Power transmission equipment for wireless power transmission systems

Abstract

The present invention provides a power transmission device for a wireless power transmission system that can accommodate all power transmission coils without increasing the number of legs in the inverter circuit, even when multiple power transmission coils are used. [Solution] A power transmission device in a wireless power transmission system that wirelessly transmits power between power transmission coils 511-519 and a power receiving coil, comprising a plurality of power transmission coils 511-519 and an inverter circuit 40 having a plurality of legs 41-43 connected to a predetermined power source and connected in parallel to each other, wherein each power transmission coil 511-519 is assigned to one of the power transmission groups corresponding to each leg 41-43, and switching circuits 581-583 are provided to switch the power supply destination so that power from the inverter circuit 40 is supplied to one power transmission coil 511-519 for each power transmission group.

Description

[Technical Field]

[0001] The present invention relates to a power transmission device for a wireless power transmission system that performs wireless power transmission between a power transmission coil and a power receiving coil. [Background technology]

[0002] A wireless power transmission system is known that arranges multiple power transmission coils in a line on the same plane and performs wireless power transmission without precise position control of the power receiving coil (see, for example, Patent Document 1). The wireless power transmission device described in Patent Document 1 includes a transmitting antenna including a series resonant capacitor and a plurality of switchable transmitting coils, an inverter whose output side is connected to the transmitting antenna, and a controller that controls the inverter, the controller determining one power transmission coil to be used for power transmission based on predetermined conditions. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-78754 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In the wireless power transmission system described in Patent Document 1, there is only one power transmission coil used for power transmission. When using multiple power transmission coils and an inverter circuit that has legs connected in parallel to each other equal to the number of power transmission coils, the number of legs in the inverter circuit increases if there are many power transmission coils.

[0005] The present invention has been made in view of the above circumstances, and its object is to provide a power transmission device for a wireless power transmission system that can accommodate all power transmission coils without increasing the number of legs in the inverter circuit when multiple power transmission coils are used. [Means for solving the problem]

[0006] In this invention, A power transmission device in a wireless power transmission system that performs wireless power transmission between a power transmission coil and a power receiving coil, Multiple power transmission coils assigned to one of multiple power transmission groups, An inverter circuit that is connected to a predetermined power source and has multiple legs provided for each of the aforementioned power transmission groups and connected in parallel with each other, and supplies power to each of the aforementioned power transmission groups, A power transmission device for a wireless power transmission system is provided, which includes a switching circuit that switches the destination of the power supply so that the power from the inverter circuit is supplied to one of the power transmission coils selected from each of the power transmission groups. [Effects of the Invention]

[0007] According to the power transmission device of the wireless power transmission system of the present invention, when multiple power transmission coils are used, it is possible to accommodate all power transmission coils without increasing the number of legs in the inverter circuit. [Brief explanation of the drawing]

[0008] [Figure 1] This is a circuit diagram of a power transmission device and a power receiving device for a wireless power transmission system showing a first embodiment of the present invention. [Figure 2] This is a plan view diagram of the power transmission coil and power receiving coil. [Figure 3] This is an explanatory diagram showing the switching timing for each leg. [Figure 4] This is a plan view illustrating a power transmission coil and a power receiving coil as a second embodiment of the present invention. [Figure 5] This is a circuit diagram of the power transmission and receiving equipment for a wireless power transmission system. [Figure 6] This is a plan view illustrating a power transmission coil as a third embodiment of the present invention. [Figure 7] This is a circuit diagram of the power transmission and receiving equipment for a wireless power transmission system. [Figure 8]This is a plan view illustrating a power transmission coil as a fourth embodiment of the present invention. [Figure 9] This is a circuit diagram of the power transmission and receiving equipment for a wireless power transmission system. [Figure 10] This is a plan view illustrating a fifth embodiment of the present invention, showing a power transmission coil and a power reception coil. [Figure 11] This is a circuit diagram of the power transmission device for a wireless power transmission system. [Figure 12] This is a plan view illustrating a power transmission coil as an embodiment of the sixth embodiment of the present invention. [Figure 13] This is a circuit diagram of the power transmission device for a wireless power transmission system. [Figure 14] This is a plan view illustrating a power transmission coil as an embodiment of the seventh embodiment of the present invention. [Figure 15] This is a circuit diagram of the power transmission device for a wireless power transmission system. [Figure 16] This is a circuit diagram of a power transmission device showing a modified example. [Figure 17] This is a circuit diagram of a power transmission device showing a modified example. [Figure 18] This is a circuit diagram of a power transmission device showing a modified example. [Figure 19] This is a circuit diagram of a power transmission device showing a modified example. [Figure 20] This is a circuit diagram of a power transmission device showing a modified example. [Figure 21] This is a circuit diagram of a power receiving device showing a modified example. [Figure 22] This is a circuit diagram of a power receiving device showing a modified example. [Figure 23] This is a circuit diagram of a power transmission device illustrating a comparative example. [Figure 24] This shows the simulation results illustrating the power transmission efficiency of the examples and comparative examples. [Modes for carrying out the invention]

[0009] Figures 1 to 3 show a first embodiment of the present invention, where Figure 1 is a circuit diagram of a wireless power transmission system, Figure 2 is a plan view of the power transmission coil and power receiving coil, and Figure 3 is an explanatory diagram showing the switching of each leg.

[0010] As shown in Figure 1, this wireless power transmission system 1 comprises a power transmission device 2 having a plurality of power transmission coils 11, 12, 13, and a power receiving device 3 having a power receiving coil 20 that wirelessly transmits power to each of the power transmission coils 11, 12, 13. In this embodiment, as shown in Figure 2, three power transmission coils 11, 12, 13, which are circular in plan view and have a predetermined thickness, are arranged adjacent to each other on the same plane so as not to overlap. In this embodiment, the three power transmission coils 11, 12, 13 are identical. The power transmission device 2 and the power receiving device 3 are relatively movable, and wireless power transmission is possible when the power receiving coil 20 is in close proximity to each of the power transmission coils 11, 12, 13.

[0011] As shown in Figure 1, the power transmission device 2 is connected to a DC power supply 30 and includes an inverter circuit 40 that supplies power to each of the transmission coils 11, 12, and 13. The inverter circuit 40 has multiple legs 41, 42, and 43 connected in parallel to each other, provided for each of the transmission coils 11, 12, and 13 between the positive and negative buses. In this embodiment, since there are three transmission coils 11, 12, and 13, there are correspondingly three legs 41, 42, and 43. Each leg 41, 42, and 43 consists of positive-side switching elements 41a, 42a, and 43a connected to the positive side of the DC power supply 30, and negative-side switching elements 41b, 42b, and 43b connected to the negative side, all connected in series. For each of the switching elements 41a, 41b, 42a, 42b, 43a, and 43b, for example, transistors such as IGBTs, MOSFETs, and HEMTs can be used. Positive nodes 41c, 42c, and 43c are set between the positive switching elements 41a, 42a, and 43a and the negative switching elements 41b, 42b, and 43b, and are connected to the other ends of the respective power transmission coils 11, 12, and 13.

[0012] Furthermore, the inverter circuit 40 has a positive capacitor 51 and a negative capacitor 52 connected in series between the positive and negative busbars. The positive capacitor 51 and the negative capacitor 52 divide the input voltage from the DC power supply 30 equally. That is, when the input voltage of the DC power supply 30 is E, the voltage between the positive capacitor 51 and the negative capacitor 52 is designed to be E / 2. A negative node 53 is set between the positive capacitor 51 and the negative capacitor 52, which is connected to one end of each transmission coil 11, 12, and 13.

[0013] As shown in Figure 1, one end of each transmission coil 11, 12, and 13 is connected to one another. In this embodiment, it is a so-called Y connection, and a connection node 14 is set at one end of each transmission coil 11, 12, and 13. In this way, one end of each transmission coil 11, 12, and 13 is connected to the intermediate voltage of the input voltage of the DC power supply 30 via the inductor 60. The other ends of each transmission coil 11, 12, and 13 are connected to the respective legs 41, 42, and 43 via resonant capacitors 61, 62, and 63, respectively. In this embodiment, the inductor 60 and the resonant capacitors 61, 62, and 63 together with the transmission coils 11, 12, and 13 form a power factor compensation circuit 70 that forms a resonant circuit.

[0014] The inductance of inductor 60 is set based on the mutual inductance between each of the transmission coils 11, 12, and 13. In addition, the capacitance of each of the resonant capacitors 61, 62, and 63 is set considering the self-inductance of each of the transmission coils 11, 12, and 13 and the mutual inductance between each of the transmission coils 11, 12, and 13.

[0015] Specifically, in this embodiment, the self-inductances of each transmission coil 11, 12, and 13 are equal to each other, and the mutual inductances between each transmission coil 11, 12, and 13 are also equal to each other. However, since each transmission coil 11, 12, and 13 weakens the magnetic field of each other when current flows in the same direction, the value of the mutual inductance is negative. The operating angular frequency of the device is ω, and the self-inductance of each transmission coil 11, 12, and 13 is L. t, the mutual inductance between the power transmission coils 11, 12, and 13 is -M t (M t >0), when the capacitances C of the resonance capacitors 61, 62, and 63 t and the inductance L0 of the inductor 60 are C t =1 / (ω 2 (L t +M t )) L0 = M t is set as such.

[0016] Also, as shown in FIG. 1, the power receiving device 3 has a resonance capacitor 21 and a load resistor 22 connected in series to the power receiving coil 20. Power transmitted from the power transmission device 2 is supplied to the load resistor 22. In the power receiving device 3, the resonance capacitor 21 forms a power factor correction circuit on the power receiving side. When the self-inductance of the power receiving coil 20 is L r , the capacitance C of the resonance capacitor 21 r is C r =1 / (ω 2 L r ) is set as such.

[0017] Also, the power transmission device 2 has a control unit 80 that controls the switching operations of the switching elements 41a, 41b, 42a, 42b, 43a, and 43b. When the mutual inductances between the first to third power transmission coils 11, 12, 13 and the power receiving coil 20 are M t1r , M t2r , M t3r , and the currents of the first to third power transmission coils 11, 12, 13 are I t1 , I t2 , I t3 , the control unit 80 M t1r : M t2r : M t3r = I t1 : I t2 : I t3 The switching elements 41a, 41b, 42a, 42b, 43a, and 43b are controlled to achieve this. Here, assuming that the winding resistance of each transmission coil 11, 12, and 13 can be ignored, the ratio of the phase voltages output by the inverter circuit 40 is equal to the mutual inductance M between each transmission coil 11, 12, and 13 and the receiving coil 20. t1r M t2r M t3r This matches the ratio of the currents in each of the power transmission coils 11, 12, and 13 according to the ratio of the output voltages of the inverter circuit 40. As shown in Figure 3, the control unit 80 controls the mutual inductance M t1r M t2r M t3r If the current is negative, the phase of the current is controlled to shift by 180° (π) relative to the positive current.

[0018] With the power transmission device 2 of the wireless power transmission system 1 configured as described above, current is supplied to each of the transmission coils 11, 12, and 13 during wireless power transmission. Compared to conventional systems that select one transmission coil to supply current, power transmission efficiency can be improved. In particular, power transmission efficiency is greatly improved when the receiving coil 20 is located in the gap between each of the transmission coils 11, 12, and 13.

[0019] Furthermore, the control unit 80 controls the current of each transmission coil 11, 12, and 13 so that the ratio of the currents in each transmission coil 11, 12, and 13 is equal to the ratio of the mutual inductances between each transmission coil 11, 12, and 13 and the receiving coil 20, resulting in extremely high power transmission efficiency. In addition, since power is supplied to multiple transmission coils 11, 12, and 13 by a single inverter circuit 40, there is no need to provide multiple inverter circuits corresponding to multiple transmission coils, and the device can be made smaller.

[0020] Furthermore, since one end of each transmission coil 11, 12, and 13 is connected to each other and then connected to a predetermined voltage portion of the power supply voltage 30 via the inductor 60, a resonant circuit can be configured corresponding to the mutual inductance between each transmission coil 11, 12, and 13. Also, since each resonant capacitor 61, 62, and 63 is provided for each transmission coil 11, 12, and 13, a resonant circuit can be configured corresponding to the self-inductance of each transmission coil 11, 12, and 13. In particular, in this embodiment, C t = 1 / (ω 2 (L t +M t )), and L0=M t (M t By setting it >0, the reactance components caused by self-inductance and mutual inductance can be canceled out.

[0021] Figures 4 and 5 show a second embodiment of the present invention; Figure 4 is a plan view illustrating the power transmission coil and the power receiving coil, and Figure 5 is a circuit diagram of the power transmission device and the power receiving device of a wireless power transmission system.

[0022] In the wireless power transmission system 101 of this embodiment, as shown in Figure 4, two power transmission coils 111 and 112, which are rectangular in plan view and have a predetermined thickness, are arranged adjacent to each other on the same plane so as not to overlap. In this embodiment, the two power transmission coils 111 and 112 are identical. The power receiving device 103 includes a power receiving coil 120, a resonant capacitor 121 connected in series with the power receiving coil 120, and a load resistor 122.

[0023] As shown in Figure 5, the power transmission device 102 is connected to a DC power supply 130 and includes an inverter circuit 140 that supplies power to each transmission coil 111, 112. The inverter circuit 140 has two legs 141, 142 connected in parallel to each other, provided for each transmission coil 111, 112 between the positive and negative buses. Positive nodes 141c, 142c are set between the positive-side switching elements 141a, 142a and the negative-side switching elements 141b, 142b, which are connected in series, and are connected to the other ends of each transmission coil 111, 112.

[0024] Furthermore, the inverter circuit 140 has a positive capacitor 151 and a negative capacitor 152 between the positive and negative busbars. The positive capacitor 151 and the negative capacitor 152 divide the input voltage from the DC power supply 130 equally. A negative node 153 is set between the positive capacitor 151 and the negative capacitor 152, which is connected to one end of each transmission coil 111, 112.

[0025] As shown in Figure 5, one end of each transmission coil 111, 112 is connected to each other, and a connection node 114 is set. With one end of each transmission coil 111, 112 connected, it is connected to the intermediate voltage of the input voltage of the DC power supply 130 via the inductor 160. The other end of each transmission coil 111, 112 is connected to each leg 141, 142 via resonant capacitors 161, 162, respectively. In this embodiment, the inductor 160 and each resonant capacitor 161, 162 together with each transmission coil 111, 112 form a power factor compensation circuit 170 that forms a resonant circuit.

[0026] The inductance of inductor 160 is set based on the mutual inductance between each power transmission coil 111, 112. Similarly, the capacitance of each resonant capacitor 161, 162 is set based on the self-inductance of each power transmission coil 111, 112 and the mutual inductance between each power transmission coil 111, 112.

[0027] In this embodiment as well, the self-inductances of each transmission coil 111 and 112 are equal, and when current flows in the same direction, they weaken each other's magnetic fields, so the mutual inductance value between each transmission coil 111 and 112 is negative. The operating angular frequency of the device is ω, and the self-inductances of each transmission coil 111 and 112 are L. t The mutual inductance between each power transmission coil 111, 112 is -M t In this case, the capacitance C of each resonant capacitor 161, 162 t And the inductance L0 of inductor 160 is C t = 1 / (ω2 (L t +M t )) L0=M t (M t >0) This is how it is set.

[0028] Furthermore, as shown in Figure 5, the power receiving device 103 has a resonant capacitor 121 and a load resistor 122 connected in series with the power receiving coil 120. The self-inductance of the power receiving coil 120 is L r In this case, the capacitance C of the resonant capacitor 121 r teeth, C r = 1 / (ω 2 L r ) This is how it is set.

[0029] Furthermore, the power transmission device 102 has a control unit 180 that controls the switching operation of each switching element 141a, 141b, 142a, 142b. The mutual inductance between the first and second power transmission coils 111, 112 and the power receiving coil 120 is M t1r M t2r The current in the first and second transmission coils 111 and 112 is I t1 ,I t2 In that case, the control unit 180, M t1r :M t2r =I t1 :I t2 The switching elements 141a, 141b, 142a, and 142b are controlled to achieve this. Here, assuming that the winding resistance of each transmission coil 111 and 112 is negligible, the ratio of the phase voltages output by the inverter circuit 140 is equal to the mutual inductance M between each transmission coil 111 and 112 and the receiving coil 120. t1r M t2r This matches the ratio. In this case, the control unit 180 only needs to control the ratio of the currents in each power transmission coil 111, 112 according to the ratio of the output voltages of the inverter circuit 140.

[0030] With the power transmission device 102 of the wireless power transmission system 101 configured as described above, current is supplied to each of the power transmission coils 111 and 112 during wireless power transmission. Compared to conventional systems that select one power transmission coil to supply current, power transmission efficiency can be improved. In particular, power transmission efficiency is greatly improved when the receiving coil 120 is located midway between the power transmission coils 111 and 112.

[0031] Furthermore, the control unit 180 controls the current of each transmission coil 111, 112 so that the ratio of the currents in each transmission coil 111, 112 is equal to the ratio of the mutual inductances between each transmission coil 111, 112 and the receiving coil 120, resulting in extremely high power transmission efficiency. In addition, since power is supplied to multiple transmission coils 111, 112 by a single inverter circuit 140, there is no need to provide multiple inverter circuits to correspond to multiple transmission coils, and the device can be made smaller.

[0032] Furthermore, since one end of each transmission coil 111, 112 is connected to each other and then connected to a predetermined voltage portion of the power supply voltage 130 via the inductor 160, a resonant circuit can be configured corresponding to the mutual inductance between each transmission coil 111, 112. Also, since each resonant capacitor 161, 162 is provided for each transmission coil 111, 112, a resonant circuit can be configured corresponding to the self-inductance of each transmission coil 111, 112. In this embodiment, C t = 1 / (ω 2 (L t +M t )), and L0=M t (M t By setting it >0, the reactance components caused by self-inductance and mutual inductance can be canceled out.

[0033] Figures 6 and 7 show a third embodiment of the present invention, where Figure 6 is a plan view of the power transmission coil and Figure 7 is a circuit diagram of the power transmission device and power receiving device of a wireless power transmission system.

[0034] As shown in Figure 6, the wireless power transmission system 201 of this embodiment is arranged such that the transmission coils 111 and 112 of the second embodiment partially overlap and mutually reinforce each other's magnetic fields when current flows in the same direction. That is, the mutual inductance between the transmission coils 111 and 112 is positive. Furthermore, as shown in Figure 7, the wireless power transmission system 201 of this embodiment is equipped with a capacitor 260 instead of the inductor 160 of the second embodiment. Otherwise, the configuration is the same as that of the second embodiment.

[0035] The capacitance of capacitor 260 is set based on the mutual inductance between each power transmission coil 111, 112. The self-inductance of each power transmission coil 111, 112 is L t The mutual inductance between each power transmission coil 111, 112 is M t In this case, the capacitance C of each resonant capacitor 161, 162 t And the capacitance C0 of capacitor 260 is C t = 1 / (ω 2 (L t -M t )) C0 = 1 / (ω 2 M t ) This is how it is set. The same effects and advantages as those of the second embodiment can be obtained with the wireless power transmission system 201 configured as described above.

[0036] Figures 8 and 9 show a fourth embodiment of the present invention, with Figure 8 being a plan view of a power transmission coil and Figure 9 being a circuit diagram of a power transmission device and a power receiving device of a wireless power transmission system.

[0037] In this embodiment, as shown in Figure 8, the wireless power transmission system 301 has another power transmission coil 113 arranged adjacent to each of the adjacent power transmission coils 111 and 112 in the direction of arrangement of the second embodiment. In this embodiment as well, the three power transmission coils 111, 112, and 113 are identical. That is, the power transmission device 302 has three power transmission coils 111, 112, and 113. In this embodiment, the mutual inductance between the power transmission coil 111 at one end and the power transmission coil 112 at the center, and between the power transmission coil 112 at the center and the power transmission coil 113 at the other end are equal, but the mutual inductance between the power transmission coil 111 at one end and the power transmission coil 113 at the other end is different.

[0038] As shown in Figure 9, the inverter circuit 340 of the power transmission device 302 has three legs 141, 142, and 143, one for each transmission coil 111, 112, and 113, between the positive and negative busbars. Positive nodes 141c, 142c, and 143c are set between the series-connected positive-side switching elements 141a, 142a, and 143a and negative-side switching elements 141b, 142b, and 143b, and are connected to the other end of each transmission coil 111, 112, and 113. One end of each transmission coil 111, 112, and 113 is connected to each other, and a connection node 314 is set. With one end of each transmission coil 111, 112, and 113 connected, it is connected to the intermediate voltage of the input voltage of the DC power supply 130 via an inductor 360. The other ends of each transmission coil 111, 112, and 113 are connected to each leg 141, 142, and 143 via resonant capacitors 361, 362, and 363, respectively. In this embodiment, the inductor 360 and each resonant capacitor 361, 362, and 363 together with each transmission coil 111, 112, and 113 form a power factor compensation circuit 370 that is a resonant circuit.

[0039] Furthermore, in the present embodiment, transformers 391 and 392 are interposed between each of the resonance capacitors 361, 362, 363 and each of the legs 141, 142, 143. In the present embodiment, two transformers 391 and 392 are provided: transformer 391 corresponding to each of the power transmission coils 111 and 112 on one end side and the center side, and transformer 392 corresponding to each of the power transmission coils 112 and 113 on the center side and the other end side. The mutual inductance of each of the transformers 391 and 392 and the sum of the mutual inductances between each of the power transmission coils 111, 112, and 113 are made equal to each other. That is, each of the transformers 391 and 392 forms a mutual inductance compensation circuit 390 that adjusts the mutual inductance based on the difference in the mutual inductances between each of the power transmission coils 111, 112, and 113. Note that the mutual inductance compensation circuit 390 can also be constituted by one transformer corresponding to each of the power transmission coils 111 and 113 on one end side and the other end side.

[0040] In the present embodiment, the inductance of the inductor 360 is set based on the adjusted mutual inductance. Also, since the mutual inductance compensation circuit 390 has self-inductance, the capacitances C t1 , C t2 , C t3 of each of the resonance capacitors 361, 362, 363 are set in consideration of the self-inductances of each of the transformers 391 and 392. Specifically, when the sum of the self-inductances of each of the transformers 391 and 392 and the self-inductances of each of the power transmission coils 111, 112, and 113 is defined as L' t1 , L' t2 , L' t3 , and the adjusted mutual inductance between each of the power transmission coils 111, 112, and 113 is -M t (M t >0), the capacitances C t1 , C t2 , C t3 of each of the resonance capacitors 361, 362, 363 and the inductance L0 of the inductor 360 are C t1 = 1 / (ω 2 (L' t1 + M t )), Ct2 = 1 / (ω 2 (L' t2 + M t )), C t3 = 1 / (ω 2 (L' t3 + M t )) L0 = M t is set as such.

[0041] Also, the control unit 380 controls the currents of the power transmission coils 111, 112, 113 such that the ratio of the currents of the power transmission coils 111, 112, 113 is equal to the ratio of the mutual inductances between the power transmission coils 111, 112, 113 and the power reception coil 120. According to the wireless power transmission system 301 configured as described above, in addition to the effects of the third embodiment, by providing the mutual inductance compensation circuit 390, the power supply to each of the power transmission coils 111, 112, 113 can be controlled in the same manner as when the mutual inductances between the power transmission coils 111, 112, 113 are equal to each other.

[0042] FIGS. 10 and 11 show a fifth embodiment of the present invention. FIG. 10 is a plan explanatory view of a power transmission coil and a power reception coil, and FIG. 11 is a circuit diagram of a power transmission device of a wireless power transmission system. In FIG. 11, the circuit diagram of the power reception device is omitted. In FIG. 11, although the power reception device, the power reception coil, etc. are not shown, the power reception device, the power reception coil, etc. are the same as those in the second embodiment.

[0043] As shown in Figure 10, the wireless power transmission system of this embodiment has two additional power transmission coils 113 and 114 adjacent to each other in a direction perpendicular to the direction in which the two power transmission coils 111 and 112 of the second embodiment are aligned. In other words, the power transmission device 402 has four power transmission coils 111, 112, 113, and 114. In this embodiment, the four power transmission coils 111, 112, 113, and 114 are identical. In this embodiment, the mutual inductance between power transmission coils 111, 112, 113, and 114 that are adjacent in the direction of alignment or perpendicular thereto is equal, but it is different from the mutual inductance between power transmission coils 111, 112, 113, and 114 that are not adjacent in either direction.

[0044] As shown in Figure 11, the inverter circuit 440 of the power transmission device 402 has four legs 141, 142, 143, and 144, provided for each power transmission coil 111, 112, 113, and 114 between the positive and negative busbars. Positive nodes 141c, 142c, 143c, and 144c are set between the series-connected positive-side switching elements 141a, 142a, 143a, and 144a and negative-side switching elements 141b, 142b, 143b, and 144b, and are connected to the other end of each power transmission coil 111, 112, 113, and 114. One end of each power transmission coil 111, 112, 113, and 114 is connected to one another, and a connection node 414 is set. One end of each transmission coil 111, 112, 113, and 114 is connected via an inductor 460 to the intermediate voltage of the input voltage of the DC power supply 130. The other end of each transmission coil 111, 112, 113, and 114 is connected to each leg 141, 142, 143, and 144 via resonant capacitors 461, 462, 463, and 464, respectively. In this embodiment, the inductor 460 and each resonant capacitor 461, 462, 463, and 464 together with each transmission coil 111, 112, 113, and 114 form a power factor compensation circuit 470 that forms a resonant circuit.

[0045] Furthermore, in this embodiment, transformers 491 and 492 are interposed between each resonant capacitor 461, 462, 463, and 464 and each leg 141, 142, 143, and 144. Each transformer 491 and 492 is configured such that the sum of its mutual inductance and the mutual inductance between each transmission coil 111, 112, 113, and 114 is equal to each other. That is, each transformer 491 and 492 constitutes a mutual inductance compensation circuit 490 that adjusts the mutual inductance based on the difference in mutual inductance between each transmission coil 111, 112, 113, and 114. Similar to the fourth embodiment, the inductance of the inductor 460 is set based on the adjusted mutual inductance, and the capacitance of each resonant capacitor 461, 462, 463, and 464 is set considering the adjusted self-inductance.

[0046] Furthermore, the control unit 480 controls the currents of each transmission coil 111, 112, 113, and 114 so that the ratio of the currents of each transmission coil 111, 112, 113, and 114 is equal to the ratio of the mutual inductances between each transmission coil 111, 112, 113, and 114 and the receiving coil 120. The same effects and advantages as those of the fourth embodiment can be obtained with the wireless power transmission system configured as described above.

[0047] Figures 12 and 13 show a sixth embodiment of the present invention, with Figure 12 being a plan view of the power transmission coil and Figure 13 being a circuit diagram of the power transmission device of a wireless power transmission system. Although the power receiving device, power receiving coil, etc. are not shown in Figures 12 and 13, they are the same as those in the first embodiment.

[0048] As shown in Figure 12, in this wireless power transmission device 502, multiple power transmission coils 511 to 519 are aligned horizontally and diagonally vertically on a predetermined plane. In this embodiment, identical power transmission coils 511 to 519 are used. In this embodiment, the angle between the horizontal direction and the diagonally vertical direction is 60°. As shown in Figure 13, the power transmission device 502 includes an inverter circuit 40 having three legs 41, 42, and 43, similar to the first embodiment. Each power transmission coil 511 to 519 is assigned to one of three power transmission groups, corresponding to the number of legs 41, 42, and 43.

[0049] In this embodiment, as shown in Figure 12, the power transmission coils 511 to 519 are arranged in a repeating order in the horizontal direction, moving toward one side (to the right in Figure 12), in the order of power transmission coils belonging to the first power transmission group, power transmission coils belonging to the second power transmission group, and power transmission coils belonging to the third power transmission group. Furthermore, the power transmission coils 511 to 519 are arranged in a repeating order in the diagonal vertical direction, moving toward one side (to the upper right in Figure 12), in the order of power transmission coils belonging to the first power transmission group, power transmission coils belonging to the third power transmission group, and power transmission coils belonging to the second power transmission group.

[0050] As shown in Figure 13, each leg 41, 42, 43 of the inverter circuit 40 of the wireless power transmission device 502 is connected to the other end of each transmission coil 511-519 via changeover switches 581, 582, 583. Each changeover switch 581, 582, 583 is provided for each power transmission group and selectively supplies power to one transmission coil 511-519 belonging to each power transmission group. In this embodiment, each changeover switch 581, 582, 583 forms a switching circuit. The control unit 580 switches each changeover switch 581, 582, 583 based on information about the receiving coil. The control unit 580 also controls the current of each transmission coil 511-519 so that the ratio of the currents of each transmission coil 511-519 is equal to the ratio of the mutual inductances between each transmission coil 511-519 and the receiving coil.

[0051] One end of each transmission coil 511 to 519 is connected to the other end via an inductor 560 and connected to the intermediate voltage of the input voltage of the DC power supply 30. The selectable switches 581, 582, and 583, which are selectively connected to the other end of each transmission coil 511 to 519, are connected to the respective legs 41, 42, and 43 via resonant capacitors 561, 562, and 563, respectively. In this embodiment, the inductor 560 and the resonant capacitors 561, 562, and 563 together with each transmission coil 511 to 519 form a power factor compensation circuit 570 that forms a resonant circuit.

[0052] According to the wireless power transmission device 502 of this embodiment, even if there are many power transmission coils 511 to 519, it is possible to accommodate all power transmission coils 511 to 519 without increasing the number of legs of the inverter circuit 40.

[0053] Figures 14 and 15 show a seventh embodiment of the present invention, with Figure 14 being a plan view of the power transmission coil and Figure 15 being a circuit diagram of the power transmission device of a wireless power transmission system. Although the power receiving device, power receiving coil, etc. are not shown in Figures 14 and 15, they are the same as those in the first embodiment.

[0054] As shown in Figure 14, in this wireless power transmission device 602, multiple power transmission coils 611 to 619 are arranged in a horizontal and vertical direction on a predetermined plane. In this embodiment, identical power transmission coils 611 to 619 are used. As shown in Figure 14, the power transmission device 602 includes an inverter circuit 640 having four legs 41, 42, 43, and 44. Each power transmission coil 611 to 619 is assigned to one of four power transmission groups, corresponding to the number of legs 41, 42, 43, and 44.

[0055] In this embodiment, as shown in Figure 14, each of the power transmission coils 611 to 619 is arranged such that a power transmission coil belonging to the second power transmission group is positioned laterally adjacent to a power transmission coil belonging to the first power transmission group, a power transmission coil belonging to the third power transmission group is positioned vertically adjacent to a power transmission coil belonging to the first power transmission group, and a power transmission coil belonging to the fourth power transmission group is positioned laterally adjacent to a power transmission coil belonging to the third power transmission group. In other words, looking at the horizontal direction, the power transmission coils belonging to the first and second power transmission groups are arranged alternately, or the power transmission coils belonging to the third and fourth power transmission groups are arranged alternately. Looking at the vertical direction, the power transmission coils belonging to the first and third power transmission groups are arranged alternately, or the power transmission coils belonging to the second and fourth power transmission groups are arranged alternately.

[0056] As shown in Figure 15, each leg 41, 42, 43, and 44 of the inverter circuit 640 of the wireless power transmission device 602 is connected to the other end of each power transmission coil 611 to 619 via changeover switches 681, 682, 683, and 684. Each changeover switch 681, 682, 683, and 684 is provided for each power transmission group and selectively supplies power to one power transmission coil 611 to 619 belonging to each power transmission group. In this embodiment, each changeover switch 681, 682, 683, and 684 constitutes a switching circuit. The control unit 680 switches each changeover switch 681, 682, 683, and 684 based on information regarding the power receiving coil. Furthermore, in this embodiment, a mutual inductance compensation circuit 690 is interposed between each changeover switch 681, 682, 683, 684 and each leg 41, 42, 43, 44, which adjusts the mutual inductance based on the difference in mutual inductance between each transmission coil 611 to 619. The control unit 680 also controls the current of each transmission coil 611 to 619 so that the ratio of the currents of each transmission coil 611 to 619 is equal to the ratio of the mutual inductance between each transmission coil 611 to 619 and the receiving coil.

[0057] One end of each transmission coil 611 to 619 is connected to the other end via an inductor 660 and connected to the intermediate voltage of the input voltage of the DC power supply 30. The selector switches 681, 682, 683, and 684, which are selectively connected to the other end of each transmission coil 611 to 619, are connected to the respective legs 41, 42, 43, and 44 via resonant capacitors 661, 662, 663, and 664, respectively. In this embodiment, the inductor 660 and the resonant capacitors 661, 662, 663, and 664 together with each transmission coil 611 to 619 form a power factor compensation circuit 670 that forms a resonant circuit.

[0058] Even with the wireless power transmission device 602 of this embodiment, it is possible to accommodate all of the power transmission coils 611 to 619 without increasing the number of legs of the inverter circuit 640, even when there are many power transmission coils 611 to 619.

[0059] In the sixth and seventh embodiments, the inverter circuit is shown with three and four legs, but the number of legs may be two, five or more, and the number of legs can be changed arbitrarily. Also, although the resonant capacitors 661, 662, 663, and 664 are shown on the other end of each transmission coil 611 to 619, as shown in Figure 16, each resonant capacitor 661, 662, 663, and 664 may be set on one end of each transmission coil 611 to 619. If the self-inductances of each transmission coil 611 to 619 are different, a resonant capacitor can be set in series with each transmission coil 611 to 619.

[0060] Furthermore, although the embodiments described above show multiple identical power transmission coils, multiple power transmission coils with different self-inductances may be provided, for example, due to differences in wire type, material, size, number of turns, shape, etc. Also, although the embodiments shown show the power transmission coils located on the same plane, they do not need to be located on the same plane, nor do they need to be arranged regularly, and there does not need to be any regularity in the mutual inductance between the power transmission coils. An example of a circuit diagram of a power transmission device in these cases is shown in Figure 17. The circuit diagram in Figure 17 is the same as in Figure 9 except for the power transmission coils 1111, 1112, 1113, the power factor compensation circuit 1370, and the mutual inductance compensation circuit 1390.

[0061] In the circuit diagram of Figure 17, the three transmission coils 1111, 1112, and 1113 have different specifications, are not arranged on the same plane, and are at different distances from each other. In the circuit diagram of Figure 17, a mutual inductance compensation circuit 1390 is provided, which includes three transformers 1391, 1392, and 1393 corresponding to each combination of transmission coils 1111, 1112, and 1113. In addition, the circuit diagram of Figure 17 is provided, which includes a power factor compensation circuit 1370, which includes an inductor 1360 and resonant capacitors 1361, 1362, and 1363 corresponding to each transmission coil 1111, 1112, and 1113.

[0062] Here, the current and self-inductance of the first to third transmission coils 1111, 1112, and 1113 are defined as I t1 ,I t2 ,I t3 ,L t1 ,L t2 ,L t3 The capacitance of each resonant capacitor 1361, 1362, and 1363 is C t1 ,C t2 ,C t3 The self-inductance and mutual inductance of the first and second transmission coils on the first and second transmission coil sides of the transformer 1391 corresponding to the first and second transmission coils are set to L c121 ,L c122 M c12The self-inductance and mutual inductance of the second and third transmission coils on the second and third transmission coil sides of the transformer 1392 corresponding to the second and third transmission coils are set to L c232 ,L c233 M c23 The self-inductance and mutual inductance of the third and first transmission coils on the third and first transmission coil sides of the transformer 1393 corresponding to the third and first transmission coils are set to L c313 ,L c311 M c31 The mutual inductance between the first transmission coil and the second transmission coil is M. t12 The mutual inductance between the second and third transmission coils is M. t23 The mutual inductance between the third transmission coil and the first transmission coil is M. t31 The inductance of inductor 1360 is L0, and the mutual inductance of the first to third transmitting coils and the receiving coil is M. t1r M t2r M t3r The current in the receiving coil is I r Assuming that the winding resistances of the first to third transmission coils 1111, 1112, and 1113 are ignored, the output phase voltage V of the inverter circuit 340 t1 ,V t2 ,V t3 It can be expressed as follows: TIFF2026063436000002.tif61155 Here, any real number M' t In contrast, TIFF2026063436000003.tif2861 is valid M c12 M c23 M c31 Set L' t1 ,L' t2 ,L' t3 of If we use TIFF2026063436000004.tif2876, then equations (1)-(3) are: This becomes TIFF2026063436000005.tif59132. To summarize this, It becomes TIFF2026063436000006.tif41154. And then C t1 ,C t2 ,Ct3 of, Let's use TIFF2026063436000007.tif4466, M' t If it is negative, By using TIFF2026063436000008.tif843, the output phase voltage V of the inverter circuit 340 is... t1 ,V t2 ,V t3 teeth, This results in TIFF2026063436000009.tif2558. In other words, the reactance components caused by the self-inductance and mutual inductance of each transmission coil are canceled out. Note M' t If the value is positive, then capacitance C0 is used instead of inductor 1360. By using a capacitor with the value TIFF2026063436000010.tif1648, equations (20)-(22) can be obtained. Furthermore, in the circuit diagram of Figure 17, the control unit 380 is, M t1r :M t2r :M t3r =I t1 :I t2 :I t3 The switching elements 141a, 141b, 142a, 142b, 143a, and 143b are controlled to achieve this. As can be understood from equations (20)-(22), the output phase voltage V of the inverter circuit 340 t1 ,V t2 ,V t3 The ratio is the mutual inductance M of each transmitting coil and receiving coil. t1r M t2r M t3r This matches the ratio. Therefore, the control unit 380 only needs to control the ratio of the currents in each power transmission coil according to the ratio of the output phase voltages of the inverter circuit 340. Furthermore, if winding resistance cannot be ignored, the resistance value of each transmission coil is r t1 ,r t2 ,r t3 Therefore, the output phase voltage V of the inverter circuit 340 t1 ,V t2 ,V t3 teeth, This is represented by TIFF2026063436000011.tif2874. Therefore, the resistance value r of each transmission coil is t1 ,r t2 ,r t3 The information regarding this can be obtained in advance through measurements, etc., and the ratio of mutual inductances can be determined from the output phase voltage and current values ​​of the inverter circuit 340.

[0063] Furthermore, although the embodiments described above show the inverter circuit connected to a DC power supply, the inverter circuit 1040 may be connected to an AC power supply 1030, for example, as shown in Figure 18, and the detailed circuit configuration can be arbitrarily changed. The circuit diagram in Figure 18 differs from the circuit diagram in Figure 1 in that an AC power supply 1030 is provided instead of a DC power supply 30, and a first circuit 1051 and a second circuit 1052 are provided instead of a positive capacitor 51 and a negative capacitor 52. The first circuit 1051 is, for example, a diode rectifier circuit, an AC-DC converter, etc., and outputs a DC voltage from the input of the AC power supply 1030. The second circuit 1054 is, for example, a diode rectifier circuit, an AC-DC converter, a DC-DC converter, a series capacitor with a balancer, etc. Its input terminals are connected to positive and negative busbars or a separate DC power supply or AC power supply, and its output terminals are connected to one end of each transmission coil 11, 12, 13, and it is designed so that each transmission coil 11, 12, 13 side is at a predetermined voltage. This predetermined voltage can be set arbitrarily, and when the input voltage of the AC power supply 1030 is E, the predetermined voltage can be E / 2, of course, but the predetermined voltage can also be 0 or E.

[0064] Furthermore, in the above embodiments, each resonant capacitor in the power factor compensation circuit of the power transmission device is shown to be connected in series with each transmission coil to form a series resonant circuit. However, each resonant capacitor and each transmission coil may be connected in parallel to form a parallel resonant circuit, or they may form an LCL resonant circuit as shown in Figure 19. The configuration of the power factor compensation circuit can be changed arbitrarily. In the power factor compensation circuit 770 of the power transmission device 702 in Figure 19, the other ends of each transmission coil 11, 12, and 13 are connected to each leg 41, 42, and 43 via resonant inductors 761, 762, and 763, respectively, and are also connected to the intermediate voltage of the input voltage via resonant capacitors 764, 765, and 766.

[0065] Furthermore, in the embodiments described above, the capacitance of each resonant capacitor was set so that the reactance component of the power transmission device becomes zero, and power could be transmitted with a relatively low input voltage. However, for example, as shown in Figure 20, capacitors 41d, 41e, 42d, 42e, 43d, and 43e can be connected in parallel with each switching element 41a, 41b, 42a, 42b, 43a, and 43b, and the capacitance of each resonant capacitor 61, 62, and 63 can be set so that the output impedance of the inverter 40 has a lagging power factor, thereby soft switching the operation of the inverter 40 and improving the power transmission efficiency. Moreover, instead of capacitors 41d, 41e, 42d, 42e, 43d, and 43e, the parasitic capacitance of each switching element 41a, 41b, 42a, 42b, 43a, and 43b can be used to set the capacitance of each resonant capacitor 61, 62, and 63 so that the output impedance of the inverter 40 has a lagging power factor.

[0066] Furthermore, in the embodiments described above, the resonant capacitor of the power factor compensation circuit of the power receiving device is shown to be connected in series with the power receiving coil to form a series resonant circuit. However, as shown in Figure 21, each resonant capacitor and each power transmitting coil may be connected in parallel to form a parallel resonant circuit, or as shown in Figure 22, an LCL resonant circuit may be formed. The configuration of the power factor compensation circuit can be arbitrarily changed. In the power receiving device 803 of Figure 21, the power receiving coil 20 and the resonant capacitor 821 are connected in parallel to the output circuit 822. In the power receiving device 903 of Figure 22, the power receiving coil 20 and the resonant capacitor 921 are connected in parallel to the output circuit 923, and a resonant inductor 922 is provided between one end of the power receiving coil 20 and the output circuit 923. The output circuits 822 and 923 can be, for example, an AC load, a DC load via a rectifier or AD converter.

[0067] Here, the power transmission device 2 of the first embodiment was used as the example, and a power transmission device with a conventional configuration was used as the comparative example, and the power transmission efficiency was compared by simulation. Figure 23 is the circuit diagram of the power transmission device showing the comparative example, and Figure 24 is the simulation result showing the power transmission efficiency of the example and the comparative example.

[0068] As shown in Figure 23, in the comparative example power transmission device, power is supplied from one inverter circuit to one of the power transmission coils 11, 12, and 13, which are arranged in the same manner as in the first embodiment. As shown in Figure 24, the power transmission device of the embodiment showed an expanded area of ​​the receiving coil 20 capable of transmitting power and improved power transmission efficiency compared to the power transmission device of the comparative example. In particular, the power transmission efficiency improved dramatically when the receiving coil 20 was located in the joint area of ​​each of the power transmission coils 11, 12, and 13.

[0069] Although embodiments of the present invention have been described above, the embodiments described above do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. [Explanation of symbols]

[0070] 1. Wireless power transmission system 2 Power transmission equipment 3. Power receiving device 11 Power transmission coil 12 Power transmission coil 13 Power transmission coil 20 Power receiving coil 30 DC power supply 40 Inverter Circuit 41 Leg 42 Legs 43 Leg 44 Legs 60 Inductors 61 Resonant Capacitor 62 Resonant Capacitors 63 Resonant Capacitor 70 Power Factor Compensation Circuit 80 Control Unit 101 Wireless Power Transmission System 102 Power transmission equipment 103 Power receiving device 111 Power transmission coil 112 Power transmission coil 113 Power transmission coil 114 Power transmission coil 120 Power receiving coil 130 DC power supply 140 Inverter Circuit 141 Leg 142 Legs 143 Leg 144 Legs 160 Inductors 161 Resonant Capacitor 162 Resonant Capacitor 170 Power Factor Compensation Circuit 180 Control Unit 201 Wireless Power Transmission System 202 Power transmission equipment 260 Capacitors 270 Power Factor Compensation Circuit 301 Wireless Power Transmission System 302 Power transmission equipment 340 Inverter Circuit 360 Inductor 361 Resonant Capacitor 362 Resonant Capacitor 363 Resonant Capacitor 370 Power Factor Compensation Circuit 380 Control Unit 390 Mutual Inductance Compensation Circuit 391 Transformer 392 Transformer 402 Power transmission equipment 440 Inverter Circuit 460 Inductors 461 Resonant Capacitor 462 Resonant Capacitor 463 Resonant Capacitor 464 Resonant Capacitor 470 Power Factor Compensation Circuit 480 Control Unit 490 Mutual Inductance Compensation Circuit 491 Transformer 492 Transformer 502 Power transmission equipment 511 Transmission coil 512 Power transmission coil 513 Power transmission coil 514 Power transmission coil 515 Power transmission coil 516 Power transmission coil 517 Power transmission coil 518 Power transmission coil 519 Power transmission coil 560 Inductors 561 Resonant Capacitor 562 Resonant Capacitor 563 Resonant Capacitor 570 Power Factor Compensation Circuit 580 Control Unit 581 Changeover switch 582 Changeover switch 583 Changeover switch 602 Power transmission equipment 611 Power transmission coil 612 Power transmission coil 613 Power transmission coil 614 Power transmission coil 615 Power transmission coil 616 Power transmission coil 617 Power transmission coil 618 Power transmission coil 619 Power transmission coil 640 Inverter Circuit 660 Inductors 661 Resonant Capacitor 662 Resonant Capacitor 663 Resonant Capacitor 664 Resonant Capacitor 670 Power Factor Compensation Circuit 680 Control Unit 681 Changeover switch 682 Changeover switch 683 Changeover switch 684 Changeover switch 690 Mutual Inductance Compensation Circuit 702 Power transmission equipment 761 Resonant Inductor 762 Resonant Inductor 763 Resonant Inductor 764 Resonant Capacitor 765 Resonant Capacitor 766 Resonant Capacitor 770 Power Factor Compensation Circuit 803 Power receiving device 821 Resonant Capacitor 822 Output Circuit 903 Power receiving device 921 Resonant Capacitor 922 Resonant Inductor 923 Output Circuit 1111 Transmission coil 1112 Transmission coil 1113 Transmission coil 1360 Inductor 1361 Resonant Capacitor 1362 Resonant Capacitor 1363 Resonant Capacitor 1370 Power Factor Compensation Circuit 1390 Mutual Inductance Compensation Circuit 1391 Transformer 1392 Transformer 1393 Transformer

Claims

1. A power transmission device in a wireless power transmission system that performs wireless power transmission between a power transmission coil and a power receiving coil, Multiple of the aforementioned power transmission coils, It comprises an inverter circuit having multiple legs connected in parallel to each other and connected to a predetermined power source, Each of the aforementioned transmission coils is assigned to one of the transmission groups corresponding to each of the aforementioned legs. A power transmission device in a wireless power transmission system, which includes a switching circuit for switching the destination of power supply so that power from the inverter circuit is supplied to one of the power transmission coils for each of the power transmission groups.

2. The power transmission device in the wireless power transmission system according to claim 1, wherein each of the power transmission coils is aligned in a horizontal and diagonal vertical direction or horizontal and vertical direction on a predetermined plane.

3. The power transmission device in the wireless power transmission system according to claim 2, wherein each of the power transmission coils is arranged adjacent to another power transmission coil belonging to a different power transmission group in the direction of alignment.

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