. Further, as shown in FIGS. 51 to 54 described above, the dimensions and shape of the power transmission coil and the power reception coil may be different, or the distance TK between the coils may be different depending on the use situation. In such a case, it is assumed that adjustment is performed to ensure the load current of the power receiving unit at the maximum inter-coil distance TK in the state of FIG. Needless to say with the above-mentioned formula (4), when the relative position of the coil is as shown in FIG. 51 or the distance TK between the coils is shortened, it is easy for the voltage on the power receiving side to rise. I can guess. That is, in the power transmission device of the present invention, the receiving coil output does not have a constant voltage characteristic. When the voltage on the power receiving side increases, the device body including the power receiving unit may be damaged. In addition, an excessive current may flow through the power receiving unit. Although the load resistance values are different, it can be seen from FIG. 80 that when the load current is reduced from 2 A to 1 A, the load voltage is increased by about 1.6 times. At least these countermeasures against excessive voltage and excessive current must be taken into consideration.

  Further, as described above, the power transmission device, the power transmission device of the power transmission device, and the power reception device of the power transmission device in the embodiment of the present invention have extremely good power transmission performance. Although depending on the current flowing through the power transmission coil 1 and the power reception coil 2, by using the coil 1G having a diameter of 5 cm described above for both the power transmission coil 1 and the power reception coil 2, it is possible to transmit power of up to about 40 W. . When such power transmission performance is achieved, the power transmission coil 1 has a metal heating action, similar to the overheating coil of the induction heater. Therefore, as described in Patent Document 5, when a metal body such as a clip approaches the power transmission coil, heat generation of the metal body must be prevented. Alternatively, it is necessary to determine a proper power receiving unit. Therefore, specific examples for solving these problems will be described below.

(Embodiment equipped with signal transmission means)
FIG. 81 shows an example in which the power transmission unit 30 and the power reception unit 40 are equipped with signal transmission means.

  In FIG. 81, the power transmission unit 30 is equipped with a signal reception circuit 30c, and the power reception unit 40 is equipped with a signal transmission circuit 40b. A signal line 61 indicates a signal transmission line from the power reception unit 40 to the power transmission unit 30. Thereby, a signal can be sent from the power receiving unit 40 to the power transmitting unit 30.

  The power transmission control circuit 30a receives a power transmission side identification information holding unit 30h that holds an ID code that is individual identification information of the power receiving unit, and the power reception control circuit 40a receives the ID code and holds it in the power transmission side identification information holding unit 30h. The transmission power control means 30i for controlling the transmission power if the received ID code is matched and the operation state on the power receiving side is normal, and the identification information, date and time information at the time of power transmission, transmission power information, etc. Storage means 30j for storing is provided. The transmission power control means 30i also operates as a transmission power variable means capable of changing the transmission power and a transmission frequency variable means capable of changing the transmission frequency.

  The power reception control circuit 40a is equipped with a rectifier circuit that converts AC power into DC power. The power reception control circuit 40a includes a power receiving side identification information holding unit 40h that holds an ID code that is identification information of each power receiving unit that operates with DC power converted by the rectifier circuit, and a received power detection unit 40i that detects the received power. Power receiving operation state detecting means 40j for detecting the operating state of the power receiving section 40, temperature detecting means 40k for detecting the temperature of the apparatus including the power receiving section 40, and 2 when the power receiving section 40 includes a secondary battery. A circuit for detecting the charge / discharge state of the secondary battery is included.

  By sending a signal from the power reception unit 40 to the power transmission unit 30, when the power reception unit 40 has an abnormality, an abnormality countermeasure such as stopping power transmission by the power transmission unit 30 can be taken. In addition, by authenticating the ID code held by the specific power receiving unit 40, power transmission can be performed only for the specific power receiving unit 40. Alternatively, the power information signal required by the power receiving unit 40 can be sent to the power transmission unit 30 to perform feedback control to increase or decrease the transmitted power of the power transmission unit 30.

  Furthermore, in the power transmission device 100 according to the embodiment of the present invention, the power transmission unit 30 and the power reception unit 40 can be separated. The power transmission unit 30 capable of transmitting a large amount of power requires a large amount of power with a built-in power receiving unit 40 according to an embodiment of the present invention from a device that requires a small amount of power with a built-in power receiving unit 40 according to an embodiment of the present invention. Applicable to a wide range of equipment, including equipment. As applications that have not been proposed in the past, in the same power transmission unit, devices that require around 2W of power, such as mobile phones, devices that require around 10W of power, such as PDAs, and power of around 50W such as personal computers Power can be transmitted to all necessary devices.

  The power receiving unit 40 holds the ID code corresponding to the device including the power receiving unit 40, and the power transmitting unit 30 transmits the power required by the power receiving unit 40 by reading the ID code transmitted from the device to the power transmitting unit 30. it can. Accordingly, 10 W of power is transmitted to a small device that requires only 2 W, and the small device can be prevented from being damaged. As will be described later, in the embodiment of the present invention, when the power transmission unit 30 malfunctions and excessive power is sent to the power reception unit 40, safety measures in the power reception unit 40 are also taken into consideration. Further, when one code is set not only for the model but also for each device, the power transmission unit 30 used by an unspecified number of people can determine how and when each device has one ID code. The power transmission unit 30 can record the operation status as to whether the operation has been performed in a proper state, and the cause of failure of each device can be traced. Conventionally, since the power transmission performance has not been achieved, the above usage has not been conceived.

  FIG. 82 is a diagram showing a basic waveform of PWM control for controlling transmission power. FIG. 82A shows the gate timing, and FIG. 82B shows the burst waveform. In the gate timing of FIG. 82A, the relationship between the cycle T (S) and the cycle T1 (S) is T1 ≦ T. However, (T1 / T) must be constant when the period T (S) is changed. Normally, such a PWM control circuit is composed of a sawtooth generator and a comparator, and in such a circuit configuration, (T1 / T) is constant even if the period T (S) is varied.

  82, a method for changing the duty by time-sharing the AC power supplied to the power transmission coil 1 will be described. The period T (S) is determined by a time constant that is the product of the minimum load resistance value RL (Ω) of the power receiving unit 40 and the capacitance C1 (F) of the smoothing capacitor 31d. The period T (S) is preferably set to T ≦ RL · C1 (S). When the maximum power that can be transmitted is Pm (W), the ratio of T1 and T is the actual transmission power P1 (W), and P1 = Pm · T1 / T (W). When T1 = T, P1 = Pm (W), and when T1 = 0, P1 = 0 (W). In the prior art, sufficient power could not be sent to the power receiving unit, so there was no need to consider the burst wave period T (S) as shown in FIG.

  FIG. 83 is a diagram illustrating an example of a PWM circuit that is another embodiment for controlling the transmission power of the power transmission unit 30 illustrated in FIG. 81.

In FIG. 83, the PWM step-down converter 30f has a sawtooth oscillator and a comparator inside, makes the period T shown in the gate timing of FIG. 82 (A) constant, and varies the period T1 to change the output voltage. Fluctuate. Since the output of the PWM step-down converter 30f is a pulse wave, it must be smoothed to a direct current. For this reason, a rectifier circuit including a regenerative diode 31b, a coil 31c, and a smoothing capacitor 31d is connected to the output of the PWM step-down converter 30f. When the output OUT of PWM buck converter 30f is Vd, the current I (A) flows through the coil 31c, the inductance of the coil 31c and L (H), the coil 31c is, ^{U =} LI 2/2 of (J) Accumulating energy. When the output of the PWM step-down converter 30f becomes zero (actually in an open state), a high voltage of an electromotive force proportional to the time change of the coil current, V = dI / dt (V), is generated in the coil 31c by self-induction. Appears at both ends, releasing energy U (J). Therefore, when the output of the PWM step-down converter 30f is in an open state, the energy U (J) stored in the coil 31c is moved to the smoothing capacitor 31d by the regenerative diode 31b, thereby reducing the voltage conversion efficiency. prevent.

  A control signal line 63 connecting the power transmission control circuit 30a and the PWM step-down converter 30f outputs a control signal for performing pulse width control (PWM). Based on this control signal, the PWM step-down converter 30f applies a voltage to one end of an internal comparator to perform PWM control. The power transmission control circuit 30a generates a voltage necessary for power transmission (based on a signal transmitted from the power reception unit, a signal detected by the power transmission unit, or the like) based on the output of the PWM step-down converter 30f.

  In another embodiment for increasing / decreasing the transmission power, a PWM converter for stepping down the DC power supply Vd to a predetermined voltage Vb (V) shown in FIG. 83 and the transmission coil 1 driven by a burst wave shown in FIG. Use the same method. As is apparent from FIG. 80, unlike the ordinary transformer, the voltage on the power receiving side can be changed by adjusting the AC power.

  A circuit for detecting the received power P2 (W) is provided in the power receiving unit 40, and the value of the received power P2 (W) is sent from the power receiving unit 40 to the power transmitting unit 30, whereby the power transmitting unit 30 transmits the transmitted power P1 (W) as From the ratio of the received power P2 (W), the power transmission efficiency η and η = P2 / P1 can be obtained. Further, the load voltage VL (V) and the load current IL (A) are obtained by the above-described circuit for detecting the operating state of the power receiving unit 40, and the load resistance value RL, RL = VL / IL (Ω) is obtained by the power receiving unit 40. , Is obtained. When the power transmission control circuit 40a includes a circuit that changes the power transmission frequency fa (Hz), the power transmission control circuit 40a is based on a signal from the power receiving unit 30, for example, fa (Hz) at a point where the power transmission efficiency η is maximized. Adjust. Alternatively, fa (Hz) is adjusted to a point where the power factor becomes maximum based on the load resistance value RL (Ω) signal from the power receiving unit 30.

  Note that it is not always necessary to use the signal transmission lines 61 and 62 shown in FIG. Using the transmission power as a carrier wave, the power transmission unit 30 performs amplitude modulation and frequency modulation, and the power reception unit 40 can demodulate the signal. Alternatively, the load resistance value of the power receiving unit 40 is varied, and the impedance of the power transmission coil 1 is varied according to the above-described equation (4). The power transmission unit 30 can detect the impedance change of the power transmission coil 1 and demodulate the signal from the power reception unit 40.

  Alternatively, as described in Patent Document 5, the signal transmission frequency fb (Hz) may be set several tens of times higher than the power transmission frequency fa (Hz), and the signal may be extracted by a filter. In this case, the signal transmission frequency fb (Hz) may be equal to or higher than f1 (Hz), which is the highest frequency at which the power transmission coil 1 satisfies Rs> Rw. On the other hand, the frequency fa (Hz) for power transmission must satisfy fa <f1. As described above, the power transmission coil 1 and the power reception coil 2 can be used as the signal transmission lines 61 and 62, and the cost can be reduced. However, if the signal transmission frequency fb (Hz) is not set away from a value that is an integer multiple of the power transmission frequency fa (Hz), the signal transmission frequency fb (Hz) is higher than the power transmission frequency fa (Hz). Care must be taken when setting fb (Hz) because it is disturbed by waves.

  For this reason, fb (Hz) may be made lower than fa (Hz), and a notch filter and a low-pass filter that attenuate fa (Hz) may be used together so that only fb (Hz) can be extracted. In this case, when fa (Hz) is about 100 kHz, fb (Hz) is set to 25 kHz or less, which is at least 1/4 of fa (Hz). This is because it is a characteristic limit of the low-pass filter and the waveform is dulled by the low-pass filter. In order to demodulate this waveform, about 25 25 kHz sine waves are required, and the signal transmission rate is reduced to about 1 KBPS. However, even if a 64-bit signal is transmitted, the transmission time is only 64 mS. Since each operation information described above needs only about 128 bits, the signal transmission time in this application is not particularly problematic.

  The method as described above is not limited to Patent Document 5 and various types have been proposed in the past. However, in the conventional technology, the power required by the power receiving unit 40 cannot be transmitted in the first place. Such a function is effective only when the power transmission performance is ensured as in each embodiment of the present invention.

  There are various signal transmission methods. As described above, even if the power transmission coil 1 and the power reception coil 2 are used as the signal transmission means, the signal can be transmitted with higher accuracy than in the prior art. Alternatively, communication means in the MHz band and the GHz band can be used. A signal may be transmitted by an infrared LED that transmits through plastic, and a signal may be received by an infrared photodiode. As described above, when the power transmission performance is improved as compared with the related art, signal transmission between the power transmission unit 30 and the power reception unit 40 can be realized using various methods.

  In FIG. 81, the power transmission unit 30 is equipped with a signal transmission circuit 30b, and the power reception unit 40 is equipped with a signal reception circuit 40c. The signal is transmitted via a signal transmission line 62. In recent years, mobile phones have a function of storing payment money, air tickets, and the like in the same way as cash cards. However, there are cases where there is a high possibility of losing a mobile phone holding data and money, such as vacation and sports. When going on vacation, sports, etc., money and air ticket data are transmitted to the power transmission unit 30 via the signal transmission line 61, and the power transmission unit 30 holds the converted money and air ticket. After the excursion, sports, etc. are completed, money and air tickets converted into data from the power transmission unit 30 are sent to the mobile phone via the signal transmission line 62. In the power transmission device 100 in which the power transmission unit 30 and the power reception unit 40 can be separated, by providing a signal transmission function between the power transmission unit 30 and the power reception unit 40, various highly convenient functions can be realized as described above.

  In addition, the utilization method of the signal transmission function between the power transmission unit 30 and the power reception unit 40 described above is only an example. Data stored in the mobile phone such as the phone number book of the mobile phone is stored in the power transmission unit 30. Alternatively, various application uses such as importing PDA data into a power transmission unit provided in a personal computer and storing it in the personal computer can be realized. The reason why these functions cannot be realized is that, as described above, the conventional technology cannot secure the power transmission performance.

  The signal transmission function between the power transmission unit 30 and the power reception unit 40 described above includes at least one of a signal transmission function from the power reception unit 40 to the power transmission unit 30 and a signal transmission function from the power transmission unit 30 to the power reception unit 40 as necessary. It only has to have. When the power receiving unit 40 includes the signal transmission circuit 40b, the power transmission unit 30 of the power transmission device only needs to include the signal reception circuit 30c. When the signal transmission circuit 30b is included in the power transmission unit 30, the power reception unit 40 of the power transmission device only needs to include the signal reception circuit 40c.

  That is, the power transmission unit 30 including the signal transmission unit with the power reception unit 40 according to the embodiment of the present invention is also an invention of the power transmission unit of the power transmission device 100 of the present invention. Moreover, the power receiving unit 40 including a signal transmission unit with the power transmission unit 30 of the power transmission device 100 according to the embodiment of the present invention is also an invention of the power receiving unit of the power transmission device of the present invention.

(Example of control circuit)
In FIG. 84, a change in the impedance Z of the power transmission coil 1 is detected by measuring a current flowing through the power transmission coil 1 to determine whether a metal body is close to the power transmission coil 1, or on the secondary side. FIG. 3 is a block diagram illustrating an example of a circuit provided in a power transmission unit 30 for determining an operation state and the like.

  In FIG. 84, the AC constant voltage V is applied to the power transmission coil 1, the AC current I flowing through the power transmission coil is detected, and the complex impedance Z is obtained as Z = V / I. In order to obtain the complex impedance Z of the power transmission coil 1, there is a method in which an AC constant current I is passed through the power transmission coil 1, the AC voltage V across the power transmission coil is measured, and the complex impedance Z is obtained as Z = V / I. In the latter case, means for detecting the AC voltage at both ends of the power transmission coil 1 is required, but the complex impedance Z of the power transmission coil 1 is similarly obtained. Alternatively, the complex impedance Z of the power transmission coil 1 can be obtained by connecting a reactive element in series to the power transmission coil 1 and measuring the voltage of the reactive element. Here, a method for obtaining the complex impedance Z of the power transmission coil 1 based on the alternating current flowing in the power transmission coil 1 will be described.

  In FIG. 84, a current detection resistor Ri is connected in series to one end of the power transmission coil 1. The other end of the power transmission coil 1 is connected to OUTH of the power transmission control circuit 30a. The resistor Ri has a value of about 0.05Ω, and the connection point between the resistor Ri and the power transmission coil 1 is connected to the non-inverting terminal of the non-inverting amplifier formed of the operational amplifier 36a. A feedback resistor Rf is connected between the output of the operational amplifier 36a and the inverting terminal. The inverting terminal of the operational amplifier 36a is connected to OUTL of the power transmission control circuit 30a and GND, which is a common reference potential with the signal processing circuit, together with the other terminal of the resistor Ri through the resistor R10. The gain G of the operational amplifier 36a is G = Rf / R10 + 1. The resistance value of Rf and R10 is selected so that the operational amplifier 36a has a gain of several tens to 1000 times. The non-inverting amplifier composed of the operational amplifier 36a amplifies an alternating voltage of several mV to several tens of mV generated at both ends of the resistor Ri to about several volts, and operates as a current detection unit.

  The output of the operational amplifier 36a is input to the analog switches 32a and 32b. The analog switches 32a and 32b are turned on and off by control signals whose phases generated by the power transmission control circuit 30a are different by 90 degrees. The timings at which the analog switches 32a and 32b are turned on and off are in the relationship between sin and cos as in the case of the sin detection signal and the cos detection signal. The output of the analog switch 32a becomes the detector sin output, and the output of the analog switch 32b becomes the detector cos output. The output of the analog switch 32a is input to an integrator (LPF: low pass filter) 33a, and the output of the integrator 33a is an integrator sin output. The output of the analog switch 32b is input to the integrator 33b, and the output of the integrator 33b becomes an integrator cos output. The outputs of the integrators 33a and 33b are switched by the switch 34 and input to the A / D conversion circuit 35, converted from an analog signal to a digital signal, and supplied to the power transmission control circuit 30a.

  The analog switches 32a and 32b, the integrators 33a and 33b, and the A / D conversion circuit 35 operate as control signal output means. The analog switches 32a and 32b and the integrators 33a and 33b operate as synchronous detection means for synchronously detecting the output of the operational amplifier 36a based on the sin detection signal and the cos detection signal having a phase difference of 90 degrees. Further, the analog switches 32a and 32b and the integrators 33a and 33b detect the phase and the amplitude at the same time, and also operate as a phase detection unit and an amplitude detection unit.

  85 to 87 are waveform diagrams showing the operation state of the circuit in FIG. 84. In particular, FIG. 85 is a waveform diagram when there is no load, FIG. 86 is a waveform diagram when there is a load, and FIG. It is a wave form diagram when a metal body approaches. FIG. 88 is a diagram for explaining signal output after synchronous detection of the power transmission coil current.

  First, with reference to FIG. 85, the operation at no load will be described. FIG. 85A shows a current I and a voltage V flowing through the power transmission coil 1 alone when there is no load. In the case of the power transmission coil 1 alone, the phase of the current I flowing through the power transmission coil 1 is delayed by 90 degrees with respect to the phase of the voltage V applied to the power transmission coil 1. Even when there is no load, a predetermined current flows through the power transmission coil 1, a voltage is generated across the current detection resistor Ri, the voltage is input to the operational amplifier 36a, and the output of the operational amplifier 36a is applied to the analog switches 32a and 32b. It is done.

  The analog switch 32a is turned on by a sin detection signal shown in FIG. 85 (B), and outputs a detector sin output signal. The detector sin output signal has a waveform obtained by half-wave rectifying a sine wave as shown in FIG. When the output of the analog switch 32a is supplied to the integrator 33a, a DC voltage of 1V is obtained as in the integrator sin output of FIG. 85 (D). When the changeover switch 34 is in the position B and the input of the A / D conversion circuit 35 is connected to the output side of the integrator 33a, the output of the integrator 33a is given to the A / D conversion circuit 35, A digital signal obtained by A / D converting the integrator sin output 1V shown in FIG. 85 (D) is output to the power transmission control circuit 30a.

  On the other hand, the analog switch 32b is turned on by a cos detection signal shown in FIG. 85 (F), and outputs a detector cos output signal. The detector cos output signal has a waveform that starts from the minimum value of the sine wave shown in FIG. 85 (G) and ends at the maximum value. In the detector cos output shown in FIG. 85 (G), the portion C is negative, the portion D is positive, and the areas of C and D are equal.

  When the output of the analog switch 32b is passed through the integrator 33b, the output of the integrator 33b becomes a DC voltage of zero (V) like the integrator cos output shown in FIG. 85 (H). When the changeover switch 34 is in the position A and the input of the A / D conversion circuit 35 is connected to the output side of the integrator 33b, the output of the integrator 33b is given to the A / D conversion circuit 35, A digital signal obtained by A / D converting the integrator cos output (0 V) shown in FIG. 85 (H) is output to the power transmission control circuit 30a.

  In addition, 1V mentioned above is a normalized value and is not an actual measurement value in order to compare with the case where the receiving coil 2 to which the load described later is connected faces the power transmitting coil 1. FIG. 85 (E), FIG. 86 (E), and FIG. 87 (E) show the reference point 0V for comparing the value of the sin output that is a DC signal after synchronous detection. Similarly, FIG. 85 (I), FIG. 86 (I), and FIG. 87 (I) show the reference point 0V for comparing the value of the cos output, which is a DC signal after synchronous detection. 85 (E), 86 (E), and 87 (E) correspond to the Y axis and X = 0 in the XY plane of FIG. 88, and FIG. 85 (I), FIG. 86 (I), and FIG. I) corresponds to the X axis in the XY plane of FIG. 88, Y = 0.

  In this way, when there is no load, the output voltage of the integrator 33a, which is the integrator sin output shown in FIG. 85 (D), is the Y axis, and the output of the integrator 33b, which is the integrator cos output shown in FIG. 85 (H). Assuming that the voltage is the X axis, the voltage value of sin (Y) is 1V and the voltage value of cos (X) is 0V, so that the signal appears on the Y axis in the XY plane of FIG.

  Next, with reference to FIG. 86, the operation at the time of load will be described. As described above, when the power receiving coil 2 connected to the load is inductively coupled to the power transmission coil 1, the inductance of the power transmission coil 1 is lower than the inductance of the power transmission coil 1 alone. And the pure resistance component of the complex impedance Z of the power transmission coil 1 increases, and the reactance component decreases. Therefore, the phase difference θ of the current I flowing through the coil with respect to the voltage V applied to the coil is smaller than 90 degrees. Moreover, since the absolute value of the complex impedance Z of the power transmission coil 1 decreases, the amplitude of the current I flowing through the coil increases. FIG. 86A shows waveforms of the voltage V applied to the power transmission coil 1 and the current I flowing through the power transmission coil 1. When there is a load, the flowing current I becomes larger than when there is no load, and the voltage generated at both ends of the current detection resistor Ri also becomes higher.

  When the analog switch 32a is turned on by the sine detection signal shown in FIG. 86 (B), the output of the analog switch 32a is a part of the sine wave like the detector sin output shown in FIG. 86 (C). The waveform is taken out. The area A of the positive part is larger than the area B of the negative part. When the output of the analog switch 32a is passed through the integrator 33a, a DC voltage of 0.86V is obtained as in the integrator sin output shown in FIG. 86 (D). The signal shown in FIG. 86D is output to the output of the A / D conversion circuit 35.

  On the other hand, when the analog switch 32b is turned on by the cos detection signal shown in FIG. 86 (F), the output of the analog switch 32b is also a sine wave like the detector cos output shown in FIG. 86 (G). The waveform is a part extracted. The area C of the negative part in FIG. 86 (G) is smaller than the area D of the positive part. When the output of the analog switch 32b is passed through the integrator 33b, the output of the integrator 33b becomes a DC voltage of 1.31 V as in the integrator cos output shown in FIG. 86 (H).

  Thus, when there is a load, the output voltage of the integrator 33a, which is the integrator sin output shown in FIG. 86 (D), is the Y axis, and the output voltage of the integrator 33b, which is the integrator cos output shown in FIG. 86 (H). Is the X axis, the signal appears at point B on the Y axis in the XY plane of FIG. Therefore, the XY signal is output within a loaded area on the XY plane shown in FIG.

  Next, with reference to FIG. 87, an operation when a metal body is close to the power transmission coil 1 will be described. When a metal body approaches the power transmission coil 1, the inductance of the power transmission coil 1 decreases and the pure resistance component increases. Therefore, the phase difference θ of the current I flowing through the coil with respect to the voltage V applied to the power transmission coil 1 is smaller than 90 degrees. Moreover, since the impedance of the power transmission coil 1 changes, the amplitude of the current I flowing through the power transmission coil 1 also changes. FIG. 87A shows the voltage V applied to the power transmission coil 1 and the current I flowing through the power transmission coil 1. The amplitude of current I shown in FIG. 87A is slightly larger than the amplitude of current I in FIG.

  The output of the analog switch 32a when the metal body is in proximity is compared with the waveform obtained by half-wave rectifying the sine wave of the detector sin output at the time of no load shown in FIG. 85 (C). As shown in FIG. The portion B includes a slight negative portion. When the output of the analog switch 32a is passed through the integrator 33a, a DC voltage of 1.13 V is obtained as in the integrator sin output shown in FIG.

  On the other hand, the output of the analog switch 32b is smaller than that of the waveform that starts from the minimum value of the sine wave and ends at the maximum value as in the detector cos output at the time of no load shown in FIG. As shown in 87 (G), there is a slight deviation. In FIG. 87 (G), as shown in the detector cos output, the C portion is negative, the D portion is positive, and the area of C is slightly smaller than the area of D. Therefore, when the output of the analog switch 32b is passed through the integrator 33b, the output of the integrator 33b becomes a DC voltage of 0.21 V as in the integrator cos output shown in FIG. 87 (H).

  As described above, when the metal body is in proximity, the output voltage of the integrator 33a, which is the integrator sin output of FIG. 87 (D), is the Y axis, and the output of the integrator 33b is the integrator cos output of FIG. 87 (H). Assuming that the voltage is the X axis, the XY signal is output in the small metal foreign object proximity area on the XY plane of FIG.

  However, depending on the size of the metal body, in the proximity of a small metal body, unlike the actual power transmission, the reactance of the power transmission coil slightly decreases and the net resistance component slightly increases. The absolute value of impedance Z increases slightly. Therefore, there is almost no change in the amplitude of the current flowing through the power transmission coil, and the phase angle θ is slightly reduced. Therefore, in the XY plane shown in FIG. 88, the detection signal is slightly to the right from the Y axis compared to the no-load state. shift. In this way, the power supplied to the power transmission coil 1 can be adjusted by detecting the proximity of the metal body and sending the control signal shown in FIG. 85 to the power transmission control circuit 30a. As a result, it is possible to prevent the heat generation of the metal plate foreign matter adjacent to the power transmission coil 1.

  When the metal body is large, the reactance of the power transmission coil is decreased and the pure resistance component is greatly increased, so that the absolute value of the impedance Z of the power transmission coil 1 is decreased. Therefore, both the amplitude of the current flowing through the power transmission coil and the phase angle θ are reduced, so that the detection signal shifts from the Y axis to the lower right direction on the XY plane shown in FIG. However, the position where the detection signal appears on the XY plane shown in FIG. 88 moves up and down compared to the no-load state, depending on the shape and material of the metal body and the position placed on the power transmission coil. Further, the moving distance in the right direction from the Y axis and the amplitude E that is the distance from the origin of the detection signal also change.

  The small metal foreign object detection area shown in FIG. 88 is a guide only. When a large metal plate is close to the power transmission coil 50, the reactance of the coil is greatly reduced, and the pure resistance component is greatly increased. And the absolute value of the impedance Z of a power transmission coil falls significantly. Therefore, the amplitude E of the current flowing through the power transmission coil 1 is greatly increased, the phase angle θ is greatly decreased, and the detection signal may appear further to the right of the loaded area shown in FIG. 88 in some cases.

  In FIG. 84, the phase and amplitude of the alternating current flowing through the power transmission coil 1 are simultaneously detected by performing synchronous detection. However, the present invention is not limited to the method of FIG. You can also. Alternatively, the peak value may be held by a peak hold amplifier, the peak value may be A / D converted, and the amplitude of the alternating current flowing through the power transmission coil 1 may be detected. When the transmitted power is several W or less, a precise circuit configuration as shown in FIG. 84 is not particularly required, and a means for detecting at least one of the phase and amplitude of the current flowing through the power transmission coil 1 may be provided.

In the circuit of FIG. 84, the amplitude E of the alternating current I flowing through the power transmission coil is represented by the distance from the origin (X = 0, Y = 0) on the XY plane shown in FIG. 88 to the signal (dots). Is done. For example, in FIG. 86, the output (D) X is 0.86 V, and the output (H) Y is 1.31 V, so the amplitude E is E = √ (0.86 ² +1.31 ² ). = 1.57 (V). The phase difference θ between the voltage V applied to the power transmission coil 1 and the current I flowing through the power transmission coil 1 is represented by the slope of the loaded signal (dots) shown in FIG. In this manner, only the amplitude E and the phase difference θ may be detected by the circuit in FIG. 84 to control the transmission power and the like. The method for adjusting the transmitted power by the power transmission control circuit 30a is as described in the embodiment of the previous invention.

  The coil 1Gb, the coil 1Gc, and the coil 1Gd according to the embodiment of the present invention described above increase the inductance Ln only by facing the same opened coil. However, the increase in effective series resistance Rn is small in the coil 1Gb, the coil 1Gc, and the coil 1Gd that define the configuration. Therefore, as in the case of the proximity of the metal body, the signal shifts on the XY plane shown in FIG. However, the increase rate of the effective series resistance Rw (Ω) is large in the proximity of the metal body to the coil facing surface. Therefore, the difference between the proximity of the metal body to the coil facing surface and the case where the same opened coil faces the coil facing surface of the coil 1Ga to the coil 1Gd can be discriminated.

  In general, the frequency fc (Hz) suitable for detecting a metal foreign object is different from the frequency fa (Hz) suitable for power transmission. When the power transmission unit 30 is in a standby state, the power transmission coil 1 is driven at a frequency fc (Hz) suitable for metal foreign object detection. Thus, by changing the frequency fc (Hz) suitable for metal foreign object detection and the frequency fa (Hz) suitable for power transmission, it is possible to realize a power transmission device with good performance for both metal foreign object detection and power transmission. .

  Further, the frequency fc (Hz) at which the detection sensitivity of the metal foreign object is optimum varies depending on the size, shape, material, and the like of the metal foreign object. Therefore, it is more preferable that a plurality of frequencies such as fc1 (Hz) and fc2 (Hz) are synthesized by an addition circuit and used for detection of a metallic foreign object. In this case, analog switches 32a and 32b and LPFs 33a and LPFs 33b shown in FIG. 84 are provided for the number of frequencies to be used. The sin detection signal and the cos detection signal are output at timings as shown in FIGS. 55 to 57 corresponding to the respective frequencies. A plurality of frequencies such as fc1 (Hz) and fc2 (Hz) are set so that a high frequency does not become an odd multiple of a low frequency. If the frequency is set in this way, the frequency components other than fc1 (Hz) become zero, and only the frequency component corresponding to fc1 (Hz) can be extracted.

  In the above case, the frequency fc (Hz) used for metal foreign object detection may be equal to or higher than the maximum frequency f1 (Hz) at which the power transmission coil 1 satisfies Rs> Rw. However, the frequency fa (Hz) for power transmission must always satisfy fa <f1. Alternatively, the frequency fc (Hz) used for metal foreign object detection may be equal to or less than the frequency fa (Hz) suitable for power transmission. Of course, the frequency fa (Hz) may be used for metal foreign object detection.

  When the frequency fa (Hz) is used for metal foreign object detection, when the phase change of the current of the power transmission coil is detected by the comparator, when the amplitude is detected by the peak hold amplifier, the burst as shown in FIG. No problem with waves. However, when the transmission power is adjusted by such a burst wave or the increase / decrease of the output amplitude, the detection signal changes depending on the transmission power in the synchronous detection circuit shown in FIG. There are various workarounds. However, the synchronous detection circuit has high accuracy, and the power transmission control circuit 30a has a function of setting T1 (S) and T (S) shown in FIG. The power transmission control circuit 30a has a function of setting the output voltage Vb (V) and the maximum DC input voltage Vm (V) of the PWM circuit shown in FIG. Therefore, in the power transmission control circuit 30a, an arithmetic process for multiplying the integrator sin output shown in FIG. 86 (D) by T / T1 times can be performed. Also, an arithmetic process for multiplying the integrator sin output shown in FIG. 86 (D) by Vm / Vb can be performed. The same applies to the integrator cos output shown in FIG. 86 (H).

  Although not shown in FIG. 84, as shown in FIGS. 85 to 87, positive and negative signals are input to the operational amplifier 36a, the analog switches 32a and 32b, and the like. Accordingly, ± power is supplied to the operational amplifier 36a, the analog switches 32a, 32b, and the like. The negative power source is generated by a DC / DC converter or the like from Vd, for example.

  FIG. 89 is a circuit diagram showing another embodiment relating to the current detection circuit of the power transmission coil in FIG. FIG. 89 shows from the current detection resistor Ri of the power transmission coil shown in FIG. 84 to the operational amplifier output connected to the inputs of the synchronous detection analog switches 32a and 32b. Other circuit configurations are the same as those in FIG.

  In FIG. 89A, the reactive element 31e is an inductor or a capacitor. The reactance element 31e is connected in series to the power transmission coil 1 in the same manner as the current detection resistor Ri of the power transmission coil shown in FIG. In FIG. 84, since the voltage across the current detection resistor Ri is about several tens of mV, as described above, the operational amplifier 36a is configured as a non-inverting amplifier having a gain of several tens to several hundreds. On the other hand, in FIG. 89A, the voltage across the reactive element 31b may be several volts to several tens of volts, depending on the type and action of the reactive element. Therefore, the voltage at the connection point F between the power transmission coil 1 and the reactive element 31b may exceed the power supply voltage of the circuit constituting FIG. For this reason, the voltage at the point F is lowered below the power supply voltage of the circuit by the voltage dividing resistors R11 and R12.

  The output of the operational amplifier 36a is connected to the inverting terminal and is an amplifier with a gain of +1. The voltage dividing resistors R11 and R12 affect the operating state of the power transmission coil 1 unless they are at least 10 kΩ or more. Therefore, the impedance of the connection point between the voltage dividing resistors R11 and R12 is high. When the impedance of the connection point between the voltage dividing resistors R11 and R12 is low, the operational amplifier 36a may be omitted, and the connection point between the voltage dividing resistors R11 and R12 may be directly connected to the inputs of the analog switches 32a and 32b. However, since the impedance at the connection point between the voltage dividing resistors R11 and R12 is high, the impedance connected to the inputs of the analog switches 32a and 32b is lowered by the gain +1 amplifier by the operational amplifier 36a. In other words, the gain +1 amplifier by the operational amplifier 36a operates as an impedance conversion circuit.

  Next, the effect of the reactive element will be described. For example, a power factor improving capacitor may be used as the reactance element, and the current detection signal may be extracted from the connection point between the power factor improving capacitor and the power transmission coil 1. In this case, as described above, the voltage Vc (V) across the power factor improving capacitor is boosted by the resonance action and exceeds the power supply voltage. Therefore, Vf (V) is stepped down by the voltage dividing resistors R11 and R12 so that the maximum voltage Vf (V) at the connection point between the power factor improving capacitor and the power transmission coil 1 does not exceed the power supply voltage.

  In this case, the voltage phase at the connection point between the power factor correction capacitor and the power transmission coil 1 differs from the current phase in FIGS. Therefore, as shown in FIG. 88, a no-load signal appears on the Y-axis, and a loaded signal and a metal foreign object proximity signal do not always appear in the first quadrant on the XY plane. However, if the position at which the no-load signal appears on the XY plane is known, it is possible to detect when there is no load and when there is no load based on the relative fluctuation (absolute value, movement angle) from there. Alternatively, the phase difference between the sin detection signal (B) and the cos detection signal (F) shown in FIGS. 85 to 87 with respect to the power supply waveform is maintained from FIG. By changing from FIG. 87, the same signal as in FIG. 88 is obtained. Further, instead of the above-described current detection resistor Ri, an inductor that is a reactive element may be used. The inductor is selected with reference to the coil embodiment described above and having a low effective series resistance. The current detection signal is taken out from a connection point between the inductor and the power transmission coil 1.

  Alternatively, a reactive element 31f may be connected as shown in FIG. In FIG. 84, one end of the gain resistor R10 of the operational amplifier 36a is connected to OUT L of the power transmission control circuit 30a, and OUTL is connected to GND which is a reference potential common to the signal processing circuit shown in FIG. As mentioned above. However, in any of the cases of FIGS. 84, 89A, and 89B, OUTL may not be connected to GND, which is a common reference potential with the signal processing circuit. For example, OUTH and OUTL may be differential outputs, and the waveform of the voltage V between OUTH and OUTL may be as shown in FIGS. 85 to 87A.

  In addition, since the power transmission device of the above-described embodiment is equipped with the above function in the power transmission unit of the above-described power transmission device, the power transmission device of the power transmission device is also an embodiment of the power transmission device.

(Explanation of operation of power transmission device)
FIG. 90 is a flowchart showing the operation of the power transmission device using the signal transmission circuit shown in FIG. 81 and the power transmission coil impedance detection circuit shown in FIG.

  The START in SP (step) 1 shown in FIG. 90 is when the power transmission unit 30 is turned on, and after the initialization of the power transmission control circuit 30a is completed, an AC voltage for detecting foreign metal is applied to the power transmission coil 1 in SP2. Enter standby state. The no-load signal shown in FIG. 88 is stored in advance in the power transmission control circuit 30a. When the power transmission control circuit 30a detects a no-load state, it enters a mode for detecting a change in the impedance Z of the power transmission coil 1 at SP3. When the power transmission control circuit 30a detects a state other than the no-load state or detects a change in the impedance Z of the power transmission coil 1, the power necessary for signal transmission is continuously transmitted from the power receiving unit 40 at SP4. At this time, if no signal is returned from the power receiving unit 40 at SP5, the repetition number N is set to N + 1 at SP6, and if N is smaller than a predetermined value at SP7, the process returns to the standby state SP2. If this is repeated a predetermined number of times, for example, 10 times, and normal operation is not entered, it may be determined that an abnormal state is detected at SP14 and an abnormality may be notified by an LED lamp, a buzzer, or the like.

  When it is detected in SP5 that a signal has been sent from the power receiving unit 40, the signal is demodulated in SP8 to confirm whether it is a normal signal. If it is not a regular signal, the process returns to the standby state SP2 again via SP6 and SP7. When the regular signal is confirmed, at SP9, the predetermined power designated by the signal is continuously transmitted for a predetermined time. Even during continuous power transmission, the impedance Z of the coil is detected at SP10. During continuous power transmission, if the impedance Z of the power transmission coil 1 is detected at SP10 and the impedance Z of the coil is other than the initial state (no load state) at SP11, a load RL is predetermined from the power transmission unit 30 to the power reception unit 40. After time separation, request to send a signal at SP17. Alternatively, even if there is no change in the impedance Z of the power transmission coil 1 at SP16 during continuous power transmission, if an abnormality occurs in the power receiving unit 40, the signal is transmitted after disconnecting the load from the power transmitting unit 30 to the power receiving unit 40 at SP17 for a predetermined time. Request to send. Furthermore, when continuous power transmission has elapsed for a predetermined time, for example, 1 minute, at SP17, a request is made to send a signal after the load is disconnected from the power transmission unit 30 to the power receiving unit 40 for a predetermined time.

  The impedance Z of the power transmission coil 1 changes when the relative position between the power transmission coil 1 and the power reception coil 2 changes, when the load resistance value of the power reception unit 40 changes, and between the power transmission coil 1 and the power reception coil 2. There is a case of entering. In order to detect a case where a metal foreign object enters between the power transmission coil 1 and the power reception coil 2, the power reception unit 40 disconnects the load for a predetermined time at SP17, and the power transmission unit 30 detects the foreign material during this time. After that, if the ID code sent from the power receiving unit 40 is genuine, the power transmitting unit 30 continuously transmits predetermined power to the power receiving unit 40.

  In SP9, when the signal includes the maximum power required by the power reception unit 40, the power transmission unit 30 adjusts the transmission power according to the signal. The signal receiving circuit 30c of the power transmission unit 30 is set so as to always receive a signal from the power reception unit 40. In SP16, the power receiving unit 40 can transmit the abnormality of the power receiving unit 40 and other information to the power transmitting unit 30 at an arbitrary time. When it is determined in SP16 that there is no abnormality in the power reception unit 40, the power transmission unit 30 continuously sends power to the power reception unit 40 while the power reception unit 40 is attached to the power transmission unit 30. When an abnormality occurs in the power receiving unit 40, a signal is transmitted from the power receiving unit 40 to the power transmitting unit 30 in SP16. Based on the signal, the power transmission unit 30 requests to send a signal after disconnecting the load from the power transmission unit 30 to the power reception unit 40 for a predetermined time in SP17. Normally, when an abnormality occurs in SP16, the signal of SP18 becomes an abnormal signal, and the process proceeds to abnormal termination of SP14. However, when a signal for increasing or decreasing the transmission power is sent from the power receiving unit 40, the continuation signal is confirmed at SP18, the predetermined power is adjusted at SP9, and continuous power transmission is performed.

  When the power reception unit 40 is separated from the power transmission unit 30, the impedance Z of the power transmission coil 1 fluctuates and returns to the original state, and no ID code is sent from the power reception unit 40, so the power transmission unit 30 stops power transmission, The process ends normally at SP19. Alternatively, when the secondary battery is included in the power receiving unit 40, when charging of the secondary battery is completed, the power receiving unit 40 sends an end signal to the power transmitting unit 30 at SP18 and the processing ends normally. If the impedance Z of the power transmission coil 1 changes during continuous power transmission and the regular ID code is not sent back from the power receiving unit 40, it is determined that the state is abnormal, and the power transmission unit 30 stops power transmission and terminates abnormally. In this case, an abnormal signal may be output as described above.

  Even in the case of normal termination, if power is supplied to the power transmission unit 30, the process returns from SP19 to the standby state of SP2. If abnormal termination is detected at SP14, an abnormal state (such as when a metal foreign object exists on the power transmission coil 1) is confirmed at SP20, and if the normal state is restored, a reset (not shown) provided in the power transmission unit 30 is performed. Press the button or the like to return to the SP2 standby state. In this case, if the abnormal state has not been resolved or if the power receiving unit 40 itself is not compatible with the power transmission unit 30, the power transmission unit 30 is reset button because the SP 14 reaches the abnormal end again according to the flow described above. Even if equipped, there is no particular problem. Rather, it is inconvenient that the abnormal termination cannot be canceled, for example, when the abnormal state is resolved or when the power receiving unit 40 that is not suitable for the power transmitting unit 30 is attached to the power transmitting unit 30. The above-described flow is just an example, and various functions can be realized by various combinations.

(Example of power receiving unit protection circuit)
FIG. 91 is a block diagram illustrating an example of a protection circuit of the power reception unit 40. Even in general electric equipment and electronic equipment, when the power is turned on, the circuit operation becomes transiently unstable until the voltage of the circuit power supply becomes stable. For this purpose, the voltage detection circuit 40d shown in FIG. 91 is used.

  The power reception control circuit 40a includes a voltage detection circuit 40d that operates as load voltage detection means for detecting the voltage of the + power supply VS. The power receiving coil 2 is connected via a fuse 42 to a diode bridge 43 including four high frequency rectifying diodes D1 to D4. The + side output of the diode bridge 43 becomes the + power source VS, and the − side output becomes GND. A smoothing capacitor 44 is connected between the + power supply VS and GND. The source of the Nch-MOSFET 45a is connected to GND, the gate is connected to OUT1 which is the control output of the voltage detection circuit 40d, and the drain is connected to the + power supply VS. A resistor 46a is connected between the gate and source of the Nch-MOSFET 45a.

  Further, the source of the Pch-MOSFET 46b is connected to the + power supply VS, the gate is connected to OUT2 which is the control output of the voltage detection circuit 40d, and the drain is connected to the power supply circuit 40e. A resistor 45b is connected between the gate and source of the Pch-MOSFET 46b. The operation of the resistors 45b and 46a will be described later.

  To describe the operation of the block diagram of the protection circuit shown in FIG. 91, first, the level of the + power supply VS is defined as follows.

V1 (V): Minimum voltage at which the power supply circuit 40e operates V2 (V): Normal operating voltage of the power supply circuit 40e V3 (V): Maximum operable voltage of the power supply circuit 40e V4 (V): Maximum rated voltage of the power supply circuit 40e V5 (V): Voltage at which the power supply circuit 40e is damaged When the power supply voltage received by the power receiving coil 2, rectified by the diode bridge 43, and smoothed by the smoothing capacitor 44 exceeds a predetermined voltage, the voltage detection circuit 40d becomes + power Start monitoring VS voltage. Until then, both control outputs of OUT1 and OUT2 of the voltage detection circuit 40d maintain a high impedance state. When the voltage of the + power supply VS rises above V1 (V), the control output OUT2 of the voltage detection circuit 40d becomes the GND level, the Pch-MOSFET 46b is turned on, and the + power supply VS is supplied to the power supply circuit 40e.

  At this stage, the + power source VS is supplied from the power supply circuit 40e to the power receiving side device 50, so that the power receiving side device 50 becomes operable. When the voltage of the + power supply VS is between V2 (V) and V3 (V), the control output of OUT1 of the voltage detection circuit 40d maintains a high impedance state, and the control output of OUT2 is at the GND level. During this time, the Pch-MOSFET 46b is ON and the Nch-MOSFET 45a is OFF.

  When detecting that the voltage of the + power supply VS is equal to or higher than V3 (V), the voltage detection circuit 40d outputs the control output OUT1 and turns on the Nch-MOSFET 45a. The voltage detection circuit 40d and the Nch-MOSFET 45a function as a shunt regulator, and control the voltage of the + power supply VS to V3 (V) or less. When the voltage of the + power supply VS exceeds V4 (V) even though the control output OUT1 of the voltage detection circuit 40d is output, the control output OUT2 becomes the level of the + power supply VS and turns off the Pch-MOSFET 46b. .

  In this state, the + power supply VS and the power supply circuit 40e are disconnected, and at least the power supply circuit 40e is prevented from being damaged. Therefore, the Pch-MOSFET 46b operates as a power shut-off means. Further, even when the shunt regulator composed of the voltage detection circuit 40d and the Nch-MOSFET 45a is operated, if the voltage of the + power supply VS exceeds V5 (V), the control output OUT1 is fixed at the level of the + power supply VS, and the Nch-MOSFET 45a Completely ON state. In this case, a large current is forced to flow from the power receiving coil 2 through the diode bridge 43 to the Nch-MOSFET 45a, and the fuse 42 that operates as the load current detection means and the protection means is cut. If the fuse 42 is cut, the + power supply VS becomes zero and no power is supplied to the power receiving device 50, but the power receiving device 50 is protected from damage due to an excessive voltage.

  When the diodes D1 to D4 constituting the diode bridge 43 are damaged in the short-circuit mode before the fuse 42 is cut for some reason, a large current flows through the fuse 42 and the fuse 42 is cut. When each diode constituting the diode bridge 43 is damaged in the open mode, the power of the power receiving unit 40 is reduced or the + power supply VS becomes zero, so that the same effect as when the fuse 42 is cut is obtained.

  Note that, even if the + power source VS is equal to or lower than the predetermined value V1 (V), the fuse 42 is naturally cut off to protect the circuit when an excessive current flows in the circuit. In FIG. 91, the power supply circuit 40e has a current detection function, and sends a current detection signal to the voltage detection circuit 40d via the signal line 64. Based on the signal, the voltage detection circuit 40d turns on the Nch-MOSFET 45a and causes a large current to flow through the Nch-MOSFET 45a. Alternatively, the Pch-MOSFET 46b is turned off to protect the power supply circuit 40e from excessive current.

  The resistors 46a and 45b described above set the voltage between the gate and the source to zero when a signal for turning on the Nch-MOSFET 45a and the Pch-MOSFET 46b is not applied to the gates of the Nch-MOSFET 45a and the Pch-MOSFET 46b. Nch-MOSFET 45a and Pch-MOSFET 46b are provided to keep the OFF state. This works so that the Nch-MOSFET 45a and the Pch-MOSFET 46b are kept off at the time of the above-described power supply startup. The resistors 45a and 45b are equipped for such a purpose.

  When the voltage detection circuit 40d is damaged for some reason, OUT1 is short-circuited with GND, and OUT2 is short-circuited with the + power supply VS, or both OUT1 and OUT2 are in a high impedance state. Therefore, the Pch-MOSFET 46b is turned OFF when the voltage detection circuit 40d is damaged, and the Pch− is not limited unless the voltage of the + power supply VS exceeds the withstand voltage between the drain and source of the Pch-MOSFET 45b (200V or more for high withstand voltage). The MOSFET 45b is not damaged. On the other hand, since the withstand voltage between the gate and the source of the MOSFET is ± 10 to 20V, OUT1 is short-circuited to the + power source VS and damaged, and when the + power source VS exceeds 20V, the Nch-MOSFET 45a is damaged. Further, if OUT2 is short-circuited to GND and damaged, and the + power supply VS exceeds 20 V, the Pch-MOSFET 45b is also damaged. Therefore, when the voltage detection circuit 40d is damaged, OUT1 and OUT2 are configured to be in the destruction mode as described above.

  Such a protection circuit is provided when the relative position between the power transmission coil 1 and the power reception coil 2 changes to change the transmission power, or when the power reception control circuit 40a of FIG. 91 described above malfunctions. 50 damage to the main body can be prevented. However, when the protection circuit operates, it becomes impossible to supply power to the power receiving side device 50 main body, and it takes time to recover. Therefore, it is desirable that at least the fuse 42 be easily replaceable. That is, the fuse 42 is made into a small module 41a so that it can be easily replaced.

  When the power supply circuit 40e is disconnected by turning off the Pch-MOSFET 46b, the power supply circuit 40e and the device main body are protected from damage due to excessive voltage. However, in general, a high-speed rectifier diode has a low reverse withstand voltage, and when the Pch-MOSFET 46b is turned OFF, the diode bridge 43 may be damaged by an excessive voltage. In such a case, it is preferable to use the small module 41b so that all the circuit portions including the diode bridge 43 can be replaced. That is, the circuit including the diode bridge 43 is made into a small module 41b and configured so that it can be easily replaced.

  Further, assuming that the protection circuit 40b does not operate normally and the voltage detection circuit 40d is damaged, a part of the protection circuit 40b is a small module 41c. You may equip the small module 41c of the protection circuit 40b so that the module 41b comprised from a diode bridge and a fuse is replaceable. You may equip the module 41b so that the module 41a comprised from a fuse is replaceable.

  Further, it is more preferable that at least one spare of the fuse 42, the module 41a, the module 41b, and the module 41c is built in the main body of the power receiving side device 50. In FIG. 91, the modules 41a, 41b, and 41c described above are all configured to be two-terminal or four-terminal modules so that they can be easily replaced. With the current mounting technology, it is considered that the module 40a can be downsized to about 3φ × 5 mm. The fuse 42 can be formed in a semiconductor element.

  In the embodiment of FIG. 91, three protection functions are provided, but at least one protection function may be provided depending on the specifications of the device. For example, if the voltage detection circuit 40d and the Pch-MOSFET 46b are provided, a low voltage circuit can be used. When it is absolutely necessary to prevent damage to the power receiving device 50, it is preferable to equip at least the voltage detection circuit 40d and the fuse 42.

  In addition, since the power transmission device of the above-described embodiment is equipped with the above function in the power reception unit of the above-described power transmission device, the power transmission device of the power transmission device is also an embodiment of the power reception device.

(Other embodiments of signal transmission system)
FIG. 92 is a block diagram illustrating another method for transmitting a signal from a power receiving unit to a power transmitting unit by load modulation.

  The embodiment shown in FIG. 92 includes a load modulation drive unit 47 and a secondary battery charge control unit 48 as main components. In this embodiment, in order to perform signal transmission from the power receiving unit 40 to the power transmitting unit 30 using the power transmitting coil 1 and the power receiving coil 2, the Nch-MOSFET 45c or the Pch-MOSFET 45d is driven by the load modulation driving unit 47. In the embodiment of FIG. 81, it has been described that when the power transmission coil and the power reception coil face each other, the impedance Z of the power transmission coil varies depending on the load resistance value connected to the power reception coil. Therefore, in FIG. 92, the reactance and the pure resistance component of the power transmission coil vary depending on whether the Pch-MOSFET 45d is ON or OFF. This change in reactance and pure resistance component appears as a signal change on the XY plane shown in FIG. 88, for example. In this manner, signal transmission by load modulation can be performed from the power reception unit 40 to the power transmission unit 30 using the power reception coil 2 and the power transmission coil 1.

  More specifically, in FIG. 92, the source of the Nch-MOSFET 45c is connected to GND, the gate is connected to the output terminal N of the load modulation driving unit 47, and the drain is connected to the diode bridge via the resistor R30. 43b is connected to the + side output. The resistance value of the resistor R30 is selected to be approximately twice the resistance value of the normal load. The source of the Pch-MOSFET 45d is connected to the + side output of the diode bridge 43b, the gate is connected to the output terminal P of the load modulation driver 47, and the drain is connected to the + power source VS.

  In the preferred embodiment, as shown in FIG. 92, when the secondary battery 60 is included on the power receiving side, the secondary battery charge control unit 48 operating as the charge control means detects the charge state of the secondary battery 60. . The state of charge of the secondary battery 60 is sent from the secondary battery charge control unit 48 to the load modulation drive unit 47 through the signal line 65. When the secondary battery 60 is nearly fully charged, the N output of the load modulation drive unit 47 is set to HI / LO, and the Nch-MOSFET 45c is driven ON / OFF to perform load modulation. Therefore, the load modulation driving unit 47 and the Nch-MOSFET 45c operate as load modulation driving means.

  When the secondary battery 60 is nearly completely discharged, the P output of the load modulation driving unit 47 is set to HI / LO, and the Pch-MOSFET 45d is driven OFF and ON to perform load modulation. As described above, the load modulation for reducing the load resistance value and the load modulation for opening the load are switched according to the charging state of the secondary battery 60. By adopting such a load modulation method, signal transmission can be performed from the power reception unit 40 to the power transmission unit 30 using the power reception coil 2 and the power transmission coil 1 without impairing the power transmission performance.

  When the load of the power receiving coil 2 is varied in this way, the impedance Z of the power transmitting coil 1 varies as shown in the XY diagram of FIG. This fluctuation of the impedance Z can be detected by a circuit as shown in FIG. The signal subjected to load modulation by the power receiving unit 40 is demodulated by the power transmission unit 30. As described above, when the proximity of the metal body and the load of the regular power receiving unit 40 vary, the variation shown in the XY diagram of FIG. 88 is different. Even if the metal body is on the power transmission coil 1, the power transmission unit 30 detects the metal body and power transmission is stopped.

  In addition, since the power transmission device of the above-described embodiment is equipped with the above function in the power receiving unit 40 of the above-described power transmission device, the power transmission device of the power transmission device is also an invention of the power transmission device.

  As described above, the embodiment equipped with the signal transmission means, the embodiment of the control circuit, the embodiment of the power receiving unit protection circuit, and the other embodiments of the signal transmission system are the same as those of the embodiments of the power transmission apparatus described above. Applicable to all. In addition, the examples of the signal transmission means and the examples of the control circuit are applicable to all the embodiments of the power transmission device of the power transmission device. The examples of the signal transmission means, the examples of the power receiving unit protection circuit, and other examples of the signal transmission method are applicable to all the embodiments of the power receiving device of the power transmission device.

  In the conventional technique, the power receiving unit 40 cannot send large power to the power receiving unit 40 that is damaged by an excessive current and an excessive voltage. Therefore, the power receiving unit protection circuit described above has not been studied.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

The power transmission device equipped with the coil of the power transmission device of the present invention, the power transmission device and the power reception device of the power transmission device, and the power required by the power reception unit from the power transmission unit to the power reception unit without using electric wires or mechanical contacts Can be used to transmit

1 is a block diagram of a power transmission device according to an embodiment of the present invention. It is a figure which shows the coil used as a power transmission coil or power receiving coil of the electric power transmission apparatus shown in FIG. It is a figure which shows the modification of the external shape of the coil shown in FIG. It is an equivalent circuit for obtaining the input impedance of the transformer. It is a figure which shows the equivalent circuit of the coil single-piece | unit in the coil of the electric power transmission apparatus in one Embodiment of this invention. It is a figure showing the equivalent circuit of the transformer part of the electric power transmission apparatus comprised like FIG. 95 demonstrated by the prior art example. It is a figure showing the equivalent circuit of a transformer when a secondary side coil is short-circuited. It is a figure showing the equivalent circuit of a transformer when load resistance RL is connected to the secondary side coil. The figure which shows the relationship between effective electric power transmission efficiency (eta) and frequency when it is set as Rw, Rn, Rs, and load resistance value RL = 10 (ohm) of the coil 1A which wound the winding of 1 turn of single conductor of wire diameter 1mm by 25 turns. It is. It is a figure which shows the relationship between Rw, Rn, Rs, kr, ki, and a frequency of the coil 1B which closely wound 40 turns of the single conductor wire with a wire diameter of 0.6 mm with an outer diameter of 70 mm. It is a figure which shows the relationship between the phase angle of the coil 1C which wound the single conducting wire of wire diameter 0.3mm closely by 70 turns with a diameter of 70 mm, and the phase angle and frequency of the coil 1C single-piece | unit. It is a figure which shows the relationship between Rw, Rn, Rs, and frequency of the coil 1D which wound the single conducting wire of wire diameter 0.3mm closely by 31 turns with a diameter of 30 mm. It is a figure which shows the relationship between Rw, Rn, Rs, kr, and the frequency of the coil 1E which wound the 14-turn coil which provided the space | gap with the outer diameter of 70 mm with the wire diameter of 1 mm. It is a figure which shows the relationship between Rw, Rn, Rs, kr, ki, and the frequency of the coil 1F which wound the Litz wire which bundled 75 formal single conductor wires with a copper wire diameter of 0.05 mm closely by 30 turns with an outer diameter of 70 mm. . It is a figure showing the relationship between Rw, Rn, Rs, kr, ki and the frequency of the coil 1G which closely wound 20 turns of Litz wire which bundled 75 formal single conductor wires with a copper wire diameter of 0.05 mm with an outer diameter of 50 mm. It is a figure which shows the relationship between the frequency of the coil which wound the formal single conducting wire of 0.2 mm, 0.4 mm, 0.8 mm, and 1 mm 25 times in the shape of a flat plate, and the effective resistance Rw of each coil. FIG. 10 is a diagram illustrating a relationship between effective power transmission efficiency η and frequency when Rw, Rn, Rs, and load resistance value RL = 10Ω when the coil 1F is opposed to the coil 1A illustrated in FIG. 9. It is an equivalent circuit diagram of a litz wire. FIG. 14 is a diagram showing a comparison of states in which the coil effective series resistance Rw of the closely wound coil 1A shown in FIG. 9 and the loosely wound coil 1E shown in FIG. 13 increases. It is a figure which shows the relationship between Rw and the frequency of each coil which provided the gap | interval width of 0, 0.2 mm, and 0.4 mm, and wound 25 turns for the formal wire of wire diameter 0.4mm. It is an actual measurement figure which shows the frequency characteristic of each resistance value and power factor when coil 1A is used for a power transmission coil and a power receiving coil, and load resistance value RL is changed. It is an actual measurement figure which shows the frequency characteristic of each resistance value and power factor when coil 1A is used for a power transmission coil, coil 1F is used for a receiving coil, and load resistance value RL is changed. It is sectional drawing which shows the other example of the conducting wire used for the coil shown in FIG. It is sectional drawing of the coil which wound conducting wire in the cross-sectional umbrella type. It is a figure showing the horizontal position and magnetic field intensity of the coil of FIG. 24 and FIG. It is sectional drawing of the coil which wound conducting wire on the insulating material. It is a figure which shows the coil of the electric power transmission apparatus in other embodiment of this invention. It is a figure which shows the coil of the electric power transmission apparatus in further another embodiment of this invention. In the coil shown in FIG. 27, it is the figure which simulated with the computer magnetic flux distribution which the coil | winding of an outermost periphery part produces | generates. It is sectional drawing of the aggregate | assembly of the bare copper wire which is an example of the conducting wire used for the coil of the electric power transmission apparatus in further another embodiment of this invention. It is a figure which shows the coil of the electric power transmission apparatus in further another embodiment of this invention. It is a figure which shows an example of the cross section of the litz wire which is the conducting wire used for the coil shown in FIG. It is sectional drawing of the conductor with which the insulating material was filled in the pipe-shaped conductor. It is sectional drawing of the conducting wire which divided | segmented and formed the conductor on the insulating material. It is sectional drawing of the conducting wire which divided | segmented and formed the conductor on the insulating material, and also formed the conductor inside the insulator. It is sectional drawing of the conducting wire which divided | segmented and formed the conductor in the cross-shaped insulation material. It is sectional drawing of the conducting wire which piled up the foil-shaped conductor and the insulating material, and was formed so that a cross section was a spiral and a conductor and an insulator might exist alternately. It is a figure which shows the structure of the coil 1f which prevents unnecessary radiation. It is a figure which shows the coil 1g which provided the insulating board between the coil and the magnetic material board. It is a figure which shows the coil 1h which provided the magnetic material board of 2 layers of the magnetic material board and the magnetic material board in the one surface side of the coil. It is a figure which shows the coil 1j which provided the insulating board with thickness I between the two magnetic material boards which comprise the coil 1h shown in FIG. It is a figure which shows the structure of the coil 1k which prevents the characteristic fluctuation | variation of a coil when a metal body adjoins to a coil. It is a figure which shows the structure of the coil 1m which prevents both the proximity | contact effect of a metal body, and unnecessary radiation. It is a figure which shows the structure of the coil 1n which prevents both the proximity | contact effect of a metal body and unnecessary radiation. It is a figure which shows the structure of the coil 1p which prevents both the proximity | contact effect of a metal body, and unnecessary radiation. It is a figure which shows the structure of the coil 1q which prevents both the proximity | contact effect of a metal body, and unnecessary radiation. It is a figure which shows the structure of the coil 1r which prevents both the proximity | contact effect of a metal body, and unnecessary radiation. It is a figure which shows the structure of the coil 1s which prevents both the proximity | contact effect of a metal body, and unnecessary radiation. It is a figure which shows the structure of the coil 1t which prevents both the proximity | contact effect of a metal body, and unnecessary radiation. It is a three-dimensional view of the elements that constitute both opposing coils. It is a figure which shows the state which each center corresponds and opposes, when the outer diameters of two coils differ. It is a figure which shows the state which each center has shifted | deviated and opposed when the outer diameters of two coils differ. It is a figure which shows the relative positional relationship of a power transmission coil and a receiving coil in case a power transmission coil and a receiving coil are both elliptical. It is a figure which shows an example of the power transmission coil 1 and the receiving coil 2 which oppose when a coil opposing surface is other than circular. It is a figure which shows the relationship between the effective series resistance Rw of each coil shown to FIGS. 38-41, and a frequency. It is a figure which shows the relationship between Q of each coil shown in FIGS. 38-41, and a frequency. It is a characteristic view which shows the effective series resistance Rw of the coil 1G single-piece | unit, and the inductance Lw of the coil 1G single-piece | unit. This is a characteristic of the coil 1Ga in which various metal plates are opposed to the coil 1G via a 10 mm insulator. FIG. 6 is a characteristic diagram showing an effective series resistance Rw and an inductance Lw when various metal plates are brought close to a coil 1Gb in which one magnetic material plate is provided on the coil 1G. FIG. 6 is a characteristic diagram showing an effective series resistance Rw and an inductance Lw when various metal plates are brought close to a coil 1Gc in which two magnetic material plates are provided on the coil 1G. It is a characteristic view which shows the structure of each coil, and the relationship of Q. It is the characteristic view which measured effective series resistance Rw and inductance Lw in the structure equivalent to the coil 1k shown in FIG. 42 for the coil 1D shown in FIG. It is the characteristic view which measured the effective series resistance Rw and the inductance Lw in the structure equivalent to the coil 1k shown in FIG. 42 for the coil 1E shown in FIG. It is a figure which shows an example of a structure of the coil which can be inductively coupled between the same two coils equipped with the core. FIG. 65 is a diagram showing a relationship between Rw, Rs, Rn and frequency of a single coil of a coil 1H having the configuration of FIG. It is a figure which shows the relationship between Lw, Ls, Ln, and a frequency of the coil 1H and the two coils 1Ha and 1Hb. It is a figure which shows the relationship between Lw, Ls, Ln, the coupling coefficient ki calculated | required approximately from Lw and Ls, and frequency measured when the coil 1G is an air-core state. It is a figure which shows the structure of the inseparable transformer which wound the primary coil and the secondary coil around the toroidal core. In coil 1Gb, it is a figure which shows the relationship between Lw, Ls, Ln, ki, ki2, and a frequency when two coils 1Gb are used. It is a characteristic view which shows the effective series resistance Rw and the inductance Lw in 100 kHz when various metal plates are made to adjoin to the coil 1H. It is a figure which shows the relationship between Rw, Rs, Rn and frequency when two coils 1Gd are used in the coil 1Gd provided with a magnetic material plate in the coil 1G. The effective series resistance Rw (Ω) of the single coil of coil 1H and two coils 1H are inductively coupled, and the other coil is opened when the other coil is short-circuited. It is a figure which shows the relationship between Rw, Rs, Rn and frequency when the effective series resistance of one coil is Rn (Ω). The inductance Lw (μH) of the single coil 1H, the inductance Ls (μH) of one coil when the two coils 1H are inductively coupled and the other coil is short-circuited, and the inductance of one coil when the other coil is opened It is a figure which shows the relationship between Lw, Ls, and Ln and frequency when letting be Ln (μH). It is a characteristic view which shows the effective series resistance Rw and the inductance Lw in 100 kHz when various metal plates are made to adjoin to the coil 1H. It is a figure which shows the relationship between Rw, Rs, Rn, and a frequency when two coils 1Gb are used and the opposing distance Z is 3 mm. It is a figure which shows the relationship between Rw, Rs, Rn and frequency when two coils 1Gd equipped with 0.5 mm-thick aluminum metal plate are used for the coil 1Gb and the opposing distance is zero. It is a figure which shows the relationship between Rw, Rs, Rn and a frequency when two coils 1Gd are used and the facing distance is 3 mm. FIG. 49 is a diagram in which a metal plate mounted on a coil is used as a wire to be taken out from the inner periphery of the coil in the coil 1 t shown in FIG. 42 to the coil 1 t shown in FIG. 49. The lead wire used for the coil of each configuration shown in FIGS. 38 to 49 is a litz wire, one end of the litz wire is connected to all the strands, and the other end of the litz wire is a strand constituting the litz wire. It is an equivalent circuit diagram when at least one is taken out as a common line. Relationship between load current of secondary winding and voltage at both ends of secondary winding in normal transformer (transformer) configured in tight coupling state, load of receiving coil of power transmission device in embodiment of the present invention It is a characteristic view which shows the relationship between an electric current and the both-ends voltage of a secondary side winding. It is a figure which shows the example which equipped the power transmission part 30 and the power receiving part 40 with the signal transmission means. It is a figure which shows the basic waveform of PWM control for controlling transmitted power. It is a figure which shows an example of the PWM circuit for controlling the transmitted power of the power transmission part 30 shown in FIG. An example of a circuit provided in the power transmission unit for measuring a current flowing through the power transmission coil 1 and determining whether a metal body is close to the power transmission coil 1 or determining an operation state on the secondary side is shown. It is a block diagram. FIG. 85 is a waveform diagram illustrating an operation state of the circuit in FIG. 84. FIG. 85 is a waveform diagram illustrating an operation state of the circuit in FIG. 84. FIG. 85 is a waveform diagram illustrating an operation state of the circuit in FIG. 84. It is a figure for demonstrating the signal output after the synchronous detection of the power transmission coil current. It is a circuit diagram showing other embodiment regarding the electric current detection circuit of the power transmission coil in FIG. It is a flowchart showing operation | movement of the electric power transmission apparatus which used together the signal transmission circuit and the impedance detection circuit of the power transmission coil. It is a circuit diagram which shows an example of the protection circuit of a power receiving part. It is a block diagram which shows the other system which transmits a signal from a power receiving part to a power transmission part by power receiving load modulation. It is a schematic block diagram of the electric power transmission apparatus which can isolate | separate a primary side coil and a secondary side coil. It is the top view and sectional drawing of a power transmission coil or a receiving coil. FIG. 93 is an equivalent circuit diagram of the power transmission device in which the primary side coil and the secondary side coil shown in FIG. 92 can be separated.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Power transmission coil, 1a-1e, 1A-1G coil, 2 Power receiving coil, 5 Insulation material, 6 Insulating resin, 7 Bobbin, 8 Litz wire, 11,56 Conductor, 12 Single conductor, 13 Insulation coating, 14 Bare single conductor , 15 conductors, 18, 19, 21, 24 Insulating material, 30 power transmission unit, 30a power transmission control circuit, 30b AC power supply, 30b, 40b signal transmission circuit, 30c, 40c signal reception circuit, 30e voltage control circuit, 30f PWM step-down inverter , 30h Transmission side identification information holding means, 30i Transmission power control means, 30j Storage means, 31b Regenerative diode, 31c Coil, 31a, 32b Analog switch, 31d, 44 Smoothing capacitor, 31e, 31f Reactive element, 33a, 33b Integrator , 35 A / D conversion circuit, 36a operational amplifier, 40 power receiving unit 40a Power reception control circuit, 40d Voltage detection circuit, 40e Power supply circuit, 40h Power reception side identification information holding means, 40j Power reception operation state detection means, 40k Temperature detection means, 41a, 43b Diode bridge, 41b Rectifier diode bridge, 42 Fuse, 45a, 45c Nch-MOSFET, 45d, 46b Pch-MOSFET, 47 Load modulation driving unit, 48 Secondary battery power receiving control unit, 50 Power receiving side device, 51, 511, 512 Magnetic material plate, 52 Insulating plate, 53, 53a, 53b Core 55, metal plate, 60 secondary battery, 61, 62, 63, 65 signal transmission line, R11, R12 voltage dividing resistor.

Claims (22)

The power transmission unit and power reception unit are configured to be separable,
A coil of a power transmission device used in a power transmission device that transmits power from the power transmission unit to the power reception unit with a power transmission coil of the power transmission unit and a power reception coil of the power reception unit facing each other,
The power transmission coil and the power reception coil are both the same two air-core coils formed in an air-core shape by winding a conducting wire,
The two identical coils are configured such that both are inductively coupled to form a transformer,
One of the two identical air-core coils is used as one coil, and the frequency characteristic of the effective series resistance of the one coil is measured.
In order to detect a change in the effective series resistance of the one coil, another coil identical to the one coil constituting the transformer is opposed to the one coil, the other coil,
The effective series resistance of the one coil alone is Rw (Ω),
When the other coil whose both ends are short-circuited is opposed to the one coil to constitute a transformer, the effective series resistance of the one coil is Rs (Ω).
The one coil uses a predetermined wire having a predetermined wire diameter so that the maximum frequency f1 satisfying the relationship of Rs> Rw is at least 100 kHz or higher, and is predetermined by a predetermined number of windings and a winding method. The coil of the electric power transmission apparatus comprised in the outer diameter and inner diameter . The conducting wire is a single conducting wire provided with insulating clothing,
When the maximum diameter of the single conductor is d2 (mm) and the outer diameter of the one coil is D (mm),
The outer diameter D of the one coil is at least 25 times the maximum diameter d2;
And the number of turns of the conducting wire is a predetermined number of turns or more,
The coil of the power transmission device according to claim 1, wherein the self-inductance of the one coil is at least 2 μH or more . The conducting wire includes a plurality of conducting wires, and each conducting wire is provided with an insulation coating on an assembly of a plurality of bare single conducting wires selected so that the maximum diameter is 0.3 mm or less,
The maximum diameter of the aggregate of the plurality of bare single conductor wires is d2 (mm),
When the outer diameter of the one coil is D (mm),
The outer diameter D of the one coil is at least 25 times the maximum diameter d2;
And the number of turns of the conducting wire is a predetermined number of turns or more,
The coil of the power transmission device according to claim 1 , wherein the self-inductance of the one coil is at least 2 μH or more . The conductor is provided with an insulator layer inside the conductor,
The cross-sectional area of the insulator layer is 11% or more of the cross-sectional area of the entire conductor,
The maximum diameter of the aggregate of the plurality of bare single conductor wires is d2 (mm),
When the outer diameter of the one coil is D (mm),
The outer diameter D of the one coil is at least 25 times the maximum diameter d2;
And the number of turns of the conducting wire is a predetermined number of turns or more,
The coil of the power transmission device according to claim 1 , wherein the self-inductance of the one coil is at least 2 μH or more . The conducting wire is composed of an assembly of a plurality of single conducting wires each coated with an insulating coating, and when the maximum diameter of the conductor in the single conducting wire is d4 (mm),
The coil of the power transmission device according to claim 4 , wherein d4 is 0.3 mm or less, and a thickness t (mm) of the insulating coating is selected to be (d4) / 30 or more . Among the plurality of single conductors constituting the conductor, at least one single conductor is a coupling line,
The coupling wire is electrically insulated from the power transmission conductor of the coil of the power transmission device, and is electromagnetically equivalent to the power transmission conductor of the coil of the power transmission device and the honey coupling transformer. The coil of the power transmission device according to claim 5 , configured as described above . The air-core coil is a coil in which a conducting wire is wound in a single layer spiral shape,
When the maximum diameter d of the conducting wire is 0.4 mm or more, a gap of 0.2 mm or more is provided between conductors of adjacent conducting wires,
The power transmission according to any one of claims 1 to 6, wherein when the maximum diameter d of the conducting wire is less than 0.4 mm, a gap of d / 2 (mm) or more is provided between conductors of adjacent conducting wires. Device coil. The air-core coil is a coil in which a conducting wire is wound in a single layer spiral shape,
The width of the gap provided between the conductors of the adjacent conductors in the outermost periphery of the air-core coil is t1 (mm),
When the width of the gap provided between the conductors of the adjacent conductors in the innermost peripheral portion of the air-core coil is t2 (mm),
t2>t1> 0, and the width of the gap increases from the outermost periphery to the inner periphery, and the width t2 of the gap provided between the conductors of adjacent conductors in the innermost periphery is The coil of the power transmission device according to any one of claims 1 to 6, wherein the coil is at least 0.2 mm or more . The air-core coil, the outer peripheral portion of the conductors has an insulating layer, between the conductors adjacent the outermost peripheral portion are closely through an insulating layer, a coil of the power transmission device according to claim 8 . The air-core coil is formed on at least one of the one insulating the member insulating plate, the coils of the power transmission device according to any one of claims 1 to 9. Wherein said air-core coil, the being configured to include at least one or more magnetic material plates of convolutions surface area equal to or larger dimension than that of the air-core coil, to any one of claims 1 to 10 The coil of the electric power transmission apparatus as described. Including the air-core coil according to any one of claims 1 to 10,
In order to prevent the characteristics of the air-core coil from fluctuating when a metal plate approaches the air-core coil, and to reduce unnecessary radiation,
A magnetic material plate having a dimension equal to or larger than the winding surface area of the air-core coil;
On the surface not equipped with the air-core coil of the magnetic material plate, including a metal plate equivalent to the dimensions,
When the coil of the power transmission device includes two or more magnetic material plates,
The metal plate is a metal plate having a thickness M (mm) of 0.01 mm or more made of a metal or alloy having a diamagnetic or paramagnetic magnetic property,
When the coil of the power transmission device is equipped with only one magnetic material plate,
The coil of the power transmission device , wherein the metal plate is a metal plate having a thickness M (mm) of 0.1 mm or more and made of a metal or alloy having diamagnetic or paramagnetic magnetic properties . Including the air-core coil according to any one of claims 1 to 10,
In order to prevent fluctuations in the characteristics of the air-core coil when a metal plate approaches the air-core coil,
An insulating plate having a dimension equal to or larger than the winding surface area of the air-core coil;
Equipped with a metal plate equivalent to the above dimensions,
When the minimum outer diameter of the air-core coil is D2 (mm),
A predetermined distance G (mm) of D2 / 10 or more is provided between the air-core coil and the metal plate by the one or more insulating plates,
The coil of the power transmission device , wherein the metal plate is a metal plate having a thickness M (mm) of 0.1 mm or more and made of a metal or alloy having diamagnetic or paramagnetic magnetic properties . In the central part of the magnetic material plate and the insulating plate, a hole through which the conducting wire can pass is provided,
Connecting the conductive wire end of the inner periphery of the coil to the metal plate;
The coil of the power transmission device according to claim 12 or 13 , wherein the metal plate is one of the two terminals of the coil . One coil of the coil of the power transmission device,
If the other coil is the other coil, facing the one coil,
The maximum distance from the center of the winding surface of the air-core coil constituting the one coil to the end of the winding surface is Da (mm),
The minimum distance from the center of the winding surface of the conducting wire constituting the other coil to the end of the winding surface is Db (mm),
When Db> Da,
Minimum distance from the center of the convolutions surface of the conductor constituting the said one coil to the edge of the magnetic material plate, at least, Db + (Db-Da) × 2, the set, from the claims 11 14, The coil of the electric power transmission apparatus in any one. A coil of two identical power transmission devices according to any one of claims 11 to 15,
The two identical coils are configured such that inductive coupling is possible when the coil winding surfaces of both coils are opposed to each other.
One of the two identical coils is set as one coil, and the frequency characteristic of the effective series resistance of the one coil is measured.
In order to detect a change in the effective series resistance of the one coil, another coil that is the same as the one coil that constitutes the transformer is opposed to the one coil, the other coil,
The effective series resistance of the one coil alone is Rw (Ω),
When the effective series resistance of the one coil is Rs (Ω) when the other coil with both ends short-circuited is opposed to the one coil to constitute a transformer,
The air core coil is equipped with only a predetermined magnetic material plate or a predetermined magnetic material plate so that the maximum frequency f1 satisfying the relationship of Rs> Rw is at least 100 kHz or more. The coil of the power transmission device according to any one of claims 11 to 15 , comprising at least two of the insulating plate and the metal plate . A power transmission device comprising the coil of the power transmission device according to any one of claims 1 to 16 in at least one of a power transmission unit and a power reception unit. Furthermore, the power transmission unit includes an AC power source including power conversion means for converting DC power into AC power, and the power transmission coil is driven by the AC power source,
The coil of the power transmission device according to any one of claims 1 to 16 is set as one coil, and a frequency characteristic of an effective series resistance of the one coil is measured.
A coil configured to be inductively coupled to the one coil, and in order to detect a change in effective series resistance of the one coil, a coil opposed to the one coil is set as the other coil,
When the one coil is used as the power transmission coil, the power receiving coil is the other coil, and when the other coil is used as the power transmission coil, the power receiving coil is the one coil. There,
The effective series resistance of the one coil alone is Rw (Ω),
When the other coil with both ends short-circuited is opposed to the one coil to constitute a transformer, the effective series resistance of the one coil is Rs (Ω),
F1 (Hz), the highest frequency that satisfies the relationship Rs> Rw.
If the output frequency of the AC power supply is fa (Hz),
The output frequency fa (fa (fa) of the AC power supply, which is the frequency fd for driving the power transmission coil, so that the one coil can transmit power in a frequency region satisfying the relationship of Rs> Rw. = fd), said set to a frequency of less than f1, the power transmission apparatus according to claim 17 for transmitting power to the power receiving portion from the power transmission unit in the frequency region of less than the f1. Furthermore, the effective series resistance of the one coil when the other coil having both ends opened is opposed to the one coil is Rn (Ω),
When the one coil has a maximum frequency satisfying the relationship of Rs> Rn ≧ Rw and f2 (Hz),
The output frequency fa of the AC power source, which is the frequency fd for driving the power transmission coil, so that the one coil can transmit power in a frequency region satisfying the relationship of Rs> Rn ≧ Rw. The power transmission device according to claim 18 , wherein (fa = fd) is set to a frequency less than f2, and power is transmitted from the power transmission unit to the power reception unit at a frequency less than f2 . Furthermore, the thermal resistance of the one coil is θi (° C./W),
The maximum allowable operating temperature of the one coil is Tw (° C.),
The ambient temperature of the place where the one coil is installed is Ta (° C.),
When transmitting power from the power transmission unit to the power reception unit, when the effective value of the alternating current flowing in the one coil is Ia (A),
In the fa (Hz), power is transmitted from the power transmission unit to the power reception unit so that the one coil satisfies the relationship Rw ≦ (Tw−Ta) / (Ia ² × θi). The power transmission device according to claim 18 or 19 . A power transmission device of a power transmission device , comprising the power transmission unit of the power transmission device according to any one of claims 17 to 20 , wherein power is transmitted from the power transmission unit to the power reception unit . A power receiving device of a power transmission device , comprising the power receiving unit of the power transmission device according to any one of claims 17 to 20 , wherein the power receiving unit receives power from the power transmission unit.

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