JP6340968B2 - Coil unit and wireless power transmission device - Google Patents

Description

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

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

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

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

JP 2011-23496 A

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

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

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

  The coil unit according to the present invention includes a first coil and an auxiliary coil, and the auxiliary coil generates a magnetic field generated by another coil that transmits and receives power to and from the first coil by electromagnetic resonance. And generating a magnetic field having an opposite phase to the above.

  According to the present invention, the auxiliary coil generates a magnetic field opposite in phase to the magnetic field generated by another coil that transmits and receives power to and from the first coil by electromagnetic resonance, so that the other coil Unnecessary leakage magnetic field generated can be reduced. As a result, an unnecessary leakage magnetic field generated from the opposed coils can be reduced while suppressing an increase in size and weight of the opposed coils.

  Preferably, further comprising: a second coil magnetically coupled to the first coil; and a resonant capacitor connected to the second coil, wherein the auxiliary coil is electrically connected to the second coil, and the other The winding may be wound so as to generate a magnetic field having a phase opposite to that of the magnetic field generated by the first coil. Here, since the first coil is magnetically coupled to the second coil, and the second coil is connected to the resonance capacitor, the phase of the current flowing through the second coil is the current flowing through the first coil. 90 degrees with respect to the phase. Furthermore, the phase of the current that flows through the other coil that wirelessly transmits and receives power to and from the first coil by electromagnetic resonance is shifted by 90 degrees with respect to the phase of the current that flows through the first coil. At this time, power is transmitted and received wirelessly between the first coil and the phase of the current flowing through the second coil and the phase of the current flowing through the auxiliary coil electrically connected to the second coil. The phases of currents flowing through the other coils are the same phase. Therefore, since the winding is wound so that the magnetic field generated by the auxiliary coil has the opposite phase to the magnetic field generated by the other coil, the auxiliary coil generates a magnetic field having the opposite phase to the other coil. It will be. Therefore, an unnecessary leakage magnetic field generated by another coil can be reduced. As a result, in order to supply power to the first coil and the second coil, a plurality of AC power sources are not required, and an increase in the size and weight of the coils that are opposed to each other by only one AC power source is suppressed. However, it is possible to reduce unnecessary leakage magnetic fields generated from the coils arranged opposite to each other. In addition, significant increase in size and weight of the entire wireless power transmission device can be suppressed.

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

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

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

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

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

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

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

1 is a schematic system configuration diagram showing a wireless power transmission device according to a first embodiment of the present invention. In the wireless power transmission device according to the first embodiment of the present invention, it is a cross-sectional view showing a coil unit together with a power receiving coil. In FIG. 2, it is the figure which showed typically direction of the magnetic field which each coil generate | occur | produces when the output current phase of a 1st inverter is 0 degree | times. In FIG. 2, it is the figure which showed typically direction of the magnetic field which each coil generate | occur | produces when the output current phase of a 1st inverter is 90 degree | times. It is a system model block diagram which shows the wireless power transmission apparatus which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows a coil unit with a receiving coil in the wireless power transmission apparatus which concerns on 2nd Embodiment of this invention. In FIG. 5, it is the figure which showed typically the direction of the magnetic field which each coil generate | occur | produces when the output current phase of a 1st inverter is 0 degree | times. In FIG. 5, it is the figure which showed typically direction of the magnetic field which each coil generate | occur | produces when the output current phase of a 1st inverter is 90 degree | times. It is a system model block diagram which shows the wireless power transmission apparatus which concerns on 3rd Embodiment of this invention. It is sectional drawing which shows a coil unit with a receiving coil in the wireless power transmission apparatus which concerns on 3rd Embodiment of this invention. In FIG. 8, it is the figure which showed typically direction of the magnetic field which each coil generate | occur | produces when the output current phase of a 1st inverter is 0 degree | times. In FIG. 8, it is the figure which showed typically the direction of the magnetic field which each coil generate | occur | produces when the output current phase of a 1st inverter is 90 degree | times. In FIG. 8, it is the figure which showed typically the magnetic flux which the 1st-4th coil | winding generate | occur | produces when the output current phase of an inverter is 0 degree | times.

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

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

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

  The wireless power transmitting apparatus Ut1 includes a first power supply PW1, a second power supply PW2, a first inverter INV1, a second inverter INV2, and a coil unit Ltu1. The wireless power receiving device Ur1 includes a power receiving coil Lr, a resonant capacitor Cr, a rectifier circuit DB, and a load R. The wireless power transmission device S1 wirelessly transmits power from the wireless power transmission device Ut1 to the wireless power reception device Ur1 when the coil unit Ltu1 of the wireless power transmission device Ut1 and the power reception coil Lr of the wireless power reception device Ur1 face each other.

  First, the wireless power transmission device Ut1 will be described. The first power supply PW1 supplies DC power to a first inverter INV1 described later. The first power source PW1 is not particularly limited as long as it outputs DC power, and is switched by 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 converter. Examples include a power supply device.

  The second power supply PW2 supplies DC power to a second inverter INV2 described later. The second power source PW2 is not particularly limited as long as it outputs DC power, and is switched by 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 converter. Examples include a power supply device.

  The first inverter INV1 has a function of converting input DC power supplied from the first power supply PW1 into AC power. The first inverter INV1 includes a switching circuit in which a plurality of switching elements are bridge-connected. Examples of the switching elements constituting the switching circuit include elements such as MOS-FET (Metal Oxide Semiconductor-Field Effect Transistor) and IBGT (Insulated Gate Bipolar Transistor). The first inverter INV1 converts the input DC power supplied from the first power supply PW1 into AC power and supplies the AC power to the first coil Ltr1 of the coil unit Ltu1 described later. A capacitor (not shown) for improving the power factor of the circuit may be inserted between the first inverter INV1 and the first coil Ltr1.

  The second inverter INV2 has a function of converting input DC power supplied from the second power supply PW2 into AC power. The second inverter INV2 includes a switching circuit in which a plurality of switching elements are bridge-connected. Examples of the switching elements constituting the switching circuit include elements such as MOS-FET (Metal Oxide Semiconductor-Field Effect Transistor) and IBGT (Insulated Gate Bipolar Transistor). The second inverter INV2 converts the input DC power supplied from the second power source PW2 into AC power and supplies the AC power to the auxiliary coil Ln of the coil unit Ltu1 described later. A capacitor (not shown) for improving the power factor of the circuit may be inserted between the second inverter INV1 and the auxiliary coil Ln. Here, the second inverter INV2 outputs an alternating current having the same frequency as the frequency of the alternating current output from the first inverter INV1. However, the second inverter INV2 outputs an alternating current having a current phase shifted by 90 degrees from the current phase of the alternating current output from the first inverter INV1.

  As shown in FIGS. 1 and 2, the coil unit Ltu1 includes a first coil Ltr1, an auxiliary coil Ln, an electromagnetic shielding plate S, a first magnetic core Ft, a second magnetic core Fn, Have The first coil Ltr1, the auxiliary coil Ln, and the electromagnetic shielding plate S are viewed from the side close to the power receiving coil Lr, which will be described later, when viewed from the direction orthogonal to the facing direction of the coil unit Ltu1 and the power receiving coil Lr, which will be described later. The first coil Ltr1, the electromagnetic shielding plate S, and the auxiliary coil Ln are arranged in this order. That is, the auxiliary coil Ln is arranged at a position farthest from the power receiving coil Lr described later. When the wireless power transmission device S1 according to this embodiment is applied to a power supply facility for a vehicle such as an electric vehicle, the coil unit Ltu1 is disposed in the ground or in the vicinity of the ground.

  The first coil Ltr1 has a function of transmitting power wirelessly to a power receiving coil Lr described later by electromagnetic resonance. That is, the first coil Ltr1 functions as a power transmission coil. In the present embodiment, the first coil Ltr1 includes a first winding LtrA and a second winding LtrB that are electrically connected to each other. The first and second windings LtrA and LtrB are planar spiral coils juxtaposed in a direction orthogonal to the facing direction of the coil unit Ltu1 and a power receiving coil Lr described later, and are made of a litz such as copper or aluminum. It is formed by winding a wire. The number of turns of the first and second windings LtrA and LtrB is appropriately set based on a separation distance between the coil unit Ltu1 and a power receiving coil Lr described later, desired power transmission efficiency, and the like. The winding direction of the first winding LtrA and the winding direction of the second winding LtrB are opposite to each other, and the axial directions of the first and second windings LtrA and LtrB are both coils. It is parallel to the facing direction of the unit Ltu1 and a power receiving coil Lr described later. That is, when a current flows through the first coil Ltr1, the first winding LtrA and the second winding LtrB generate magnetic fields having opposite phases. Therefore, the leakage magnetic field generated by the first coil Ltr1 can be reduced by the first winding LtrA and the second winding LtrB that generate magnetic fields having phases opposite to each other.

  The auxiliary coil Ln is electrically connected to the second inverter INV2. That is, a current having a phase that is shifted by 90 degrees from the phase of the current flowing through the first coil Ltr1 flows through the auxiliary coil Ln. The auxiliary coil Ln is a solenoid-structured coil and is formed by spirally winding a litz wire such as copper or aluminum. The axial direction of the auxiliary coil Ln substantially coincides with the axial direction of the power receiving coil Lr described later. In the present embodiment, the axial direction of the auxiliary coil Ln is the opposing direction of the coil unit Ltu1 and the power receiving coil Lr described later. The direction of the axis of the auxiliary coil Ln is perpendicular to the direction of the axes of the first and second windings LtrA and LtrB of the first coil Ltr1. Further, the auxiliary coil Ln is wound with a winding such that the magnetic field generated by the auxiliary coil Ln has an opposite phase to the magnetic field generated by the power receiving coil Lr described later. Still further, the number of turns of the auxiliary coil Ln is appropriately set based on a separation distance between the coil unit Ltu1 and a power receiving coil Lr, which will be described later, a desired leakage magnetic field reduction effect, and the like.

  The electromagnetic shielding plate S is disposed between the first coil Ltr1 and the auxiliary coil Ln and along the axial direction of the auxiliary coil Ln. Specifically, the electromagnetic shielding plate S is disposed between the first magnetic core Ft and the auxiliary coil Ln to be operated later. The electromagnetic shielding plate S functions as a shielding material that suppresses unnecessary magnetic coupling between the first coil Ltr1 and the auxiliary coil Ln. In other words, the electromagnetic shielding plate S functions as a shield material that cancels the magnetic field by an induced current, an eddy current, or the like and suppresses the passage of magnetic flux. Thereby, unnecessary electromagnetic interference between the first coil Ltr1 and the auxiliary coil Ln can be reduced. The electromagnetic shielding plate S is not particularly limited as long as the surface is a nonmagnetic conductor that functions as an electromagnetic shielding material, and examples thereof include copper, aluminum, and a steel plate having a surface galvanized.

  The first magnetic core Ft is made of a magnetic material such as ferrite and has a substantially U shape having protrusions at both ends of the plate shape. One protrusion is the first winding of the first coil Ltr1. It is arranged so as to penetrate the axis of the line LtrA, and the other protrusion penetrates the axis of the second winding LtrB of the first coil Ltr1. That is, the first magnetic core Ft functions as the core of the first and second windings LtrA and LtrB of the first coil Ltr1. Therefore, the magnetic flux for wireless power transmission can be efficiently generated by the first magnetic core Ft.

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

  Next, the configuration of the wireless power receiving device Ur1 will be described. In the present embodiment, the other coil that transmits and receives power to and from the first coil by electromagnetic resonance means the power receiving coil Lr. The power receiving coil Lr is a coil having a solenoid structure, and is formed by winding a winding Wr made of a litz wire such as copper or aluminum around the third magnetic core Fr in a spiral shape. The axial direction of the power receiving coil Lr is a direction orthogonal to the facing direction of the coil unit Ltu1 and the power receiving coil Lr. The number of turns of the power receiving coil Lr is appropriately set based on the distance between the coil unit Ltu1 and the power receiving coil Lr, the desired power transmission efficiency, and the like. The power receiving coil Lr configured as described above has a function of receiving AC power transmitted from the first coil Ltr1. Further, the power receiving coil Lr is electrically connected to a rectifier circuit DB described later. In addition, when the wireless power transmission device S1 according to the present embodiment is applied to a power supply facility for a vehicle such as an electric vehicle, the power receiving coil Lr is mounted on the lower portion of the vehicle. Here, the third magnetic core Fr is made of a magnetic material such as a plate-like or rod-like ferrite, and is disposed so as to penetrate the shaft of the power receiving coil Lr. That is, the third magnetic core Fr functions as the core of the power receiving coil Lr. Therefore, since the magnetic flux generated by the first coil Ltr1 selectively forms a magnetic path that passes through the third magnetic core Fr, the magnetic flux interlinked with the power receiving coil Lr is increased, and the power transmission efficiency is improved. be able to.

  The resonant capacitor Cr is inserted between the power receiving coil Lr and a rectifier circuit DB described later. The capacitance of the resonance capacitor Cr is set so as to resonate at the frequency of the current supplied from the first inverter INV1 with respect to the impedance of the power receiving coil Lr. As a result, power is transmitted wirelessly between the power receiving coil Lr and the first coil Ltr1 by electromagnetic resonance. In this embodiment, the resonance capacitor Cr is connected in parallel with the power receiving coil Lr, but the resonance capacitor Cr may be connected in series with the power receiving coil Lr. In any case, it is only necessary that the capacitance of the resonance capacitor Cr is set so that the impedance of the power receiving coil Lr resonates at the frequency of the current supplied from the first inverter INV1.

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

  Next, with reference to FIG. 3, the magnetic field generated by each of the first coil Ltr1, the auxiliary coil Ln, and the power receiving coil Lr in this embodiment and the action of reducing unnecessary leakage magnetic fields will be described in detail. FIG. 3a is a diagram schematically showing the direction of the magnetic field generated by each coil when the output current phase of the first inverter is 0 degree in FIG. FIG. 3b is a diagram schematically showing the direction of the magnetic field generated by each coil when the output current phase of the first inverter is 90 degrees in FIG. 3A and 3B, the first magnetic core Ft, the second magnetic core Fn, and the third magnetic core Fr are omitted for convenience of explanation.

  When the output current phase of the first inverter INV1 that supplies current to the first coil Ltr1 is 0 degree, that is, when the instantaneous value of the output current of the sinusoidal first inverter INV1 is the maximum, it is shown in FIG. As described above, the strengths of the magnetic fields HLtrA and HLtrB generated by the first and second windings LtrA and LtrB of the first coil Ltr1 are maximized. The magnetic fields HLtrA and HLtrB are parallel to the facing direction of the coil unit Ltu1 and the power receiving coil Lr, and are magnetic fields having opposite phases. Therefore, the leakage magnetic field generated by the first coil Ltr1 can be reduced by the first winding LtrA and the second winding LtrB that generate magnetic fields having phases opposite to each other.

  Further, since the magnetic fields HLtrA and HLtrB are opposite in phase to each other, the magnetic fields HLtrA and HLtrB generate the first magnetic flux that links the first and second windings LtrA and LtrB of the first coil Ltr1. To do. When the first magnetic flux is linked to the power receiving coil Lr, an electromotive force is generated in the power receiving coil Lr, and a current flows. The current generated in the power receiving coil Lr is rectified by the rectifier circuit DB, and power is output to the load R. Here, since the electromagnetic shielding plate S that suppresses magnetic coupling is installed between the first coil Ltr1 and the auxiliary coil Ln, the generated magnetic flux is linked to the auxiliary coil Ln by the magnetic fields HLtrA and HLtrB. That is suppressed.

  Furthermore, since the resonance capacitor Cr is connected to the power receiving coil Lr, the phase of the current in the power receiving coil Lr is shifted by 90 degrees with respect to the phase of the current flowing in the first coil Ltr1. That is, as shown in FIG. 3b, when the output current phase of the first inverter INV1 that supplies current to the first coil Ltr1 is 90 degrees, the intensity of the magnetic field HLr generated by the current flowing through the power receiving coil Lr is maximum. It becomes.

  On the other hand, the auxiliary coil Ln is supplied with a current that is 90 degrees out of phase with the phase of the current output from the first inverter INV1 to the first coil Ltr1 from the second inverter INV2. As shown in FIG. 4, when the output current phase of the first inverter INV1 that supplies current to the first coil Ltr1 is 90 degrees, the instantaneous current value flowing through the auxiliary coil Ln becomes the maximum, and the magnetic field generated by the auxiliary coil Ln. The intensity of HLn is maximized. Further, the axial direction of the auxiliary coil Ln coincides with the axial direction of the power receiving coil Lr. Further, the auxiliary coil Ln has a magnetic field HLn generated by the auxiliary coil Ln opposite to the magnetic field HLr generated by the power receiving coil Lr. Since the coils are wound so as to be in phase, the magnetic field HLn generated by the auxiliary coil Ln and the magnetic field HLr generated by the power receiving coil Lr have opposite phases. As a result, at a place away from the wireless power transmission device S1, the magnetic field HLr generated by the power receiving coil Lr and the magnetic field HLn generated by the auxiliary coil Ln cancel each other, thereby reducing the leakage magnetic field. At this time, since there is an electromagnetic shielding plate S between the auxiliary coil Ln and the first coil Ltr1, unnecessary electromagnetic interference between the first coil Ltr1 and the auxiliary coil Ln can be reduced. The auxiliary coil Ln can more reliably reduce the leakage magnetic field generated by the power receiving coil Lr.

  As described above, in the wireless power transmission device S1 according to the present embodiment, the auxiliary coil Ln in the coil unit Ltu1 transmits and receives power wirelessly between the first coil Ltr1 and electromagnetic resonance. A magnetic field HLn having a phase opposite to that of the magnetic field HLr generated by the power receiving coil Lr, which is a coil, is generated. Therefore, the auxiliary coil Ln generates a magnetic field having a phase opposite to that of the power receiving coil Lr, which is another coil that wirelessly transmits and receives power to and from the first coil Ltr1 by electromagnetic resonance. An unnecessary leakage magnetic field generated by the power receiving coil Lr, which is a coil, can be reduced. As a result, it is possible to reduce an unnecessary leakage magnetic field generated from the power receiving coil Lr, which is a coil disposed oppositely, while suppressing an increase in size and weight of the power receiving coil Lr, which is a coil disposed oppositely.

  In addition, the wireless power transmission device S1 according to the present embodiment includes an electromagnetic shielding plate S that suppresses the magnetic coupling between the first coil Ltr1 and the auxiliary coil Ln. As a result, unnecessary electromagnetic interference between the first coil Ltr1 and the auxiliary coil Ln can be reduced, so that an unnecessary leakage magnetic field generated by the power receiving coil Lr, which is another coil, can be more reliably reduced. Can do.

  Furthermore, in the wireless power transmission device S1 according to the present embodiment, the first coil Ltr1 includes first and second windings LtrA and LtrB that are electrically connected to each other, and the first coil LtrA and the first coil LtrA. The second winding LtrB generates a magnetic field HLtrA and a magnetic field HLtrB having opposite phases. Therefore, an unnecessary leakage magnetic field generated by the first coil Ltr1 can be reduced by the first winding LtrA and the second winding LtrB that generate the magnetic field HLtrA and the magnetic field HLtrB having opposite phases to each other.

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

  As illustrated in FIG. 4, the wireless power transmission device S2 includes a wireless power transmission device Ut2 and a wireless power reception device Ur1. The wireless power transmission device Ut2 includes a first power supply PW1, a first inverter INV1, and a coil unit Ltu2. The wireless power receiving device Ur1 includes a power receiving coil Lr, a resonant capacitor Cr, a rectifier circuit DB, and a load R. The wireless power transmission device S2 wirelessly transmits power from the wireless power transmission device Ut2 to the wireless power reception device Ur1 when the coil unit Ltu2 of the wireless power transmission device Ut2 and the power reception coil Lr of the wireless power reception device Ur1 face each other. Here, the configurations of the first power supply PW1, the first inverter INV1, the power receiving coil Lr, the resonance capacitor Cr, the rectifier circuit DB, and the load R are the same as those of the wireless power transmission device S1 according to the first embodiment. The wireless power transmission device S2 according to the second embodiment includes a coil unit Ltu2 and an electromagnetic shielding plate Sb, respectively, instead of the coil unit Ltu1 and the electromagnetic shielding plate S of the wireless power transmission device S1 according to the first embodiment. The second power source PW2 is different from the wireless power transmission device S1 according to the first embodiment in that the second power source PW2 and the second inverter INV2 are not provided. Hereinafter, a description will be given focusing on differences from the first embodiment. In the present embodiment, the other coil that transmits and receives power to and from the first coil by electromagnetic resonance means the power receiving coil Lr as in the first embodiment.

  As shown in FIGS. 4 and 5, the coil unit Ltu2 includes the first coil Ltr1, the second coil Lte, the resonance capacitor Ct, the auxiliary coil Ln, the electromagnetic shielding plate Sb, and the first magnetic It has a core Ft and a second magnetic core Fn. Here, the first coil Ltr1, the first magnetic core Ft, and the second magnetic core Fn are the same as those of the wireless power transmission device S1 according to the first embodiment.

  Since the second coil Lte is disposed in the vicinity of the first coil Ltr1, it is strongly magnetically coupled to the first coil Ltr1. In the present embodiment, the second coil Lte is on the side opposite to the side facing the power receiving coil Lr of the first winding LtrA included in the first coil Ltr1, and is close to the first winding LtrA. The second coil Lte is arranged so that the axis of the second coil Lte coincides with the axis of the first winding LtrA, and one protrusion of the first magnetic core Ft is formed of a litz wire such as copper or aluminum. It is constructed by winding a wire. The second coil Lte is opposite to the side facing the power receiving coil Lr of the second winding LtrB included in the first coil Ltr, is close to the second winding LtrB, The coil Lte may be configured such that the axis of the coil Lte coincides with the axis of the second winding LtrB, and the winding is wound around the other protrusion of the first magnetic core Fr. Further, the number of turns of the second coil Lte is set to be smaller than the number of turns of the first or second winding LtrA, LtrB of the first coil Ltr. Here, since a resonance capacitor Ct, which will be described later, is connected to the second coil Lte, the electrical impedance of the second coil Lte viewed from the first coil Ltr1 is very small. Even if the number of turns of Lte is small, a sufficient current can be generated in the second coil Lte and the auxiliary coil Ln.

  The resonant capacitor Ct is electrically connected to the second coil Lte and the auxiliary coil Ln. The capacitance of the resonance capacitor Ct is set so as to resonate with the impedance of the second coil Lte and the auxiliary coil Ln at the frequency of the current supplied from the first inverter INV1. In the present embodiment, the resonance capacitor Ct is connected in series with the second coil Lte and the auxiliary coil Ln. However, the present invention is not limited to this, and the resonance capacitor Ct is in parallel with the second coil Lte and the auxiliary coil Ln. May be connected. In either case, the capacitance of the resonance capacitor Ct is set so that the impedance of the second coil Lte and the auxiliary coil Ln resonates at the frequency of the current supplied from the first inverter INV1. That's fine.

  The auxiliary coil Ln is electrically connected to the second coil Lte and the resonance capacitor Ct. The auxiliary coil Ln is a solenoid-structured coil and is formed by spirally winding a litz wire such as copper or aluminum. The axial direction of the auxiliary coil Ln substantially coincides with the axial direction of the power receiving coil Lr described later. In this embodiment, the axial direction of the auxiliary coil Ln is the facing direction between the coil unit Ltu2 and the power receiving coil Lr described later. The direction of the axis of the auxiliary coil Ln is perpendicular to the direction of the axes of the first and second windings LtrA and LtrB of the first coil Ltr1. The auxiliary coil Ln generates a magnetic field having an opposite phase to the magnetic field generated by the power receiving coil Lr described later. Here, in order to set the magnetic field generated by the auxiliary coil Ln in reverse phase to the magnetic field generated by the power receiving coil Lr, which will be described later, the winding direction of the winding of the power receiving coil Lr, which is described later, It may be wound in the opposite direction. The number of turns of the auxiliary coil Ln is appropriately set based on a separation distance between the coil unit Ltu1 and a power receiving coil Lr described later, a desired leakage magnetic field reduction effect, and the like.

  The electromagnetic shielding plate Sb is disposed between the first coil Ltr1, the second coil Lte, and the auxiliary coil Ln and along the axial direction of the auxiliary coil Ln. Specifically, the electromagnetic shielding plate Sb is disposed between the first magnetic core Ft and the auxiliary coil Ln. The electromagnetic shielding plate Sb functions as a shielding material that suppresses unnecessary magnetic coupling between the first coil Ltr1, the second coil Lte, and the auxiliary coil Ln. In other words, the electromagnetic shielding plate Sb functions as a shielding material that cancels the magnetic field by an induced current, an eddy current, or the like and suppresses the passage of magnetic flux. Thereby, unnecessary electromagnetic interference between the first coil Ltr1 and the second coil Lte and the auxiliary coil Ln can be reduced. The electromagnetic shielding plate Sb is not particularly limited as long as the surface is a nonmagnetic conductor that functions as an electromagnetic shielding material, and examples thereof include copper, aluminum, and a steel plate having a surface galvanized. It should be noted that the wiring that electrically connects the second coil Lte and the auxiliary coil Ln may be routed so as to penetrate the hole formed in the electromagnetic shielding plate Sb, or may be routed around the electromagnetic shielding plate Sb. .

  Next, with reference to FIG. 6, details of the magnetic field generated by each of the first coil Ltr1, the second coil Lte, the auxiliary coil Ln, and the power receiving coil Lr and the action of reducing unnecessary leakage magnetic fields in the present embodiment. Explained. FIG. 6a is a diagram schematically showing the direction of the magnetic field generated by each coil when the output current phase of the first inverter is 0 degree in FIG. FIG. 6b is a diagram schematically showing the direction of the magnetic field generated by each coil when the output current phase of the first inverter is 90 degrees in FIG. In FIGS. 6a and 6b, the first magnetic core Ft, the second magnetic core Fn, and the third magnetic core Fr are omitted for convenience of explanation.

  When the output current phase of the first inverter INV1 that supplies current to the first coil Ltr1 is 0 degrees, that is, when the instantaneous value of the output current of the sine wave-like first inverter INV1 is maximized, it is shown in FIG. As described above, the strengths of the magnetic fields HLtrA and HLtrB generated by the first and second windings LtrA and LtrB of the first coil Ltr1 are maximized. The magnetic fields HLtrA and HLtrB are parallel to the facing direction of the coil unit Ltu2 and the power receiving coil Lr, and are magnetic fields having opposite phases. Therefore, the leakage magnetic field generated by the first coil Ltr1 can be reduced by the first winding LtrA and the second winding LtrB that generate magnetic fields having phases opposite to each other.

  In addition, since the magnetic fields HLtrA and HLtrB are in opposite phases, the magnetic fields HLtrA and HLtrB generate a first magnetic flux that links the first and second windings LtrA and LtrB of the first coil Ltr1. . When the first magnetic flux is linked to the power receiving coil Lr, an electromotive force is generated in the power receiving coil Lr, and a current flows. The current generated in the power receiving coil Lr is rectified by the rectifier circuit DB, and power is output to the load R.

  Further, since the resonance capacitor Cr is connected to the power receiving coil Lr, the phase of the current flowing through the power receiving coil Lr is shifted by 90 degrees with respect to the phase of the current flowing through the first coil Ltr1. That is, as shown in FIG. 6b, when the output current phase of the first inverter INV1 that supplies current to the first coil Ltr1 is 90 degrees, the intensity of the magnetic field HLr generated by the current flowing through the power receiving coil Lr is maximum. It becomes.

  On the other hand, since the magnetic flux generated by the first and second windings LtrA and LtrB of the first coil Ltr1 is also linked to the second coil Lte, an electromotive force is generated in the second coil Lte, and current is generated. Flowing. At this time, since the resonance capacitor Ct is connected to the second coil Lte, the electrical impedance of the second coil Lte viewed from the first coil Ltr1 is very small. Even if the number of turns is small, a sufficient current is generated in the second coil Lte. In addition, since the resonance capacitor Ct is connected to the second coil Lte, the phase of the current in the second coil Lte is shifted by 90 degrees with respect to the phase of the current flowing in the first coil Ltr1. That is, the phase of the current flowing through the second coil Lte is the same as the phase of the current flowing through the power receiving coil Lr. Here, since the electromagnetic shielding plate Sb that suppresses magnetic coupling is installed between the first coil Ltr1 and the second coil Lte and the auxiliary coil Ln, the magnetic flux generated by the magnetic fields HLtrA and HLtrB is supplemented. Interlinking with the coil Ln is suppressed.

  Furthermore, since the auxiliary coil Ln is electrically connected to the second coil Lte, a current having the same phase as that of the second coil Lte flows through the auxiliary coil Ln. That is, a current having the same phase as the current flowing through the power receiving coil Lr flows through the auxiliary coil Ln, and is generated by the current flowing through the auxiliary coil Ln when the inverter output current phase for supplying current to the first coil Ltr1 is 90 degrees. The intensity of the magnetic field HLn to be maximized. Here, the axial direction of the auxiliary coil Ln coincides with the axial direction of the power receiving coil Lr, and the winding direction of the winding of the auxiliary coil Ln and the winding direction of the winding of the power receiving coil Lr are opposite to each other. The magnetic field HLn generated by the auxiliary coil Ln and the magnetic field HLr generated by the power receiving coil Lr are in opposite phases. As a result, at a place away from the wireless power transmission device S2, the magnetic field HLr generated by the power receiving coil Lr and the magnetic field HLn generated by the auxiliary coil Ln cancel each other, thereby reducing the leakage magnetic field. At this time, the magnetic field HLte is generated by the second coil Lte through which the same current as that of the auxiliary coil Ln flows. However, since the number of turns of the second coil Lte is small, the strength of the magnetic field HLte is low. Therefore, the strength of the leakage magnetic field formed at a location away from the coil unit Ltu2 by the second coil Lte is also low, and the influence is small.

  As described above, in the wireless power transmission device S2 according to the present embodiment, the auxiliary coil Ln in the coil unit Ltu2 transmits and receives power wirelessly with the first coil Ltr1 by electromagnetic resonance. A magnetic field HLn having a phase opposite to that of the magnetic field HLr generated by the power receiving coil Lr, which is a coil, is generated. Therefore, the auxiliary coil Ln generates a magnetic field having a phase opposite to that of the power receiving coil Lr, which is another coil that wirelessly transmits and receives power to and from the first coil Ltr1 by electromagnetic resonance. An unnecessary leakage magnetic field generated by the power receiving coil Lr, which is a coil, can be reduced. As a result, it is possible to reduce an unnecessary leakage magnetic field generated from the power receiving coil Lr, which is a coil disposed oppositely, while suppressing an increase in size and weight of the power receiving coil Lr, which is a coil disposed oppositely.

  In the wireless power transmission device S2 according to the present embodiment, the coil unit Ltu2 includes a second coil Lte that is magnetically coupled to the first coil Ltr1, and a resonance capacitor Ct that is connected to the second coil Lte. The auxiliary coil Ln is electrically connected to the second coil Lte, and the winding is wound so as to generate a magnetic field HLn having a phase opposite to that of the magnetic field HLr generated by the power receiving coil Lr, which is another coil. It has been turned. Here, since the first coil Ltr1 is magnetically coupled to the second coil Lte, and the second coil Lte is connected to the resonance capacitor Ct, the phase of the current flowing through the second coil Lte is the first 90 degrees with respect to the phase of the current flowing through the coil Ltr1. Furthermore, the phase of the current that flows through the power receiving coil Lr, which is another coil that wirelessly transmits and receives power by electromagnetic resonance with the first coil Ltr1, is the phase of the current that flows through the first coil Ltr1. It is 90 degrees off. At this time, power is transmitted wirelessly between the phase of the current flowing through the second coil Lte and the phase of the current flowing through the auxiliary coil Ln electrically connected to the second coil Lte and the first coil Ltr1. The phase of the current flowing through the power receiving coil Lr, which is another coil that receives power, is the same phase. Therefore, since the auxiliary coil Ln is wound so that the magnetic field generated by the auxiliary coil Ln is opposite in phase to the magnetic field generated by the power receiving coil Lr, which is another coil, A magnetic field HLn having a phase opposite to that of a certain receiving coil Lr is generated. Therefore, an unnecessary leakage magnetic field generated by the power receiving coil Lr, which is another coil, can be reduced. As a result, in order to supply power to the first coil Ltr1 and the second coil Lte, a plurality of AC power sources are not required, and the power receiving coil Lr, which is a coil arranged to be opposed to only one AC power source, is used. While suppressing an increase in size and weight, an unnecessary leakage magnetic field generated from the power receiving coil Lr, which is a coil arranged oppositely, can be reduced. Moreover, the remarkable enlargement and weight increase of the entire wireless power transmission device S2 can be suppressed.

  Furthermore, in the wireless power transmission device S2 according to the present embodiment, the coil unit Ltu2 further includes an electromagnetic shielding plate Sb that suppresses magnetic coupling between the first coil Ltr1 and the second coil Lte and the auxiliary coil Ln. . As a result, unnecessary electromagnetic interference between the first coil Ltr1 and the auxiliary coil Ln can be reduced, so that an unnecessary leakage magnetic field generated by the power receiving coil Lr, which is another coil, can be more reliably reduced. Can do.

(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 schematic system configuration diagram showing a wireless power transmission device according to the third embodiment of the present invention. FIG. 8 is a cross-sectional view showing a coil unit together with a power receiving coil in a wireless power transmission device according to a third embodiment of the present invention. The coil unit according to the present invention can be applied to either a wireless power transmission device or a wireless power reception device in a wireless power transmission device, but here, an example in which the coil unit according to the present invention is applied to a wireless power transmission device. It explains using.

  As illustrated in FIG. 7, the wireless power transmission device S3 includes a wireless power transmission device Ut3 and a wireless power reception device Ur1. The wireless power transmitting apparatus Ut3 includes a first power supply PW1, a first inverter INV1, and a coil unit Ltu3. The wireless power receiving device Ur1 includes a power receiving coil Lr, a resonant capacitor Cr, a rectifier circuit DB, and a load R. In the wireless power transmission device S3, the coil unit Ltu3 of the wireless power transmission device Ut3 and the power reception coil Lr of the wireless power reception device Ur1 face each other, so that power is transmitted wirelessly from the wireless power transmission device Ut3 to the wireless power reception device Ur1. Here, the configurations of the first power supply PW1, the first inverter INV1, the power receiving coil Lr, the resonance capacitor Cr, the rectifier circuit DB, and the load R are the same as those of the wireless power transmission device S2 according to the second embodiment. The wireless power transmission device S3 according to the third embodiment is different from the wireless power transmission device S2 according to the second embodiment in that a coil unit Ltu3 is provided instead of the coil unit Ltu2. Hereinafter, a description will be given focusing on differences from the second embodiment. In the present embodiment, the other coil that transmits and receives power to and from the first coil by electromagnetic resonance means the power receiving coil Lr as in the first embodiment.

  The coil unit Ltu3 includes a first coil Ltr2, a second coil Lte, a resonance capacitor Ct, an auxiliary coil Ln, an electromagnetic shielding plate Sb, a first magnetic core Ft, and a second magnetic core Fn. , A fourth magnetic core FtC, and a fifth magnetic core FtD. Here, the configurations of the resonant capacitor Ct, the second coil Lte, the auxiliary coil Ln, the electromagnetic shielding plate Sb, the first magnetic core Fn, and the second magnetic core Fn are related to the second embodiment. This is the same as the wireless power transmission device S2.

  The first coil Ltr2 includes a first winding LtrA, a second winding LtrB, a third winding LtrC, and a fourth winding LtrD. In the present embodiment, the first winding LtrA, the second winding LtrB, the third winding LtrC, and the fourth winding LtrD are electrically connected in series. Here, the configurations of the first and second windings LtrA and LtrB are the same as those of the first and second windings LtrA and LtrB of the first coil Ltr1 of the wireless power transmission device S2 according to the second embodiment. is there.

  The third winding LtrC is disposed on the back side of the first winding LtrA. That is, the third winding LtrC is disposed on the opposite side of the surface of the first winding LtrA that faces the power receiving coil Lr. More specifically, as shown in FIG. 8, the third winding LtrC is arranged so as to overlap the first winding LtrA when viewed from the facing direction of the coil unit Ltu3 and the power receiving coil Lr. Yes. The third winding LtrC is a solenoid-structured coil and is formed by spirally winding a litz wire such as copper or aluminum. The axial direction of the third winding LtrC is a direction orthogonal to the facing direction of the coil unit Ltu3 and the power receiving coil Lr. That is, the axial direction of the third winding LtrC is a direction orthogonal to the axial direction of the first winding LtrA. Therefore, the third winding LtrC can more easily generate a magnetic flux that circulates to a place away from the third winding LtrC, and the leakage magnetic field generated by the first coil Ltr2 can be further reduced. . Furthermore, the number of turns of the third winding LtrC is appropriately set based on a desired leakage magnetic field reduction effect or the like.

  Here, the third winding LtrC generates a second magnetic flux interlinking with the first winding LtrA. Specifically, in FIG. 8, when the first winding LtrA generates a magnetic field in the direction (upward in the drawing) from the first winding LtrA to the power receiving coil Lr, the third winding LtrC If a magnetic field in the direction from the third winding LtrC toward the first winding LtrA (rightward in the figure) is generated, the third winding LtrC is linked to the first winding LtrA by the second magnetic flux. Will be generated. On the other hand, when the first winding LtrA generates a magnetic field in the direction (downward in the drawing) from the power receiving coil Lr to the first winding LtrA, the third winding LtrC is converted into the first winding LtrA. If a magnetic field in the direction (leftward in the figure) from the first to the third winding LtrC is generated, the third winding LtrC generates a second magnetic flux interlinking with the first winding LtrA. In order to generate such a magnetic field, the direction of the current passing through the portion of the third winding LtrC that is closest to the first winding LtrA (the upper surface portion of the third winding LtrC in the drawing) is the first direction. The winding direction of the litz wire is selected so that the direction of the current passing through the portion closest to the third winding LtrC (the left portion of the first winding LtrA in the figure) in the winding LtrA of The third winding LtrC may be configured. Further, in the third winding LtrC, the circulation direction of the second magnetic flux generated by the third winding LtrC is the same as the rotation direction of the first magnetic flux generated by the first and second windings LtrA and LtrB. Are arranged in the opposite direction. In order to obtain such a magnetic flux, the second winding LtrB from the center of the first winding LtrA in the arrangement direction of the first winding LtrA and the second winding LtrB as seen from the power receiving coil Lr. The third winding LtrC only needs to be arranged at a position shifted to the opposite side to the direction toward the center.

  The fourth winding LtrD is disposed on the back side of the second winding LtrB. That is, the fourth winding LtrD is disposed on the opposite side of the surface of the second winding LtrB that faces the power receiving coil Lr. More specifically, as shown in FIG. 8, the fourth winding LtrD is arranged so as to overlap the second winding LtrB when viewed from the facing direction of the coil unit Ltu3 and the power receiving coil Lr. Yes. The fourth winding LtrD is a solenoid-structured coil, and is formed by spirally winding a litz wire such as copper or aluminum. The axial direction of the fourth winding LtrD is a direction orthogonal to the facing direction of the coil unit Ltu3 and the power receiving coil Lr. That is, the axial direction of the fourth winding LtrD is a direction orthogonal to the axial direction of the second winding LtrB. Therefore, the fourth winding LtrD can more easily generate a magnetic flux that circulates to a place away from the fourth winding LtrD, and the leakage magnetic field generated by the first coil Ltr2 can be further reduced. . Furthermore, the number of turns of the fourth winding LtrD is appropriately set based on a desired leakage magnetic field reduction effect or the like.

  Here, the fourth winding LtrD generates a third magnetic flux interlinking with the second winding LtrB. Specifically, in FIG. 8, when the second winding LtrB generates a magnetic field in the direction (upward in the drawing) from the second winding LtrB to the power receiving coil Lr, the fourth winding LtrD If a magnetic field is generated in the direction from the fourth winding LtrD toward the second winding LtrB (leftward in the figure), the fourth winding LtrD is linked to the second winding LtrB by the third magnetic flux. Will be generated. On the other hand, when the second winding LtrB generates a magnetic field in the direction (downward in the drawing) from the power receiving coil Lr to the second winding LtrB, the fourth winding LtrD is converted into the second winding LtrB. If a magnetic field is generated in a direction (rightward in the figure) from the first to the fourth winding LtrD, the fourth winding LtrD generates a third magnetic flux interlinking with the second winding LtrB. In order to generate such a magnetic field, the direction of the current passing through the portion of the fourth winding LtrD that is closest to the second winding LtrB (the upper surface portion of the fourth winding LtrD in the drawing) is The winding direction of the litz wire is selected so that the direction of the current passing through the portion closest to the fourth winding LtrD in the winding LtrB (the right side portion of the second winding LtrB shown in the drawing) is the same. The fourth winding LtrD may be configured. Further, in the fourth winding LtrD, the circulation direction of the third magnetic flux generated by the fourth winding LtrD is the same as the rotation direction of the first magnetic flux generated by the first and second windings LtrA and LtrB. Are arranged in the opposite direction. In order to obtain such a magnetic flux, the first winding LtrA from the center of the second winding LtrB in the arrangement direction of the first winding LtrA and the second winding LtrB as seen from the power receiving coil Lr. The fourth winding LtrD has only to be arranged at a position shifted to the opposite side to the direction toward the center.

  The fourth magnetic core FtC is made of a magnetic material such as plate-like or rod-like ferrite, and is arranged so as to penetrate the axis of the third winding LtrC. That is, the fourth magnetic core FtC functions as the core of the third winding LtrC of the first coil Ltr2. Therefore, the magnetic flux for reducing the leakage magnetic field is efficiently generated by the third winding LtrC. The fourth magnetic core FtC is connected to the first magnetic core Ft. Therefore, the third winding LtrC can efficiently generate the second magnetic flux interlinking with the first winding LtrA. Note that the fourth magnetic core FtC and the first magnetic core Ft may be integrally formed.

  The fifth magnetic core FtD is made of a magnetic material such as a plate-like or rod-like ferrite, and is disposed so as to penetrate the axis of the fourth winding LtrD. That is, the fifth magnetic core FtD functions as the core of the fourth winding LtrD of the first coil Ltr2. Therefore, a magnetic flux for reducing the leakage magnetic field is efficiently generated by the fourth winding LtrD. The fifth magnetic core FtD is connected to the first magnetic core Ft. Therefore, the fourth winding LtrD can efficiently generate the third magnetic flux interlinking with the second winding LtrB. Note that the fifth magnetic core FtD and the first magnetic core Ft may be integrally formed.

  Subsequently, with reference to FIG. 9, the details of the magnetic field generated by each of the first coil Ltr2, the second coil Lte, the auxiliary coil Ln, and the power receiving coil Lr and the action of reducing unnecessary leakage magnetic fields in the present embodiment. Explained. FIG. 9a is a diagram schematically showing the direction of the magnetic field generated by each coil when the output current phase of the first inverter is 0 degree in FIG. FIG. 9b is a diagram schematically showing the direction of the magnetic field generated by each coil when the output current phase of the first inverter is 90 degrees in FIG. In FIG. 9a and FIG. 9b, the first magnetic core Ft, the second magnetic core Fn, the third magnetic core Fr, the fourth magnetic core FtC, and the fifth magnetic core FtD are omitted for convenience of explanation. doing.

  When the output current phase of the first inverter INV1 that supplies current to the first coil Ltr2 is 0 degrees, that is, when the instantaneous value of the output current of the sine wave-like first inverter INV1 is maximized, it is shown in FIG. 9a. As described above, the strengths of the magnetic fields HLtrA and HLtrB generated by the first and second windings LtrA and LtrB of the first coil Ltr2 are maximized. The magnetic fields HLtrA and HLtrB are parallel to the facing direction of the coil unit Ltu3 and the power receiving coil Lr, and are magnetic fields having opposite phases. Therefore, the leakage magnetic field generated by the first coil Ltr2 can be reduced by the first winding LtrA and the second winding LtrB that generate magnetic fields having phases opposite to each other.

  Further, since the magnetic fields HLtrA and HLtrB are opposite in phase, the magnetic fields HLtrA and HLtrB generate a first magnetic flux that links the first and second windings LtrA and LtrB of the first coil Ltr2. . When the first magnetic flux is linked to the power receiving coil Lr, an electromotive force is generated in the power receiving coil Lr, and a current flows. The current generated in the power receiving coil Lr is rectified by the rectifier circuit DB, and power is output to the load R.

  Furthermore, since the resonance capacitor Cr is connected to the power receiving coil Lr, the phase of the current in the power receiving coil Lr is shifted by 90 degrees with respect to the phase of the current flowing in the first coil Ltr2. That is, as shown in FIG. 9b, when the output current phase of the first inverter INV1 that supplies current to the first coil Ltr2 is 90 degrees, the intensity of the magnetic field HLr generated by the current flowing through the power receiving coil Lr is maximum. It becomes.

  On the other hand, since the magnetic flux generated by the first and second windings LtrA and LtrB of the first coil Ltr2 is also linked to the second coil Lte, an electromotive force is generated in the second coil Lte, and current is generated. Flowing. At this time, since the resonance capacitor Ct is connected to the second coil Lte, the electrical impedance of the second coil Lte viewed from the first coil Ltr2 is very small. Even if the number of turns is small, a sufficient current is generated in the second coil Lte. Further, since the resonance capacitor Ct is connected to the second coil Lte, the phase of the current flowing through the second coil Lte is shifted by 90 degrees with respect to the phase of the current flowing through the first coil Ltr2. That is, the phase of the current flowing through the second coil Lte is in phase with the current flowing through the power receiving coil Lr. Here, since the electromagnetic shielding plate Sb that suppresses magnetic coupling is installed between the first coil Ltr2 and the second coil Lte and the auxiliary coil Ln, the magnetic flux generated by the magnetic fields HLtrA and HLtrB is supplemented. Interlinking with the coil Ln is suppressed.

  Furthermore, since the auxiliary coil Ln is electrically connected to the second coil Lte, a current having the same phase as that of the second coil Lte flows through the auxiliary coil Ln. That is, a current having the same phase as the current flowing through the power receiving coil Lr flows through the auxiliary coil Ln, and when the output current phase of the first inverter INV1 that supplies current to the first coil Ltr2 is 90 degrees, the auxiliary coil Ln The intensity of the magnetic field HLn generated by the current flowing in the current becomes maximum. Here, the axial direction of the auxiliary coil Ln coincides with the axial direction of the power receiving coil Lr, and the winding direction of the winding of the auxiliary coil Ln and the winding direction of the winding of the power receiving coil Lr are the same direction. The magnetic field HLn generated by the auxiliary coil Ln and the magnetic field HLr generated by the power receiving coil Lr are in opposite phases. As a result, in a place away from the wireless power transmission device S3, the magnetic field HLr generated by the power receiving coil Lr and the magnetic field HLn generated by the auxiliary coil Ln cancel each other, thereby reducing the leakage magnetic field.

  Subsequently, the reduction of the leakage magnetic field generated by the first coil Ltr2 will be described in detail with reference to FIG. FIG. 10 is a diagram schematically showing the magnetic flux generated by the first to fourth windings when the output current phase of the first inverter is 0 degree in FIG. However, in FIG. 10, illustration of magnetic flux in the first magnetic core Ft, the second magnetic core Fn, the third magnetic core Fr, the fourth magnetic core FtC, and the fifth magnetic core FtD is omitted. ing. In FIG. 10, among the first magnetic fluxes generated by the first and second windings LtrA and LtrB, magnetic fluxes Bt1a to Bt1d are shown as body surfaces, and the third and fourth windings LtrC, Of the second and third magnetic fluxes generated by LtrD, magnetic fluxes Bc1a to Bc1d are schematically shown as representative ones. However, these magnetic fluxes schematically show only the direction of each magnetic flux, and do not show the magnetic flux density.

  As shown in FIG. 10, the first and second windings LtrA and LtrB generate first magnetic fluxes Bt1a to Bt1d that link the first and second windings LtrA and LtrB together. Among these, the first magnetic fluxes Bt1a and Bt1b are magnetic fluxes linked to the power receiving coil Lr, and the first magnetic fluxes Bt1a and Bt1b are linked to the power receiving coil Lr, whereby an electromotive force is generated in the power receiving coil Lr. On the other hand, in the present embodiment, since the first and second windings LtrA and LtrB are wound in a plane, the first and second windings LtrA and LtrB are connected to the power receiving coil Lr. Without crossing the first coil Ltr2. The first magnetic fluxes Bt1c and Bt1d that circulate greatly to a place away from the center are also generated. The first magnetic fluxes Bt1c and Bt1d are supplied to the first coil Ltr2. The magnetic flux forms an unnecessary leakage magnetic field at a location away from

  The third winding LtrC generates second magnetic fluxes Bc1a and Bc1b that link the third winding LtrC and the first winding LtrA together. The third winding LtrC is on the back side of the first winding LtrA and is the first winding in the direction in which the first winding LtrA and the second winding LtrB are viewed from the power receiving coil Lr. Since the third magnetic fluxes Bc1a and Bc1b are arranged around the first magnetic fluxes Bt1a to Bt1d because the third magnetic fluxes Bc1a and Bc1b are arranged at positions shifted from the center of the LtrA toward the center of the second winding LtrB. The direction is the opposite of the direction of rotation. In the present embodiment, since the axial direction of the third winding LtrC is orthogonal to the axial direction of the first winding LtrA, the second magnetic fluxes Bc1a and Bc1b are separated from the first coil Ltr2. It becomes easy to go around to the place.

  The fourth winding LtrD generates third magnetic fluxes Bc1c and Bc1d that link the fourth winding LtrD and the second winding LtrB together. The fourth winding LtrD is on the back side of the second winding LtrB, and is the second winding in the arrangement direction of the first winding LtrA and the second winding LtrB when viewed from the power receiving coil Lr. Since the third magnetic fluxes Bc1a and Bc1b are arranged around the first magnetic fluxes Bt1a to Bt1d because the third magnetic fluxes Bc1a and Bc1b are arranged at positions shifted from the center of the LtrB toward the opposite side to the direction of the first winding LtrA. The direction is the opposite of the direction of rotation. In the present embodiment, since the axial direction of the fourth winding LtrD is orthogonal to the axial direction of the second winding LtrB, the third magnetic fluxes Bc1c and Bc1d are separated from the first coil Ltr2. It becomes easy to go around to the place.

  Here, as shown in FIG. 10, in the vicinity of the first coil Ltr2, the first magnetic fluxes Bt1a to Bt1d and the second and third magnetic fluxes Bc1a to Bc1d are substantially in the same direction. That is, the second magnetic fluxes Bc1a and Bc1b strengthen the magnetic field in the vicinity of the first winding LtrA, and the third magnetic fluxes Bc1c and Bc1d strengthen the magnetic field in the vicinity of the second winding LtrB. Therefore, the third and fourth windings LtrC and LtrD are prevented from reducing the power transmission efficiency. On the other hand, in a place away from the first coil Ltr2, the first magnetic fluxes Bt1c and Bt1d and the second and third magnetic fluxes Bc1a to Bc1d are opposite to each other. As a result, the first magnetic fluxes Bt1c and Bt1d and the second and third magnetic fluxes Bc1a to Bc1d cancel each other at a place away from the coil unit Ltu3, and the magnetic flux density is lowered. As a result, the first coils Ltr2. The leakage magnetic field strength indicated by the magnetic flux density at a location away from the magnetic field becomes low. That is, of the magnetic fields generated by the first and second windings LtrA and LtrB, only the leakage magnetic field is selectively reduced by the third and fourth windings LtrC and LtrD, and the first coil Ltr2 is generated. The leakage magnetic field can be further reduced. In particular, in the present embodiment, since the axial directions of the third and fourth windings LtrC and LtrD are orthogonal to the axial directions of the first and second windings LtrA and LtrB, 3 magnetic fluxes Bc1a to Bc1d are applied to the first coil Ltr2. It becomes easy to circulate greatly to a place away from the magnetic field, and the leakage magnetic field generated by the first coil Ltr2 can be further reduced.

  As described above, in the wireless power transmission device S3 according to the present embodiment, the auxiliary coil Ln in the coil unit Ltu3 transmits and receives power wirelessly between the first coil Ltr2 and electromagnetic resonance. A magnetic field HLn having a phase opposite to that of the magnetic field HLr generated by the power receiving coil Lr, which is a coil, is generated. Therefore, the auxiliary coil Ln generates a magnetic field having a phase opposite to that of the power receiving coil Lr, which is another coil in which power is transmitted and received wirelessly with the first coil Ltr2 by electromagnetic resonance. An unnecessary leakage magnetic field generated by the power receiving coil Lr, which is a coil, can be reduced. As a result, it is possible to reduce an unnecessary leakage magnetic field generated from the power receiving coil Lr, which is a coil disposed oppositely, while suppressing an increase in size and weight of the power receiving coil Lr, which is a coil disposed oppositely.

  In the wireless power transmission device S3 according to the present embodiment, the coil unit Ltu3 includes a second coil Lte that is magnetically coupled to the first coil Ltr2, and a resonance capacitor Ct that is connected to the second coil Lte. The auxiliary coil Ln is electrically connected to the second coil Lte, and the winding is wound so as to generate a magnetic field HLn having a phase opposite to that of the magnetic field HLr generated by the power receiving coil Lr, which is another coil. It has been turned. Here, since the first coil Ltr2 is magnetically coupled to the second coil Lte, and the second coil Lte is connected to the resonance capacitor Ct, the phase of the current flowing through the second coil Lte is the first 90 degrees with respect to the phase of the current flowing through the coil Ltr2. Furthermore, the phase of the current flowing through the power receiving coil Lr, which is another coil that wirelessly transmits and receives power by electromagnetic resonance with the first coil Ltr2, is the same as the phase of the current flowing through the first coil Ltr2. It is 90 degrees off. At this time, power is transmitted wirelessly between the phase of the current flowing through the second coil Lte and the phase of the current flowing through the auxiliary coil Ln electrically connected to the second coil Lte and the first coil Ltr2. The phase of the current flowing through the power receiving coil Lr, which is another coil that receives power, is the same phase. Therefore, since the auxiliary coil Ln is wound so that the magnetic field generated by the auxiliary coil Ln is opposite in phase to the magnetic field generated by the power receiving coil Lr, which is another coil, A magnetic field HLn having a phase opposite to that of a certain receiving coil Lr is generated. Therefore, an unnecessary leakage magnetic field generated by the power receiving coil Lr, which is another coil, can be reduced. As a result, in order to supply power to the first coil Ltr2 and the second coil Lte, a plurality of AC power sources are not required, and the power receiving coil Lr, which is a coil that is arranged to be opposed to only one AC power source, is used. While suppressing an increase in size and weight, an unnecessary leakage magnetic field generated from the power receiving coil Lr, which is a coil arranged oppositely, can be reduced. Moreover, the remarkable enlargement and weight increase of the entire wireless power transmission device S3 can be suppressed.

  Furthermore, in the wireless power transmission device S3 according to the present invention, the first coil Ltr2 in the coil unit Ltu3 includes the third winding LtrC disposed on the back side of the first winding LtrA and the second winding. A fourth winding LtrD disposed on the back side of the line LtrB, and the first winding LtrA, the second winding LtrB, the third winding LtrC, and the fourth winding LtrD are: The first and second windings LtrA and LtrB are electrically connected in series, and generate first magnetic fluxes Bt1a to Bt1d that link the first and second windings LtrA and LtrB together. The third winding LtrC generates second magnetic fluxes Bc1a and Bc1b interlinking with the first winding LtrA, and the fourth winding LtrD is the third magnetic flux interlinking with the second winding LtrB. Bc1c and Bc1d are generated, Rotating direction of the second and third flux Bc1a~Bc1d is the circumferential direction of the first magnetic flux Bt1a~Bt1d is configured to be opposite to. Therefore, the second magnetic fluxes Bc1a and Bc1b strengthen the magnetic field in the vicinity of the first winding LtrA, and the third magnetic fluxes Bc1c and Bc1d strengthen the magnetic field in the vicinity of the second winding LtrB. On the other hand, in a place away from the first coil Ltr2, the first and second magnetic fluxes Bc1a to Bc1d whose directions of rotation are opposite to each other and the second and third magnetic fluxes Bc1a to Bc1d cancel each other. As a result, the leakage magnetic field generated by the first coil Ltr2 can be further reduced without reducing the power transmission efficiency.

  Still further, in the wireless power transmission device S3 according to the present invention, the axial direction of the third winding LtrC in the coil unit Ltu3 is substantially orthogonal to the axial direction of the first winding LtrA, and the fourth winding The axial direction of LtrD is configured to be substantially orthogonal to the axial direction of the second winding LtrB. Therefore, the third and fourth windings LtrC and LtrD can easily generate the second magnetic fluxes Bc1a and Bc1b and the third magnetic fluxes Bc1c and Bc1d that circulate to a place away from the first coil Ltr2. As a result, the leakage magnetic field generated by the first coil Ltr2 can be further reduced.

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

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

  S1, S2, S3 ... wireless power transmission device, Ut1, Ut2, Ut3 ... wireless power transmission device, PW1 ... first power source, PW2 ... second power source, INV1 ... first inverter, INV2 ... second inverter, Ltu1 , Ltu2, Ltu3 ... coil unit, Ltr1, Ltr2 ... first coil, LtrA ... first winding, LtrB ... second winding, Ct ... resonant capacitor, Lte ... second coil, Ln ... auxiliary coil, S, Sb ... electromagnetic shielding plate, Ft ... first magnetic core, Fn ... second magnetic core, Ur1 ... wireless power receiving device, Lr ... receiving coil, Wr ... winding of receiving coil, Fr ... third magnetic core , Cr ... resonant capacitor, DB ... rectifier circuit, R ... load, LtrC ... third winding, LtrD ... fourth winding, FtC ... fourth magnetic core, FtD ... fifth magnetic core, LtrA: magnetic field generated by the first winding, HLtrB: magnetic field generated by the second winding, HLte: magnetic field generated by the second coil, HLn: magnetic field generated by the auxiliary coil, HLr: receiving coil generated HLtrC ... magnetic field generated by the third winding, HLtrD ... magnetic field generated by the fourth winding, Bt1a to Bt1d ... first magnetic flux, Bc1a, Bc1b ... second magnetic flux, Bc1c, Bc1d ... first 3 magnetic flux.

Claims (7)

A first coil included in one of the wireless power transmitting device and the wireless power receiving device ;
An auxiliary coil,
The auxiliary coil generates a magnetic field having a phase opposite to that of the magnetic field generated by the wireless power transmitting apparatus that transmits and receives power to and from the first coil by electromagnetic resonance and the other coil of the other of the wireless power receiving apparatus. A coil unit characterized by: A second coil magnetically coupled to the first coil;
A resonance capacitor connected to the second coil;
The auxiliary coil is electrically connected to the second coil, and a winding is wound so as to generate a magnetic field having a phase opposite to that of the magnetic field generated by the other coil. The coil unit according to claim 1 .   The coil unit according to claim 1, further comprising an electromagnetic shielding plate that suppresses magnetic coupling between the first and second coils and the auxiliary coil. The first coil includes first and second windings electrically connected to each other;
The coil unit according to any one of claims 1 to 3, wherein the first winding and the second winding generate magnetic fields opposite to each other. The first coil further includes a third winding disposed on the back side of the first winding and a fourth winding disposed on the back side of the second winding. ,
The first to fourth windings are electrically connected in series,
The first and second windings generate a first magnetic flux that links the first and second windings together;
The third winding generates a second magnetic flux interlinking with the first winding;
The fourth winding generates a third magnetic flux interlinking with the second winding,
The coil unit according to claim 4, wherein a circulation direction of the second and third magnetic fluxes is opposite to a circulation direction of the first magnetic flux. The axial direction of the third winding is substantially orthogonal to the axial direction of the first winding,
The coil unit according to claim 5, wherein an axial direction of the fourth winding is substantially orthogonal to an axial direction of the second winding. The power in wireless to the wireless power receiving apparatus from the wireless power transmission device is a wireless power transmission device is transmitted,
The said wireless power transmission apparatus has a coil unit as described in any one of Claims 1-6, The wireless power transmission apparatus characterized by the above-mentioned.

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