JP5903579B2 - Power transmission coil - Google Patents

Description

  The present invention relates to a power transmission coil for transmitting power without contact.

  In recent years, a non-contact power feeding technology has been developed that does not have a direct electrical connection and transmits power in a non-contact manner. Patent Document 1 proposes a non-contact power transmission system using such a non-contact power feeding technique. A block diagram of this contactless power transmission system is shown in FIG.

  In FIG. 3, power transmission device 101 includes a converter 102, an inverter 103, and a power transmission coil 104. Commercial AC power is DC converted by the converter 102, converted to AC power of a predetermined frequency by the inverter 103, and supplied to the power transmission coil 104.

  The power receiving device 105 includes a substrate 106, a low electronic component 107, a high electronic component 108, a magnetic sheet 109, and a power receiving coil 110. On the surface of the substrate 106, a power conversion circuit that converts AC power received by the power receiving coil 110 by the electronic components 107 and 108 into DC power is formed. Here, the magnetic sheet 109 is provided so as to cover a region where the electronic component 107 having a low height is disposed. On the other hand, the magnetic sheet 109 is not provided on the electronic component 108 having a high height. With such a configuration, the height of the power receiving device 105 can be suppressed low.

  Here, since the magnetic sheet 109 is not provided on the electronic component 108 having a high height, the portion of the substrate 106 on which the electronic component 108 having a high height is disposed is configured as shown in the cross-sectional view of FIG. That is, the front surface electrode 111 of the substrate 106 is divided, and the back surface electrode 113 of the substrate 106 is connected to each other through the via hole 115. Thereby, the eddy current I2 generated by the leakage magnetic flux from the power transmission coil 104 or the power reception coil 110 flows through the surface electrode 111 but does not flow through the via hole 115 but circulates in the surface electrode 111. With such a configuration, it is possible to reduce eddy current loss that occurs because the magnetic sheet 109 is not provided.

International Publication No. 2010/087317

  According to the contactless power transmission system of FIGS. 3 and 4, the eddy current loss can be reduced. However, since the eddy current is still circulated through the surface electrode 111 and is released as heat, The problem of generating losses remains.

  Further, the above non-contact power transmission system has a configuration in which a magnetic sheet 109 is provided between the substrate 106 and the power receiving coil 110, and the connection cable from the power receiving coil 110 to the substrate 106 is magnetic as shown in FIG. Since the body sheet 109 is routed so as to avoid it, the length of the body sheet is increased, and there is a problem that the loss of the connection cable also occurs.

  Furthermore, since the front and back of the substrate 106 are connected by the via holes 115, there is a problem that the configuration of the substrate 106 is complicated.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a power transmission coil that can achieve both a further reduction in loss and a simple configuration.

In order to solve the conventional problems, a power transmission coil according to the present invention includes a planar coil, a resonant circuit board electrically connected to the planar coil via a cable , the planar coil, and the resonant circuit board. And a magnetic body disposed on the farthest side of the resonant circuit board from the planar coil in the casing, and the resonant circuit board includes the planar coil in the casing. It is arrange | positioned so that it may become substantially parallel to the direction of the magnetic field in the height direction of the said housing | casing produced | generated by.

  According to the power transmission coil of the present invention, since the surface electrode of the resonant circuit board is substantially parallel to the direction of the magnetic field from the planar coil, almost no eddy current is generated. Therefore, eddy current loss can be further reduced.

  In addition, by storing the resonant circuit board in the casing together with the planar coil, it is not necessary to route the connection cable so as to avoid the conventional magnetic sheet, and the length can be shortened. Loss can also be reduced.

  Furthermore, since a via hole is not required in the resonant circuit board, a simple configuration can be achieved.

  From these things, there exists an effect that the reduction | restoration of a further loss and the electric power transmission coil which can make simple structure compatible are realizable.

1 is a partially cutaway perspective view of a power transmission coil according to Embodiment 1 of the present invention. Partially cutaway perspective view of a power transmission coil according to Embodiment 2 of the present invention Block diagram of a conventional contactless power transmission system Cross-sectional view of a conventional contactless power transmission system board

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a partially cutaway perspective view of a power transmission coil according to Embodiment 1 of the present invention.

  In FIG. 1, the power transmission coil 11 includes a planar coil 13, a resonant circuit board 15 electrically connected to the planar coil 13, and a casing 17 that houses the planar coil 13 and the resonant circuit board 15. The resonance circuit board 15 has a configuration arranged in the casing 17 so as to be substantially parallel to the direction of the magnetic field generated by the planar coil 13 in the height direction of the casing 17.

  Thereby, since the resonant circuit board 15 becomes substantially parallel to the direction of the magnetic field from the planar coil 13, eddy current loss can be further reduced. Further, by housing the resonant circuit board 15 in the casing 17 together with the planar coil 13, the connection cable (described later) can be shortened and the loss can be reduced. Furthermore, since no via hole is required in the resonant circuit board 15, a simple configuration can be achieved. From these facts, it is possible to realize the power transmission coil 11 that achieves both a further loss reduction and a simple configuration.

  Hereinafter, the configuration and operation of the first embodiment will be described more specifically.

  The power transmission coil 11 in FIG. 1 has a planar coil 13 for transmitting power. The planar coil 13 is composed of a litz wire. The litz wire is wound spirally from the center of the planar coil 13 toward the outside. Both ends of the planar coil 13 are pulled out by the connection cable 19 in the downward direction of the housing 17 in FIG. 1 and are electrically connected to the resonant circuit board 15. The resonant circuit board 15 is electrically connected to a power transmission circuit (not shown) by a connection cable 19.

  A resonant capacitor 21 that resonates with the planar coil 13 is mounted on the resonant circuit board 15. The planar coil 13 and the resonant capacitor 21 are electrically connected so as to be in series.

  The resonant capacitor 21 is a multilayer chip capacitor. Then, it is mounted on the wiring pattern 23 provided on the surface of the resonant circuit board 15. At this time, the internal electrode of the resonant capacitor 21 is mounted on the resonant circuit board 15 so as to be substantially parallel to the wiring pattern 23. Here, “substantially parallel” is defined to mean parallel within the range of accuracy of parallelism in the internal electrode of the resonant capacitor 21 and assembly accuracy when connecting to the wiring pattern 23.

  The connection cable 19 is also electrically connected by solder 25 at both ends of the wiring pattern 23.

  The planar coil 13 and the resonance circuit board 15 are accommodated in a resin casing 17. Specifically, in FIG. 1, the planar coil 13 is disposed on the upper surface of the housing 17. The resonant circuit board 15 is arranged upright in the height direction of the housing 17. At this time, as shown in FIG. 1, the resonant circuit board 15 is disposed at a position outside the outer periphery of the planar coil 13, that is, a position outside the projection surface of the planar coil 13 onto the magnetic body (described later).

  A magnetic body 27 made of, for example, ferrite is disposed on the bottom surface of the housing 17. As shown in FIG. 1, the lower end surface of the resonant circuit board 15 is fixed to the magnetic body 27. Therefore, the magnetic body 27 is disposed in the casing 17 on the side of the resonance circuit board 15 farthest from the planar coil 13 (here, the lower end surface).

  In the configuration of the first embodiment, the entire bottom surface of the housing 17 is the magnetic body 27, but this is because the sheet of the magnetic body 27 is placed on the surface of the bottom plate of the housing 17 that faces the planar coil 13. The structure which attaches may be sufficient.

  With such a configuration, the magnetic body 27 is arranged in the casing 17 in a direction substantially parallel to the planar coil 13. As a result, a magnetic shield on the bottom surface of the power transmission coil 11 can be realized. Note that “substantially parallel” is defined as parallel within the range of the processing accuracy of the casing 17 and the magnetic body 27 and the assembly accuracy of both.

  Further, since the magnetic body 27 is arranged on the bottom surface of the power transmission coil 11 and the planar coil 13 and the resonant circuit board 15 are accommodated in the housing 17, the gap between the planar coil 13 and the resonant circuit board 15 is It can be electrically connected directly by the connection cable 19. Therefore, unlike the prior art, the connection cable 19 does not need to be routed so as to avoid the magnetic body 27, and the connection cable 19 can be shortened accordingly, and loss due to the connection cable 19 can be reduced. It becomes possible.

  When the planar coil 13 is operated, a leakage magnetic flux indicated by a dotted line in FIG. 1 is generated from the planar coil 13 in the height direction of the housing 17. Therefore, the resonant circuit board 15 is disposed in the casing 17 so as to be substantially parallel to the direction of the magnetic field (leakage magnetic flux) generated by the planar coil 13 in the height direction of the casing 17. It will be. Here, “substantially parallel” means that the resonance circuit board 15 has a high height of the casing 17 within the range of the dimensional accuracy of the resonance circuit board 15 itself and the assembly accuracy when the resonance circuit board 15 is attached to the magnetic body 27. It is defined as parallel to the vertical direction. With such a configuration, the wiring pattern 23 provided on the surface of the resonant circuit board 15 is substantially parallel to the leakage magnetic flux indicated by the dotted line in FIG. 1, so that almost no eddy current is generated in the wiring pattern 23.

  Similarly, since the internal electrode of the resonant capacitor 21 is substantially parallel to the wiring pattern 23, the direction of the internal electrode and the leakage magnetic flux is also substantially parallel. Therefore, almost no eddy current is generated in the resonant capacitor 21.

  Furthermore, as described above, since the resonant circuit board 15 is disposed at a position outside the outer periphery of the planar coil 13, the strength of the leakage magnetic flux reaching the resonant circuit board 15 is weakened.

  As a result, eddy current loss can be further reduced as compared with the conventional configuration. Further, since the resonant circuit board 15 is not provided with a via hole, the structure is simplified.

  With the above configuration and operation, the power transmission coil 11 that can achieve both a further reduction in loss and a simple configuration can be realized.

  In the first embodiment, the resonant circuit board 15 is disposed at a position outside the outer periphery of the planar coil 13, but this is a small amount of power transmitted by the power transmission coil 11, and a small amount of leakage magnetic flux. In this case, the resonant circuit board 15 may be disposed at a position inside the outer periphery of the planar coil 13. In this case, the leakage magnetic flux easily reaches the resonant circuit board 15, but the eddy current loss can be suppressed because the wiring pattern 23 is parallel to the leakage magnetic flux. However, in order to reduce the eddy current loss as much as possible and improve the efficiency, the resonant circuit board 15 is disposed away from the leakage magnetic flux and disposed outside the outer periphery of the planar coil 13 as in the first embodiment. Is preferable.

(Embodiment 2)
FIG. 2 is a partially cutaway perspective view of the power transmission coil according to Embodiment 2 of the present invention.

  In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 2, the resonant circuit board 15 is arranged in a state bent in the outer peripheral direction of the planar coil 13.

  As a result, the distance from the planar coil 13 in each part of the wiring pattern 23 provided on the resonant circuit board 15 is substantially equal. Therefore, in addition to the effect that the eddy current loss itself generated in the wiring pattern 23 is reduced, the eddy current loss is reduced. The variation of this can also be reduced. As a result, even if heat is generated in the resonant circuit board 15 due to eddy current loss, there is an effect that the variation is reduced.

  Hereinafter, the configuration and operation of the second embodiment will be described more specifically.

  In FIG. 2, the planar coil 13 is disposed in a cylindrical casing 17. The resonant circuit board 15 is arranged in a state bent in the outer circumferential direction of the planar coil 13. In order to arrange in this way, the resonant circuit board 15 is formed of a flexible board.

  Here, the radius of curvature of the bent resonance circuit board 15 is larger than the circumscribed radius of the planar coil 13. In the second embodiment, since the planar coil 13 has a spiral shape, the circumscribed circle radius is equivalent to the outer peripheral radius of the planar coil 13. Further, the resonant circuit board 15 is arranged at a position outside the outer periphery of the planar coil 13.

  With such a configuration, the resonance circuit substrate 15 can be moved away from the planar coil 13 as much as possible in the casing 17, so that the casing is moved from the planar coil 13 in the direction shown by the dotted arrow in FIG. 2. Even if a magnetic field (leakage magnetic flux) in the height direction of 17 is generated, eddy current loss can be further reduced. Further, the distance from the planar coil 13 in each part of the wiring pattern 23 provided on the resonant circuit board 15 is substantially equal. Therefore, in addition to the effect of reducing the eddy current loss itself generated in the wiring pattern 23 as described above, the variation in eddy current can also be reduced. As a result, even if heat is generated in the resonant circuit board 15 due to eddy current loss, thermal variation is suppressed and the possibility of locally generating heat is reduced.

  Here, the radius of curvature of the resonant circuit board 15 is larger than the circumscribed radius (outer radius) of the planar coil 13, and the resonant circuit board 15 is arranged at a position outside the outer circumference of the planar coil 13. However, it is not limited to this. That is, for example, when the height of the casing 17 is high and the resonance circuit board 15 is applied within the projection surface of the planar coil 13 onto the magnetic body 27, the resonance circuit board is not greatly affected by the eddy current loss due to the leakage magnetic flux. The radius of curvature of 15 may be smaller than the circumscribed circle radius of the planar coil 13, or the resonant circuit board 15 may be disposed at a position inside the outer periphery of the planar coil 13. However, in order to reduce the eddy current loss as much as possible, as shown in the second embodiment, the radius of curvature of the resonant circuit board 15 is larger than the circumscribed radius of the planar coil 13 and the resonant circuit board 15 is flat. It is desirable to adopt a configuration in which the coil 13 is arranged at a position outside the outer periphery of the coil 13.

  A resonant capacitor 21 is mounted on the resonant circuit board 15. Here, a cylindrical capacitor 21 was used as the resonance capacitor 21. Accordingly, the lead wire of the resonance capacitor 21 is electrically connected to the wiring pattern 23.

  Here, the cylindrical resonant capacitor 21 has a configuration in which an internal electrode is wound in the circumferential direction of the cylinder. Therefore, as in the first embodiment, the direction of the magnetic field (leakage magnetic flux) in the height direction of the casing 17 generated from the planar coil 13 is substantially parallel to the internal electrode. For this purpose, the resonant capacitor 21 is arranged so that the height direction of the resonant capacitor 21 shown in FIG. 2 and the height direction of the housing 17 are substantially parallel to each other. Thereby, the eddy current loss which generate | occur | produces in the said internal electrode can be reduced. Note that “substantially parallel” means within the range of assembly accuracy such as the dimensional accuracy of the resonant capacitor 21, the mounting accuracy of the resonant capacitor 21 to the resonant circuit substrate 15, and the fixing accuracy of the resonant circuit substrate 15 to the magnetic body 27. Is defined as parallel.

  As described above, the configuration in which the resonance circuit board 15 is bent allows the resonance circuit board 15 to be disposed along the casing 17 even when the casing 17 is cylindrical, thereby reducing eddy current loss. Can do. Similarly to the first embodiment, in the second embodiment, since the magnetic body 27 is arranged at the bottom of the housing 17, the connection cable 19 does not have to avoid the magnetic body 27. 19 can be shortened and loss can be reduced. In addition, since it is not necessary to provide a large number of via holes in the resonant circuit board 15, the resonant circuit board 15 can have a simple configuration.

  With the above configuration and operation, the power transmission coil 11 that can achieve both a further reduction in loss and a simple configuration can be realized.

  In the second embodiment, the resonance capacitor 21 has a cylindrical shape, but this may be a multilayer resonance capacitor 21 as in the first embodiment. Further, the resonance capacitor 21 of the first embodiment may have the cylindrical shape shown in the second embodiment. In any of these cases, the internal electrodes may be arranged so as to be parallel to the direction of the leakage magnetic flux. Thereby, the eddy current loss in the internal electrode of the resonant capacitor 21 can be reduced.

  Further, the bent resonant circuit board 15 described in the second embodiment may be applied to the configuration of the first embodiment. In this case as well, variation in eddy current can be reduced as in the second embodiment.

  In the second embodiment, the planar coil 13 has a spiral shape, but this may be a polygonal planar coil 13. In this case, the circumscribed circle radius of the planar coil 13 is the radius of the circumscribed circle in the polygon formed by the outermost litz wire.

  The resonant circuit board 15 of the second embodiment is a flexible board, but is not limited to this. For example, a glass epoxy circuit board may be mechanically bent and fixed.

  In the first and second embodiments, the internal electrode of the resonant capacitor 21 is mounted on the resonant circuit board 15 so as to be substantially parallel to the direction of the magnetic field (the direction of the leakage magnetic flux). On the other hand, when the capacity of the resonance capacitor 21 is small, the internal electrode is also small, and when the eddy current is not so much generated, the resonance capacitor 21 is mounted in an arbitrary direction regardless of the direction of the magnetic field. May be.

  In the first and second embodiments, the planar coil 13 of the power transmission coil 11 has been described for power transmission. However, this may be applied for power reception. In this case, a power receiving circuit is electrically connected to the power transmission coil 11.

  When the power transmission coil 11 in the first and second embodiments needs to be thinned, the width of the resonant circuit board 15, that is, the length in the height direction of the casing 17 is set to the mounting of the resonant capacitor 21 and the like. What is necessary is just to make it the elongate shape narrowed to the extent of the magnitude | size of components.

  Since the power transmission coil according to the present invention can achieve both a further reduction in loss and a simple configuration, it is particularly useful as a power transmission coil for non-contact power feeding.

DESCRIPTION OF SYMBOLS 11 Power transmission coil 13 Planar coil 15 Resonance circuit board 17 Case 21 Resonance capacitor 27 Magnetic body

Claims (6)

A planar coil;
A resonant circuit board electrically connected to the planar coil via a cable ;
A housing for housing the planar coil and the resonant circuit board;
A magnetic body disposed on the side of the resonant circuit board farthest from the planar coil in the housing,
The resonance circuit board is a power transmission coil arranged in the casing so as to be substantially parallel to a direction of a magnetic field generated by the planar coil in a height direction of the casing. The power transmission coil according to claim 1, wherein the resonant circuit board is disposed at a position outside the outer periphery of the planar coil. The resonant circuit board has a configuration in which a resonant capacitor is mounted,
The power transmission coil according to claim 1, wherein the resonance capacitor is mounted on the resonance circuit board so that an internal electrode of the resonance capacitor is substantially parallel to the direction of the magnetic field. The power transmission coil according to claim 1, wherein the resonant circuit board is arranged in a state bent in an outer peripheral direction of the planar coil. The power transmission according to claim 4, wherein a radius of curvature of the bent resonant circuit board is larger than a circumscribed circle radius of the planar coil, and the resonant circuit board is disposed at a position outside the outer periphery of the planar coil. coil. The power transmission coil according to claim 1, wherein the magnetic body is disposed in a direction substantially parallel to the planar coil.

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