JP6460373B2 - Coil unit and wireless power transmission device - Google Patents

Description

  The present invention relates to a coil unit and a wireless power transmission device for wirelessly transmitting power.

  In recent years, in order to transmit electric power without mechanical contact such as a cable, wireless power transmission technology using electromagnetic induction action between a primary (power transmission) coil and a secondary (power reception) coil that have been opposed has attracted attention. Therefore, the use as a power supply device for charging a secondary battery mounted on an electric vehicle (EV) or a plug-in hybrid electric vehicle (PHEV) is expected to be expanded.

  However, when the wireless power transmission technology is applied to a charging device in a power electronics device such as an electric vehicle, a large current needs to flow through the coil because high power transmission is required. As a result, the strength of the leakage magnetic field formed on the substrate increases, which may cause electromagnetic interference that adversely affects surrounding electronic devices.

  On the other hand, Patent Document 1 includes a plurality of coils in non-contact power feeding using a resonance method, and includes a second resonance coil for performing electromagnetic resonance with a first resonance coil arranged oppositely, The first coil of the plurality of coils is different from at least one of the other coils different from the first coil of the plurality of coils with a magnetic field generated against the surface facing the first resonance coil. There has been proposed a technique for reducing a leakage electromagnetic field by using a coil unit arranged so as to have an opposite phase.

JP 2011-23496 A

  However, like the technique disclosed in Patent Literature 1, both the vehicle side and the power feeding device side are configured with a plurality of coils arranged so that the generated magnetic fields are in opposite phases (FIG. 17 of Patent Literature 1). Etc.) and the coil mounted on the vehicle increases in size and weight, so that there is a problem that the requirements for reducing the size and weight of the components mounted on the vehicle cannot be satisfied.

  Further, as in the technique disclosed in Patent Document 1, only the power feeding device side is configured with a plurality of coils arranged so that the generated magnetic field is in reverse phase (see FIG. 19 of Patent Document 1). There was a problem that the leakage electromagnetic field generated from the vehicle side was insufficiently reduced.

  Accordingly, the present invention has been made in view of the above problems, and can suppress an unnecessary leakage magnetic field generated from the opposed coils while suppressing the increase in size and weight of the opposed coils. An object is to provide a unit and a wireless power transmission device.

  The coil unit according to the present invention includes a first coil, a resonant capacitor connected to the first coil, a second coil magnetically coupled to the first coil, and a second current supplied from the outside. A coil and an auxiliary coil electrically connected to the second coil, wherein the first coil and the second coil are magnetically coupled, and the auxiliary coil is coupled to the first coil by electromagnetic resonance. And generating a magnetic field having a phase opposite to that of a magnetic field generated by another coil that transmits and receives power wirelessly.

  According to the present invention, the auxiliary coil generates a magnetic field having a phase opposite to that of the magnetic field generated by another coil that performs wireless power transmission / reception with the first coil by electromagnetic resonance. Here, since the first coil is connected to the resonant capacitor and magnetically coupled to the second coil, the phase of the current flowing through the first coil is the same as the phase of the current flowing through the second coil. Is shifted 90 degrees. Furthermore, the phase of the current flowing through the other coil that is wirelessly transmitting and receiving power to and from the first coil by electromagnetic resonance is 90 degrees out of phase with the phase of the current flowing through the first coil. . At this time, the phase of the current flowing through the second coil is opposite to the phase of the current flowing through the other coil. Therefore, by electrically connecting the auxiliary coil to the second coil and making the phase of the current flowing through the auxiliary coil the same as the phase of the current flowing through the second coil, the phase of the current flowing through the auxiliary coil is The phase of the current flowing through the other coil is opposite to that of the current. That is, the auxiliary coil generates a magnetic field having the opposite phase to the magnetic field generated by the other coils. Therefore, an unnecessary leakage magnetic field generated by another coil can be reduced. As a result, an unnecessary leakage magnetic field generated from the opposed coils can be reduced while suppressing an increase in size and weight of the opposed coils.

  Preferably, an electromagnetic shielding plate that suppresses magnetic coupling between the first and second coils and the auxiliary coil is further provided. In this case, since unnecessary electromagnetic interference between the first and second coils and the auxiliary coil can be reduced, an unnecessary leakage magnetic field generated by other coils can be more reliably reduced.

  Preferably, the first coil includes first and second windings that are electrically connected to each other, and the first winding and the second winding may generate magnetic fields having opposite phases to each other. In this case, an unnecessary leakage magnetic field generated by the first coil can be reduced by the first winding and the second winding that generate magnetic fields having phases opposite to each other.

  More preferably, the first coil further includes a third winding disposed on the back side of the first winding, and a fourth winding disposed on the back side of the second winding. The first to fourth windings are electrically connected in series, and the first and second windings generate a first magnetic flux that links the first and second windings together. And the third winding generates a second magnetic flux interlinking with the first winding, the fourth winding generates a third magnetic flux interlinking with the second winding, The circulation directions of the second and third magnetic fluxes may be configured to be opposite to the circulation direction of the first magnetic flux. In this case, the second magnetic flux strengthens the magnetic field near the first winding, and the third magnetic flux strengthens the magnetic field near the second winding. On the other hand, in a place away from the first coil, the first magnetic flux and the second and third magnetic fluxes whose rotation directions are opposite to each other cancel each other, so that the magnetic fields are weakened. As a result, the leakage magnetic field generated by the first coil can be further reduced without reducing the power transmission efficiency.

  More preferably, the axial direction of the third winding is substantially orthogonal to the axial direction of the first winding, and the axial direction of the fourth winding is substantially orthogonal to the axial direction of the second winding. It is good to be configured. In this case, the third and fourth windings facilitate the generation of the second magnetic flux and the third magnetic flux that circulate to a place away from the first coil. As a result, the leakage magnetic field generated by the first coil can be further reduced.

  A wireless power transmission apparatus according to the present invention is a wireless power transmission apparatus that wirelessly transmits power from a wireless power transmission apparatus to a wireless power reception apparatus, and the wireless power transmission apparatus includes the coil unit.

  According to the present invention, there is provided a wireless power transmission device capable of reducing an unnecessary leakage magnetic field generated from the power receiving coil while suppressing an increase in size and weight of the power receiving coil to be mounted on the wireless power receiving device. can do.

  As described above, according to the present invention, the coil unit and the wireless power transmission capable of reducing unnecessary leakage magnetic field generated from the opposed coils while suppressing the increase in size and weight of the opposed coils. An apparatus can be provided.

1 is a schematic system configuration diagram showing a wireless power transmission device according to a first embodiment of the present invention. In the wireless power transmission device according to the first embodiment of the present invention, it is a cross-sectional view showing a coil unit together with a power receiving coil. In FIG. 2, it is the figure which showed typically direction of the magnetic field which each coil generate | occur | produces when the output current phase of an inverter is 0 degree | times. In FIG. 2, it is the figure which showed typically direction of the magnetic field which each coil generate | occur | produces when the output current phase of an inverter is 90 degree | times. It is a system model block diagram which shows the wireless power transmission apparatus which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows a coil unit with a receiving coil in the wireless power transmission apparatus which concerns on 2nd Embodiment of this invention. In FIG. 5, it is the figure which showed typically direction of the magnetic field which each coil generate | occur | produces when the output current phase of an inverter is 0 degree | times. In FIG. 5, it is the figure which showed typically direction of the magnetic field which each coil generate | occur | produces when the output current phase of an inverter is 90 degree | times. In FIG. 5, it is the figure which showed typically the magnetic flux which the 1st-4th coil | winding generate | occur | produces when the output current phase of an inverter is 90 degree | times.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

(First embodiment)
First, the configuration of the wireless power transmission device S1 according to the first embodiment of the present invention will be described with reference to FIG. 1 and FIG. FIG. 1 is a schematic system configuration diagram showing a wireless power transmission device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a coil unit and a receiving coil in the wireless power transmission device according to the first embodiment of the present invention. The coil unit according to the present invention can be applied to either a wireless power transmission device or a wireless power reception device in a wireless power transmission device, but here, an example in which the coil unit according to the present invention is applied to a wireless power transmission device. It explains using.

  As illustrated in FIG. 1, the wireless power transmission device S1 includes a wireless power transmission device Ut1 and a wireless power reception device Ur1.

  The wireless power transmission device Ut1 includes a power source PW1, an inverter INV1, and a coil unit Ltu1. The wireless power receiving device Ur1 includes a power receiving coil Lr, a resonant capacitor Cr, a rectifier circuit DB, and a load R. The wireless power transmission device S1 wirelessly transmits power from the wireless power transmission device Ut1 to the wireless power reception device Ur1 when the coil unit Ltu1 of the wireless power transmission device Ut1 and the power reception coil Lr of the wireless power reception device Ur1 face each other.

  First, the wireless power transmission device Ut1 will be described. The power supply PW1 supplies DC power to an inverter INV1 described later. The power source PW1 is not particularly limited as long as it outputs DC power, and is a DC power source rectified and smoothed from a commercial AC power source, a secondary battery, a DC power source generated by photovoltaic power, or a switching power source device such as a switching converter. Is mentioned.

  The inverter INV1 has a function of converting input DC power supplied from the power source PW1 into AC power. The inverter INV1 includes a switching circuit in which a plurality of switching elements are bridge-connected. Examples of the switching elements constituting the switching circuit include elements such as MOS-FET (Metal Oxide Semiconductor-Field Effect Transistor) and IBGT (Insulated Gate Bipolar Transistor). The inverter INV1 converts input DC power supplied from the power source PW1 into AC power and supplies the AC power to a coil unit Ltu1 described later. A capacitor (not shown) for improving the power factor of the circuit may be inserted between the inverter INV1 and the coil unit Ltu1.

  As shown in FIGS. 1 and 2, the coil unit Ltu1 includes a first coil Ltr, a resonance capacitor Ctr, a second coil Lte, an auxiliary coil Ln, an electromagnetic shielding plate S, and a first magnetic plate. It has a core Ft and a second magnetic core Fn. The first coil Ltr, the second coil Lte, the auxiliary coil Ln, and the electromagnetic shielding plate S will be described later when viewed from a direction orthogonal to the facing direction of the coil unit Ltu1 and a power receiving coil Lr described later. From the side close to the power receiving coil Lr, the first coil Ltr, the second coil Lte, the electromagnetic shielding plate S, and the auxiliary coil Ln are arranged in this order. That is, the auxiliary coil Ln is arranged at a position farthest from the power receiving coil Lr described later. When the wireless power transmission device S1 according to this embodiment is applied to a power supply facility for a vehicle such as an electric vehicle, the coil unit Ltu1 is disposed in the ground or in the vicinity of the ground.

  The first coil Ltr has a function of wirelessly transmitting power to a power receiving coil Lr described later by electromagnetic resonance. That is, the first coil Ltr functions as a power transmission coil. In the present embodiment, the first coil Ltr includes a first winding LtrA and a second winding LtrB that are electrically connected to each other. The first and second windings LtrA and LtrB are planar spiral coils juxtaposed in a direction orthogonal to the facing direction of the coil unit Ltu1 and a power receiving coil Lr described later, and are made of a litz such as copper or aluminum. It is formed by winding a wire. The number of turns of the first and second windings LtrA and LtrB is appropriately set based on a separation distance between the coil unit Ltu1 and a power receiving coil Lr described later, desired power transmission efficiency, and the like. The winding direction of the first winding LtrA and the winding direction of the second winding LtrB are opposite to each other, and the axial directions of the first and second windings LtrA and LtrB are both coils. It is parallel to the facing direction of the unit Ltu1 and a power receiving coil Lr described later. That is, when a current flows through the first coil Ltr, the first winding LtrA and the second winding LtrB generate magnetic fields having opposite phases to each other. Therefore, the leakage magnetic field generated by the first coil Ltr can be reduced by the first winding LtrA and the second winding LtrB that generate magnetic fields having phases opposite to each other.

  The resonant capacitor Ctr is electrically connected to the first coil Ltr. The capacitance of the resonance capacitor Ctr is set so as to resonate with the impedance of the first coil Ltr at the frequency of the current supplied from the inverter INV1. In the present embodiment, the resonant capacitor Ctr is connected in series with the first and second windings LtrA and LtrB of the first coil Ltr. However, the present invention is not limited to this, and the resonant capacitor Ctr The first and second windings LtrA and LtrB of the second coil Ltr may be connected in parallel. In any case, the capacitance of the resonance capacitor Ctr may be set so that the impedance of the first coil Ltr resonates at the frequency of the current supplied from the inverter INV1.

  The second coil Lte is electrically connected to the inverter INV1. Since the second coil Lte is disposed in the vicinity of the first coil Ltr, it is strongly magnetically coupled to the first coil Ltr. In the present embodiment, the second coil Lte includes two windings LteA and LteB that are electrically connected in series. The axis of the winding LteA coincides with the axis of the first winding LtrA of the first coil Ltr, and the axis of the winding LteB coincides with the axis of the second winding LtrB of the first coil Ltr. The winding direction of the winding LteA and the winding direction of the winding LteB are opposite to each other. With this configuration, when an alternating current is supplied from the inverter INV1 to the second coil Lte, an electromotive force is generated in the first coil Ltr and the first coil Ltr is generated according to the principle of electromagnetic induction. AC current flows. That is, the second coil Lte serves to supply the power supplied from the inverter INV1 to the first coil Ltr. Further, the number of turns of the windings LteA and LteB of the second coil Lte is set smaller than the number of turns of the first and second windings LtrA and LtrB of the first coil Ltr. Here, since the resonance capacitor Ctr is connected to the first coil Ltr, the electrical impedance of the first coil Ltr viewed from the second coil Lte is very small. Even if the number of turns of the windings LteA and LteB is small, the first coil Ltr can generate a sufficient current for wireless power transmission. In the present embodiment, the second coil Lte is configured by two windings LteA and LteB, but may be configured by only one of the winding LteA and the winding LteB.

  The auxiliary coil Ln is electrically connected to the second coil Lte. In the present embodiment, as shown in FIG. 1, the auxiliary coil Ln is connected in series to the winding LteA and the winding LteB of the second coil Lte. The auxiliary coil Ln is a solenoid-structured coil, and is formed by spirally winding a litz wire such as copper or aluminum. The axial direction of the auxiliary coil Ln substantially coincides with the axial direction of the power receiving coil Lr described later. In the present embodiment, the axial direction of the auxiliary coil Ln is the opposing direction of the coil unit Ltu1 and the power receiving coil Lr described later. The axial direction of the auxiliary coil Ln is the axial direction of the first and second windings LtrA and LtrB of the first coil Ltr and the axis of the windings LteA and LteB of the second coil Lte. It is a direction orthogonal to the direction. The auxiliary coil Ln generates a magnetic field having an opposite phase to the magnetic field generated by the power receiving coil Lr described later. Here, in order to set the magnetic field generated by the auxiliary coil Ln in reverse phase to the magnetic field generated by the power receiving coil Lr described later, the winding direction of the winding of the auxiliary coil Ln is set to the winding of the power receiving coil Lr described later. The direction may be the same as the winding direction. The number of turns of the auxiliary coil Ln is appropriately set based on a separation distance between the coil unit Ltu1 and a power receiving coil Lr described later, a desired leakage magnetic field reduction effect, and the like.

  The electromagnetic shielding plate S is disposed between the first coil Ltr and the second coil Lte and the auxiliary coil Ln and along the axial direction of the auxiliary coil Ln. Specifically, the electromagnetic shielding plate S is disposed between the first magnetic core Ft and the auxiliary coil Ln to be operated later. The electromagnetic shielding plate S functions as a shielding material that suppresses unnecessary magnetic coupling between the first coil Ltr, the second coil Lte, and the auxiliary coil Ln. In other words, the electromagnetic shielding plate S functions as a shield material that cancels the magnetic field by an induced current, an eddy current, or the like and suppresses the passage of magnetic flux. Thereby, unnecessary electromagnetic interference between the first coil Ltr and the second coil Lte and the auxiliary coil Ln can be reduced. The electromagnetic shielding plate S is not particularly limited as long as the surface is a nonmagnetic conductor that functions as an electromagnetic shielding material, and examples thereof include copper, aluminum, and a steel plate having a surface galvanized. It should be noted that the wiring that electrically connects the second coil Lte and the auxiliary coil Ln may be routed so as to penetrate the hole formed in the electromagnetic shielding plate S, or may be routed around the electromagnetic shielding plate S. .

  The first magnetic core Ft is made of a magnetic material such as ferrite and has a substantially U shape having protrusions at both ends of the plate shape. One protrusion is the first winding of the first coil Ltr. The line LteA and the axis of the winding LteA of the second coil Lte pass through, and the other protrusion penetrates the axis of the second winding LtrB of the first coil Ltr and the winding LteB of the second coil Lte. Are arranged as follows. That is, the first magnetic core Ft functions as a core of the first and second windings LtrA and LtrB of the first coil Ltr and the windings LteA and LteB of the second coil Lte. Therefore, by the first magnetic core Ft, the magnetic coupling degree of the first winding LtrA of the first coil Ltr and the winding LteA of the second coil Lte and the second winding LtrB of the first coil Ltr The magnetic coupling degree of the winding LteB of the second coil Lte can be improved, and the magnetic flux for wireless power transmission can be efficiently generated by the first coil Ltr.

  The second magnetic core Fn is made of a magnetic material such as a plate-like or rod-like ferrite, and is disposed so as to penetrate the axis of the auxiliary coil Ln. That is, the second magnetic core Fn functions as the core of the auxiliary coil Ln. Therefore, the auxiliary coil Ln can efficiently generate a magnetic flux for reducing a leakage magnetic field generated by the power receiving coil Lr described later.

  Next, the configuration of the wireless power receiving device Ur1 will be described. In the present embodiment, the other coil that transmits and receives power to and from the first coil by electromagnetic resonance means the power receiving coil Lr. The power receiving coil Lr is a coil having a solenoid structure, and is formed by winding a winding Wr made of a litz wire such as copper or aluminum around the third magnetic core Fr in a spiral shape. The axial direction of the power receiving coil Lr is a direction orthogonal to the facing direction of the coil unit Ltu1 and the power receiving coil Lr. The number of turns of the power receiving coil Lr is appropriately set based on the distance between the coil unit Ltu1 and the power receiving coil Lr, the desired power transmission efficiency, and the like. The power receiving coil Lr configured as described above has a function of receiving AC power transmitted from the first coil Ltr. Further, the power receiving coil Lr is electrically connected to a rectifier circuit DB described later. In addition, when the wireless power transmission device S1 according to the present embodiment is applied to a power supply facility for a vehicle such as an electric vehicle, the power receiving coil Lr is mounted on the lower portion of the vehicle. Here, the third magnetic core Fr is made of a magnetic material such as a plate-like or rod-like ferrite, and is disposed so as to penetrate the shaft of the power receiving coil Lr. That is, the third magnetic core Fr functions as the core of the power receiving coil Lr. Therefore, since the magnetic flux generated by the first coil Ltr selectively forms a magnetic path that passes through the third magnetic core Fr, the magnetic flux interlinked with the power receiving coil Lr is increased, and the power transmission efficiency is improved. be able to.

  The resonant capacitor Cr is inserted between the power receiving coil Lr and a rectifier circuit DB described later. The capacitance of the resonance capacitor Cr is set so as to resonate at the frequency of the current supplied from the inverter INV1 with respect to the impedance of the power receiving coil Lr. As a result, power is transmitted wirelessly between the power receiving coil Lr and the first coil Ltr by electromagnetic resonance. In this embodiment, the resonance capacitor Cr is connected in parallel with the power receiving coil Lr, but the resonance capacitor Cr may be connected in series with the power receiving coil Lr. In any case, the capacitance of the resonance capacitor Cr may be set so that the impedance of the power receiving coil Lr resonates at the frequency of the current supplied from the inverter INV1.

  The rectifier circuit DB has a function of rectifying AC power received by the power receiving coil Lr into DC power. Examples of the rectifier circuit DB include a conversion circuit having a full-wave rectification function using a diode bridge and a power smoothing function using a capacitor and a three-terminal regulator. The DC power rectified by the rectifier circuit DB is output to the load R. Here, as the load R, when the wireless power transmission device S1 according to the present embodiment is applied to a power supply facility for a vehicle such as an electric vehicle, a secondary battery included in the vehicle may be used.

  Next, with reference to FIG. 3, details of the magnetic field generated by each of the first coil Ltr, the second coil Lte, the auxiliary coil Ln, and the power receiving coil Lr and the action of reducing unnecessary leakage magnetic fields in the present embodiment. Explained. FIG. 3a is a diagram schematically showing the direction of the magnetic field generated by each coil when the output current phase of the inverter is 0 degree in FIG. FIG. 3b is a diagram schematically showing the direction of the magnetic field generated by each coil when the output current phase of the inverter is 90 degrees in FIG. 3A and 3B, the first magnetic core Ft, the second magnetic core Fn, and the third magnetic core Fr are omitted for convenience of explanation.

  When the output current phase of the inverter INV1 is 0 degree, that is, when the instantaneous output current value of the sinusoidal inverter INV1 is the maximum, as shown in FIG. 3a, it is generated in the windings LteA and LteB of the second coil Lte. The strengths of the magnetic fields HLteA and HLteB and the magnetic field HLn generated in the auxiliary coil Ln are maximized. The magnetic field HLteA and the magnetic field HLteB are magnetic fields having opposite phases to each other, and are parallel to the facing direction of the coil unit Ltu1 and the power receiving coil Lr. The magnetic field HLn is in a direction orthogonal to the facing direction of the coil unit Ltu1 and the power receiving coil Lr. Furthermore, since the number of turns of the windings LteA and LteB of the second coil Lte is small, the strength of the magnetic field HLteA and the magnetic field HLteB is low. Therefore, the strength of the leakage magnetic field formed at a location away from the coil unit Ltu1 by the second coil Lte is also low, and the influence is small.

  Next, the winding LteA of the second coil Lte is magnetically coupled to the first winding LtrA of the first coil Ltr, and the winding LteB of the second coil Lte is the second winding of the first coil Ltr. Since the magnetic coupling is performed with the line LtrB, a current flows through the first winding LtrA of the first coil Ltr and the second winding LtrB of the first coil Ltr by the magnetic field HLteA and the magnetic field HLteB, and the first winding LteA. A magnetic field is generated in the second winding LteB. At this time, since the resonance capacitor Ctr is connected to the first coil Ltr, the electrical impedance of the first coil Ltr viewed from the second coil Lte is very small, so that the magnetic field HLteA and the magnetic field HLteB are Even if the strength is low, a sufficient current flows through the first and second windings LtrA and LtrB of the first coil Ltr, and a relatively high strength magnetic field is generated.

  Further, since the resonance capacitor Ctr is connected to the first coil Ltr, the currents of the first and second windings LtrA and LtrB and the phase of the generated magnetic field are the same as the phase of the current flowing through the second coil Lte. It is 90 degrees off. That is, as shown in FIG. 3b, when the output current phase of the inverter INV1 is 90 degrees, the strengths of the magnetic fields HLtrA and HLtrB generated by the first and second windings LtrA and LtrB of the first coil Ltr, respectively. Is the maximum. It should be noted that the magnetic field HLtrA and the magnetic field HLtrB are magnetic fields having opposite phases to each other, and are parallel to the facing direction of the coil unit Ltu1 and the power receiving coil Lr. Therefore, the leakage magnetic field generated by the first coil Ltr can be reduced.

  Further, since the magnetic field HLtrA and the magnetic field HLtrB are in opposite phases, the first magnetic flux that links the first and second windings LtrA and LtrB of the first coil Ltr together by the magnetic field HLtrA and the magnetic field HLtrB. Will occur. The first magnetic flux is also linked to the power receiving coil Lr, so that an electromotive force is generated in the power receiving coil Lr and a current flows. The current generated in the power receiving coil Lr is rectified by the rectifier circuit DB and power is output to the load R. Here, since an electromagnetic shielding plate for suppressing magnetic coupling is installed between the first coil Ltr and the auxiliary coil Ln, the first magnetic flux generated by the magnetic field HLtrA and the magnetic field HLtrB is chained to the auxiliary coil Ln. Intercourse is suppressed.

  Furthermore, since the resonance capacitor Cr is connected to the power receiving coil Lr, the phase of the current flowing through the power receiving coil Lr is shifted by 90 degrees with respect to the phase of the current flowing through the first coil Ltr. That is, as shown in FIG. 3a, when the output current phase of the inverter INV1 is 0 degree, the intensity of the magnetic field HLr generated by the current flowing through the power receiving coil Lr is maximized. Specifically, the phase of the current flowing through the second coil Lte and the auxiliary coil Ln and the phase of the current flowing through the first coil Ltr are shifted by 90 degrees, and the phase of the current flowing through the first coil Ltr and the receiving coil Lr Since the phase of the flowing current is shifted by 90 degrees, the current flowing through the auxiliary coil Ln and the current flowing through the power receiving coil Lr are opposite to each other. Here, the axial direction of the auxiliary coil Ln coincides with the axial direction of the power receiving coil Lr, and the winding direction of the winding of the auxiliary coil Ln and the winding direction of the winding of the power receiving coil Lr are the same direction. When currents having opposite phases flow through the auxiliary coil Ln and the power receiving coil Lr, the magnetic field HLn generated by the auxiliary coil Ln and the magnetic field HLr generated by the power receiving coil Lr are also opposite in phase. That is, the auxiliary coil Ln generates a magnetic field HLn having a phase opposite to that of the magnetic field HLr generated by the power receiving coil Lr, which is a coil that wirelessly transmits and receives power to and from the first coil Ltr by electromagnetic resonance. Therefore, at a place away from the wireless power transmission device S1, the magnetic field HLr generated by the power receiving coil Lr and the magnetic field HLn generated by the auxiliary coil Ln cancel each other, thereby reducing the leakage magnetic field.

  As described above, in the wireless power transmission device S1 according to this embodiment, the auxiliary coil Ln in the coil unit Ltu1 transmits and receives power wirelessly between the first coil Ltr and the first coil Ltr by electromagnetic resonance. A magnetic field HLn having a phase opposite to that of the magnetic field HLr generated by the power receiving coil Lr, which is a coil, is generated. Here, since the first coil Ltr is connected to the resonance capacitor Ctr and is magnetically coupled to the second coil Lte, the phase of the current flowing through the first coil Ltr is the same as the current flowing through the second coil Lte. The phase is 90 degrees out of phase. Further, the phase of the current flowing through the power receiving coil Lr, which is another coil that wirelessly transmits and receives power to and from the first coil Ltr by electromagnetic resonance, is the phase of the current flowing through the first coil Ltr. On the other hand, the phase is shifted by 90 degrees. At this time, the phase of the current flowing through the second coil Lte is opposite to the phase of the current flowing through the power receiving coil Lr, which is another coil. Accordingly, the auxiliary coil Ln is electrically connected to the second coil Lte, and the phase of the current flowing through the auxiliary coil Ln is set to the same phase as the current flowing through the second coil Lte. The phase of the flowing current is opposite to the phase of the current flowing through the power receiving coil Lr, which is another coil. That is, the auxiliary coil Ln generates a magnetic field HLn having a phase opposite to that of the magnetic field HLr generated by the power receiving coil Lr, which is another coil. Therefore, an unnecessary leakage magnetic field generated by the power receiving coil Lr, which is another coil, can be reduced. As a result, it is possible to reduce an unnecessary leakage magnetic field generated from the power receiving coil Lr, which is a coil disposed oppositely, while suppressing an increase in size and weight of the power receiving coil Lr, which is a coil disposed oppositely.

  In addition, the wireless power transmission device S1 according to the present embodiment includes an electromagnetic shielding plate S that suppresses magnetic coupling between the first coil Ltr, the second coil Lte, and the auxiliary coil Ln. Therefore, since unnecessary electromagnetic interference between the first coil Ltr and the second coil Lte and the auxiliary coil Ln can be reduced, an unnecessary leakage magnetic field generated by the power receiving coil Lr which is another coil is reduced. It can reduce more reliably.

  Furthermore, in the wireless power transmission device S1 according to the present embodiment, the first coil Ltr includes first and second windings LtrA and LtrB that are electrically connected to each other, and the first winding LtrA and the first winding LtrA. The second winding LtrB generates a magnetic field HLtrA and a magnetic field HLtrB having opposite phases. Therefore, an unnecessary leakage magnetic field generated by the first coil Ltr can be reduced by the first winding LtrA and the second winding LtrB that generate the magnetic field HLtrA and the magnetic field HLtrB having opposite phases to each other.

(Second Embodiment)
Next, the configuration of the wireless power transmission device S2 according to the second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a schematic system configuration diagram showing a wireless power transmission device according to the second embodiment of the present invention. FIG. 5 is a cross-sectional view showing a coil unit together with a power receiving coil in a wireless power transmission device according to a second embodiment of the present invention. The coil unit according to the present invention can be applied to either a wireless power transmission device or a wireless power reception device in a wireless power transmission device, but here, an example in which the coil unit according to the present invention is applied to a wireless power transmission device. It explains using.

  As illustrated in FIG. 4, the wireless power transmission device S2 includes a wireless power transmission device Ut2 and a wireless power reception device Ur1. The wireless power transmitting apparatus Ut2 includes a power supply PW1, an inverter INV1, and a coil unit Ltu2. The wireless power receiving device Ur1 includes a power receiving coil Lr, a resonant capacitor Cr, a rectifier circuit DB, and a load R. The wireless power transmission device S2 wirelessly transmits power from the wireless power transmission device Ut2 to the wireless power reception device Ur1 when the coil unit Ltu2 of the wireless power transmission device Ut2 and the power reception coil Lr of the wireless power reception device Ur1 face each other. Here, the configurations of the power source PW1, the inverter INV1, the power receiving coil Lr, the resonant capacitor Cr, the rectifier circuit DB, and the load R are the same as those of the wireless power transmission device S1 according to the first embodiment. The wireless power transmission device S2 according to the second embodiment is different from the wireless power transmission device S1 according to the first embodiment in that a coil unit Ltu2 is provided instead of the coil unit Ltu1. Hereinafter, a description will be given focusing on differences from the first embodiment. In the present embodiment, the other coil that transmits and receives power to and from the first coil by electromagnetic resonance means the power receiving coil Lr as in the first embodiment.

  The coil unit Ltu2 includes a first coil Ltr, a resonant capacitor Ctr, a second coil Lte, an auxiliary coil Ln, an electromagnetic shielding plate S, a first magnetic core Ft, and a second magnetic core Fn. , A fourth magnetic core FtC, and a fifth magnetic core FtD. Here, the configurations of the resonant capacitor Ctr, the second coil Lte, the auxiliary coil Ln, the electromagnetic shielding plate S, the first magnetic core Fn, and the second magnetic core Fn are related to the first embodiment. This is the same as the wireless power transmission device S1.

  The first coil Ltr includes a first winding LtrA, a second winding LtrB, a third winding LtrC, and a fourth winding LtrD. In the present embodiment, the first winding LtrA, the second winding LtrB, the third winding LtrC, the fourth winding LtrD, and the resonance capacitor Ctr are electrically connected in series. Here, the configurations of the first and second windings LtrA and LtrB are the same as the first and second windings LtrA and LtrB of the first coil Ltr of the wireless power transmission device S1 according to the first embodiment. It is.

  The third winding LtrC is disposed on the back side of the first winding LtrA. That is, the third winding LtrC is disposed on the opposite side of the surface of the first winding LtrA that faces the power receiving coil Lr. More specifically, as shown in FIG. 5, the third winding LtrC is disposed so as to overlap the first winding LtrA when viewed from the facing direction of the coil unit Ltu2 and the power receiving coil Lr. Yes. The third winding LtrC is a solenoid-structured coil and is formed by spirally winding a litz wire such as copper or aluminum. The axial direction of the third winding LtrC is a direction orthogonal to the facing direction of the coil unit Ltu2 and the power receiving coil Lr. That is, the axial direction of the third winding LtrC is a direction orthogonal to the axial direction of the first winding LtrA. Therefore, the third winding LtrC can more easily generate a magnetic flux that circulates to a place away from the third winding LtrC, and the leakage magnetic field generated by the first coil Ltr can be further reduced. . Furthermore, the number of turns of the third winding LtrC is appropriately set based on a desired leakage magnetic field reduction effect or the like.

  Here, the third winding LtrC generates a second magnetic flux interlinking with the first winding LtrA. Specifically, in FIG. 5, when the first winding LtrA generates a magnetic field in the direction from the first winding LtrA toward the power receiving coil Lr (upward in the drawing), the third winding LtrC If a magnetic field in the direction from the third winding LtrC toward the first winding LtrA (rightward in the figure) is generated, the third winding LtrC is linked to the first winding LtrA by the second magnetic flux. Will be generated. On the other hand, when the first winding LtrA generates a magnetic field in the direction (downward in the drawing) from the power receiving coil Lr to the first winding LtrA, the third winding LtrC is converted into the first winding LtrA. If a magnetic field in the direction (leftward in the figure) from the first to the third winding LtrC is generated, the third winding LtrC generates a second magnetic flux interlinking with the first winding LtrA. In order to generate such a magnetic field, the direction of the current passing through the portion of the third winding LtrC that is closest to the first winding LtrA (the upper surface portion of the third winding LtrC in the drawing) is the first direction. The winding direction of the litz wire is selected so that the direction of the current passing through the portion closest to the third winding LtrC (the left portion of the first winding LtrA in the figure) in the winding LtrA of The third winding LtrC may be configured. Further, in the third winding LtrC, the circulation direction of the second magnetic flux generated by the third winding LtrC is the same as the rotation direction of the first magnetic flux generated by the first and second windings LtrA and LtrB. Are arranged in the opposite direction. In order to obtain such a magnetic flux, the second winding LtrB from the center of the first winding LtrA in the arrangement direction of the first winding LtrA and the second winding LtrB as seen from the power receiving coil Lr. The third winding LtrC only needs to be arranged at a position shifted to the opposite side to the direction toward the center.

  The fourth winding LtrD is disposed on the back side of the second winding LtrB. That is, the fourth winding LtrD is disposed on the opposite side of the surface of the second winding LtrB that faces the power receiving coil Lr. More specifically, as shown in FIG. 5, the fourth winding LtrD is disposed so as to overlap the second winding LtrB when viewed from the opposing direction of the coil unit Ltu2 and the power receiving coil Lr. Yes. The fourth winding LtrD is a solenoid-structured coil, and is formed by spirally winding a litz wire such as copper or aluminum. The axial direction of the fourth winding LtrD is a direction orthogonal to the facing direction of the coil unit Ltu2 and the power receiving coil Lr. That is, the axial direction of the fourth winding LtrD is a direction orthogonal to the axial direction of the second winding LtrB. Therefore, the fourth winding LtrD can more easily generate a magnetic flux that circulates to a place away from the fourth winding LtrD, and the leakage magnetic field generated by the first coil Ltr can be further reduced. . Furthermore, the number of turns of the fourth winding LtrD is appropriately set based on a desired leakage magnetic field reduction effect or the like.

  Here, the fourth winding LtrD generates a third magnetic flux interlinking with the second winding LtrB. Specifically, in FIG. 5, when the second winding LtrB generates a magnetic field in the direction (upward in the drawing) from the second winding LtrB to the power receiving coil Lr, the fourth winding LtrD If a magnetic field is generated in the direction from the fourth winding LtrD toward the second winding LtrB (leftward in the figure), the fourth winding LtrD is linked to the second winding LtrB by the third magnetic flux. Will be generated. On the other hand, when the second winding LtrB generates a magnetic field in the direction (downward in the drawing) from the power receiving coil Lr to the second winding LtrB, the fourth winding LtrD is converted into the second winding LtrB. If a magnetic field is generated in a direction (rightward in the figure) from the first to the fourth winding LtrD, the fourth winding LtrD generates a third magnetic flux interlinking with the second winding LtrB. In order to generate such a magnetic field, the direction of the current passing through the portion of the fourth winding LtrD that is closest to the second winding LtrB (the upper surface portion of the fourth winding LtrD in the drawing) is The winding direction of the litz wire is selected so that the direction of the current passing through the portion closest to the fourth winding LtrD in the winding LtrB (the right side portion of the second winding LtrB shown in the drawing) is the same. The fourth winding LtrD may be configured. Further, in the fourth winding LtrD, the circulation direction of the third magnetic flux generated by the fourth winding LtrD is the same as the rotation direction of the first magnetic flux generated by the first and second windings LtrA and LtrB. Are arranged in the opposite direction. In order to obtain such a magnetic flux, the first winding LtrA from the center of the second winding LtrB in the arrangement direction of the first winding LtrA and the second winding LtrB as seen from the power receiving coil Lr. The fourth winding LtrD has only to be arranged at a position shifted to the opposite side to the direction toward the center.

  The fourth magnetic core FtC is made of a magnetic material such as plate-like or rod-like ferrite, and is arranged so as to penetrate the axis of the third winding LtrC. That is, the fourth magnetic core FtC functions as the core of the third winding LtrC of the first coil Ltr. Therefore, the magnetic flux for reducing the leakage magnetic field is efficiently generated by the third winding LtrC. The fourth magnetic core FtC is connected to the first magnetic core Ft. Therefore, the third winding LtrC can efficiently generate the second magnetic flux interlinking with the first winding LtrA. Note that the fourth magnetic core FtC and the first magnetic core Ft may be integrally formed.

  The fifth magnetic core FtD is made of a magnetic material such as a plate-like or rod-like ferrite, and is disposed so as to penetrate the axis of the fourth winding LtrD. That is, the fifth magnetic core FtD functions as the core of the fourth winding LtrD of the first coil Ltr. Therefore, a magnetic flux for reducing the leakage magnetic field is efficiently generated by the fourth winding LtrD. The fifth magnetic core FtD is connected to the first magnetic core Ft. Therefore, the fourth winding LtrD can efficiently generate the third magnetic flux interlinking with the second winding LtrB. Note that the fifth magnetic core FtD and the first magnetic core Ft may be integrally formed.

  Next, with reference to FIG. 6, details of the magnetic field generated by each of the first coil Ltr, the second coil Lte, the auxiliary coil Ln, and the power receiving coil Lr and the action of reducing unnecessary leakage magnetic fields in the present embodiment. Explained. FIG. 6a is a diagram schematically showing the direction of the magnetic field generated by each coil when the output current phase of the inverter is 0 degree in FIG. FIG. 6b is a diagram schematically showing the direction of the magnetic field generated by each coil when the output current phase of the inverter is 90 degrees in FIG. In FIGS. 6a and 6b, the first magnetic core Ft, the second magnetic core Fn, the third magnetic core Fr, the fourth magnetic core FtC, and the fifth magnetic core FtD are omitted for convenience of explanation. doing.

  When the output current phase of the inverter INV1 is 0 degree, that is, when the output current instantaneous value of the sinusoidal inverter INV1 is the maximum, as shown in FIG. 6a, it occurs in the windings LteA and LteB of the second coil Lte. The strengths of the magnetic fields HLteA and HLteB and the magnetic field HLn generated in the auxiliary coil Ln are maximized. The magnetic field HLteA and the magnetic field HLteB are magnetic fields with opposite phases, and are parallel to the facing direction of the coil unit Ltu2 and the power receiving coil Lr. The magnetic field HLn is in a direction orthogonal to the facing direction of the coil unit Ltu2 and the power receiving coil Lr. Furthermore, since the number of turns of the windings LteA and LteB of the second coil Lte is small, the strength of the magnetic field HLteA and the magnetic field HLteB is low. Therefore, the strength of the leakage magnetic field formed at a location away from the coil unit Ltu2 by the second coil Lte is also low, and the influence is small.

  Next, the winding LteA of the second coil Lte is magnetically coupled to the first winding LtrA of the first coil Ltr, and the winding LteB of the second coil Lte is the second winding of the first coil Ltr. In order to magnetically couple with the line LtrB, a current is supplied to the first winding LtrA, the second winding LteB, the third winding LtrC, and the fourth winding LtrD of the first coil Ltr by the magnetic field HLteA and the magnetic field HLteB. Flows, and a magnetic field is generated in the first winding LtrA, the second winding LteB, the third winding LtrC, and the fourth winding LtrD. Here, since the first coil Ltr is connected to the resonance capacitor Ctr, the electrical impedance of the first coil Ltr viewed from the second coil Lte is very small, so the strengths of the magnetic field HLteA and the magnetic field HLteB. Even if the current is low, a sufficient current flows through the first winding LtrA, the second winding LteB, the third winding LtrC, and the fourth winding LtrD of the first coil Ltr, which is relatively high. A strong magnetic field is generated.

  In addition, since the resonance capacitor Ctr is connected to the first coil Ltr, the currents of the first winding LtrA, the second winding LteB, the third winding LtrC, and the fourth winding LtrD and The phase of the generated magnetic field is shifted by 90 degrees with respect to the phase of the current flowing through the second coil Lte. That is, as shown in FIG. 6b, when the output current phase of the inverter INV1 is 90 degrees, the first winding LtrA, the second winding LteB, the third winding LtrC of the first coil Ltr, and The strengths of the magnetic fields HLtrA, HLtrB, HLtrC, and the magnetic field HLtrD generated by each of the fourth windings LtrD are maximized. Note that the magnetic field HLtrA and the magnetic field HLtrB are magnetic fields having opposite phases to each other, and are parallel to the facing direction of the coil unit Ltu2 and the power receiving coil Lr. Therefore, the leakage magnetic field generated by the first coil Ltr can be reduced.

  Further, since the magnetic field HLtrA and the magnetic field HLtrB are in opposite phases, the first magnetic flux that links the first and second windings LtrA and LtrB of the first coil Ltr together by the magnetic field HLtrA and the magnetic field HLtrB. Will occur. The first magnetic flux is also linked to the power receiving coil Lr, so that an electromotive force is generated in the power receiving coil Lr and a current flows. The current generated in the power receiving coil Lr is rectified by the rectifier circuit DB and power is output to the load R. Here, since an electromagnetic shielding plate for suppressing magnetic coupling is installed between the first coil Ltr and the auxiliary coil Ln, the first magnetic flux generated by the magnetic field HLtrA and the magnetic field HLtrB is chained to the auxiliary coil Ln. Intercourse is suppressed.

  Furthermore, since the resonance capacitor Cr is connected to the power receiving coil Lr, the phase of the current flowing through the power receiving coil Lr is shifted by 90 degrees with respect to the phase of the current flowing through the first coil Ltr. That is, as shown in FIG. 6a, when the output current phase of the inverter INV1 is 0 degree, the intensity of the magnetic field HLr generated by the current flowing through the power receiving coil Lr is maximized. Specifically, the phase of the current flowing through the second coil Lte and the auxiliary coil Ln and the phase of the current flowing through the first coil Ltr are shifted by 90 degrees, and the phase of the current flowing through the first coil Ltr and the receiving coil Lr Since the phase of the flowing current is shifted by 90 degrees, the current flowing through the auxiliary coil Ln and the current flowing through the power receiving coil Lr are opposite to each other. Here, the axial direction of the auxiliary coil Ln coincides with the axial direction of the power receiving coil Lr, and the winding direction of the winding of the auxiliary coil Ln and the winding direction of the winding of the power receiving coil Lr are the same direction. When currents having opposite phases flow through the auxiliary coil Ln and the power receiving coil Lr, the magnetic field HLn generated by the auxiliary coil Ln and the magnetic field HLr generated by the power receiving coil Lr are also opposite in phase. That is, the auxiliary coil Ln generates a magnetic field HLn having a phase opposite to that of the magnetic field HLr generated by the power receiving coil Lr, which is a coil that wirelessly transmits and receives power to and from the first coil Ltr by electromagnetic resonance. Therefore, at a place away from the wireless power transmission device S1, the magnetic field HLr generated by the power receiving coil Lr and the magnetic field HLn generated by the auxiliary coil Ln cancel each other, thereby reducing the leakage magnetic field.

  Next, with reference to FIG. 7, the reduction of the leakage magnetic field generated by the first coil Ltr will be described in detail. FIG. 7 is a diagram schematically showing the magnetic flux generated by the first to fourth windings when the output current phase of the inverter is 90 degrees in FIG. However, in FIG. 7, illustration of magnetic flux in the first magnetic core Ft, the second magnetic core Fn, the third magnetic core Fr, the fourth magnetic core FtC, and the fifth magnetic core FtD is omitted. ing. Further, in FIG. 7, magnetic fluxes Bt1a to Bt1d are shown as body surfaces out of the first magnetic fluxes generated by the first and second windings LtrA and LtrB, and the third and fourth windings LtrC, Of the second and third magnetic fluxes generated by LtrD, magnetic fluxes Bc1a to Bc1d are schematically shown as representative ones. However, these magnetic fluxes schematically show only the direction of each magnetic flux, and do not show the magnetic flux density.

  As shown in FIG. 7, the first and second windings LtrA and LtrB generate first magnetic fluxes Bt1a to Bt1d that link the first and second windings LtrA and LtrB together. Among these, the first magnetic fluxes Bt1a and Bt1b are magnetic fluxes linked to the power receiving coil Lr, and the first magnetic fluxes Bt1a and Bt1b are linked to the power receiving coil Lr, whereby an electromotive force is generated in the power receiving coil Lr. On the other hand, in the present embodiment, since the first and second windings LtrA and LtrB are wound in a plane, the first and second windings LtrA and LtrB are connected to the power receiving coil Lr. The first magnetic fluxes Bt1c and Bt1d that largely circulate up to a place away from the first coil Ltr are also generated. The first magnetic fluxes Bt1c and Bt1d become magnetic fluxes that form an unnecessary leakage magnetic field in a place away from the first coil Ltr.

  The third winding LtrC generates second magnetic fluxes Bc1a and Bc1b that link the third winding LtrC and the first winding LtrA together. The third winding LtrC is on the back side of the first winding LtrA and is the first winding in the direction in which the first winding LtrA and the second winding LtrB are viewed from the power receiving coil Lr. Since the third magnetic fluxes Bc1a and Bc1b are arranged around the first magnetic fluxes Bt1a to Bt1d because the third magnetic fluxes Bc1a and Bc1b are arranged at positions shifted from the center of the LtrA toward the center of the second winding LtrB. The direction is the opposite of the direction of rotation. In the present embodiment, since the axial direction of the third winding LtrC is orthogonal to the axial direction of the first winding LtrA, the second magnetic fluxes Bc1a and Bc1b are separated from the first coil Ltr. It becomes easy to go around to the place.

  The fourth winding LtrD generates third magnetic fluxes Bc1c and Bc1d that link the fourth winding LtrD and the second winding LtrB together. The fourth winding LtrD is on the back side of the second winding LtrB, and is the second winding in the arrangement direction of the first winding LtrA and the second winding LtrB when viewed from the power receiving coil Lr. Since the third magnetic fluxes Bc1a and Bc1b are arranged around the first magnetic fluxes Bt1a to Bt1d because the third magnetic fluxes Bc1a and Bc1b are arranged at positions shifted from the center of the LtrB toward the opposite side to the direction of the first winding LtrA. The direction is the opposite of the direction of rotation. In the present embodiment, since the axial direction of the fourth winding LtrD is orthogonal to the axial direction of the second winding LtrB, the third magnetic fluxes Bc1c and Bc1d are separated from the first coil Ltr. It becomes easy to go around to the place.

  Here, as shown in FIG. 7, in the vicinity of the first coil Ltr, the first magnetic fluxes Bt1a to Bt1d and the second and third magnetic fluxes Bc1a to Bc1d are substantially in the same direction. That is, the second magnetic fluxes Bc1a and Bc1b strengthen the magnetic field in the vicinity of the first winding LtrA, and the third magnetic fluxes Bc1c and Bc1d strengthen the magnetic field in the vicinity of the second winding LtrB. Therefore, the third and fourth windings LtrC and LtrD are prevented from reducing the power transmission efficiency. On the other hand, in a place away from the first coil Ltr, the first magnetic fluxes Bt1c and Bt1d and the second and third magnetic fluxes Bc1a to Bc1d are opposite to each other. As a result, the first magnetic fluxes Bt1c and Bt1d and the second and third magnetic fluxes Bc1a to Bc1d cancel each other at a place away from the coil unit Ltu2, and the magnetic flux density is lowered. As a result, the leakage magnetic field strength indicated by the magnetic flux density away from the first coil Ltr is also reduced. That is, of the magnetic fields generated by the first and second windings LtrA and LtrB, only the leakage magnetic field is selectively reduced by the third and fourth windings LtrC and LtrD, and the first coil Ltr is generated. The leakage magnetic field can be further reduced. In particular, in the present embodiment, since the axial directions of the third and fourth windings LtrC and LtrD are orthogonal to the axial directions of the first and second windings LtrA and LtrB, The magnetic fluxes Bc1a to Bc1d of No. 3 are easily circulated to a place away from the first coil Ltr, and the leakage magnetic field generated by the first coil 243 can be further reduced.

  As described above, in the wireless power transmission device S2 according to the present embodiment, the auxiliary coil Ln in the coil unit Ltu2 transmits and receives power wirelessly with the first coil Ltr by electromagnetic resonance. A magnetic field HLn having a phase opposite to that of the magnetic field HLr generated by the power receiving coil Lr, which is a coil, is generated. Here, since the first coil Ltr is connected to the resonance capacitor Ctr and is magnetically coupled to the second coil Lte, the phase of the current flowing through the first coil Ltr is the same as the current flowing through the second coil Lte. The phase is 90 degrees out of phase. Further, the phase of the current flowing through the power receiving coil Lr, which is another coil that wirelessly transmits and receives power to and from the first coil Ltr by electromagnetic resonance, is the phase of the current flowing through the first coil Ltr. On the other hand, the phase is shifted by 90 degrees. At this time, the phase of the current flowing through the second coil Lte is opposite to the phase of the current flowing through the power receiving coil Lr, which is another coil. Accordingly, the auxiliary coil Ln is electrically connected to the second coil Lte, and the phase of the current flowing through the auxiliary coil Ln is set to the same phase as the current flowing through the second coil Lte. The phase of the flowing current is opposite to the phase of the current flowing through the power receiving coil Lr, which is another coil. That is, the auxiliary coil Ln generates a magnetic field HLn having a phase opposite to that of the magnetic field HLr generated by the power receiving coil Lr, which is another coil. Therefore, an unnecessary leakage magnetic field generated by the power receiving coil Lr, which is another coil, can be reduced. As a result, it is possible to reduce an unnecessary leakage magnetic field generated from the power receiving coil Lr, which is a coil disposed oppositely, while suppressing an increase in size and weight of the power receiving coil Lr, which is a coil disposed oppositely.

  In the wireless power transmission device S2 according to the present invention, the first coil Ltr in the coil unit Ltu2 includes the third winding LtrC arranged on the back side of the first winding LtrA and the second winding. A fourth winding LtrD disposed on the back side of the line LtrB, and the first winding LtrA, the second winding LtrB, the third winding LtrC, and the fourth winding LtrD are: The first and second windings LtrA and LtrB are electrically connected in series, and generate first magnetic fluxes Bt1a to Bt1d that link the first and second windings LtrA and LtrB together. The third winding LtrC generates second magnetic fluxes Bc1a and Bc1b interlinking with the first winding LtrA, and the fourth winding LtrD is the third magnetic flux interlinking with the second winding LtrB. Bc1c and Bc1d are generated and the second Preliminary circumferential direction of the third magnetic flux Bc1a~Bc1d is the circumferential direction of the first magnetic flux Bt1a~Bt1d is configured to be opposite to. Therefore, the second magnetic fluxes Bc1a and Bc1b strengthen the magnetic field in the vicinity of the first winding LtrA, and the third magnetic fluxes Bc1c and Bc1d strengthen the magnetic field in the vicinity of the second winding LtrB. On the other hand, in a place away from the first coil Ltr, the first and second magnetic fluxes Bc1a to Bc1d whose directions of rotation are opposite to each other and the second and third magnetic fluxes Bc1a to Bc1d cancel each other. As a result, the leakage magnetic field generated by the first coil Ltr can be further reduced without reducing the power transmission efficiency.

  Further, in the wireless power transmission device S2 according to the present invention, the axial direction of the third winding LtrC in the coil unit Ltu2 is substantially orthogonal to the axial direction of the first winding LtrA, and the fourth winding LtrD The axial direction is configured to be substantially orthogonal to the axial direction of the second winding LtrB. Therefore, the third and fourth windings LtrC and LtrD can easily generate the second magnetic fluxes Bc1a and Bc1b and the third magnetic fluxes Bc1c and Bc1d that circulate to a place away from the first coil Ltr. As a result, the leakage magnetic field generated by the first coil Ltr can be further reduced.

  The present invention has been described based on the embodiments. It will be understood by those skilled in the art that the embodiments are illustrative, and that various modifications and changes are possible within the scope of the claims of the present invention, and that such modifications and changes are also within the scope of the claims of the present invention. By the way. Accordingly, the description and drawings herein are to be regarded as illustrative rather than restrictive.

  For example, “power transmission / reception by electromagnetic resonance” means that a capacitor is connected to a coil that receives power at least wirelessly and resonates at an arbitrary frequency, so that wireless power transmission is more efficient than when there is no capacitor. Means to do. However, even if the resonant frequency and the frequency of the current flowing through the coil deviate to some extent, wireless power transmission can be performed more efficiently than when there is no capacitor by canceling the impedance of the coil and the impedance of the capacitor. It is. In other words, the term “power transmission / reception by electromagnetic resonance” is intended to transmit power by a coil to which a resonance capacitor is electrically connected. Strictly, the resonance frequency and the frequency of the current flowing through the coil are used. It does not mean to exclude the case where does not match. It should be understood that the noise reduction effect of the present invention can be obtained even when the phase difference between the power transmission coil and the power reception coil does not exactly match 90 degrees in wireless power transmission by electromagnetic resonance.

  S1, S2 ... Wireless power transmission device, UtLtu10 ... Wireless power transmission device, PW1 ... Power source, INV1 ... Inverter, LtuLte0 ... Coil unit, Ltr, Ltr ... First coil, LtrA ... First winding, LtrB ... Second Winding, Ctr ... Resonant capacitor, Lte ... Second coil, LteA, LteB ... Winding, Ln ... Auxiliary coil, S ... Electromagnetic shielding plate, Ft ... First magnetic core, Fn ... Second magnetic core, Ur1 ... wireless power receiving device, Lr ... receiving coil, Wr ... winding of receiving coil, Fr ... third magnetic core, Cr ... resonant capacitor, DB ... rectifier circuit, R ... load, LtrC ... third winding, LtrD ... Fourth winding, FtC ... fourth magnetic core, FtD ... fifth magnetic core, HLtrA ... magnetic field generated by the first winding, HLtrB ... second winding is generated. HLteA, HLteB ... magnetic field generated by the second coil, HLn ... magnetic field generated by the auxiliary coil, HLr ... magnetic field generated by the receiving coil, HLtrC ... magnetic field generated by the third winding, HLtrD ... fourth Magnetic field generated by the windings, Bt1a to Bt1d, first magnetic flux, Bc1a, Bc1b, second magnetic flux, Bc1c, Bc1d, third magnetic flux.

Claims (6)

A first coil;
A resonant capacitor connected to the first coil;
A second coil to which current is supplied from the outside;
An auxiliary coil electrically connected to the second coil,
The first coil and the second coil are magnetically coupled,
The auxiliary coil generates a magnetic field having a phase opposite to a magnetic field generated by another coil that wirelessly transmits and receives electric power to and from the first coil by electromagnetic resonance.   The coil unit according to claim 1, further comprising an electromagnetic shielding plate that suppresses magnetic coupling between the first and second coils and the auxiliary coil. The first coil includes first and second windings electrically connected to each other;
The coil unit according to claim 1 or 2, wherein the first winding and the second winding generate magnetic fields having opposite phases to each other. The first coil further includes a third winding disposed on the back side of the first winding and a fourth winding disposed on the back side of the second winding. ,
The first to fourth windings are electrically connected in series,
The first and second windings generate a first magnetic flux that links the first and second windings together;
The third winding generates a second magnetic flux interlinking with the first winding;
The fourth winding generates a third magnetic flux interlinking with the second winding,
The coil unit according to claim 3, wherein a circulation direction of the second and third magnetic fluxes is opposite to a circulation direction of the first magnetic flux. The axial direction of the third winding is substantially orthogonal to the axial direction of the first winding,
5. The coil unit according to claim 4, wherein an axial direction of the fourth winding is substantially orthogonal to an axial direction of the second winding. A wireless power transmission device in which power is transmitted wirelessly from a wireless power transmission device to a wireless power reception device,
The said wireless power transmission apparatus has the coil unit as described in any one of Claims 1-5, The wireless power transmission apparatus characterized by the above-mentioned.

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