JP2015106938A - Power transmission coil unit and wireless power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power transmission coil unit and a wireless power transmission device which are suppressed in reduction of power transmission efficiency while reducing unnecessary leakage magnetic field formed in a place separated from a power transmission coil.SOLUTION: A power transmission coil unit Ltu1 includes: power transmission coils Lta, Ltb; and auxiliary coils Lca, Lcb. In magnetic fluxes generated by the auxiliary coils Lca, Lcb, among magnet fluxes generated by the power transmission coils Lta, Ltb, a part of the magnetic fluxes (magnetic fluxes Bt1c, Bt1d) is set off which are prevented from being interlinked with a power receiving coil Lr which is opposed to the power transmission coils Lta, Ltb when transmitting power without setting off the magnetic fluxes Bt1a, Bt1d interlinked with the power receiving coil Lr.

Description

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

  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, there is an increasing demand for the development of technology capable of transmitting power with high efficiency and low loss.

  At this time, an unnecessary leakage magnetic field formed around the power transmission coil due to the leakage magnetic flux of the power transmission coil is regarded as a problem. For example, when the wireless power transmission technology is applied to a charging device in a power electronics device such as an electric vehicle, a large power transmission is required. Therefore, it is necessary to flow a large current through a power transmission coil. Since the intensity of the unnecessary leakage magnetic field also increases, there is a concern that it may cause electromagnetic interference that adversely affects surrounding electronic devices.

  In order to solve such a problem, for example, Patent Document 1 discloses a technique for eliminating noise caused by leakage magnetic flux of a power transmission coil by a noise canceling coil interlinked with the magnetic flux generated by the power transmission coil. Yes.

Japanese Patent Laid-Open No. 09-74034

  However, in the technique disclosed in Patent Document 1, since the magnetic flux generated by the power transmission coil is linked to the noise cancellation coil, even the magnetic flux that should originally contribute to power transmission is canceled. As a result, there is a problem that the power transmission efficiency is lowered.

  Therefore, the present invention has been made in view of the above problems, and a power transmission coil unit and a wireless power transmission in which a decrease in power transmission efficiency is suppressed while reducing an unnecessary leakage magnetic field formed in a place away from the power transmission coil. An object is to provide an apparatus.

  The power transmission coil unit according to the present invention is a power transmission coil unit that wirelessly transmits power, and includes a power transmission coil and an auxiliary coil, and the magnetic flux generated by the auxiliary coil is the magnetic flux generated by the power transmission coil. A part of the magnetic flux not linked to the power receiving coil is canceled without canceling the magnetic flux linked to the power receiving coil that faces the power transmitting coil when power is transmitted.

  Here, most of the magnetic flux that forms an unnecessary leakage magnetic field in a place away from the power transmission coil is a magnetic flux that does not interlink with the power reception coil. On the other hand, in the power transmission coil unit according to the present invention, the magnetic flux generated by the auxiliary coil cancels a part of the magnetic flux not interlinked with the power receiving coil. Therefore, the strength of the magnetic field formed at a location away from the power transmission coil is reduced. On the other hand, the magnetic flux contributing to power transmission is a magnetic flux interlinking with the power receiving coil. On the other hand, in the power transmission coil unit according to the present invention, the magnetic flux generated by the auxiliary coil does not cancel the magnetic flux interlinked with the power receiving coil. Accordingly, it is possible to suppress a decrease in power transmission efficiency while reducing an unnecessary leakage magnetic field formed in a place away from the power transmission coil. Here, “without canceling the magnetic flux interlinked with the power receiving coil” means that a part of the magnetic flux interlinking the power receiving coil circulates to a place away from the power transmitting coil due to the influence of some surrounding environment. In this case, it does not mean that the magnetic flux generated by the auxiliary coil accidentally cancels a part of the magnetic flux interlinked with the power receiving coil at a location away from the power transmitting coil.

  Moreover, in the power transmission coil unit according to the present invention, the magnetic field generated by the auxiliary coil may be configured to intensify a part of the magnetic field generated between the power transmission coil and the power reception coil. In this case, the direction of the magnetic flux generated by the power transmission coil and the direction of the magnetic flux generated by the auxiliary coil are substantially the same between the power transmission coil and the power reception coil. Therefore, the magnetic flux that contributes to the power transmission that links the power transmitting coil and the power receiving coil together is not offset by the magnetic flux generated by the auxiliary coil. As a result, a decrease in power transmission efficiency can be suppressed.

  Preferably, each of the power transmission coil and the auxiliary coil further includes a magnetic core, and the magnetic core of the auxiliary coil is connected to the magnetic core of the power transmission coil. In this case, the auxiliary coil easily generates magnetic flux that strengthens the magnetic field generated between the power transmission coil and the power reception coil. That is, between the power transmission coil and the power reception coil, the direction of the magnetic flux generated by the power transmission coil and the direction of the magnetic flux generated by the auxiliary coil are substantially the same. Therefore, the magnetic flux that contributes to power transmission that links the power transmission coil and the power reception coil together is not offset by the magnetic flux generated by the auxiliary coil. As a result, it is possible to further suppress a decrease in power transmission efficiency.

  More preferably, the axial direction of the auxiliary coil is not parallel to the opposing direction of the power transmission coil and the power reception coil. In this case, the magnetic flux generated by the auxiliary coil easily circulates to a place away from the auxiliary coil without interlinking with the power receiving coil. As a result, the effect of reducing an unnecessary leakage magnetic field formed at a location away from the power transmission coil is further enhanced.

  Moreover, in the power transmission coil unit according to the present invention, the auxiliary coil is arranged not to interlink with the magnetic flux interlinked with the power receiving coil among the magnetic flux generated by the power transmission coil, and the circulation direction of the magnetic flux generated by the auxiliary coil May be configured to be in a direction opposite to the direction of the magnetic flux generated by the power transmission coil. In this case, since the auxiliary coil is arranged so as not to be linked to the magnetic flux linked to the power receiving coil among the magnetic flux generated by the power transmission coil, the magnetic flux contributing to power transmission is not canceled by the auxiliary coil. In addition, since the rotating direction of the magnetic flux generated by the auxiliary coil is opposite to the rotating direction of the magnetic flux generated by the power transmission coil, in a place away from the power transmission coil and the auxiliary coil that are the magnetic flux generation sources, Since the direction of the magnetic flux generated by the power transmission coil and the direction of the magnetic flux generated by the auxiliary coil are opposite to each other, the magnetic fluxes cancel each other, and the strength of the magnetic field formed at a location away from the power transmission coil decreases. Accordingly, it is possible to suppress a decrease in power transmission efficiency while reducing an unnecessary leakage magnetic field formed in a place away from the power transmission coil.

  Preferably, the axial direction of the auxiliary coil is substantially orthogonal to the opposing direction of the power transmission coil and the power reception coil. In this case, the auxiliary coil can more easily generate a magnetic flux that circulates to a place away from the auxiliary coil. Therefore, the effect of reducing an unnecessary leakage magnetic field formed at a location away from the power transmission coil is further enhanced.

  Preferably, the auxiliary coil may be located on the side opposite to the side facing the power receiving coil of the power transmitting coil. In this case, the auxiliary coil can easily generate magnetic flux that strengthens the magnetic field between the power transmission coil and the power reception coil. That is, between the power transmission coil and the power reception coil, the direction of the magnetic flux generated by the power transmission coil and the direction of the magnetic flux generated by the auxiliary coil are substantially the same. Therefore, the magnetic flux that contributes to the power transmission that links the power transmitting coil and the power receiving coil together is not offset by the magnetic flux generated by the auxiliary coil. As a result, it is possible to further suppress a decrease in power transmission efficiency.

  Preferably, part or all of the auxiliary coil overlaps with the power transmission coil when viewed from the opposing direction of the power transmission coil and the power reception coil. In this case, since the auxiliary coil and the power transmission coil are arranged closer to each other, the density distribution of the magnetic flux generated by the auxiliary coil at a location away from the power transmission coil is closer to the density distribution of the magnetic flux generated by the power transmission coil. It can be a distribution. As a result, the effect of reducing an unnecessary leakage magnetic field formed at a location away from the power transmission coil is further enhanced.

  Moreover, in the power transmission coil unit according to the present invention, the power transmission coil includes a first power transmission coil and a second power transmission coil juxtaposed, and the first power transmission coil and the second power transmission coil are generated from each other. You may comprise so that the magnetic path which links both power transmission coils may be formed with a magnetic field. In this case, both the power transmission coils efficiently generate the magnetic flux linked to the power reception coil, so that the power transmission efficiency can be improved.

  More preferably, at least a part of the magnetic flux generated by the auxiliary coil is linked to the power transmission coil. In this case, the auxiliary coil can easily generate magnetic flux that strengthens the magnetic field between the power transmission coil and the power reception coil. That is, between the power transmission coil and the power reception coil, the direction of the magnetic flux generated by the power transmission coil and the direction of the magnetic flux generated by the auxiliary coil are substantially the same. Therefore, the magnetic flux that contributes to power transmission that links the power transmission coil and the power reception coil together is not offset by the magnetic flux generated by the auxiliary coil. As a result, it is possible to further suppress a decrease in power transmission efficiency.

  Preferably, the additional portion is arranged such that the central portion of the coil is disposed between the central portion of the first power transmitting coil and the central portion of the second power transmitting coil on the side opposite to the side facing the power receiving coil of the power transmitting coil. A coil is further provided, and the first power transmission coil, the second power transmission coil, and the additional coil may form a magnetic path that links the coils by a magnetic field generated by each other. In this case, the density of magnetic flux generated by the power transmission coil can be further increased. Therefore, the magnetic flux contributing to the power transmission is generated more efficiently, so that the power transmission efficiency can be further increased.

  Preferably, the auxiliary coil includes a first auxiliary coil and a second auxiliary coil, and the first auxiliary coil and the second auxiliary coil are the center of the first auxiliary coil and the center of the second auxiliary coil. It is good to arrange | position so that the center part of a power transmission coil may be located between these parts. In this case, since the two auxiliary coils are arranged on both outer sides of the power transmission coil, an unnecessary leakage magnetic field formed in a place away from the power transmission coil can be further reduced.

  A wireless power transmission device according to the present invention includes the power transmission coil unit and a power reception coil. ADVANTAGE OF THE INVENTION According to this invention, the wireless power transmission apparatus which suppressed the fall of power transmission efficiency can be provided, reducing the unnecessary leakage magnetic field formed in the place away from the power transmission coil.

  ADVANTAGE OF THE INVENTION According to this invention, the power transmission coil unit and wireless power transmission apparatus which suppressed the reduction | decrease in power transmission efficiency can be provided, reducing the unnecessary leakage magnetic field formed in the place away from the power transmission coil.

1 is a system configuration diagram showing a wireless power transmission device according to a first embodiment of the present invention together with a load. It is sectional drawing which shows the power transmission coil unit which concerns on 1st Embodiment of this invention with a receiving coil. In FIG. 2, it is the figure which showed typically the magnetic flux which the 1st and 2nd power transmission coil generate | occur | produces. In FIG. 2, it is the figure which showed typically the magnetic flux which the 1st and 2nd power transmission coil and the 1st and 2nd auxiliary coil generate | occur | produce. It is a system block diagram which shows the wireless power transmission apparatus which concerns on 2nd Embodiment of this invention with load. It is sectional drawing which shows the power transmission coil unit which concerns on 2nd Embodiment of this invention with a receiving coil. In FIG. 5, it is the figure which showed typically the magnetic flux which a 1st and 2nd power transmission coil and an additional coil generate | occur | produce. In FIG. 5, it is the figure which showed typically the magnetic flux which a 1st and 2nd power transmission coil, an additional coil, and a 1st and 2nd auxiliary coil generate | occur | produce. It is a system block diagram which shows the wireless power transmission apparatus which concerns on 3rd Embodiment of this invention with load. It is sectional drawing which shows the power transmission coil unit which concerns on 3rd Embodiment of this invention with a receiving coil. In FIG. 8, it is the figure which showed typically the magnetic flux which a power transmission coil generate | occur | produces. In FIG. 8, it is the figure which showed typically the magnetic flux which a power transmission coil and a 1st and 2nd auxiliary coil generate | occur | produce. It is a system block diagram which shows the wireless power transmission apparatus which concerns on 4th Embodiment of this invention with load. It is sectional drawing which shows the power transmission coil unit which concerns on 4th Embodiment of this invention with the 1st and 2nd power receiving coil. In FIG. 11, it is the figure which showed typically the magnetic flux which a power transmission coil generate | occur | produces. In FIG. 11, it is the figure which showed typically the magnetic flux which a power transmission coil and a 1st and 2nd auxiliary coil generate | occur | produce. It is sectional drawing which shows the power transmission coil unit of the comparative example 1 with a receiving coil. It is sectional drawing which shows the power transmission coil unit of the comparative example 2 with a receiving coil. It is sectional drawing which shows the power transmission coil unit of the comparative example 3 with a receiving coil. It is sectional drawing which shows the power transmission coil unit of the comparative example 4 with a receiving coil. It is sectional drawing which shows the power transmission coil unit of the comparative example 5 with the 1st and 2nd power receiving coil. It is sectional drawing which shows the power transmission coil unit of the comparative example 6 with the 1st and 2nd power receiving coil. It is a measurement result of the power transmission efficiency and leakage magnetic field intensity of Example 1 and Comparative Examples 1 and 2 according to the present invention. It is a measurement result of the power transmission efficiency and leakage magnetic field intensity of Example 2 and Comparative Examples 3 and 4 according to the present invention. It is a measurement result of the power transmission efficiency and leakage magnetic field intensity of Example 3 and Comparative Examples 5 and 6 according to the present invention.

  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 FIGS. FIG. 1 is a system configuration diagram showing a wireless power transmission device according to a first embodiment of the present invention together with a load. FIG. 2 is a cross-sectional view showing the power transmission coil unit according to the first embodiment of the present invention together with the power receiving coil.

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

  The wireless power transmission device Ut1 includes a power source PW, an inverter INV, and a power transmission coil unit Ltu1. The power source PW supplies DC power to an inverter INV described later. The power source PW is not particularly limited as long as it outputs DC power. 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, etc. Is mentioned.

  The inverter INV has a function of converting input DC power supplied from the power source PW into AC power. In the present embodiment, the inverter INV converts input DC power supplied from the power source PW into AC power and supplies the AC power to a power transmission coil unit Ltu1 described later. The inverter INV is composed of 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 power transmission coil unit Ltu1 includes a first power transmission coil Lta, a second power transmission coil Ltb, a first auxiliary coil Lca, a second auxiliary coil Lcb, and a magnetic body F1. In the present embodiment, the first and second power transmission coils Lta and Ltb and the four coils of the first and second auxiliary coils Lca and Lcb are electrically connected in series as shown in FIG. Yes. 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 transmission coil unit Ltu1 is disposed in the ground or in the vicinity of the ground.

  Then, with reference to FIG. 2, each coil which the power transmission coil unit Ltu1 has is demonstrated. The first power transmission coil Lta includes a magnetic core Cta and a winding Wta. The first power transmission coil Lta is a coil having a planar spiral structure having a substantially square shape, and is formed by winding a winding Wta made of litz wire such as copper or aluminum around a magnetic core Cta. The axial direction of the first power transmission coil Lta is parallel to the facing direction of the first and second power transmission coils Lta, Ltb and a power receiving coil Lr described later. The number of turns of the first power transmission coil Lta is appropriately set based on a distance from the power receiving coil Lr described later, a desired power transmission efficiency, and the like.

  The second power transmission coil Ltb includes a magnetic core Ctb and a winding Wtb. The second power transmission coil Ltb is a flat spiral coil having a substantially square shape, and is formed by winding a winding Wtb made of a litz wire such as copper or aluminum around a magnetic core Ctb. The axial direction of the second power transmission coil Ltb is parallel to the opposing direction of the first and second power transmission coils Lta, Ltb and a power receiving coil Lr described later. The second power transmission coil Ltb is juxtaposed on the same plane as the first power transmission coil Lta, and the arrangement interval of the first and second power transmission coils Lta, Ltb and the number of turns of the second power transmission coil Ltb will be described later. It is set as appropriate based on the distance from the receiving coil Lr to be performed, the desired power transmission efficiency, and the like. The first and second power transmission coils Lta and Ltb have a function of wirelessly transmitting AC power supplied from the inverter INV to a power receiving coil Lr described later.

  Further, the first power transmission coil Lta and the second power transmission coil Ltb are configured such that a magnetic path that links both the power transmission coils Lta and Ltb is formed by a magnetic field generated by each other. In this case, since both the power transmission coils Lta and Ltb efficiently generate a magnetic flux linked to the power receiving coil Lr described later, the power transmission efficiency is improved. Specifically, the first power transmission coil Lta and the second power transmission coil Ltb generate magnetic flux that circulates so as to link both power transmission coils Lta and Ltb. In the magnetic flux circulating around both the power transmission coils Lta and Ltb, the direction linked to the first power transmission coil Lta and the direction linked to the second power transmission coil Ltb are opposite to each other. Here, in order to form a magnetic path that links both the power transmission coils Lta and Ltb, the direction of the magnetic field generated by the first power transmission coil Lta and the direction of the magnetic field generated by the second power transmission coil Ltb are opposite to each other. What is necessary is just to electrically connect the 1st power transmission coil Lta and the 2nd power transmission coil Ltb so that it may become direction. That is, when the winding direction of the first power transmission coil Lta and the second power transmission coil Ltb is the same direction, the direction of the current flowing through the first power transmission coil Lta and the direction of the current flowing through the second power transmission coil Ltb are What is necessary is just to connect so that it may become a mutually reverse direction. Alternatively, when the winding directions of the first power transmission coil Lta and the second power transmission coil Ltb are opposite to each other, the direction of the current flowing in the first power transmission coil Lta and the direction of the current flowing in the second power transmission coil Ltb May be connected so that they are in the same direction. In addition, the direction of the magnetic flux which circulates so that both power transmission coil Lta and Ltb may be linked | interrupted is a circulation direction of the magnetic flux which a "power transmission coil" generate | occur | produces.

  The first auxiliary coil Lca includes a magnetic core Cca and a winding Wca. The first auxiliary coil Lca is a solenoid coil wound spirally, and is formed by winding a winding Wca made of litz wire such as copper or aluminum around a plate-like or rod-like magnetic core Cca. Yes. The axial direction of the first auxiliary coil Lca is not parallel to the opposing direction of the first and second power transmission coils Lta, Ltb and a power receiving coil Lr described later. With such a configuration, the magnetic flux generated by the first auxiliary coil Lca can easily circulate to a place away from the first auxiliary coil Lca without interlinking with the power receiving coil Lr described later. In the present embodiment, the axial direction of the first auxiliary coil Lca is orthogonal to the facing direction between the first and second power transmission coils Lta, Ltb and a power receiving coil Lr described later. In this case, the first auxiliary coil Lca makes it easier to generate a magnetic flux that circulates to a place away from the first auxiliary coil Lca.

  The first auxiliary coil Lca is opposed to the first and second power transmission coils Lta and Ltb when transmitting power out of the magnetic flux generated by the first and second power transmission coils Lta and Ltb. It arrange | positions so that it may not be linked to the magnetic flux linked to the receiving coil Lr mentioned later. That is, the magnetic flux that contributes to power transmission is not canceled out by the first auxiliary coil Lca, so that a decrease in power transmission efficiency can be suppressed. In the present embodiment, as shown in FIG. 2, the first auxiliary coil Lca is disposed on the side opposite to the side where the first and second power transmission coils Lta and Ltb face the power receiving coil Lr described later. ing. More specifically, the first auxiliary coil Lca is disposed so as to overlap the first power transmission coil Lta when viewed from the opposing direction of the first and second power transmission coils Lta, Ltb and a power receiving coil Lr described later. Has been. With this arrangement, the first auxiliary coil Lca can easily generate a magnetic flux that strengthens the magnetic field generated between the first power transmission coil Lta and a power receiving coil Lr described later. That is, between the first power transmission coil Lta and the power receiving coil Lr described later, the direction of the magnetic flux generated by the first power transmission coil Lta and the direction of the magnetic flux generated by the first auxiliary coil Lca are substantially the same. . Therefore, the magnetic flux that contributes to the power transmission that links the first power transmission coil Lta and the power receiving coil Lr described later is not offset by the magnetic flux generated by the first auxiliary coil Lca. As a result, it is possible to further suppress a decrease in power transmission efficiency. In addition, since the first auxiliary coil Lca and the first power transmission coil Lta are arranged closer to each other, the density of the magnetic flux generated by the first auxiliary coil Lca in a place away from the first power transmission coil Lta. The distribution can be made closer to the density distribution of the magnetic flux generated by the first power transmission coil Lta.

  Furthermore, the circulation direction of the magnetic flux generated by the first auxiliary coil Lca is opposite to the rotation direction of the magnetic flux generated by the first and second power transmission coils Lta and Ltb. Specifically, in FIG. 2, the magnetic flux generated by the first and second power transmission coils Lta and Ltb moves the first power transmission coil Lta from the first power transmission coil Lta toward the power reception coil Lr described later ( The second auxiliary coil Lca is linked to the second power transmission coil Ltb in a direction (downward in the figure) from the power receiving coil Lr, which will be described later, to the second power transmission coil Ltb. However, if a magnetic flux interlinking in the direction from the first auxiliary coil Lca toward the center of the first power transmission coil Lta (rightward in the drawing) is generated, the circulation direction of the magnetic flux generated by the first auxiliary coil Lca is The first and second power transmission coils Lta and Ltb are in the opposite direction to the direction in which the magnetic flux generated by the first and second power transmission coils Lta and Ltb is generated. Alternatively, in FIG. 2, the magnetic flux generated by the first and second power transmission coils Lta and Ltb moves the first power transmission coil Lta from the power receiving coil Lr described later to the first power transmission coil Lta (downward in the drawing). And the second power transmission coil Ltb is interlinked in a direction (upward in the drawing) from the second power transmission coil Ltb toward the power receiving coil Lr described later, and the first auxiliary coil Lca is If a magnetic flux interlinking in the direction from the center of one power transmission coil Lta toward the first auxiliary coil Lca (leftward in the figure) is generated, the circulation direction of the magnetic flux generated by the first auxiliary coil Lca is the first and The direction of the magnetic flux generated by the second power transmission coils Lta and Ltb is opposite to that of the magnetic flux. In order to generate such a magnetic flux, the portion of the winding Wta of the first auxiliary coil Lca that is closest to the winding Wta of the first power transmission coil Lta (the upper surface of the winding Wta of the first auxiliary coil Lca shown in the figure). The direction of the current passing through the portion) is the portion closest to the winding Wta of the first auxiliary coil Lca in the winding Wta of the first power transmission coil Lta (the left side of the winding Wta of the first power transmission coil Lta shown in the figure). The winding Wca of the first auxiliary coil Lca may be wound around the magnetic core Cca so that the direction of the current passing through the portion) is the same. By adopting such a configuration, the direction of the magnetic flux generated by the first power transmission coil Lta and the first direction are separated from the first power transmission coil Lta and the first auxiliary coil Lca, which are magnetic flux generation sources. Since the directions of the magnetic fluxes generated by the auxiliary coils Lca are opposite to each other, the magnetic fluxes cancel each other, and the strength of the magnetic field formed at a location away from the first power transmission coil Lta decreases. Therefore, it is possible to reduce an unnecessary leakage magnetic field formed in a place away from the first and second power transmission coils Lta and Ltb.

  The second auxiliary coil Lcb includes a magnetic core Ccb and a winding Wcb. The second auxiliary coil Lcb is a solenoid coil that is spirally wound, and is formed by winding a winding Wcb composed of a litz wire such as copper or aluminum around a plate-like or rod-like magnetic core Ccb. Yes. The axial direction of the second auxiliary coil Lcb is not parallel to the opposing direction of the first and second power transmission coils Lta, Ltb and a power receiving coil Lr described later. With such a configuration, the magnetic flux generated by the second auxiliary coil Lcb can easily circulate to a place away from the second auxiliary coil Lcb without interlinking with the power receiving coil Lr described later. In the present embodiment, the axial direction of the second auxiliary coil Lcb is orthogonal to the facing direction between the first and second power transmission coils Lta, Ltb and a power receiving coil Lr described later. In this case, the second auxiliary coil Lcb makes it easier to generate a magnetic flux that circulates to a place away from the second auxiliary coil Lcb.

  The second auxiliary coil Lcb faces the first and second power transmission coils Lta and Ltb when transmitting power out of the magnetic flux generated by the first and second power transmission coils Lta and Ltb. It arrange | positions so that it may not be linked to the magnetic flux linked to the receiving coil Lr mentioned later. That is, the magnetic flux that contributes to power transmission is not canceled out by the second auxiliary coil Lcb, so that a decrease in power transmission efficiency can be suppressed. In the present embodiment, as shown in FIG. 2, the second auxiliary coil Lcb is disposed on the side opposite to the side where the first and second power transmission coils Lta, Ltb face the power receiving coil Lr described later. ing. More specifically, the second auxiliary coil Lcb is disposed so as to overlap the second power transmission coil Ltb when viewed from the opposing direction of the first and second power transmission coils Lta, Ltb and a power receiving coil Lr described later. Has been. With this arrangement, the second auxiliary coil Lcb can easily generate a magnetic flux that reinforces the magnetic field generated between the second power transmission coil Ltb and a power receiving coil Lr described later. That is, between the second power transmission coil Ltb and a power receiving coil Lr described later, the direction of the magnetic flux generated by the second power transmission coil Ltb and the direction of the magnetic flux generated by the second auxiliary coil Lcb are substantially the same. . Therefore, the magnetic flux that contributes to power transmission that links the second power transmission coil Ltb and the power receiving coil Lr described later is not canceled by the magnetic flux generated by the second auxiliary coil Lcb. As a result, it is possible to further suppress a decrease in power transmission efficiency. In addition, since the second auxiliary coil Lcb and the second power transmission coil Ltb are arranged closer to each other, the density of the magnetic flux generated by the second auxiliary coil Lcb at a location away from the second power transmission coil Ltb. The distribution can be made closer to the density distribution of the magnetic flux generated by the second power transmission coil Ltb.

  Furthermore, the direction of the magnetic flux generated by the second auxiliary coil Lcb is opposite to the direction of the magnetic flux generated by the first and second power transmission coils Lta and Ltb. Specifically, in FIG. 2, the magnetic flux generated by the first and second power transmission coils Lta and Ltb moves the first power transmission coil Lta from the first power transmission coil Lta toward the power reception coil Lr described later ( The second auxiliary coil Lcb is linked to the second auxiliary coil Lcb in the direction (downward in the figure) from the power receiving coil Lr described later to the second power transmitting coil Ltb. However, if a magnetic flux interlinking in the direction from the center of the second power transmission coil Ltb toward the second auxiliary coil Lcb (rightward in the drawing) is generated, the circulation direction of the magnetic flux generated by the second auxiliary coil Lcb is The first and second power transmission coils Lta and Ltb are in the opposite direction to the direction in which the magnetic flux generated by the first and second power transmission coils Lta and Ltb is generated. Alternatively, in FIG. 2, the magnetic flux generated by the first and second power transmission coils Lta and Ltb moves the first power transmission coil Lta from the power receiving coil Lr described later to the first power transmission coil Lta (downward in the drawing). And the second power transmission coil Ltb is linked in a direction (upward in the drawing) from the second power transmission coil Ltb toward the power receiving coil Lr described later, and the second auxiliary coil Lcb If a magnetic flux interlinking in the direction (leftward in the figure) from the second auxiliary coil Lcb toward the center of the second power transmission coil Ltb is generated, the circulation direction of the magnetic flux generated by the second auxiliary coil Lcb is the first and The direction of the magnetic flux generated by the second power transmission coils Lta and Ltb is opposite to that of the magnetic flux. In order to generate such a magnetic flux, the portion of the winding Wtb of the second auxiliary coil Lcb that is closest to the winding Wtb of the second power transmission coil Ltb (the upper surface of the winding Wtb of the second auxiliary coil Lcb in the drawing). Portion of the winding Wtb of the second power transmission coil Ltb is close to the winding Wtb of the second auxiliary coil Lcb (the right side portion of the winding Wtb of the second power transmission coil Ltb). The winding Wcb of the second auxiliary coil Lcb may be wound around the magnetic core Ccb so that the direction of the current passing through By adopting such a configuration, the direction of the magnetic flux generated by the second power transmission coil Ltb and the second direction are separated from the second power transmission coil Ltb and the second auxiliary coil Lcb, which are magnetic flux generation sources. Since the directions of the magnetic fluxes generated by the auxiliary coils Lcb are opposite to each other, the magnetic fluxes cancel each other, and the strength of the magnetic field formed at a location away from the second power transmission coil Ltb decreases. Therefore, it is possible to reduce an unnecessary leakage magnetic field formed in a place away from the first and second power transmission coils Lta and Ltb.

  The first auxiliary coil Lca and the second auxiliary coil Lcb are arranged between the central part of the first power transmission coil Lta and the first auxiliary coil Lca between the central part of the first auxiliary coil Lca and the central part of the second auxiliary coil Lcb. It arrange | positions so that the center part of the 2 power transmission coil Ltb may be located. Specifically, in the juxtaposition direction of the first and second power transmission coils Lta and Ltb, the central portion of the first auxiliary coil Lca and the central portion of the second auxiliary coil Lcb are the first and second power transmission coils Lta. , Ltb are arranged so as to be located on both outer sides of the central part. In this case, since the first and second auxiliary coils Lca and Lcb are arranged on both outer sides of the first and second power transmission coils Lta and Ltb, they are separated from the first and second power transmission coils Lta and Ltb. It is possible to further reduce the unnecessary leakage magnetic field that is formed.

  The magnetic body F1 extends along the surface of the first and second power transmission coils Lta, Ltb opposite to the side facing a power receiving coil Lr, which will be described later. In the present embodiment, as shown in FIG. 2, the magnetic body F <b> 1 is a surface on the power receiving coil Lr side (illustrated) in the facing direction between the first and second power transmitting coils Lta and Ltb and the power receiving coil Lr described later (illustrated). Near both ends of the upper surface), the magnetic core Cta of the first power transmission coil Lta and the magnetic core Ctb of the second power transmission coil Ltb are respectively connected. Further, as shown in FIG. 2, the magnetic body F <b> 1 has magnetic properties of the first auxiliary coil Lca on both side surfaces (the left side surface and the right side surface in the drawing) in the juxtaposition direction of the first and second power transmission coils Lta and Ltb, respectively. The core Cca and the magnetic core Ccb of the second auxiliary coil Lcb are connected. With such a configuration, the magnetic core Cca of the first auxiliary coil Lca and the magnetic core Ccb of the second auxiliary coil Lcb are respectively connected to the magnetic core Cta and the second core of the first power transmission coil Lta via the magnetic body F1. The power transmission coil Ltb is connected to the magnetic core Ctb. Therefore, the first auxiliary coil Lca easily generates a magnetic flux that strengthens a magnetic field generated between the first power transmission coil Lta and a power receiving coil Lr described later, and the second auxiliary coil Lcb is a second power transmission coil. It becomes easy to generate a magnetic flux that strengthens the magnetic field generated between Ltb and a power receiving coil Lr described later. That is, between the first power transmission coil Lta and the power receiving coil Lr described later, the direction of the magnetic flux generated by the first power transmission coil Lta and the direction of the magnetic flux generated by the first auxiliary coil Lca are substantially the same. At the same time, the direction of the magnetic flux generated by the second power transmission coil Ltb and the direction of the magnetic flux generated by the second auxiliary coil Lcb are substantially the same between the second power transmission coil Ltb and the power receiving coil Lr described later. . Therefore, the magnetic flux that contributes to power transmission that links the first and second power transmission coils Lta and Ltb and the power receiving coil Lr described later is not offset by the magnetic flux generated by the first and second auxiliary coils Lca and Lcb. . As a result, it is possible to further suppress a decrease in power transmission efficiency.

  As shown in FIG. 1, the wireless power receiving device Ur includes a power receiving coil Lr and a rectifier circuit DB.

  The power receiving coil Lr includes a magnetic core Cr and a winding Wr, as shown in FIG. The power receiving coil Lr is a solenoid coil wound spirally, and is formed by winding a winding Wr around a plate-shaped or rod-shaped magnetic core Cr. The power reception coil Lr has a function of receiving AC power transmitted from the first and second power transmission coils Lta and Ltb of the power transmission coil unit Ltu1. 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.

  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 or a rotating machine included in the vehicle may be used. In addition, when the load R is an AC rotating machine, it is necessary to add an inverter (not shown) between the rectifier circuit DB of the wireless power receiving device Ur and the load R to supply AC power to the AC rotating machine. is there.

  Next, with reference to FIG. 3, the relative relationship between the magnetic flux generated by the power transmission coil and the magnetic flux generated by the auxiliary coil and the action of reducing unnecessary leakage magnetic fields will be described in detail. FIG. 3a is a diagram schematically showing the magnetic flux generated by the first and second power transmission coils in FIG. FIG. 3b is a diagram schematically showing the magnetic flux generated by the first and second power transmission coils and the first and second auxiliary coils in FIG. Here, in FIG. 3a, magnetic fluxes Bt1a to Bt1d are shown as body surfaces out of the magnetic fluxes generated by the first and second power transmission coils Lta and Ltb. Also, in FIG. 3b, out of the magnetic fluxes generated by the first and second power transmission coils Lta and Ltb, magnetic fluxes Bt1a to Bt1d are shown as the body surface, and the first and second auxiliary coils Lca and Lcb are generated. Among the magnetic fluxes to be performed, 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. 3a and 3b, the magnetic cores Cta and Ctb of the first and second power transmission coils Lta and Ltb, the magnetic cores Cca and Ccb of the first and second auxiliary coils Lca and Lcb, and the magnetic body F1 The illustration of the magnetic flux in the magnetic core Cr of the power receiving coil Lr is omitted.

  First, the magnetic flux generated by the first and second power transmission coils Lta and Ltb will be described with reference to FIG. 3a. As shown in FIG. 3a, the first and second power transmission coils Lta and Ltb link the first power transmission coil Lta in the direction from the first power transmission coil Lta to the power reception coil Lr (upward in the drawing). In addition, magnetic fluxes Bt1a to Bt1d that link the second power transmission coil Ltb in a direction (downward in the drawing) from the power reception coil Lr to the second power transmission coil Ltb are generated. That is, the first and second power transmission coils Lta and Ltb generate magnetic fluxes Bt1a to Bt1d that circulate in the same direction. In this example, the magnetic fluxes Bt1a to Bt1d generated by the first and second power transmission coils Lta and Ltb are linked to the power receiving coil Lr, and the magnetic fluxes Bt1a and Bt1b contributing to power transmission are linked to the power receiving coil Lr. Without having to do so, there are magnetic fluxes Bt1c and Bt1d that circulate away from the first and second power transmission coils Lta and Ltb, and the magnetic fluxes Bt1a and Bt1b are linked to the power reception coil Lr, so that the winding of the power reception coil Lr An electromotive force is generated in Wr. The electric power generated in the power receiving coil Lr is rectified by the rectifier circuit DB and output to the load R. Here, in the present embodiment, a magnetic path that links the power transmission coils Lta and Ltb is formed by the magnetic fields generated by the first power transmission coil Lta and the second power transmission coil Ltb. Since Bt1a and Bt1b can be generated efficiently, the magnetic flux density of the magnetic fluxes Bt1a and Bt1b that circulate in the vicinity of the first and second power transmission coils Lta and Ltb is derived from the first and second power transmission coils Lta and Ltb. Compared with magnetic fluxes Bt1c and Bt1d that circulate greatly to a distant place, it is very high. That is, most of the magnetic flux generated by the first and second power transmission coils Lta and Ltb is linked to the power reception coil Lr. As a result, the coupling between the first and second power transmission coils Lta, Ltb and the power reception coil Lr is increased, and the power transmission efficiency is also increased. The magnetic fluxes Bt1a to Bt1d generated by the first and second power transmission coils Lta and Ltb are not interlinked with the first and second auxiliary coils Lca and Lcb, and the magnetic fluxes Bt1a and Bt1a, Since Bt1b is not canceled by the first and second auxiliary coils Lca and Lcb, it is possible to suppress a decrease in power transmission efficiency.

  Subsequently, the magnetic flux generated by the first and second auxiliary coils Lca and Lcb will be described with reference to FIG. The magnetic fluxes Bt1a to Bt1d generated by the first and second power transmission coils Lta and Ltb in FIG. 3b are as shown in FIG. 3a. As shown in FIG. 3b, the first auxiliary coil Lca is linked to the first auxiliary coil Lca in a direction (rightward in the drawing) from the first auxiliary coil Lca toward the center of the first power transmission coil Lta. In addition, the first power transmission coil Lta generates magnetic fluxes Bc1a and Bc1b that are linked in a direction (upward in the drawing) from the first power transmission coil Lta toward the power reception coil Lr. Specifically, in the present embodiment, the axial direction of the first auxiliary coil Lca is not parallel to the opposing direction of the first and second power transmission coils Lta, Ltb and the power reception coil Lr. Therefore, the magnetic fluxes Bc1a and Bc1b generated by the first auxiliary coil Lca circulate around a place away from the first auxiliary coil Lca without interlinking with the power receiving coil Lr. In particular, in this embodiment, since the axial direction of the first auxiliary coil Lca is orthogonal to the opposing direction of the first and second power transmission coils Lta, Ltb and the power receiving coil Lr, the first auxiliary coil The magnetic fluxes Bc1a and Bc1b generated by Lca circulate greatly to a place away from the first auxiliary coil Lca. Further, since the first auxiliary coil Lca is arranged on the opposite side of the first and second power transmission coils Lta, Ltb from the side facing the power receiving coil Lr, the magnetic flux generated by the first auxiliary coil Lca. Bc1a and Bc1b are linked to the first power transmission coil Lta.

  Similarly, as shown in FIG. 3b, the second auxiliary coil Lcb links the second auxiliary coil Lcb in a direction (rightward in the drawing) from the second power transmission coil Ltb to the second auxiliary coil Lcb. In addition, the second power transmission coil Ltb generates magnetic fluxes Bc1c and Bc1d that are linked in a direction (downward in the drawing) from the power reception coil Lr to the second power transmission coil Ltb. Specifically, in the present embodiment, the axial direction of the second auxiliary coil Lcb is not parallel to the opposing direction of the first and second power transmission coils Lta, Ltb and the power reception coil Lr. Therefore, the magnetic fluxes Bc1c and Bc1d generated by the second auxiliary coil Lcb circulate around a place away from the second auxiliary coil Lcb without interlinking with the power receiving coil Lr. In particular, in the present embodiment, since the axial direction of the second auxiliary coil Lcb is orthogonal to the opposing direction of the first and second power transmission coils Lta, Ltb and the power receiving coil Lr, the second auxiliary coil The magnetic fluxes Bc1c and Bc1d generated by Lcb largely circulate to a place away from the second auxiliary coil Lcb. Further, since the second auxiliary coil Lcb is disposed on the opposite side of the first and second power transmission coils Lta, Ltb from the side facing the power receiving coil Lr, the magnetic flux generated by the second auxiliary coil Lcb. Bc1c and Bc1d are linked to the second power transmission coil Ltb.

  Next, the effect of reducing unnecessary leakage magnetic fields in the present embodiment will be described. As described above, the first and second power transmission coils Lta and Ltb generate magnetic fluxes Bt1c and Bt1d that circulate around locations away from the first and second power transmission coils Lta and Ltb. The magnetic fluxes Bt1c and Bt1d have a very low magnetic flux density compared to the magnetic fluxes Bt1a and Bt1b that circulate in the vicinity of the first and second power transmission coils Lta and Ltb, but are not linked to the power receiving coil Lr. This is a magnetic flux that forms an unnecessary leakage magnetic field around the first and second power transmission coils Lta and Ltb. In the present embodiment, the circumferential directions of the magnetic fluxes Bc1a and Bc1b generated by the first auxiliary coil Lca and the magnetic fluxes Bc1c and Bc1d generated by the second auxiliary coil Lcb are both the first and second power transmission coils Lta and Ltb. The direction of rotation of the magnetic fluxes Bt1a to Bt1d generated by the Therefore, as shown in FIG. 3b, in the place away from the first and second power transmission coils Lta, Ltb, the direction of the magnetic fluxes Bt1c, Bt1d generated by the first and second power transmission coils Lta, Ltb and the first The directions of the magnetic fluxes Bc1a to Bc1d generated by the second auxiliary coils Lca and Lcb are opposite to each other. That is, the magnetic fluxes Bt1c and Bt1d generated by the first and second power transmission coils Lta and Ltb are separated from the first and second power transmission coils Lta and Ltb at the first and second auxiliary coils Lca and Lcb. Is canceled by the magnetic fluxes Bc1a to Bc1d generated. Here, since the magnetic field is indicated by the density of the magnetic flux, the magnetic fluxes Bt1c and Bt1d generated by the first and second power transmission coils Lta and Ltb that form an unnecessary leakage magnetic field are canceled, so that the magnetic fluxes Bt1c and Bt1d The magnetic flux density decreases, and as a result, unnecessary leakage magnetic fields are reduced.

  On the other hand, in the vicinity of the first power transmission coil Lta, the direction of the magnetic fluxes Bt1a and Bt1b generated by the first and second power transmission coils Lta and Ltb and the direction of the magnetic flux Bc1a and Bc1b generated by the first auxiliary coil Lca. Are in the same direction. That is, the magnetic field generated by the first auxiliary coil Lca strengthens a part of the magnetic field generated between the first power transmission coil Lta and the power reception coil Lr. As described above, between the first power transmission coil Lta and the power reception coil Lr, the direction of the magnetic fluxes Bt1a and Bt1b generated by the first power transmission coil Lta and the direction of the magnetic flux Bc1a and Bc1b generated by the first auxiliary coil Lca. Are almost in the same direction. Therefore, the magnetic fluxes Bt1a and Bt1b that contribute to the power transmission interlinking the first power transmission coil Lta and the power reception coil Lr are not canceled by the magnetic fluxes Bc1a and Bc1b generated by the first auxiliary coil Lca. As a result, a decrease in power transmission efficiency can be suppressed. Similarly, in the vicinity of the second power transmission coil Ltb, the direction of the magnetic fluxes Bt1a and Bt1b generated by the first and second power transmission coils Lta and Ltb and the direction of the magnetic flux Bc1c and Bc1d generated by the second auxiliary coil Lcb. Are in the same direction. That is, the magnetic field generated by the second auxiliary coil Lcb intensifies a part of the magnetic field generated between the second power transmission coil Ltb and the power reception coil Lr. Thus, between the second power transmission coil Ltb and the power reception coil Lr, the direction of the magnetic fluxes Bt1a and Bt1b generated by the second power transmission coil Ltb and the direction of the magnetic flux Bc1c and Bc1d generated by the second auxiliary coil Lcb. Are almost in the same direction. Therefore, the magnetic fluxes Bt1a and Bt1b contributing to the power transmission that links the second power transmission coil Ltb and the power reception coil Lr are not canceled by the magnetic fluxes Bc1c and Bc1d generated by the second auxiliary coil Lcb. As a result, a decrease in power transmission efficiency can be suppressed.

  As described above, in the power transmission coil unit Ltu1 according to the present embodiment, the magnetic fluxes Bc1a to Bc1d generated by the first and second auxiliary coils Lca and Lcb are generated by the first and second power transmission coils Lta and Ltb. Of the magnetic fluxes Bt1a to Bt1d, the magnetic fluxes Bt1a and Bt1d linked to the power receiving coil Lr are not canceled and a part of the magnetic flux not linked to the power receiving coil Lr (magnetic fluxes Bt1c and Bt1d) is canceled. Therefore, it is possible to suppress a decrease in power transmission efficiency while reducing an unnecessary leakage magnetic field formed in a place away from the first and second power transmission coils Lta and Ltb.

(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 system configuration diagram showing a wireless power transmission device according to the second embodiment of the present invention together with a load. FIG. 5 is a cross-sectional view showing a power transmission coil unit according to a second embodiment of the present invention together with a power receiving coil.

  As illustrated in FIG. 4, the wireless power transmission device S2 includes a wireless power transmission device Ut2 and a wireless power reception device Ur.

  The wireless power transmission device Ut2 includes a power source PW, an inverter INV, and a power transmission coil unit Ltu2. The configurations of the power source PW and the inverter INV are the same as those of the wireless power transmission device S1 according to the first embodiment. The present embodiment is different from the wireless power transmission device S1 according to the first embodiment in that a power transmission coil unit Ltu2 is provided instead of the power transmission coil unit Ltu1 of the wireless power transmission device S1 according to the first embodiment. . The wireless power receiving device Ur is the same as the wireless power receiving device Ur of the wireless power transmission device S1 according to the first embodiment. Hereinafter, a description will be given focusing on differences from the first embodiment.

  As shown in FIG. 4, the power transmission coil unit Ltu2 includes a first power transmission coil Lta, a second power transmission coil Ltb, a first auxiliary coil Lca, a second auxiliary coil Lcb, and an additional coil Lt2c. Have. As shown in FIG. 4, the first power transmission coil Lta, the second power transmission coil Ltb, the second auxiliary coil Lca, the second auxiliary coil Lcb, and the additional coil Lt2c are electrically connected in series. ing. The coil configurations of the first power transmission coil Lta, the second power transmission coil Ltb, the second auxiliary coil Lca, and the second auxiliary coil Lcb are the first power transmission coil Lta and the second coil configuration in the first embodiment. This is the same as the power transmission coil Ltb, the first auxiliary coil Lca, and the second auxiliary coil Lcb. The present embodiment is different from the power transmission coil unit Ltu1 according to the first embodiment in that an additional coil Lt2c is provided instead of the magnetic body F1 of the power transmission coil unit Ltu1 according to the first embodiment.

  As shown in FIG. 5, the additional coil Lt2c includes a magnetic core Ct2c and a winding Wt2c. The additional coil Lt2c is a solenoid coil that is spirally wound, and is formed by winding a winding Wt2c composed of a litz wire such as copper or aluminum around a plate-like magnetic core Ct2c. As shown in FIG. 5, the additional coil Lt2c is on the opposite side of the first and second power transmission coils Lta, Ltb from the side facing the power reception coil Lr, and is connected to the central portion of the first power transmission coil Lta. It arrange | positions so that the center part of a coil may be located between the center part of 2 power transmission coil Ltb. The magnetic core Ct2c of the additional coil Lt2c has a first power transmission in the vicinity of both ends of the power receiving coil Lr side surface (upper surface in the drawing) in the opposing direction of the first and second power transmitting coils Lta, Ltb and the power receiving coil Lr. The magnetic core Cta of the coil Lta and the magnetic core Ctb of the second power transmission coil Ltb are connected. In this case, the first and second power transmission coils Lta, Ltb and the additional coil Lt2c more efficiently generate a magnetic flux interlinking with the power receiving coil Lr described later, so that the power transmission efficiency is further improved. The number of turns of the additional coil Lt2c is set as appropriate based on the desired power transmission efficiency.

  The first power transmission coil Lta, the second power transmission coil Ltb, and the additional coil Lt2c are configured to form a magnetic path that links the coils Lta, Ltb, and Lt2c with magnetic fields generated from each other. That is, the first power transmission coil Lta, the second power transmission coil Ltb, and the additional coil Lt2c generate magnetic flux that circulates so as to link the coils Lta, Ltb, and Lt2c. Here, as described above, the first power transmission coil Lta and the second power transmission coil Ltb are configured such that the directions of the magnetic fields generated by both the coils Lta and Ltb are opposite to each other. That is, in FIG. 5, when the first power transmission coil Lta generates a magnetic flux interlinking in the direction (upward in the drawing) from the first power transmission coil Lta to the power reception coil Lr, the second power transmission coil Ltb A magnetic flux that links in a direction (downward in the drawing) from the coil Lr to the second power transmission coil Ltb is generated. Therefore, at this time, if the additional coil Lt2c generates a magnetic flux interlinking in the direction from the center of the second power transmission coil Ltb toward the center of the first power transmission coil Lta (leftward in the drawing), the additional coil Lt2c is interlinked with each coil. The magnetic flux circulates. Similarly, in FIG. 5, when the first power transmission coil Lta generates a magnetic flux interlinking in the direction (downward in the drawing) from the power reception coil Lr to the first power transmission coil Lta, the second power transmission coil Ltb Generates a magnetic flux interlinking in the direction (upward in the figure) from the second power transmission coil Ltb toward the power reception coil Lr. Accordingly, at this time, if the additional coil Lt2c generates a magnetic flux that links in the direction (rightward in the drawing) from the center of the first power transmission coil Lta to the center of the second power transmission coil Ltb, the additional coil Lt2c links the coils. The magnetic flux circulates. In order to make the additional coil Lt2c configured as described above, the portion of the winding Wt2c of the additional coil Lt2c that is closest to the winding Wta of the first power transmission coil Lta and the winding Wtb of the second power transmission coil Ltb (illustrated) The direction of the current passing through the winding Wt2c of the additional coil Lt2c is the portion of the winding Wta of the first power transmission coil Lta that is closest to the winding Wt2c of the additional coil Lt2c (of the first power transmission coil Lta in the drawing). The winding Wt2c of the additional coil Lt2c may be wound around the magnetic core Ct2c so that the direction of the current passing through the right side of the winding Wta is the same. The direction of the magnetic flux that circulates so as to link the first and second power transmission coils Lta and Ltb and the additional coil Lt2c is the direction of the magnetic flux generated by the “power transmission coil”.

  In the present embodiment, the power transmission coil unit Ltu2 includes the additional coil Lt2c in addition to the first power transmission coil Lta and the second power transmission coil Ltb, thereby efficiently generating magnetic flux contributing to power transmission. Therefore, the power transmission efficiency can be increased. In this case, not only the magnetic flux that contributes to power transmission but also more magnetic flux that forms an unnecessary leakage magnetic field may be generated, but by increasing the number of turns of the first and second auxiliary coils Lca and Lcb, By appropriately adjusting the magnetic flux generated by the first and second auxiliary coils Lca and Lcb, a desired leakage magnetic field reduction effect can be maintained. At this time, since the first and second auxiliary coils Lca and Lcb are not elements that consume electric energy, significant power loss occurs even if the number of turns of the first and second auxiliary coils Lca and Lcb is increased. Does not occur and no significant reduction in power transmission efficiency occurs. Specifically, the energy consumed by the first and second auxiliary coils Lca and Lcb is a joule generated by a slight resistance parasitic on the windings Wca and Wcb of the first and second auxiliary coils Lca and Lcb. Only heat.

  Further, as shown in FIG. 5, the magnetic core Ct2c of the additional coil Lt2c is a surface opposite to the surface on the power receiving coil Lr side in the facing direction of the first and second power transmitting coils Lta, Ltb and the power receiving coil Lr. Near both ends of the lower surface (shown in the figure), the magnetic core Cca of the first auxiliary coil Lca and the magnetic core Ccb of the second auxiliary coil Lcb are respectively connected. With such a configuration, the magnetic core Cca of the first auxiliary coil Lca and the magnetic core Ccb of the second auxiliary coil Lcb are respectively connected to the magnetic core of the first power transmission coil Lta via the magnetic core Ct2c of the additional coil Lt2c. Cta and the magnetic core Ctb of the second power transmission coil Ltb are connected. Therefore, the first auxiliary coil Lca easily generates a magnetic flux that strengthens the magnetic field generated between the first power transmission coil Lta and the power reception coil Lr, and the second auxiliary coil Lcb is connected to the second power transmission coil Ltb. Magnetic flux that strengthens the magnetic field generated between the power receiving coils Lr is easily generated. That is, between the first power transmission coil Lta and the power reception coil Lr, the direction of the magnetic flux generated by the first power transmission coil Lta and the direction of the magnetic flux generated by the first auxiliary coil Lca are substantially the same, Between the second power transmission coil Ltb and the power reception coil Lr, the direction of the magnetic flux generated by the second power transmission coil Ltb and the direction of the magnetic flux generated by the second auxiliary coil Lcb are substantially the same. Therefore, the magnetic flux that contributes to power transmission that links the first and second power transmission coils Lta, Ltb, the additional coil Lt2c, and the power reception coil Lr together is the magnetic flux generated by the first and second auxiliary coils Lca, Lcb. It is not offset. As a result, it is possible to further suppress a decrease in power transmission efficiency.

  Further, as shown in FIG. 5, the axes of the first and second auxiliary coils Lca and Lcb do not coincide with the axis of the additional coil Lt2c. Here, since the direction of the magnetic flux interlinking the first auxiliary coil Lca and the direction of the magnetic flux interlinking the additional coil Lt2c are opposite to each other, the magnetic flux generated by the first auxiliary coil Lca is applied to the additional coil Lt2c. When linked, there is a risk of canceling out the magnetic flux contributing to power transmission. In the present embodiment, since the axis of the first auxiliary coil Lca does not coincide with the axis of the additional coil Lt2c, the magnetic flux generated by the first auxiliary coil Lca is difficult to interlink with the additional coil Lt2c. As a result, the magnetic flux contributing to the power transmission that links the first and second power transmission coils Lta, Ltb, the additional coil Lt2c, and the power receiving coil Lr together is not offset by the magnetic flux generated by the first auxiliary coil Lca. Similarly, since the direction of the magnetic flux interlinking the second auxiliary coil Lcb and the direction of the magnetic flux interlinking the additional coil Lt2c are opposite to each other, the magnetic flux generated by the second auxiliary coil Lcb is added to the additional coil Lt2c. If they are interlinked, there is a risk of canceling out the magnetic flux contributing to the power transmission. In the present embodiment, since the axis of the second auxiliary coil Lcb does not coincide with the axis of the additional coil Lt2c, the magnetic flux generated by the second auxiliary coil Lcb is difficult to interlink with the additional coil Lt2c. As a result, the magnetic flux that contributes to power transmission that links the first and second power transmission coils Lta, Ltb, the additional coil Lt2c, and the power receiving coil Lr together is not offset by the magnetic flux generated by the second auxiliary coil Lcb. Therefore, it is possible to further suppress a decrease in power transmission efficiency.

  Next, with reference to FIG. 6, the relative relationship between the magnetic flux generated by the power transmission coil, the magnetic flux generated by the additional coil, and the magnetic flux generated by the auxiliary coil and the action of reducing unnecessary leakage magnetic fields in this embodiment will be described in detail. explain. FIG. 6a is a diagram schematically showing the magnetic flux generated by the first and second power transmission coils and the additional coil in FIG. FIG. 6b is a diagram schematically showing the magnetic flux generated by the first and second power transmission coils and the first and second auxiliary coils in FIG. Here, in FIG. 6 a, magnetic fluxes Bt <b> 2 a to Bt <b> 2 d are shown as body surface out of the magnetic fluxes generated by the first and second power transmission coils Lta, Ltb and the additional coil Lt <b> 2 c. Also, in FIG. 6b, magnetic fluxes Bt2a to Bt2d are shown as body surfaces out of the magnetic fluxes generated by the first and second power transmission coils Lta, Ltb and the additional coil Lt2c, and the first and second auxiliary coils Lca are shown. , Lcb schematically shows magnetic fluxes Bc2a to Bc2d as representative ones. However, these magnetic fluxes schematically show only the direction of each magnetic flux, and do not show the magnetic flux density. 6a and 6b, the magnetic cores Cta and Ctb of the first and second power transmission coils Lta and Ltb, the magnetic core Ct2c of the additional coil Lt2c, and the magnetic properties of the first and second auxiliary coils Lca and Lcb. Illustration of magnetic flux in the cores Cca and Ccb and the magnetic core Cr of the power receiving coil Lr is omitted.

  First, the magnetic flux generated by the first and second power transmission coils Lta, Ltb and the additional coil Lt2c will be described with reference to FIG. 6a. As shown in FIG. 6a, the first and second power transmission coils Lta, Ltb and the additional coil Lt2c are arranged in a direction (upward in the drawing) from the first power transmission coil Lta toward the power reception coil Lr. And the second power transmission coil Ltb is linked in the direction from the power receiving coil Lr to the second power transmission coil Ltb (downward in the drawing), and the additional coil Lt2c is coupled to the second power transmission coil Ltb. Magnetic fluxes Bt2a to Bt2d that are linked in the direction from the center toward the center of the first power transmission coil Lta (leftward in the figure) are generated. That is, the first and second power transmission coils Lta and Ltb and the additional coil Lt2c generate magnetic fluxes Bt2a to Bt2d that circulate in the same direction. In this example, the magnetic fluxes Bt2a to Bt2d generated by the first and second power transmission coils Lta and Ltb and the additional coil Lt2c are linked to the power receiving coil Lr, and the magnetic fluxes Bt2a and Bt2b contributing to power transmission are received. There are magnetic fluxes Bt2c and Bt2d that circulate around locations away from the first and second power transmission coils Lta and Ltb without interlinking with Lr, and the magnetic fluxes Bt2a and Bt2b interlink with the power reception coil Lr so that the power reception coil An electromotive force is generated in the winding Wr of Lr. The electric power generated in the power receiving coil Lr is rectified by the rectifier circuit DB and output to the load R. Here, in the present embodiment, a magnetic path that links the coils Lta, Ltb, and Lt2c is formed by the magnetic fields generated by the first power transmission coil Lta, the second power transmission coil Ltb, and the additional coil Lt2c. Therefore, the magnetic fluxes Bt2a and Bt2b can be generated more efficiently. As a result, the coupling between the first and second power transmission coils Lta, Ltb, the additional coil Lt2c, and the power reception coil Lr becomes higher, and the power transmission efficiency becomes higher. The magnetic fluxes Bt2a to Bt2d generated by the first and second power transmission coils Lta and Ltb and the additional coil Lt2c are not linked to the first and second auxiliary coils Lca and Lcb, and contribute to power transmission. Since the magnetic fluxes Bt2a and Bt2b to be performed are not canceled by the first and second auxiliary coils Lca and Lcb, it is possible to suppress a decrease in power transmission efficiency.

  Subsequently, the magnetic flux generated by the first and second auxiliary coils Lca and Lcb will be described with reference to FIG. The magnetic fluxes Bt2a to Bt2d generated by the first and second power transmission coils Lta, Ltb and the additional coil Lt2c in FIG. 6b are as shown in FIG. 6a. As shown in FIG. 6b, the first auxiliary coil Lca links the first auxiliary coil Lca in a direction (rightward in the drawing) from the first auxiliary coil Lca toward the center of the first power transmission coil Lta. In addition, the first power transmission coil Lta generates magnetic fluxes Bc2a and Bc2b that are linked in a direction (upward in the drawing) from the first power transmission coil Lta toward the power reception coil Lr. Specifically, in the present embodiment, the axial direction of the first auxiliary coil Lca is not parallel to the opposing direction of the first and second power transmission coils Lta, Ltb and the power reception coil Lr. Therefore, the magnetic fluxes Bc2a and Bc2b generated by the first auxiliary coil Lca circulate around a place away from the first auxiliary coil Lca without interlinking with the power receiving coil Lr. In particular, in this embodiment, since the axial direction of the first auxiliary coil Lca is orthogonal to the opposing direction of the first and second power transmission coils Lta, Ltb and the power receiving coil Lr, the first auxiliary coil The magnetic fluxes Bc2a and Bc2b generated by Lca circulate greatly to a place away from the first auxiliary coil Lca. Further, since the first auxiliary coil Lca is arranged on the opposite side of the first and second power transmission coils Lta, Ltb from the side facing the power receiving coil Lr, the magnetic flux generated by the first auxiliary coil Lca. Bc2a and Bc12 are linked to the first power transmission coil Lta. Further, since the axis of the first auxiliary coil Lca does not coincide with the axis of the additional coil Lt2c, the magnetic fluxes Bc2a and Bc2b generated by the first auxiliary coil Lca are not linked to the additional coil Lt2c.

  Similarly, as shown in FIG. 6B, the second auxiliary coil Lcb moves the second auxiliary coil Lcb from the center of the second power transmission coil Ltb toward the second auxiliary coil Lcb (rightward in the drawing). And the second power transmission coil Ltb generates magnetic fluxes Bc2c and Bc2d that link in the direction (downward in the drawing) from the power reception coil Lr to the second power transmission coil Ltb. Specifically, in the present embodiment, the axial direction of the second auxiliary coil Lcb is not parallel to the opposing direction of the first and second power transmission coils Lta, Ltb and the power reception coil Lr. Therefore, the magnetic fluxes Bc2c and Bc2d generated by the second auxiliary coil Lcb circulate around a place away from the second auxiliary coil Lcb without interlinking with the power receiving coil Lr. In particular, in the present embodiment, since the axial direction of the second auxiliary coil Lcb is orthogonal to the opposing direction of the first and second power transmission coils Lta, Ltb and the power receiving coil Lr, the second auxiliary coil Magnetic fluxes Bc2c and Bc2d generated by Lcb circulate greatly to a place away from the second auxiliary coil Lcb. Further, since the second auxiliary coil Lcb is disposed on the opposite side of the first and second power transmission coils Lta, Ltb from the side facing the power receiving coil Lr, the magnetic flux generated by the second auxiliary coil Lcb. Bc2c and Bc2d are linked to the second power transmission coil Ltb. Furthermore, since the axis of the second auxiliary coil Lcb does not coincide with the axis of the additional coil Lt2c, the magnetic fluxes Bc2c and Bc2d generated by the second auxiliary coil Lcb do not interlink with the additional coil Lt2c.

  Next, the effect of reducing unnecessary leakage magnetic fields in the present embodiment will be described. As described above, the first and second power transmission coils Lta and Ltb and the additional coil Lt2c generate magnetic fluxes Bt2c and Bt2d that circulate around locations away from the first and second power transmission coils Lta and Ltb. The magnetic fluxes Bt2c and Bt2d are much lower in magnetic flux density than the magnetic fluxes Bt2a and Bt2b that circulate in the vicinity of the first and second power transmission coils Lta and Ltb, but are not linked to the power receiving coil Lr. This is a magnetic flux that forms an unnecessary leakage magnetic field around the first and second power transmission coils Lta and Ltb. In the present embodiment, the circulation directions of the magnetic fluxes Bc2a and Bc2b generated by the first auxiliary coil Lca and the magnetic fluxes Bc2c and Bc2d generated by the second auxiliary coil Lcb are both the first and second power transmission coils Lta and Ltb. The direction of rotation of the magnetic fluxes Bt2a to Bt2d generated by the additional coil Lt2c is opposite. Accordingly, as shown in FIG. 6b, the magnetic fluxes Bt2c and Bt2d generated by the first and second power transmission coils Lta and Ltb and the additional coil Lt2c are separated from the first and second power transmission coils Lta and Ltb. The direction and the directions of the magnetic fluxes Bc2a to Bc2d generated by the first and second auxiliary coils Lca and Lcb are opposite to each other. That is, the magnetic fluxes Bt2c and Bt2d generated by the first and second power transmission coils Lta and Ltb and the additional coil Lt2c are separated from the first and second power transmission coils Lta and Ltb by the first and second auxiliary coils. The magnetic fluxes Bc2a to Bc2d generated by the coils Lca and Lcb are canceled out. As a result, an unnecessary leakage magnetic field is reduced.

  On the other hand, in the vicinity of the first power transmission coil Lta, the direction of the magnetic fluxes Bt2a and Bt2b generated by the first and second power transmission coils Lta and Ltb and the direction of the magnetic flux Bc2a and Bc2b generated by the first auxiliary coil Lca. Are in the same direction. That is, the magnetic field generated by the first auxiliary coil Lca strengthens a part of the magnetic field generated between the first power transmission coil Lta and the power reception coil Lr. As described above, between the first power transmission coil Lta and the power reception coil Lr, the direction of the magnetic fluxes Bt2a and Bt2b generated by the first power transmission coil Lta and the direction of the magnetic flux Bc2a and Bc2b generated by the first auxiliary coil Lca. Are almost in the same direction. Therefore, the magnetic fluxes Bt2a and Bt2b that contribute to power transmission that links the first power transmission coil Lta and the power reception coil Lr are not canceled by the magnetic fluxes Bc2a and Bc2b generated by the first auxiliary coil Lca. As a result, a decrease in power transmission efficiency can be suppressed. Similarly, in the vicinity of the second power transmission coil Ltb, the direction of the magnetic fluxes Bt2a and Bt2b generated by the first and second power transmission coils Lta and Ltb and the direction of the magnetic flux Bc2c and Bc2d generated by the second auxiliary coil Lcb. Are in the same direction. That is, the magnetic field generated by the second auxiliary coil Lcb intensifies a part of the magnetic field generated between the second power transmission coil Ltb and the power reception coil Lr. As described above, between the second power transmission coil Ltb and the power reception coil Lr, the direction of the magnetic fluxes Bt2a and Bt2b generated by the second power transmission coil Ltb and the direction of the magnetic flux Bc2c and Bc2d generated by the second auxiliary coil Lcb. Are almost in the same direction. Therefore, the magnetic fluxes Bt2a and Bt2b that contribute to power transmission that links the second power transmission coil Ltb and the power reception coil Lr are not canceled by the magnetic fluxes Bc2c and Bc2d generated by the second auxiliary coil Lcb. As a result, a decrease in power transmission efficiency can be suppressed.

  As described above, in the power transmission coil unit Ltu2 according to the present embodiment, the magnetic fluxes Bc2a to Bt2d generated by the first and second auxiliary coils Lca and Lcb are generated by the first and second power transmission coils Lta and Ltb. Of the magnetic fluxes Bt2a to Bc2d, the magnetic fluxes Bt2a and Bt2d linked to the power receiving coil Lr are not canceled and a part of the magnetic fluxes not linked to the power receiving coil Lr (magnetic fluxes Bt2c and Bt2d) are canceled. Therefore, it is possible to suppress a decrease in power transmission efficiency while reducing an unnecessary leakage magnetic field formed in a place away from the first and second power transmission coils Lta and Ltb.

  Furthermore, the power transmission coil unit Ltu2 according to the present embodiment is on the opposite side of the first and second power transmission coils Lta, Ltb from the side facing the power reception coil Lr, and the center of the first power transmission coil Lta. An additional coil Lt2c is disposed between the center of the second power transmission coil Ltb and the center of the coil. The first power transmission coil Lta, the second power transmission coil Ltb, and the additional coil Lt2c are generated from each other. A magnetic path that links the coils is formed by the magnetic field to be generated. Therefore, the density of the magnetic fluxes Bt2a to Bt2d generated by the first and second power transmission coils Lta and Ltb can be further increased. Therefore, since the magnetic fluxes Bt2a and Bt2b contributing to power transmission are generated more efficiently, the power transmission efficiency can be further increased.

(Third embodiment)
Next, the configuration of the wireless power transmission device S3 according to the third embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a system configuration diagram showing the wireless power transmission device according to the third embodiment of the present invention together with a load. FIG. 8 is a cross-sectional view showing a power transmission coil unit according to a third embodiment of the present invention together with a power reception coil.

  As illustrated in FIG. 7, the wireless power transmission device S3 includes a wireless power transmission device Ut3 and a wireless power reception device Ur.

  The wireless power transmission device Ut3 includes a power source PW, an inverter INV, and a power transmission coil unit Ltu3. The configurations of the power source PW and the inverter INV are the same as those of the wireless power transmission device S1 according to the first embodiment. The present embodiment is different from the wireless power transmission device S1 according to the first embodiment in that a power transmission coil unit Ltu3 is provided instead of the power transmission coil unit Ltu1 of the wireless power transmission device S1 according to the first embodiment. . The wireless power receiving device Ur is the same as the wireless power receiving device Ur of the wireless power transmission device S1 according to the first embodiment. Hereinafter, a description will be given focusing on differences from the first embodiment.

  As shown in FIG. 7, the power transmission coil unit Ltu3 includes a power transmission coil Lt3, a first auxiliary coil Lc3a, and a second auxiliary coil Lc3b. In the present embodiment, the power transmission coil Lt3 and the three coils of the first and second auxiliary coils Lc3a and Lc3b are electrically connected in series as shown in FIG.

  As shown in FIG. 8, the power transmission coil Lt3 includes a magnetic core Ct3 and a winding Wt3. The power transmission coil Lt3 is a solenoid coil wound spirally, and is formed by winding a winding Wt3 made of litz wire such as copper or aluminum around a plate-like or rod-like magnetic core Ct3. The axial direction of the power transmission coil Lt3 is orthogonal to the facing direction of the power transmission coil Lt3 and the power reception coil Lr. The number of turns of the power transmission coil Lt3 is appropriately set based on the distance from the power reception coil Lr, the desired power transmission efficiency, and the like.

  The first auxiliary coil Lc3a includes a magnetic core Cc3a and a winding Wc3a. The first auxiliary coil Lc3a is a solenoid coil wound in a spiral shape, and is formed by winding a winding Wc3a composed of a litz wire such as copper or aluminum around a plate-like or rod-like magnetic core Cc3a. Yes. The axial direction of the first auxiliary coil Lc3a is not parallel to the opposing direction of the power transmission coil Lt3 and the power reception coil Lr. With such a configuration, the magnetic flux generated by the first auxiliary coil Lc3a can easily circulate to a place away from the first auxiliary coil Lc3a without interlinking with the power receiving coil Lr. In the present embodiment, the axial direction of the first auxiliary coil Lc3a is orthogonal to the opposing direction of the power transmission coil Lt3 and the power receiving coil Lr, and the axial direction of the first auxiliary coil Lc3a is the power transmission coil Lt3. It is parallel to the axial direction. In this case, the first auxiliary coil Lc3a can more easily generate a magnetic flux that circulates to a place away from the first auxiliary coil Lc3a.

  In addition, the first auxiliary coil Lc3a is arranged so as not to interlink with the magnetic flux interlinked with the power receiving coil Lr that faces the power transmitting coil Lt3 when transmitting electric power, among the magnetic flux generated by the power transmitting coil Lt3. Has been. That is, since the magnetic flux that contributes to power transmission is not canceled by the first auxiliary coil Lc3a, it is possible to suppress a decrease in power transmission efficiency. In the present embodiment, as shown in FIG. 8, the first auxiliary coil Lc3a is disposed on the opposite side of the power transmission coil Lt3 from the side facing the power reception coil Lr. With this arrangement, the first auxiliary coil Lc3a can easily generate a magnetic flux that strengthens the magnetic field generated between the power transmission coil Lt3 and the power reception coil Lr. That is, between the power transmission coil Lt3 and the power reception coil Lr, the direction of the magnetic flux generated by the power transmission coil Lt3 and the direction of the magnetic flux generated by the first auxiliary coil Lc3a are substantially the same. Therefore, the magnetic flux that contributes to power transmission that links the power transmission coil Lt3 and the power reception coil Lr together is not offset by the magnetic flux generated by the first auxiliary coil Lc3a. As a result, it is possible to further suppress a decrease in power transmission efficiency.

  Furthermore, the direction of the magnetic flux generated by the first auxiliary coil Lc3a is opposite to the direction of the magnetic flux generated by the power transmission coil Lt3. Here, since the axial direction of the first auxiliary coil Lc3a in this embodiment is parallel to the axial direction of the power transmission coil Lt3, the power transmission coil Lt3 generates the circulation direction of the magnetic flux generated by the first auxiliary coil Lc3a. In order to make the direction opposite to the direction in which the magnetic flux circulates, the direction of the magnetic field generated by the first auxiliary coil Lc3a and the direction of the magnetic field generated by the power transmission coil Lt3 may be opposite to each other. That is, when the winding directions of the first auxiliary coil Lc3a and the power transmission coil Lt3 are the same, the direction of the current flowing through the first auxiliary coil Lc3a and the direction of the current flowing through the power transmission coil Lt3 are opposite to each other. In addition, the first auxiliary coil Lc3a and the power transmission coil Lt3 may be electrically connected. Alternatively, when the winding directions of the first auxiliary coil Lc3a and the power transmission coil Lt3 are opposite to each other, the direction of the current flowing through the first auxiliary coil Lc3a is the same as the direction of the current flowing through the power transmission coil Lt3. Thus, what is necessary is just to electrically connect 1st auxiliary | assistant coil Lc3a and power transmission coil Lt3. Further, the axis of the first auxiliary coil Lc3a does not coincide with the axis of the power transmission coil Lt3. Here, since the direction of the magnetic flux interlinking the first auxiliary coil Lc3a and the direction of the magnetic flux interlinking the power transmission coil Lt3 are opposite to each other, the magnetic flux generated by the first auxiliary coil Lc3a is transmitted to the power transmission coil Lt3. When linked, there is a risk of canceling out the magnetic flux contributing to power transmission. In the present embodiment, since the axis of the first auxiliary coil Lc3a does not coincide with the axis of the power transmission coil Lt3, the magnetic flux generated by the first auxiliary coil Lc3a is difficult to interlink with the power transmission coil Lt3. As a result, the magnetic flux contributing to the power transmission that links the power transmission coil Lt3 and the power receiving coil Lr together is not offset by the magnetic flux generated by the first auxiliary coil Lc3a. Therefore, it is possible to further suppress a decrease in power transmission efficiency.

  The second auxiliary coil Lc3b includes a magnetic core Cc3b and a winding Wc3b. The second auxiliary coil Lc3b is a solenoid coil wound spirally, and is formed by winding a winding Wc3b composed of a litz wire such as copper or aluminum around a plate-like or rod-like magnetic core Cc3b. Yes. The axial direction of the second auxiliary coil Lc3b is not parallel to the opposing direction of the power transmission coil Lt3 and the power reception coil Lr. With such a configuration, the magnetic flux generated by the second auxiliary coil Lc3b can easily circulate to a place away from the second auxiliary coil Lc3b without interlinking with the power receiving coil Lr. In the present embodiment, the axial direction of the second auxiliary coil Lc3b is orthogonal to the facing direction of the power transmission coil Lt3 and the power receiving coil Lr, and the axial direction of the first auxiliary coil Lc3b is the power transmission coil Lt3. It is parallel to the axial direction. In this case, the second auxiliary coil Lc3b makes it easier to generate a magnetic flux that circulates to a place away from the second auxiliary coil Lc3b.

  In addition, the second auxiliary coil Lc3b is arranged so as not to interlink with the magnetic flux interlinked with the power receiving coil Lr that faces the power transmitting coil Lt3 when power is transmitted among the magnetic flux generated by the power transmitting coil Lt3. Has been. That is, since the magnetic flux that contributes to power transmission is not offset by the second auxiliary coil Lc3b, it is possible to suppress a decrease in power transmission efficiency. In the present embodiment, as shown in FIG. 8, the second auxiliary coil Lc3b is arranged on the opposite side of the power transmission coil Lt3 from the side facing the power reception coil Lr. With such an arrangement, the second auxiliary coil Lc3b can easily generate a magnetic flux that strengthens the magnetic field generated between the power transmission coil Lt3 and the power reception coil Lr. That is, between the power transmission coil Lt3 and the power reception coil Lr, the direction of the magnetic flux generated by the power transmission coil Lt3 is substantially the same as the direction of the magnetic flux generated by the second auxiliary coil Lc3b. Therefore, the magnetic flux that contributes to power transmission that links the power transmission coil Lt3 and the power reception coil Lr together is not offset by the magnetic flux generated by the second auxiliary coil Lc3b. As a result, it is possible to further suppress a decrease in power transmission efficiency.

  Furthermore, the circulation direction of the magnetic flux generated by the second auxiliary coil Lc3b is opposite to the rotation direction of the magnetic flux generated by the power transmission coil Lt3. Here, since the axial direction of the second auxiliary coil Lc3b in this embodiment is parallel to the axial direction of the power transmission coil Lt3, the power transmission coil Lt3 generates the circulation direction of the magnetic flux generated by the second auxiliary coil Lc3b. In order to make the direction opposite to the direction in which the magnetic flux rotates, the direction of the magnetic field generated by the second auxiliary coil Lc3b and the direction of the magnetic field generated by the power transmission coil Lt3 may be opposite to each other. That is, when the winding directions of the second auxiliary coil Lc3b and the power transmission coil Lt3 are the same, the direction of the current flowing through the second auxiliary coil Lc3b and the direction of the current flowing through the power transmission coil Lt3 are opposite to each other. In addition, the second auxiliary coil Lc3b and the power transmission coil Lt3 may be electrically connected. Alternatively, when the winding directions of the second auxiliary coil Lc3b and the power transmission coil Lt3 are opposite to each other, the direction of the current flowing through the second auxiliary coil Lc3b is the same as the direction of the current flowing through the power transmission coil Lt3. Thus, what is necessary is just to electrically connect 2nd auxiliary | assistant coil Lc3b and power transmission coil Lt3. Further, the axis of the second auxiliary coil Lc3b does not coincide with the axis of the power transmission coil Lt3. Here, since the direction of the magnetic flux interlinking the second auxiliary coil Lc3b and the direction of the magnetic flux interlinking the power transmission coil Lt3 are opposite to each other, the magnetic flux generated by the second auxiliary coil Lc3b is transmitted to the power transmission coil Lt3. When linked, there is a risk of canceling out the magnetic flux contributing to power transmission. In the present embodiment, since the axis of the second auxiliary coil Lc3b does not coincide with the axis of the power transmission coil Lt3, the magnetic flux generated by the second auxiliary coil Lc3b is difficult to interlink with the power transmission coil Lt3. As a result, the magnetic flux contributing to the power transmission that links the power transmission coil Lt3 and the power receiving coil Lr together is not offset by the magnetic flux generated by the second auxiliary coil Lc3b. Therefore, it is possible to further suppress a decrease in power transmission efficiency.

  Further, as shown in FIG. 8, the magnetic core Ct3 of the power transmission coil Lt3 is near both ends of a surface (the lower surface in the drawing) opposite to the surface on the power reception coil Lr side in the facing direction of the power transmission coil Lt3 and the power reception coil Lr. Are respectively connected to the magnetic core Cc3a of the first auxiliary coil Lc3a and the magnetic core Cc3b of the second auxiliary coil Lc3b. With such a configuration, the magnetic core Cc3a of the first auxiliary coil Lc3a and the magnetic core Cc3b of the second auxiliary coil Lc3b are coupled to the magnetic core Ct3 of the power transmission coil Lt3, respectively. Therefore, the first auxiliary coil Lc3a is likely to generate a magnetic flux that strengthens the magnetic field generated between the power transmission coil Lt3 and the power receiving coil Lr, and the second auxiliary coil Lc3b is between the power transmission coil Lt3 and the power receiving coil Lr. Magnetic flux that enhances the generated magnetic field is easily generated. That is, between the power transmission coil Lt3 and the power reception coil Lr, the direction of the magnetic flux generated by the power transmission coil Lt3 is substantially the same as the direction of the magnetic flux generated by the first auxiliary coil Lc3a, and the power transmission coil Lt3 is generated. The direction of the magnetic flux and the direction of the magnetic flux generated by the second auxiliary coil Lc3b are substantially the same. Therefore, the magnetic flux that contributes to power transmission that links the power transmission coil Lt3 and the power reception coil Lr together is not offset by the magnetic flux generated by the first and second auxiliary coils Lc3a and Lc3b. As a result, it is possible to further suppress a decrease in power transmission efficiency.

  Next, with reference to FIG. 9, the relative relationship between the magnetic flux generated by the power transmission coil and the magnetic flux generated by the auxiliary coil and the effect of reducing unnecessary leakage magnetic fields will be described in detail. FIG. 9 a is a diagram schematically showing the magnetic flux generated by the power transmission coil in FIG. 8. FIG. 9b is a diagram schematically showing the magnetic flux generated by the power transmission coil and the first and second auxiliary coils in FIG. Here, in FIG. 9 a, magnetic fluxes Bt <b> 3 a to Bt <b> 3 d are shown as body surfaces out of the magnetic fluxes generated by the power transmission coil Lt <b> 3. Moreover, in FIG. 9b, magnetic fluxes Bt3a to Bt3d are shown as body surface out of magnetic fluxes generated by the power transmission coil Lt3, and typical magnetic fluxes generated by the first and second auxiliary coils Lc3a and Lc3b are shown. As a thing, magnetic flux Bc3a-Bc3d is shown typically. However, these magnetic fluxes schematically show only the direction of each magnetic flux, and do not show the magnetic flux density. 9a and 9b, the magnetic core Ct3 of the power transmission coil Lt3, the magnetic cores Cc3a and Cc3b of the first and second auxiliary coils Lc3a and Lc3b, and the magnetic flux in the magnetic core Cr of the power reception coil Lr are illustrated. Is omitted.

  First, the magnetic flux generated by the power transmission coil Lt3 will be described with reference to FIG. 9a. 9a, the power transmission coil Lt3 generates magnetic fluxes Bt3a to Bt3d that link the power transmission coil Lt3 in the direction from the second auxiliary coil Lc3b toward the first auxiliary coil Lc3a (leftward in the drawing). Yes. In this example, the magnetic fluxes Bt3a to Bt3d generated by the power transmission coil Lt3 are linked to the power receiving coil Lr, and the magnetic fluxes Bt3a and Bt3b contributing to power transmission from the power transmission coil Lt3 without being linked to the power receiving coil Lr. There are magnetic fluxes Bt3c and Bt3d that circulate in remote places, and the magnetic fluxes Bt3a and Bt3b are linked to the power receiving coil Lr, so that an electromotive force is generated in the winding Wr of the power receiving coil Lr. The electric power generated in the power receiving coil Lr is rectified by the rectifier circuit DB and output to the load R. Note that the magnetic fluxes Bt3a to Bt3d generated by the power transmission coil Lt3 are not linked to the first and second auxiliary coils Lc3a and Lc3b, and the magnetic fluxes Bt3a and Bt3b contributing to power transmission are the first and second magnetic fluxes. Since the auxiliary coils Lc3a and Lc3b are not canceled out, it is possible to suppress a decrease in power transmission efficiency.

  Subsequently, the magnetic flux generated by the first and second auxiliary coils Lc3a and Lc3b will be described with reference to FIG. 9b. The magnetic fluxes Bt3a to Bt3d generated by the power transmission coil Lt3 in FIG. 9b are as shown in FIG. 9a. As shown in FIG. 9b, the first auxiliary coil Lc3a links the first auxiliary coil Lc3a in a direction (rightward in the drawing) from the first auxiliary coil Lc3a toward the center of the power transmission coil Lt3, and The magnetic fluxes Bc3a and Bc3b that circulate in a direction (upward in the drawing) from the power transmission coil Lt3 to the power reception coil Lr are generated without interlinking with the power transmission coil Lt3. Specifically, in the present embodiment, since the axial direction of the first auxiliary coil Lc3a is not parallel to the opposing direction of the power transmission coil Lt3 and the power reception coil Lr, the first auxiliary coil Lc3a The magnetic fluxes Bc3a and Bc3b generated by circulate around a place away from the first auxiliary coil Lc3a without interlinking with the power receiving coil Lr. In particular, in the present embodiment, since the axial direction of the first auxiliary coil Lc3a is orthogonal to the facing direction of the power transmission coil Lt3 and the power receiving coil Lr, the magnetic fluxes Bc3a and Bc3b generated by the first auxiliary coil Lc3a. Circulates greatly up to a place away from the first auxiliary coil Lc3a. Further, since the axis of the first auxiliary coil Lc3a does not coincide with the axis of the power transmission coil Lt3, the magnetic fluxes Bc3a and Bc3b generated by the first auxiliary coil Lc3a are not linked to the power transmission coil Lt3.

  Similarly, as shown in FIG. 9b, the second auxiliary coil Lc3b is linked to the second auxiliary coil Lc3b in a direction (rightward in the drawing) from the center of the power transmission coil Lt3 toward the second auxiliary coil Lc3b. In addition, magnetic fluxes Bc3c and Bc3d that circulate in a direction (downward in the drawing) from the power receiving coil Lr to the power transmitting coil Lt3 are generated without interlinking with the power transmitting coil Lt3. Specifically, in the present embodiment, since the axial direction of the second auxiliary coil Lc3b is not parallel to the opposing direction of the power transmission coil Lt3 and the power reception coil Lr, the second auxiliary coil Lc3b The magnetic fluxes Bc3c and Bc3d generated by both circulate around a place away from the second auxiliary coil Lc3b without interlinking with the power receiving coil Lr. In particular, in the present embodiment, since the axial direction of the second auxiliary coil Lc3b is orthogonal to the facing direction of the power transmission coil Lt3 and the power receiving coil Lr, the magnetic fluxes Bc3c and Bc3d generated by the second auxiliary coil Lc3b. Circulates greatly up to a place away from the second auxiliary coil Lc3b. Further, since the axis of the second auxiliary coil Lc3b does not coincide with the axis of the power transmission coil Lt3, the magnetic fluxes Bc3c and Bc3d generated by the second auxiliary coil Lc3b do not interlink with the power transmission coil Lt3.

  Next, the effect of reducing unnecessary leakage magnetic fields in the present embodiment will be described. As described above, the power transmission coil Lt3 generates magnetic fluxes Bt3c and Bt3d that circulate around a place away from the power transmission coil Lt3. The magnetic fluxes Bt3c and Bt3d do not contribute to power transmission, and become magnetic fluxes that form an unnecessary leakage magnetic field around the power transmission coil Lt3. In the present embodiment, the magnetic fluxes Bc3a and Bc3b generated by the first auxiliary coil Lc3a and the magnetic fluxes Bc3c and Bc3d generated by the second auxiliary coil Lc3b are all the magnetic fluxes Bt3a to Bt3d generated by the power transmission coil Lt3. The direction is the opposite of the lap direction. Therefore, as shown in FIG. 9b, in a place away from the power transmission coil Lt3, the direction of the magnetic fluxes Bt3c and Bt3d generated by the power transmission coil Lt3 and the magnetic fluxes Bc3a to Bc3d generated by the first and second auxiliary coils Lc3a and Lc3b. The directions are opposite to each other. That is, the magnetic fluxes Bt3c and Bt3d generated by the power transmission coil Lt3 are offset by the magnetic fluxes Bc3a to Bc3d generated by the first and second auxiliary coils Lc3a and Lc3b at a location away from the power transmission coil Lt3. As a result, an unnecessary leakage magnetic field is reduced.

  On the other hand, in the vicinity of the power transmission coil Lt3, the directions of the magnetic fluxes Bt3a and Bt3b generated by the power transmission coil Lt3 and the directions of the magnetic fluxes Bc3a and Bc3b generated by the first auxiliary coil Lc3a are substantially the same. That is, the magnetic field generated by the first auxiliary coil Lc3a intensifies a part of the magnetic field generated between the power transmission coil Lt3 and the power reception coil Lr. Thus, between the power transmission coil Lt3 and the power reception coil Lr, the directions of the magnetic fluxes Bt3a and Bt3b generated by the power transmission coil Lt3 and the directions of the magnetic fluxes Bc3a and Bc3b generated by the first auxiliary coil Lc3a are substantially the same. . Therefore, the magnetic fluxes Bt3a and Bt3b that contribute to the power transmission that links the power transmission coil Lt3 and the power reception coil Lr are not canceled by the magnetic fluxes Bc3a and Bc3b generated by the first auxiliary coil Lc3a. As a result, a decrease in power transmission efficiency can be suppressed. Similarly, in the vicinity of the power transmission coil Lt3, the directions of the magnetic fluxes Bt3a and Bt3b generated by the power transmission coil Lt3 and the directions of the magnetic fluxes Bc3c and Bc3d generated by the second auxiliary coil Lc3b are substantially the same. That is, the magnetic field generated by the second auxiliary coil Lc3b intensifies a part of the magnetic field generated between the power transmission coil Lt3 and the power reception coil Lr. Thus, between the power transmission coil Lt3 and the power reception coil Lr, the directions of the magnetic fluxes Bt3a and Bt3b generated by the power transmission coil Lt3 and the directions of the magnetic fluxes Bc3c and Bc3d generated by the second auxiliary coil Lc3b are substantially the same. . Therefore, the magnetic fluxes Bt3a and Bt3b contributing to the power transmission that links the power transmission coil Lt3 and the power reception coil Lr are not canceled by the magnetic fluxes Bc3c and Bc3d generated by the second auxiliary coil Lc3b. As a result, a decrease in power transmission efficiency can be suppressed.

  As described above, in the power transmission coil unit Ltu3 according to the present embodiment, the magnetic fluxes Bc3a to Bc3d generated by the first and second auxiliary coils Lc3a and Lc3b are received from the magnetic fluxes Bt3a to Bt3d generated by the power transmission coil Lt3. The magnetic fluxes Bt3a and Bt3d linked to the coil Lr are not canceled, and a part of the magnetic fluxes not linked to the power receiving coil Lr (magnetic fluxes Bt3c and Bt3d) is canceled. Therefore, it is possible to suppress a decrease in power transmission efficiency while reducing an unnecessary leakage magnetic field formed in a place away from the power transmission coil Lt3.

(Fourth embodiment)
Next, the configuration of the wireless power transmission device S4 according to the fourth embodiment of the present invention will be described with reference to FIG. 10 and FIG. FIG. 10 is a system configuration diagram showing the wireless power transmission device according to the fourth embodiment of the present invention together with a load. FIG. 11 is a cross-sectional view showing a power transmission coil unit according to a fourth embodiment of the present invention together with first and second power receiving coils.

  As illustrated in FIG. 10, the wireless power transmission device S4 includes a wireless power transmission device Ut4 and a wireless power reception device Ur4.

  The wireless power transmission device Ut4 includes a power source PW, an inverter INV, and a power transmission coil unit Ltu4. The configurations of the power source PW and the inverter INV are the same as those of the wireless power transmission device S1 according to the first embodiment. The present embodiment differs from the wireless power transmission device S1 according to the first embodiment in that a power transmission coil unit Ltu4 is provided instead of the power transmission coil unit Ltu1 of the wireless power transmission device S1 according to the first embodiment. . Hereinafter, a description will be given focusing on differences from the first embodiment.

  The power transmission coil unit Ltu4 includes a power transmission coil Lt4, a first auxiliary coil Lc4a, a second auxiliary coil Lc4b, and a magnetic body F4. In the present embodiment, the power transmission coil Lt4 and the three coils of the first and second auxiliary coils Lc4a and Lc4b are electrically connected in series as shown in FIG.

  As shown in FIG. 11, the power transmission coil Lt4 includes a magnetic core Ct4 and a winding Wt4. The power transmission coil Lt4 is a flat spiral coil having a substantially rectangular shape, and is formed by winding a winding Wt4 made of a litz wire such as copper or aluminum around a plate-like or rod-like magnetic core Ct4. Yes. The axial direction of the power transmission coil Lt4 is parallel to the opposing direction of the power transmission coil Lt4 and first and second power reception coils Lr4a and Lr4b described later. The number of turns of power transmission coil Lt4 is appropriately set based on the distance between first and second power receiving coils Lr4a and Lr4b, which will be described later, the desired power transmission efficiency, and the like.

  The first auxiliary coil Lc4a includes a magnetic core Cc4a and a winding Wc4a. The first auxiliary coil Lc4a is a solenoid coil wound spirally, and is formed by winding a winding Wc4a composed of a litz wire such as copper or aluminum around a plate-like or rod-like magnetic core Cc4a. Yes. The axial direction of the first auxiliary coil Lc4a is not parallel to the facing direction between the power transmission coil Lt4 and first and second power receiving coils Lr4a and Lr4b described later. With such a configuration, the magnetic flux generated by the first auxiliary coil Lc4a circulates to a place away from the first auxiliary coil Lc4a without interlinking with the first and second power receiving coils Lr4a and Lr4b. It becomes easy. In the present embodiment, the axial direction of the first auxiliary coil Lc4a is orthogonal to the opposing direction of the power transmission coil Lt4 and first and second power receiving coils Lr4a and Lr4b described later. In this case, the first auxiliary coil Lc4a makes it easier to generate a magnetic flux that circulates to a place away from the first auxiliary coil Lc4a.

  The first auxiliary coil Lc4a is connected to first and second power receiving coils Lr4a and Lr4b, which will be described later, that face the power transmitting coil Lt4 when transmitting power out of the magnetic flux generated by the power transmitting coil Lt4. It arrange | positions so that it may not interlink with the magnetic flux to intersect. That is, the magnetic flux that contributes to power transmission is not canceled out by the first auxiliary coil Lc4a, and hence a decrease in power transmission efficiency can be suppressed. In the present embodiment, as shown in FIG. 11, the first auxiliary coil Lc4a is disposed on the opposite side of the power transmission coil Lt4 from the side facing first and second power receiving coils Lr4a and Lr4b, which will be described later. ing. With this arrangement, the first auxiliary coil Lc4a can easily generate magnetic flux that intensifies part of the magnetic field generated between the power transmission coil Lt4 and first and second power reception coils Lr4a and Lr4b described later. . That is, between the power transmission coil Lt4 and first and second power receiving coils Lr4a and Lr4b, which will be described later, in the region where the magnetic flux generated by the power transmission coil Lt4 and the magnetic flux generated by the first auxiliary coil Lc4a overlap each other, The directions are almost the same. Therefore, the magnetic flux that contributes to power transmission that links the power transmission coil Lt4 and first and second power receiving coils Lr4a and Lr4b described later is not offset by the magnetic flux generated by the first auxiliary coil Lc4a. As a result, it is possible to further suppress a decrease in power transmission efficiency.

  Furthermore, the direction of the magnetic flux generated by the first auxiliary coil Lc4a is opposite to the direction of the magnetic flux that links the power transmission coil Lt4 and the first power receiving coil Lr4a together. Specifically, in FIG. 11, the magnetic flux interlinking the power transmission coil Lt4 and the first power reception coil Lr4a causes the power transmission coil Lt4 to move in the direction (upward in the figure) from the power transmission coil Lt4 to the first power reception coil Lr4a. When interlinking, this magnetic flux circulates around the first power receiving coil Lr4a while interlinking in the direction from the second power receiving coil Lr4b toward the first power receiving coil Lr4a (leftward in the figure) (counterclockwise in the figure). Therefore, if the magnetic flux generated by the first auxiliary coil Lc4a is linked to the first auxiliary coil Lc4a in the direction from the power transmission coil Lt4 toward the first auxiliary coil Lc4a, the magnetic flux F4 The direction of the magnetic flux that links the power transmitting coil Lt4 and the first power receiving coil Lr4a is opposite (clockwise in the figure). Alternatively, in FIG. 11, the magnetic flux interlinking the power transmission coil Lt4 and the first power reception coil Lr4a interlinks the power transmission coil Lt4 in the direction (downward in the figure) from the first power reception coil Lr4a to the power transmission coil Lt4. At this time, the magnetic flux becomes a circulation direction (clockwise in the figure) in which the first power reception coil Lr4a circulates while interlinking in a direction (rightward in the figure) from the first power reception coil Lr4a to the second power reception coil Lr4b. The magnetic flux generated by the first auxiliary coil Lc4a is linked to the first auxiliary coil Lc4a in the direction from the first auxiliary coil Lc4a toward the power transmission coil Lt4. While passing, the direction of rotation of the magnetic flux interlinking the power transmission coil Lt4 and the first power reception coil Lr4a is opposite (counterclockwise in the figure). In order to generate such a magnetic flux, the winding Wt4a of the first auxiliary coil Lc4a is closest to the winding Wt4 of the power transmission coil Lt4 (the upper surface portion of the winding Wt4a of the first auxiliary coil Lc4a in the drawing). The direction of the current passing through the winding Wt4 of the power transmission coil Lt4 is the direction of the current passing through the portion where the winding Wt4a of the first auxiliary coil Lc4a is close (the left side portion of the winding Wta of the power transmission coil Lt4). The winding Wc4a of the first auxiliary coil Lc4a may be wound around the magnetic path core Cc4a so as to be reversed.

  The second auxiliary coil Lc4b includes a magnetic core Cc4b and a winding Wc4b. The second auxiliary coil Lc4b is a solenoid coil wound spirally, and is formed by winding a winding Wc4b composed of a litz wire such as copper or aluminum around a plate-like or rod-like magnetic core Cc4b. Yes. The axial direction of the second auxiliary coil Lc4b is not parallel to the facing direction between the power transmission coil Lt4 and first and second power receiving coils Lr4a and Lr4b described later. With such a configuration, the magnetic flux generated by the second auxiliary coil Lc4b circulates to a place away from the second auxiliary coil Lc4b without interlinking with the first and second power receiving coils Lr4a and Lr4b. It becomes easy. In the present embodiment, the axial direction of the second auxiliary coil Lc4b is orthogonal to the opposing direction of the power transmission coil Lt4 and first and second power receiving coils Lr4a and Lr4b described later. In this case, the second auxiliary coil Lc4b makes it easier to generate a magnetic flux that circulates to a place away from the second auxiliary coil Lc4b.

  The second auxiliary coil Lc4b is connected to first and second power receiving coils Lr4a and Lr4b, which will be described later, that face the power transmitting coil Lt4 when power is transmitted among the magnetic flux generated by the power transmitting coil Lt4. It arrange | positions so that it may not interlink with the magnetic flux to intersect. That is, since the magnetic flux contributing to power transmission is not canceled by the second auxiliary coil Lc4b, it is possible to suppress a decrease in power transmission efficiency. In the present embodiment, as shown in FIG. 11, the second auxiliary coil Lc4b is disposed on the opposite side of the power transmission coil Lt4 from the side facing first and second power receiving coils Lr4a and Lr4b, which will be described later. ing. With this arrangement, the second auxiliary coil Lc4b can easily generate a magnetic flux that intensifies part of the magnetic field generated between the power transmission coil Lt4 and first and second power reception coils Lr4a and Lr4b described later. . That is, between the power transmission coil Lt4 and first and second power receiving coils Lr4a and Lr4b described later, in the region where the magnetic flux generated by the power transmission coil Lt4 and the magnetic flux generated by the second auxiliary coil Lc4b overlap, the mutual magnetic flux The directions are almost the same. Therefore, the magnetic flux that contributes to power transmission that links the power transmission coil Lt4 and first and second power receiving coils Lr4a and Lr4b, which will be described later, is not offset by the magnetic flux generated by the second auxiliary coil Lc4b. As a result, it is possible to further suppress a decrease in power transmission efficiency.

  Furthermore, the direction of the magnetic flux generated by the second auxiliary coil Lc4b is opposite to the direction of the magnetic flux that links the power transmission coil Lt4 and the second power receiving coil Lr4b together. Specifically, in FIG. 11, the magnetic flux interlinking both the power transmission coil Lt4 and the second power reception coil Lr4b causes the power transmission coil Lt4 to move in the direction (upward in the figure) from the power transmission coil Lt4 toward the first power reception coil Lr4a. When interlinking, this magnetic flux circulates around the second power receiving coil Lr4b while interlinking in the direction from the second power receiving coil Lr4b to the second power receiving coil Lr4b (rightward in the figure) (clockwise in the figure). Therefore, the magnetic flux generated by the second auxiliary coil Lc4b is interlinked with the second auxiliary coil Lc4b in the direction from the power transmission coil Lt4 toward the second auxiliary coil Lc4b. While passing through the section, the direction of rotation of the magnetic flux interlinking the power transmission coil Lt4 and the second power reception coil Lr4b is opposite (counterclockwise in the figure). Alternatively, in FIG. 11, the magnetic flux that links the power transmission coil Lt4 and the second power reception coil Lr4b interlinks the power transmission coil Lt4 in a direction (downward in the drawing) from the second power reception coil Lr4b to the power transmission coil Lt4. At this time, the magnetic flux is in a circulating direction (counterclockwise in the figure) in which the second power receiving coil Lr4b circulates while interlinking in a direction (leftward in the figure) from the second power receiving coil Lr4b toward the first power receiving coil Lr4a. Therefore, if the magnetic flux generated by the second auxiliary coil Lc4b is linked to the second auxiliary coil Lc4b in the direction from the second auxiliary coil Lc4b to the power transmission coil Lt4, this magnetic flux is a part of the magnetic body F4. The direction of rotation of the magnetic flux interlinking the power transmission coil Lt4 and the second power reception coil Lr4b is opposite (clockwise in the figure). In order to generate such a magnetic flux, the winding Wt4b of the second auxiliary coil Lc4b is closest to the winding Wt4 of the power transmission coil Lt4 (the upper surface portion of the winding Wt4b of the second auxiliary coil Lc4b in the drawing). The direction of the current passing through the winding Wt4 of the power transmission coil Lt4 is the direction of the current passing through the portion where the winding Wt4b of the second auxiliary coil Lc4b is close (the right side portion of the winding Wta of the power transmission coil Lt4). The winding Wc4b of the second auxiliary coil Lc4b may be wound around the magnetic path core Cc4b so as to be in the same direction.

  The magnetic body F4 extends along the surface of the power transmission coil Lt4 opposite to the side facing first and second power receiving coils Lr4a and Lr4b, which will be described later. In the present embodiment, as shown in FIG. 11, the power transmission coil Lt4 is located at the center of the surface (the upper surface in the drawing) of the power receiving coils Lr4a and Lr4b (described later) in the facing direction between the power transmission coil Lt4 and the power receiving coils Lr4a and Lr4b described later. Is connected to the magnetic core Ct4. Further, as shown in FIG. 11, the magnetic body F4 is near both ends of the opposite surface (the lower surface in the drawing) opposite to the power receiving coils Lr4a and Lr4b in the facing direction of the power transmitting coil Lt4 and power receiving coils Lr4a and Lr4b described later. Each is connected to the magnetic core Cc4a of the first auxiliary coil Lc4a and the magnetic core Cc4b of the second auxiliary coil Lc4b. With such a configuration, the magnetic core Cc4a of the first auxiliary coil Lc4a and the magnetic core Cc4b of the second auxiliary coil Lc4b are each connected to the magnetic body F4. Therefore, the first auxiliary coil Lc4a can easily generate a magnetic flux that strengthens the magnetic field generated between the power transmission coil Lt4 and a first power receiving coil Lr4a described later, and the second auxiliary coil Lc4b is connected to the power transmission coil Lt4 and described later. It is easy to generate a magnetic flux that strengthens the magnetic field generated between the second power receiving coils Lr4b. That is, in a part between the power transmission coil Lt4 and power reception coils Lra and Lr4b described later, the direction of the magnetic flux generated by the power transmission coil Lt4 and the direction of the magnetic flux generated by the first auxiliary coil Lc4a are substantially the same. The direction of the magnetic flux generated by the power transmission coil Lt4 and the direction of the magnetic flux generated by the second auxiliary coil Lc4b are substantially the same. Therefore, the magnetic flux that contributes to power transmission that links the power transmission coil Lt4 and the power receiving coils Lr4a and Lr4b, which will be described later, is not offset by the magnetic flux generated by the first and second auxiliary coils Lc4a and Lc4b. As a result, it is possible to further suppress a decrease in power transmission efficiency.

  The wireless power receiving device Ur4 includes first and second power receiving coils Lr4a and Lr4b, and a rectifier circuit DB. The configuration of the rectifier circuit DB is the same as that of the rectifier circuit DB of the wireless power transmission device S1 according to the first embodiment. In this embodiment, in place of the power receiving coil Lr of the wireless power transmission device S1 according to the first embodiment, the wireless power according to the first embodiment is provided with the first and second power receiving coils Lr4a and Lr4b. Different from the transmission device S1. Hereinafter, a description will be given focusing on differences from the first embodiment.

  The first power receiving coil Lr4a is a solenoid coil wound spirally, and is formed by winding a winding Wr4a around a plate-shaped or rod-shaped magnetic core Cr4a.

  The second power receiving coil Lr4b is a solenoid coil that is spirally wound, and is formed by winding a winding Wr4b around a plate-shaped or rod-shaped magnetic core Cr4b.

  The first power receiving coil Lr4a and the second power receiving coil Lr4b are juxtaposed on the same plane, and are electrically connected in series as shown in FIG. Further, the axis of the first power receiving coil Lr4a and the axis of the second power receiving coil Lr4b coincide. Furthermore, the winding directions of the winding Wr4a of the first power receiving coil Lr4a and the winding Wr4b of the second power receiving coil Lr4b are opposite to each other.

  Next, with reference to FIG. 12, the relative relationship between the magnetic flux generated by the power transmission coil and the magnetic flux generated by the auxiliary coil and the effect of reducing unnecessary leakage magnetic fields will be described in detail. FIG. 12 a is a diagram schematically illustrating the magnetic flux generated by the power transmission coil in FIG. 11. 12b is a diagram schematically showing the magnetic flux generated by the power transmission coil and the first and second auxiliary coils in FIG. Here, in FIG. 12 a, magnetic fluxes Bt <b> 4 a to Bt <b> 4 d are shown as body surfaces out of the magnetic flux generated by the power transmission coil Lt <b> 4. Moreover, in FIG. 9b, magnetic fluxes Bt4a to Bt4d are shown as body surface out of the magnetic fluxes generated by the power transmission coil Lt4, and typical magnetic fluxes generated by the first and second auxiliary coils Lc3a and Lc3b are shown. As an example, magnetic fluxes Bc4a and Bc4b are schematically shown. However, these magnetic fluxes schematically show only the direction of each magnetic flux, and do not show the magnetic flux density. 12a and 12b, the magnetic core Ct4 of the power transmission coil Lt4, the magnetic cores Cc4a and Cc4b of the first and second auxiliary coils Lc4a and Lc4b, and the magnetic properties of the first and second power receiving coils Lr4a and Lr4b. The illustration of the magnetic flux in the cores Cr4a and Cr4b is omitted.

  First, the magnetic flux generated by the power transmission coil Lt4 will be described with reference to FIG. 12a. As shown in FIG. 12a, the power transmission coil Lt4 generates magnetic fluxes Bt4a to Bt4d that are linked from the center of the power transmission coil Lt4 in a direction (upward in the drawing) toward the first and second power reception coils Lr4a and Lr4b. ing. In this example, the magnetic fluxes Bt4a to Bt4d generated by the power transmission coil Lt4 are linked to the first power receiving coil Lr4a, and are linked to the magnetic flux Bt4a contributing to power transmission and the second power receiving coil Lr4b. There are magnetic fluxes Bt4c and Bt4d that circulate around a place away from the power transmission coil Lt4 without interlinking with the magnetic flux Bt4b and the first and second power receiving coils Lr4a and Lr4b, and the magnetic flux Bt4a is the first power receiving coil Lr4a. And the magnetic flux Bt4b is linked to the second power receiving coil Lr4b, so that electromotive force is generated in the windings Wr4a and Wr4b of the first and second power receiving coils Lr4a and Lr4b. The electric power generated in the first and second power receiving coils Lr4a and Lr4b is rectified by the rectifier circuit DB and output to the load R. The magnetic fluxes Bt4a to Bt4d generated by the power transmission coil Lt4 are not linked to the first and second auxiliary coils Lc4a and Lc4b, and the magnetic fluxes Bt4a and Bt4b contributing to power transmission are the first and second magnetic fluxes. Since the auxiliary coils Lc4a and Lc4b are not cancelled, it is possible to suppress a decrease in power transmission efficiency.

  Next, the magnetic flux generated by the first and second auxiliary coils Lc4a and Lc4b will be described with reference to FIG. 12b. The magnetic fluxes Bt4a to Bt4d generated by the power transmission coil Lt4 in FIG. 12b are as shown in FIG. 12a. As shown in FIG. 12b, the first auxiliary coil Lc4a interlinks the first auxiliary coil Lc4a from the power transmission coil Lt4 in the direction (leftward in the drawing) toward the first auxiliary coil Lc4a. A magnetic flux Bc4a that circulates in a direction (downward in the drawing) from the first power receiving coil Lr4a to the first auxiliary coil Lc4a is generated without interlinking with the coil Lt4 and the first power receiving coil Lr4a. Specifically, in the present embodiment, the axial direction of the first auxiliary coil Lc4a is not parallel to the opposing direction of the power transmission coil Lt4 and the first and second power reception coils Lr4a and Lr4b. Therefore, the magnetic flux Bc4a generated by the first auxiliary coil Lc4a circulates in a place away from the first auxiliary coil Lc4a without interlinking with the first and second power receiving coils Lr4a and Lr4b. In particular, in the present embodiment, since the axial direction of the first auxiliary coil Lc4a is orthogonal to the opposing direction of the power transmission coil Lt4 and the first and second power receiving coils Lr4a and Lr4b, the first auxiliary coil The magnetic flux Bc4a generated by Lc4a circulates greatly to a place away from the first auxiliary coil Lc4a.

  Similarly, as shown in FIG. 12b, the second auxiliary coil Lc4b is linked to the second auxiliary coil Lc4b in a direction (rightward in the drawing) from the power transmission coil Lt4 to the second auxiliary coil Lc4b, and The magnetic flux Bc4b that circulates in the direction (downward in the drawing) from the second power receiving coil Lr4b to the second auxiliary coil Lc4b is generated without interlinking with the power transmitting coil Lt4 and the second power receiving coil Lr4b. Specifically, in the present embodiment, the axial direction of the second auxiliary coil Lc4b is not parallel to the facing direction of the power transmission coil Lt4 and the first and second power reception coils Lr4a and Lr4b. Thus, the magnetic flux Bc4b generated by the second auxiliary coil Lc4b circulates in a place away from the second auxiliary coil Lc4b without interlinking with the first and second power receiving coils Lr4a and Lr4b. In particular, in the present embodiment, since the axial direction of the second auxiliary coil Lc4b is orthogonal to the opposing direction of the power transmission coil Lt4 and the first and second power receiving coils Lr4a and Lr4b, the second auxiliary coil The magnetic flux Bc4b generated by Lc4b circulates greatly to a place away from the second auxiliary coil Lc4b.

  Next, the effect of reducing unnecessary leakage magnetic fields in the present embodiment will be described. As described above, the power transmission coil Lt4 generates magnetic fluxes Bt4c and Bt4d that circulate around a place away from the power transmission coil Lt4. The magnetic fluxes Bt4c and Bt4d do not contribute to power transmission, and become magnetic fluxes that form an unnecessary leakage magnetic field around the power transmission coil Lt4. In the present embodiment, the circulation direction of the magnetic flux Bc4a generated by the first auxiliary coil Lc4a is opposite to the rotation direction of the magnetic flux Bt4c generated by the power transmission coil Lt4. Further, the rotating direction of the magnetic flux Bc4b generated by the second auxiliary coil Lc4b is opposite to the rotating direction of the magnetic flux Bt4d generated by the power transmission coil Lt4. Therefore, as shown in FIG. 12b, in a place away from the power transmission coil Lt4, the direction of the magnetic fluxes Bt4c and Bt4d generated by the power transmission coil Lt4 and the magnetic flux Bc4a and Bc4b generated by the first and second auxiliary coils Lc4a and Lc4b The directions are opposite to each other. That is, the magnetic fluxes Bt4c and Bt4d generated by the power transmission coil Lt4 are offset by the magnetic fluxes Bc4a and Bc4b generated by the first and second auxiliary coils Lc4a and Lc4b at a location away from the power transmission coil Lt4. As a result, an unnecessary leakage magnetic field is reduced.

  On the other hand, in the vicinity between the power transmission coil Lt4 and the first auxiliary coil Lc4a, the direction of the magnetic flux Bt4a generated by the power transmission coil Lt4 and the direction of the magnetic flux Bc4a generated by the first auxiliary coil Lc4a are substantially the same. . That is, the magnetic field generated by the first auxiliary coil Lc4a intensifies part of the magnetic field generated between the power transmission coil Lt4 and the first power reception coil Lr4a. Thus, between the power transmission coil Lt4 and the first power reception coil Lr4a, the direction of the magnetic flux Bt4a generated by the power transmission coil Lt3 and the direction of the magnetic flux Bc4a generated by the first auxiliary coil Lc4a are substantially the same. Therefore, the magnetic flux Bt4a that contributes to power transmission that links the power transmission coil Lt4 and the first power receiving coil Lr4a together is not offset by the magnetic flux Bc4a generated by the first auxiliary coil Lc4a. As a result, a decrease in power transmission efficiency can be suppressed. Similarly, in the vicinity between the power transmission coil Lt4 and the second auxiliary coil Lc4b, the direction of the magnetic flux Bt4b generated by the power transmission coil Lt4 and the direction of the magnetic flux Bc4b generated by the second auxiliary coil Lc4b are substantially the same. . That is, the magnetic field generated by the second auxiliary coil Lc4b intensifies part of the magnetic field generated between the power transmission coil Lt4 and the second power reception coil Lr4b. Thus, between the power transmission coil Lt4 and the second power receiving coil Lr4b, the direction of the magnetic flux Bt4b generated by the power transmission coil Lt4 and the direction of the magnetic flux Bc4b generated by the second auxiliary coil Lc4b are substantially the same. Therefore, the magnetic flux Bt4b that contributes to power transmission that links the power transmission coil Lt4 and the second power receiving coil Lr4b together is not offset by the magnetic flux Bc4b generated by the second auxiliary coil Lc4b. As a result, a decrease in power transmission efficiency can be suppressed.

  As described above, in the power transmission coil unit Ltu4 according to the present embodiment, the magnetic fluxes Bc4a and Bc4b generated by the first and second auxiliary coils Lc4a and Lc4b are the first of the magnetic fluxes Bt4a to Bt4d generated by the power transmission coil Lt4. The magnetic fluxes Bt4a and Bt4b linked to the first and second power receiving coils Lr4a and Lr4b are not canceled and a part of the magnetic flux not linked to the first and second power receiving coils Lr4a and Lr4b (magnetic fluxes Bt4c and Bt4d) is canceled. doing. Therefore, it is possible to suppress a decrease in power transmission efficiency while reducing an unnecessary leakage magnetic field formed in a place away from the power transmission coil Lt4.

  Hereinafter, according to the present embodiment, it is specifically described in Examples 1 to 3 and Comparative Examples 1 to 6 that a decrease in power transmission efficiency can be suppressed while reducing an unnecessary leakage magnetic field formed in a place away from the power transmission coil. Shown in

  As Example 1, the wireless power transmission device S1 according to the first embodiment described above was used. As Example 2, the wireless power transmission device S3 according to the third embodiment described above was used. As Example 3, the wireless power transmission device S4 according to the fourth embodiment described above was used. As a comparative example 1, in order to compare the characteristics with the example 1, the wireless power transmission device S1 according to the first embodiment used a wireless power transmission device from which the auxiliary coil was removed. As Comparative Example 2, in order to compare the characteristics with Example 1, a wireless power transmission device in which noise canceling coils Ln20a and Ln20b linked to the magnetic flux generated by the power transmission coil were added to Comparative Example 1 was used. As a comparative example 3, in order to compare the characteristics with the example 2, a wireless power transmission device in which the auxiliary coil was removed was used in the wireless power transmission device S3 according to the third embodiment. As a comparative example 4, in order to compare the characteristics with the example 2, a wireless power transmission device in which a noise canceling coil Ln40 linked to the magnetic flux generated by the power transmission coil was added to the comparative example 3 was used. As a comparative example 5, in order to compare the characteristics with the example 3, the wireless power transmission device in which the auxiliary coil is removed is used in the wireless power transmission device S4 according to the fourth embodiment. As a comparative example 6, in order to compare the characteristics with the example 3, a wireless power transmission device in which a noise canceling coil Ln60 linked to the magnetic flux generated by the power transmission coil was added to the comparative example 5 was used.

  First, with reference to FIG. 13, the structure of the power transmission coil unit Ltu10 and the receiving coil Lr10 in the wireless power transmission apparatus of the comparative example 1 is demonstrated. FIG. 13 is a cross-sectional view showing the power transmission coil unit of Comparative Example 1 together with the power receiving coil. The power transmission coil unit Ltu10 includes a magnetic body F10 and first and second power transmission coils Lt10a and Lt10b. Each of the first and second power transmission coils Lt10a and Lt10b is a flat spiral coil having a substantially square shape, and the first power transmission coil Lt10a is formed by winding a winding Wt10a around a magnetic core Ct10a. The second power transmission coil Lt10b is formed by winding a winding Wt10b around a magnetic core Ct10b. The magnetic cores Ct10a and Ct10b are connected via a magnetic body F10. That is, the power transmission coil unit Ltu10 of Comparative Example 1 has a configuration in which the first auxiliary coil Lca and the second auxiliary coil Lcb are removed from the power transmission coil unit Ltu1 of the wireless power transmission device S1 of Example 1. The power receiving coil Lr10 is a solenoid coil wound spirally, and is formed by winding a winding Wr10 around a plate-shaped or rod-shaped magnetic core Cr10. The power receiving coil Lr10 of Comparative Example 1 is the same as the power receiving coil Lr in the wireless power transmission device S1 of Example 1.

  Next, with reference to FIG. 14, the structure of the power transmission coil unit Ltu20 and the receiving coil Lr10 in the wireless power transmission apparatus of the comparative example 2 is demonstrated. FIG. 14 is a cross-sectional view showing the power transmission coil unit of Comparative Example 2 together with the power receiving coil. The power transmission coil unit Ltu20 includes a magnetic body F10, first and second power transmission coils Lt10a and Lt10b, and first and second noise canceling coils Ln20a and Ln20b. The power transmission coil unit Ltu20 of Comparative Example 2 has a configuration in which first and second noise canceling coils Ln20a and Ln20b are added to the power transmission coil unit Ltu10 of Comparative Example 1. The first and second noise canceling coils Ln20a and Ln20b are coils having a planar spiral structure each having a substantially square shape. As shown in FIG. 14, between the first power transmission coil Lt10a and the magnetic body F10, the winding Wn20a of the first noise canceling coil Ln20a is wound around the magnetic core Ct10a, and the second power transmission coil Lt10b. Between the magnetic bodies F10, the winding Wn20b of the second noise canceling coil Ln20b is wound around the magnetic core Ct10b. With such a configuration, the first and second noise canceling coils Ln20a and Ln20b are linked to the magnetic flux generated by the first and second power transmission coils Lt10a and Lt10b. Here, the winding directions of the first and second noise canceling coils Ln20a and Ln20b are opposite to those of the first and second power transmission coils Lt10a and Lt10b, respectively. The power receiving coil Lr10 is a solenoid coil wound spirally, and is formed by winding a winding Wr10 around a plate-shaped or rod-shaped magnetic core Cr10. Note that the power receiving coil Lr10 of Comparative Example 2 is the same as the power receiving coil Lr in Example 1.

  Next, with reference to FIG. 15, the structure of the power transmission coil unit Ltu30 and the receiving coil Lr10 in the wireless power transmission apparatus of the comparative example 3 is demonstrated. FIG. 15 is a cross-sectional view showing the power transmission coil unit of Comparative Example 2 together with the power receiving coil. The power transmission coil unit Ltu30 of Comparative Example 3 includes a power transmission coil Lt30. The power transmission coil Lt30 is a coil having a solenoid structure wound spirally, and is formed by winding a winding Wt30 around a magnetic core Ct30 as shown in FIG. The power transmission coil unit Ltu30 of Comparative Example 3 has a configuration in which the first auxiliary coil Lc3a and the second auxiliary coil Lc3b are removed from the power transmission coil unit Ltu3 of the wireless power transmission device S3 of Example 2. The power receiving coil Lr10 is a solenoid coil wound spirally, and is formed by winding a winding Wr10 around a plate-shaped or rod-shaped magnetic core Cr10. The power receiving coil Lr10 of Comparative Example 3 is the same as the power receiving coil Lr in Example 2.

  Next, with reference to FIG. 16, the structure of the power transmission coil unit Ltu40 and the receiving coil Lr10 in the wireless power transmission apparatus of the comparative example 4 is demonstrated. FIG. 16 is a cross-sectional view showing the power transmission coil unit of Comparative Example 2 together with the power receiving coil. The power transmission coil unit Ltu40 includes a power transmission coil Lt40 and a noise canceling coil Ln40. The power transmission coil unit Ltu40 of the comparative example 4 is a form in which a noise canceling coil Ln40 is added to the power transmission coil unit Ltu30 of the comparative example 3. The noise canceling coil Ln40 is a coil having a solenoid structure wound spirally, and as shown in FIG. 16, a winding Wn40 of the noise canceling coil Ln40 is wound around the magnetic core Ct30, and further, noise The winding Wt40 of the power transmission coil Lt40 is wound outside the canceling coil Ln40. With such a configuration, the noise canceling coil Ln40 is linked to the magnetic flux generated by the power transmission coil Lt40. Here, the winding direction of the noise canceling coil Ln40 is opposite to that of the power transmission coil Lt40. The power receiving coil Lr10 is a solenoid coil wound spirally, and is formed by winding a winding Wr10 around a plate-shaped or rod-shaped magnetic core Cr10. The power receiving coil Lr10 of Comparative Example 4 is the same as the power receiving coil Lr in Example 2.

  Next, the configuration of the power transmission coil unit Ltu50 and the first and second power reception coils Lr50a and Lr50b in the wireless power transmission device of Comparative Example 5 will be described with reference to FIG. FIG. 17 is a cross-sectional view showing the power transmission coil unit of Comparative Example 5 together with the first and second power receiving coils. The power transmission coil unit Ltu50 includes a magnetic body F50 and a power transmission coil Lt50. The power transmission coil Lt50 is a flat spiral coil having a substantially square shape, and is formed by winding a winding Wt50 around a magnetic core Ct50 as shown in FIG. The magnetic core Ct50 is connected to the magnetic body F50. The power transmission coil unit Ltu50 of the comparative example 5 is a form in which the first auxiliary coil Lc4a and the second auxiliary coil Lc4b are removed from the power transmission coil unit Ltu4 of the wireless power transmission device S4 of the third embodiment. The first and second power receiving coils Lr50a and Lr50b are solenoid coils wound in a spiral shape. The first power receiving coil Lr50a is formed by winding a winding Wr50a around a plate-shaped or rod-shaped magnetic core Cr50a, and the second power receiving coil Lr50b is formed by winding the winding Wr50b on a plate-shaped or rod-shaped magnetic core Cr50b. It is formed by winding. Note that the winding directions of the first power receiving coil Lr50a and the second power receiving coil Lr50b are opposite to each other. The first and second power receiving coils Lr50a and Lr50b of Comparative Example 5 are the same as the first and second power receiving coils Lr4a and Lr4b in the wireless power transmission device S4 of Example 3.

  Next, the configuration of the power transmission coil unit Ltu60 and the first and second power reception coils Lr50a and Lr50b in the wireless power transmission device of Comparative Example 6 will be described with reference to FIG. FIG. 18 is a cross-sectional view showing the power transmission coil unit of Comparative Example 6 together with the first and second power receiving coils. The power transmission coil unit Ltu60 includes a magnetic body F50, a power transmission coil Lt50, and a noise canceling coil Ln60. The power transmission coil unit Ltu60 of Comparative Example 6 has a form in which a noise canceling coil Ln60 is added to the power transmission coil unit Ltu50 of Comparative Example 5. The noise canceling coil Ln60 is a coil having a planar spiral structure having a substantially square shape. As illustrated in FIG. 18, the winding Wn60 of the noise canceling coil Ln60 is wound around the magnetic core Ct50 between the power transmission coil Lt50 and the magnetic body F50. With such a configuration, the noise canceling coil Ln60 is linked to the magnetic flux generated by the power transmission coil Lt50. Here, the winding direction of the noise canceling coil Ln60 is opposite to that of the power transmission coil Lt50. The first power receiving coil Lr50a is formed by winding a winding Wr50a around a plate-shaped or rod-shaped magnetic core Cr50a, and the second power receiving coil Lr50b is wound around a plate-shaped or rod-shaped magnetic core Cr50b. It is formed by winding Wr50b. Note that the winding directions of the first power receiving coil Lr50a and the second power receiving coil Lr50b are opposite to each other. The first and second power receiving coils Lr50a and Lr50b of Comparative Example 5 are the same as the first and second power receiving coils Lr4a and Lr4b in the wireless power transmission device S4 of Example 3.

  Here, in each example and each comparative example, the windings Wta, Wtb, Wt10a, Wt10b of the first and second power transmission coils Lta, Ltb, Lt10a, Lt10b, power transmission coils Lt3, Lt4, Lt30, Lt40, Lt50 Windings Wt3, Wt4, Wt30, Wt40, Wt50, first and second auxiliary coils Lca, Lcb, Lc3a, Lc3b, Lc4a, Lc4b, windings Wca, Wcb, Wc3a, Wc3b, Wc4a, Wc4b, first and first 2 windings Wn20a and Wn20b of noise canceling coils Ln20a and Ln20b, windings Wn40 and Wn60 of noise canceling coils Ln40 and Ln60, and windings Wr, Wr10, Wr50a and Wr50b of receiving coils Lr, Lr10, Lr50a and Lr50b. Has a diameter of 0.1 mm coated with polyimide. The 5mm copper wire using a Litz wire having a diameter of about 6mm tailored twisted about 4,000. In addition, the magnetic cores Cta, Ctb, Ct10a, Ct10b of the first and second power transmission coils Lta, Ltb, Lt10a, Lt10b, the magnetic cores Ct3, Ct4, Ct30, Ct40 of the power transmission coils Lt3, Lt4, Lt30, Lt40, Lt50, Ct50, first and second auxiliary coils Lca, Lcb, Lc3a, Lc3b, Lc4a, Lc4b magnetic cores Cca, Ccb, Cc3a, Cc3b, Cc4a, Cc4b, magnetic bodies F1, F10, F50, and receiving coils Lr, Lr10 For the magnetic cores Cr, Cr10, Cr50a, and Cr50b of Lr50a and Lr50b, the same material ferrite (relative permeability of about 3000) was used.

  Further, in the power transmission coil unit Ltu1 of the first embodiment, the magnetic body F1 having a length of 300 mm, a width of 300 mm, and a thickness of 15 mm, and the first and second power transmission coils Lta having a length of 100 mm, a width of 300 mm, and a thickness of 24 mm, Magnetic cores Cta, Ctb of Ltb, magnetic cores Cca, Ccb of the first and second auxiliary coils Lca, Lcb of length 40 mm, width 300 mm, thickness 15 mm, length 300 mm, width 300 mm, thickness 10 mm The magnetic core Cr of the power receiving coil Lr was used. In the power transmission coil unit Ltu10 of Comparative Example 1 and the power transmission coil unit Ltu20 of Comparative Example 2, the magnetic body F10 having a length of 300 mm, a width of 300 mm, and a thickness of 15 mm, and the first and The magnetic cores Ct10a and Ct10b of the second power transmission coils Lt10a and Lt10b and the magnetic core Cr10 of the power reception coil Lr10 having a length of 300 mm, a width of 300 mm, and a thickness of 10 mm were used.

  Furthermore, the number of turns of each coil in Example 1 and Comparative Examples 1 and 2 was set as shown in Table 1 below.

  In the power transmission coil unit Ltu3 in the second embodiment, the magnetic core Ct3 of the power transmission coil Lt3 having a length of 300 mm, a width of 300 mm, and a thickness of 15 mm, and the first and second auxiliary coils having a length of 60 mm, a width of 300 mm, and a thickness of 15 mm The magnetic cores Cc3a and Cc3b of Lc3a and Lc3b and the magnetic core Cr of the receiving coil Lr having a length of 300 mm, a width of 300 mm, and a thickness of 10 mm were used. In the power transmission coil unit Ltu30 of Comparative Example 3 and the power transmission coil unit Ltu40 of Comparative Example 4, the power transmission coil Lt30 having a length of 300 mm, a width of 300 mm, and a thickness of 15 mm, and the magnetic core Ct30 of Lt40, 300 mm, a width of 300 mm, and a thickness of 10 mm The magnetic core Cr10 of the power receiving coil Lr10 was used.

  Furthermore, the number of turns of each coil in Example 2 and Comparative Examples 3 and 4 was set as shown in Table 2 below.

  In the power transmission coil unit Ltu4 of Example 3, a magnetic body F4 having a length of 400 mm, a width of 300 mm, and a thickness of 15 mm, a magnetic core Ct4 of the power transmission coil Lt4 having a length of 100 mm, a width of 300 mm, and a thickness of 24 mm, and a length of 40 mm The magnetic cores Cc4a and Cc4b of the first and second auxiliary coils Lc4a and Lc4b having a width of 300 mm and a thickness of 15 mm and the first and second power receiving coils Lr4a and Lr4b having a length of 150 mm, a width of 300 mm and a thickness of 10 mm Magnetic cores Cr4a and Cr4b were used. In the power transmission coil unit Ltu50 of Comparative Example 5 and the power transmission coil unit Ltu60 of Comparative Example 6, the magnetic body F50 having a length of 400 mm, a width of 300 mm, and a thickness of 15 mm, and a power transmission coil Lt50 having a length of 100 mm, a width of 300 mm, and a thickness of 24 mm And the magnetic cores Cr50a and Cr50b of the first and second power receiving coils Lr50a and Lr50b having a length of 150 mm, a width of 300 mm, and a thickness of 10 mm were used.

  Furthermore, the number of turns of each coil in Example 3 and Comparative Examples 5 and 6 was set as shown in Table 3 below.

  In Examples 1 to 3 and Comparative Examples 1 to 6, the distance between each power transmission coil unit and the power receiving coil was set to 150 mm.

  Subsequently, in Examples 1 to 3 and Comparative Examples 1 to 6, power transmission efficiency and unnecessary leakage magnetic field were measured. At this time, the power receiving coils Lr and Lr10 (or the first and second power receiving coils Lr4a and Lr4b) are not displaced, that is, the power transmitting coil unit and the power receiving coils Lr and Lr10 (or the first and second power receiving coils). The distance between the centers of the power receiving coils Lr and Lr10 (or the first and second power receiving coils Lr4a and Lr4b) and the center of each power transmitting coil unit is also 150 mm while keeping the distance between Lr4a and Lr4b) at 150 mm. The measurement was performed. The power supplied from the power source PW was adjusted so that the power supplied to the load R was 3 kW.

  The power transmission efficiency is determined by measuring the power supplied from the power source PW and the power supplied to the load R while taking into account the loss in the inverter INV and the loss in the rectifier circuit DB measured in advance, and the power transmission coil unit and the power receiving efficiency. The efficiency between the coils was calculated.

  Unnecessary leakage magnetic field was determined using the magnetic field strength at a position 10 m away from the center of the power transmission coil unit as an index. A loop antenna was installed at a position 10 m away from the center of the power transmission coil unit in the axial direction of the power reception coils Lr and Lr10 (or the first and second power reception coils Lr4a and Lr4b), and the magnetic field strength was measured. Here, in the loop antenna, the magnetic field strength in three orthogonal directions (X, Y, and Z directions) was measured, and the leakage magnetic field strength was calculated by combining these. Note that the power transmission coil unit was installed at a height of 500 mm from the floor surface with the power transmission surface facing upward, and the power reception coil was installed on the power transmission coil unit with an interval of 150 mm. The loop antenna was installed so that its center was 1.5 m above the floor of the anechoic chamber.

  The measurement results are shown in FIGS. 19 shows the measurement results of Example 1 and Comparative Examples 1 and 2, FIG. 20 shows the measurement results of Example 2 and Comparative Examples 3 and 4, and FIG. 20 shows the results of Example 3 and Comparative Examples 5 and 6. It is a measurement result. In the figure, the bar graph indicates the power transmission efficiency, and the line graph indicates the leakage magnetic field strength.

  First, the measurement results of Example 1 and Comparative Examples 1 and 2 will be considered. As shown in FIG. 19, the power transmission efficiency of Example 1 is substantially the same as that of Comparative Example 1, and the leakage magnetic field strength is low. Further, Example 1 has higher power transmission efficiency and lower leakage magnetic field strength than Comparative Example 2. That is, since the auxiliary coils of the first embodiment (first and second auxiliary coils Lca and Lcb) do not cancel the magnetic flux contributing to the power transmission, the power transmission efficiency is higher than that of the comparative example 1 that does not include the auxiliary coil. The decrease is suppressed. Specifically, it is considered that the loss slightly increased by the amount of Joule heat generated by a small resistance parasitic on the auxiliary coil. Moreover, in Example 1, since the magnetic flux which forms an unnecessary leakage magnetic field with an auxiliary coil cancels out, compared with the comparative example 1 which does not have an auxiliary coil, the leakage magnetic field strength is remarkably small. On the other hand, in Comparative Example 2, the noise canceling coils (first and second noise canceling coils Ln20a and Ln20b) cancel both the magnetic flux contributing to power transmission and the magnetic flux forming an unnecessary leakage magnetic field. It is considered that both the power transmission efficiency and the leakage magnetic field strength have decreased. As described above, it was confirmed that the power transmission coil unit Ltu1 of Example 1 can suppress a decrease in power transmission efficiency while reducing an unnecessary leakage magnetic field.

  Subsequently, the measurement results of Example 2 and Comparative Examples 3 and 4 will be considered. As shown in FIG. 20, Example 2 has substantially the same power transmission efficiency and lower leakage magnetic field strength than Comparative Example 3. Moreover, Example 2 has higher power transmission efficiency and comparable leakage magnetic field strength as compared with Comparative Example 4. Since the auxiliary coils of the second embodiment (first and second auxiliary coils Lc3a and Lc3b) do not cancel the magnetic flux contributing to the power transmission, the power transmission efficiency is reduced as compared with the comparative example 3 that does not include the auxiliary coil. It is suppressed. Specifically, it is considered that the loss slightly increased by the amount of Joule heat generated by a small resistance parasitic on the auxiliary coil. In Example 2, since the magnetic flux that forms an unnecessary leakage magnetic field is canceled by the auxiliary coil, the leakage magnetic field strength is significantly smaller than that of Comparative Example 3 that does not include the auxiliary coil. On the other hand, in Comparative Example 4, the noise canceling coil (noise canceling coil Ln40) cancels both the magnetic flux that contributes to power transmission and the magnetic flux that forms an unnecessary leakage magnetic field. It is thought that both declined. As described above, it was confirmed that the power transmission coil unit Ltu3 of Example 2 can suppress a decrease in power transmission efficiency while reducing an unnecessary leakage magnetic field. From the above, the effectiveness of the present embodiment was confirmed.

  Subsequently, the measurement results of Example 3 and Comparative Examples 5 and 6 will be considered. As shown in FIG. 21, the power transmission efficiency of Example 3 is substantially the same as that of Comparative Example 5, and the leakage magnetic field strength is low. In addition, Example 3 has higher power transmission efficiency and lower leakage magnetic field strength than Comparative Example 6. The auxiliary coils of the third embodiment (first and second auxiliary coils Lc4a and Lc4b) do not cancel out the magnetic flux that contributes to power transmission. Therefore, the power transmission efficiency is reduced as compared with Comparative Example 5 that does not include the auxiliary coil. It is suppressed. Specifically, it is considered that the loss slightly increased by the amount of Joule heat generated by a small resistance parasitic on the auxiliary coil. Moreover, in Example 5, since the auxiliary coil cancels out the magnetic flux that forms an unnecessary leakage magnetic field, the leakage magnetic field strength is significantly smaller than that in Comparative Example 5 that does not include the auxiliary coil. On the other hand, in Comparative Example 6, the noise canceling coil (noise canceling coil Ln60) cancels both the magnetic flux that contributes to power transmission and the magnetic flux that forms an unnecessary leakage magnetic field. It is thought that both declined. As described above, it was confirmed that the power transmission coil unit Ltu4 of Example 3 can suppress a decrease in power transmission efficiency while reducing an unnecessary leakage magnetic field. From the above, the effectiveness of the present embodiment was confirmed.

  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.

  S1, S2, S3, S4 ... Wireless power transmission device, Ut1, Ut2, Ut3, Ut4 ... Wireless power transmission device, PW ... Power source, INV ... Inverter, Ur, Ur4 ... Wireless power reception device, Ltu1, Ltu2, Ltu3, Ltu4, Ltu10 , Ltu20, Ltu30, Ltu40, Ltu50, Ltu60 ... power transmission coil unit, Lta, Lt10a ... first power transmission coil, Ltb, Lt10b ... second power transmission coil, Lt3, Lt4, Lt30, Lt40, Lt50 ... power transmission coil, Lt2c ... Additional coil, Cta, Ct10a ... Magnetic core of first power transmission coil, Ctb, Ct10b ... Magnetic core of second power transmission coil, Ct3, Ct4, Ct30, Ct50 ... Magnetic core of power transmission coil, Ct2c ... Magnetic property of additional coil Core, Wta, Wt10a ... 1st Winding of power transmission coil, Wtb, Wt10b ... Winding of second power transmission coil, Wt2c ... Winding of additional coil, Wt3, Wt4, Wt30, Wt40, Wt50 ... Winding of power transmission coil, Lca, Lc3a, Lc4a ... 1 auxiliary coil, Lcb, Lc3b, Lc4b, second auxiliary coil, Cca, Cc3a, Cc4a, magnetic core of the first auxiliary coil, Ccb, Cc3b, Cc4b, magnetic core of the second auxiliary coil, Wca, Wc3a, Wc4a ... first auxiliary coil winding, Wcb, Wc3b, Wc4b ... second auxiliary coil winding, F1, F10, F50 ... magnetic material, Lr, Lr10 ... receiving coil, Lr4a, Lr50a ... first Receiving coil, Lr4b, Lr50b ... second receiving coil, Cr, Cr10 ... magnetic core of receiving coil, Cr4a, Cr50a ... Magnetic core of receiving coil, Cr4b, Cr50b ... Magnetic core of second receiving coil, Wr, Wr10 ... Winding of receiving coil, Wr4a, Wr50a ... Winding of first receiving coil, Wr4b, Wr50b ... Second Receiving coil winding, DB ... rectifier circuit, R ... load, Ln20a ... first noise canceling coil, Ln20b ... second noise canceling coil, Ln40, Ln60 ... noise canceling coil, Wn20a ... first noise Winding of canceling coil, Wn20b ... Winding of second noise canceling coil, Wn40, Wn60 ... Winding of noise canceling coil, Bt1a to Bt1d ... Magnetic flux generated by first and second power transmission coils, Bt2a ~ Bt2d ... magnetic flux generated by the first and second power transmission coils and the additional coil, Bt3a-Bt3d, Bt4a-Bt4d ... the power transmission coil is generated Bc1a, Bc1b, Bc2a, Bc2b, Bc3a, Bc3b, Bc4a ... Magnetic flux generated by the first auxiliary coil, Bc1c, Bc1d, Bc2c, Bc2d, Bc3c, Bc3d, Bc4b ... Magnetic flux generated by the second auxiliary coil .

Claims (10)

A power transmission coil unit for transmitting power wirelessly,
A power transmission coil and an auxiliary coil;
The magnetic flux generated by the auxiliary coil is generated in the power receiving coil without canceling out the magnetic flux interlinked with the power receiving coil that faces the power transmitting coil when power is transmitted among the magnetic flux generated by the power transmitting coil. A power transmission coil unit that cancels a part of magnetic flux not interlinked. Each of the power transmission coil and the auxiliary coil further includes a magnetic core,
The power transmission coil unit according to claim 1, wherein the magnetic core of the auxiliary coil is connected to the magnetic core of the power transmission coil.   The power transmission coil unit according to claim 1, wherein the axis of the auxiliary coil is substantially orthogonal to a facing direction of the power transmission coil and the power reception coil.   The power transmission coil unit according to any one of claims 1 to 3, wherein the auxiliary coil is located on a side of the power transmission coil opposite to a side facing the power reception coil.   5. The power transmission coil unit according to claim 4, wherein a part or all of the auxiliary coil overlaps with the power transmission coil when viewed from a facing direction of the power transmission coil and the power reception coil. The power transmission coil includes a first power transmission coil and a second power transmission coil juxtaposed,
The first power transmission coil and the second power transmission coil are each formed with a magnetic path interlinking both coils by a magnetic field generated by each other. The power transmission coil unit described.   The power transmission coil unit according to claim 6, wherein at least a part of the magnetic flux generated by the auxiliary coil is interlinked with the power transmission coil. The center of the power transmission coil is opposite to the side facing the power reception coil, and the center of the coil is positioned between the center of the first power transmission coil and the center of the second power transmission coil. An additional coil disposed in the
The magnetic path which links each coil is formed by the magnetic field which a said 1st power transmission coil, a said 2nd power transmission coil, and the said additional coil generate | occur | produce mutually, The Claim 6 or 7 characterized by the above-mentioned. Power transmission coil unit. The auxiliary coil includes a first auxiliary coil and a second auxiliary coil,
The first auxiliary coil and the second auxiliary coil are arranged such that a central portion of the power transmission coil is positioned between a central portion of the first auxiliary coil and a central portion of the second auxiliary coil. The power transmission coil unit according to any one of claims 1 to 8, wherein the power transmission coil unit is provided. A wireless power transmission device for transmitting power wirelessly,
The power transmission coil unit according to any one of claims 1 to 9,
A wireless power transmission device comprising: a power receiving coil.

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