Power transmission device

Abstract

This power transmission device is provided with: a coil 45 that transmits power in a non-contact manner; a power supply device connected to the coil and applying a voltage to the coil; and a control device for controlling the power supply device. When the coil transmits power in a non-contact manner, the control device controls the power supply device so as to apply an AC voltage to the coil. The control device controls the power supply device to maintain both output terminals of the power supply device at the same potential different from the ground potential when detecting the electric leakage of the power transmission device, and detects the electric leakage on the basis of electrical characteristics in the power transmission device at that time.

Description

Technical Field

[0001] The present disclosure relates to a power transmission device. Background Art

[0002] A known above-ground power supply device has a coil for non-contact power transmission and a power source that supplies AC power to the coil, and performs non-contact power transmission to a vehicle by supplying AC power from the AC power source to the coil (for example, Japanese Patent Application Laid-Open No. 2019-526219). Summary of the Invention

[0003] In a power transmission device such as an above-ground power supply device, accidental leakage may occur in a resonance circuit including a coil, and thus it is necessary to detect the leakage.

[0004] In view of the above problems, an object of the present disclosure is to be able to detect leakage in a resonance circuit of a power transmission device.

[0005] The gist of the disclosure is as follows.

[0006] (1) A power transmission device having: a coil for non-contact power transmission or reception; a power supply device connected to the coil and applying a voltage to the coil; and a control device for controlling the power supply device, In the power transmission device, when detecting leakage of the power transmission device, the control device controls the power supply device to maintain both output terminals of the power supply device at the same potential different from the ground potential, and detects leakage based on the electrical characteristics in the power transmission device at this time. (2) The power transmission device according to (1) above, wherein the electrical characteristics include the current flowing through the output terminals of the power supply device. (3) The power transmission device according to (1) above, further having a filter circuit provided between the coil and the power supply device, wherein the electrical characteristics include the current flowing between the filter circuit and the coil. (4) The power transmission device according to (2) or (3) above, wherein when the control device detects that the current is not zero when controlling the power supply device to maintain both output terminals of the power supply device at the same potential different from the ground potential, it is determined that leakage has occurred in the power transmission device. (5) The power transmission device according to any one of (1) to (4) above, further having a filter circuit provided between the coil and the power supply device, The filter circuit has a plurality of capacitors. One end of one of the capacitors is connected to one end portion of the coil and the other end is grounded. One end of another capacitor is connected to the other end portion of the coil and the other end is grounded. The control device detects leakage current based on the rising speed of the current flowing through the output terminals of the power supply device when the two output terminals are formed to have the same potential different from the ground potential. (6) The power transmission device according to any one of (1) to (5) above, further comprising a resonant capacitor connected in series with the coil, The electrical characteristics include the voltage between both ends of the resonant capacitor. (7) The power transmission device according to (6) above, wherein when the control device detects that the voltage between both ends of the resonant capacitor is not zero when controlling the power supply device to maintain the two output terminals of the power supply device at the same potential different from the ground potential, it is determined that leakage current has occurred in the power transmission device. (8) The power transmission device according to any one of (1) to (7) above, further comprising a resonant capacitor connected in series with the coil and a resistor connected in parallel with the resonant capacitor, The electrical characteristics include the current flowing through the resistor. (9) The power transmission device according to (8) above, wherein when the control device detects that the current flowing through the resistor is not zero when controlling the power supply device to maintain the two output terminals of the power supply device at the same potential different from the ground potential, it is determined that leakage current has occurred in the power transmission device. (10) The power transmission device according to any one of (1) to (9) above, wherein when the control device determines that leakage current has occurred in the power transmission device, it notifies the user of the occurrence of leakage current. (11) The power transmission device according to any one of (1) to (10) above, wherein the coil is a power transmission coil for non-contact power transmission, When the power transmission coil performs non-contact power transmission, the control device controls the power supply device to supply alternating current power to the power transmission coil. (12) The power transmission device according to (11) above, wherein when the control device determines that leakage current has occurred in association with the power transmission coil constituting the power transmission device, it prohibits power supply to the power transmission coil. (13) The power transmission device according to (11) or (12) above, wherein the power transmission device has a plurality of power transmission coils, and the plurality of power transmission coils are respectively connected to one power supply device via a changeover switch, When detecting the leakage of the power transmission device, the control device controls the power supply device to maintain the two output terminals of the power supply device at the same potential different from the ground potential in a state where one switch is turned on and the remaining switches are turned off, and detects the leakage based on the electrical characteristics in the power transmission device at this time. (14) The power transmission device according to any one of (11) to (13) above, wherein the control device determines that a leakage occurs only in a state where one switch is turned on and the remaining switches are turned off, and does not determine that a leakage occurs in a state where other switches are respectively turned on and the remaining switches are turned off, and determines that a leakage occurs in the resonance circuit including the power transmission coil connected to the one switch. (15) The power transmission device according to any one of (1) to (10) above, wherein the coil is a power receiving coil that receives power non - contact, and the power supply device is configured to be charged by the power received in the power receiving coil. When the power receiving coil receives power non - contact, the control device controls the power supply device to charge the power after rectifying the received AC power into DC power. Description of the Drawings

[0007] Figure 1 is a diagram schematically showing the configuration of a non - contact power supply system including a ground power supply device according to the first embodiment. Figure 2 is a diagram schematically showing the circuit configuration in the power supply unit and the power transmission unit. Figure 3 is a diagram schematically showing the circuit configuration in the power supply unit and the power transmission unit, which is Figure 2 the same as. Figure 4 is a diagram schematically showing the circuit configuration in the power supply unit and the power transmission unit, which is Figure 2 the same as. Figure 5 is a diagram for explaining the operation of the power supply unit and the power transmission unit during power transmission. Figure 6 is a diagram schematically showing the circuit state when no leakage occurs in the power transmission side resonance circuit. Figure 7 is a diagram schematically showing the circuit state when a leakage occurs in the power transmission side resonance circuit. Figure 8 is a diagram showing the change of the current detected by the ammeter. Figure 9It is a diagram schematically showing the circuit configuration of the power supply unit and the power transmission unit when a converter circuit is connected to a plurality of power transmission side resonance circuits, and is the same as Figure 2 the same figure. Figure 10 It is a diagram schematically showing the circuit configuration in the power supply unit and the power transmission unit according to the second embodiment, and is the same as Figure 2 the same figure. Figure 11 It is a diagram schematically showing the circuit configuration in the power supply unit and the power transmission unit according to the third embodiment, and is the same as Figure 2 the same figure. Figure 12 It is a diagram schematically showing the circuit configuration in the power receiving unit. Figure 13 It is a diagram for explaining the operation of the power receiving unit during power reception. Figure 14 It is a timing chart of the input current to the power receiving side rectifier circuit, the state of the switching transistor, and the output current from the power receiving side rectifier circuit. Figure 15 It is a diagram for explaining the operation of the power receiving unit when detecting leakage in the power receiving side resonance circuit. Detailed Embodiments

[0008] Hereinafter, embodiments will be described in detail with reference to the drawings. In addition, in the following description, the same reference numerals are assigned to the same constituent elements.

[0009] First Embodiment <Outline of Non-contact Power Supply System> Figure 1 It is a diagram schematically showing the configuration of a non-contact power supply system 100 including a ground power supply device 1 according to the first embodiment. The non-contact power supply system 100 includes a ground power supply device 1 and a vehicle 5 that can receive power from the ground power supply device 1. In the non-contact power supply system 100, non-contact power transmission based on magnetic resonance coupling (magnetic field resonance) is performed from the ground power supply device 1 to the vehicle 5. Both the ground power supply device 1 and the vehicle 5 function as power transmission devices that transmit power non-contact. In the present embodiment, non-contact power transmission is performed not only when the vehicle 5 is parked but also when the vehicle 5 is running.

[0010] The on - ground power supply device 1 has a power transmission unit 32 configured to non - contactlessly transmit power to the vehicle 5, and the vehicle 5 has a power reception unit 14 configured to non - contactlessly receive power. If power is supplied to the power transmission unit 32 of the on - ground power supply device 1, a magnetic field is generated by the power transmission coil 45 of the power transmission unit 32. If the power reception coil 22 of the power reception unit 14 of the vehicle 5 is located on the power transmission coil 45, a current flows through the power reception coil 22 due to the magnetic field generated by the power transmission coil 45, and thus power is received through the power reception unit 14.

[0011] <Configuration of the vehicle> Next, Figure 1 the configuration of the vehicle 5 will be described. As Figure 1 shown, the vehicle 5 has a motor 11, a battery 12, a power control unit (PCU) 13, a power reception unit 14, and an electronic control unit (ECU) 15. The vehicle 5 is an electric vehicle (BEV) driven by the motor 11 or a hybrid electric vehicle (HEV) driven by the motor 11 plus an internal combustion engine.

[0012] The motor 11 is, for example, an AC synchronous motor and functions as both a motor and a generator. The motor 11 functions as a motor and is driven using the power stored in the battery 12 as a power source. The output of the motor 11 is transmitted to the wheels via a reduction gear and an axle.

[0013] The battery 12 is a rechargeable secondary battery and is composed of, for example, a lithium - ion battery, a nickel - metal hydride battery, etc. The battery 12 stores the power required for the vehicle 5 to travel (for example, the driving power of the motor 11). If the power received by the power reception unit 14 is supplied to the battery 12, the battery 12 is charged. If the battery 12 is charged, the state of charge (SOC) of the battery 12 is restored. In addition, the battery 12 can also be charged by an external power source other than the on - ground power supply device 1 via a charging port provided on the vehicle 5.

[0014] The PCU 13 is electrically connected to the motor 11 and the battery 12. The PCU 13 has a converter, a boost converter, and a DC / DC converter. The converter converts the DC power supplied from the battery 12 into AC power and supplies the AC power to the motor 11. When the power stored in the battery 12 is supplied to the motor 11, the boost converter boosts the voltage of the battery 12 as needed. When the power stored in the battery 12 is supplied to electronic instruments such as headlights, the DC / DC converter steps down the voltage of the battery 12.

[0015] The power reception unit 14 receives power from the power transmission unit 32 and supplies the received power to the battery 12. The power reception unit 14 has a power - receiving - side resonance circuit 21, a power - receiving - side rectifying circuit 24, and a charging circuit 25.

[0016] The power receiving side resonance circuit 21 is arranged at the bottom of the vehicle 5 so that the distance from the road surface becomes smaller. The power receiving side resonance circuit 21 includes a power receiving coil 22 and a power receiving side resonance capacitor 23. The power receiving coil 22 is arranged such that after a magnetic field is generated around it, a current flows through the power receiving coil 22. The power receiving coil 22 and the power receiving side resonance capacitor 23 form a resonator. Various parameters of the power receiving coil 22 and the power receiving side resonance capacitor 23 (such as the outer diameter and inner diameter of the power receiving coil 22, the number of turns of the power receiving coil 22, the capacitance of the power receiving side resonance capacitor 23, etc.) are determined such that the resonance frequency of the power receiving side resonance circuit 21 is the same as the resonance frequency of the power transmission side resonance circuit 44. In addition, if the deviation amount between the resonance frequency of the power receiving side resonance circuit 21 and the resonance frequency of the power transmission side resonance circuit 44 is small, for example, within ±10% of the resonance frequency of the power transmission side resonance circuit 44 for the resonance frequency of the power receiving side resonance circuit 21, the resonance frequency of the power receiving side resonance circuit 21 does not have to be the same as the resonance frequency of the power transmission side resonance circuit 44.

[0017] The power receiving side rectifier circuit 24 is electrically connected to the power receiving side resonance circuit 21 and the charging circuit 25. The power receiving side rectifier circuit 24 rectifies the AC power supplied from the power receiving side resonance circuit 21 and converts it into DC power, and supplies the DC power to the charging circuit 25. The power receiving side rectifier circuit 24 is, for example, an AC / DC converter.

[0018] The charging circuit 25 is electrically connected to the power receiving side rectifier circuit 24 and the battery 12. The charging circuit 25 converts the DC power supplied from the power receiving side rectifier circuit 24 into the voltage level of the battery 12 and supplies it to the battery 12. If the power transmitted from the power transmission unit 32 is supplied to the battery 12 through the power receiving unit 14, the battery 12 is charged. The charging circuit 25 is, for example, a DC / DC converter.

[0019] The ECU 15 performs various controls of the vehicle 5. For example, the ECU 15 is electrically connected to the charging circuit 25 of the power receiving unit 14 and controls the charging circuit 25 in order to control the charging of the battery 12 with the power transmitted from the power transmission unit 32. In addition, the ECU 15 is electrically connected to the PCU 13 and controls the PCU 13 in order to control the reception / sending of power between the battery 12 and the motor 11.

[0020] <Configuration of the Ground Power Supply Device> Next, with reference to Figure 1 , the configuration of the ground power supply device 1 will be briefly described. As Figure 1 shown, the ground power supply device 1 includes a power source 2, a power supply unit 31, a power transmission unit 32, and a controller 33. In the present embodiment, one ground power supply device 1, for example, has a plurality of power transmission coils 45 arranged in a row and buried in the lane of the road.

[0021] The power source 2 supplies power to the power transmission unit 32 via the power supply unit 31. The power source 2 is, for example, a commercial AC power source that supplies single-phase AC power. In addition, the power source 2 may also be another AC power source that supplies three-phase AC power, or may be a DC power source such as a fuel cell.

[0022] The power supply unit 31 converts the AC power supplied from the power source 2 into high-frequency AC power for supply to the power transmission unit 32. The power supply unit 31 has a power transmission side rectifier circuit 41 and a converter circuit 42. In the power supply unit 31, the AC power supplied from the power source 2 is rectified in the power transmission side rectifier circuit 41 to be converted into DC power, and this DC power is converted into AC power in the converter circuit 42. The power source 2 and the power supply unit 31 function as a power supply device that applies a voltage to the power transmission coil 45 to which the power transmission coil 45 is connected.

[0023] The power transmission side rectifier circuit 41 is electrically connected to the power source 2 and the converter circuit 42. The power transmission side rectifier circuit 41 rectifies the AC power supplied from the power source 2 to be converted into DC power, and supplies the DC power to the converter circuit 42. The power transmission side rectifier circuit 41 is, for example, an AC / DC converter. In the present embodiment, one power transmission side rectifier circuit 41 is provided in one power supply unit 31. In addition, when the power source 2 is a DC power source, the power supply unit 31 may be omitted.

[0024] The converter circuit 42 is electrically connected to the power transmission side rectifier circuit 41 and the power transmission side filter circuit 43. The converter circuit 42 converts the DC power supplied from the power supply unit 31 into AC power (high-frequency AC power) having a frequency higher than that of the power source 2, and supplies the high-frequency AC power to the power transmission side resonance circuit 44 via the power transmission side filter circuit 43. In the present embodiment, the power supply unit 31 has converter circuits 42 corresponding to the number of power transmission units 32. Each converter circuit 42 is respectively connected to one of the corresponding power transmission units 32 that are different from each other. Regarding the specific circuit configuration of the converter circuit 42, refer to Figure 2 described later.

[0025] A plurality of power transmission units 32 are provided in one in-ground power supply device 1. Accordingly, a plurality of power transmission units 32 are connected to the power supply unit 31. Each power transmission unit 32 has a power transmission side filter circuit 43 and a power transmission side resonance circuit 44. When high-frequency power is supplied from the power supply unit 31, an alternating magnetic field is generated in the power transmission coil 45 of the power transmission unit 32. Regarding the specific circuit configuration in the power transmission unit 32, refer to Figure 2 described later.

[0026] The power transmission side filter circuit 43 removes the noise generated in the power transmission unit 32, particularly common mode noise and differential mode noise. In the present embodiment, the power transmission side filter circuit 43 is disposed between the converter circuit 42 and the power transmission side resonance circuit 44. However, instead of or in addition to the power transmission side filter circuit 43, the power transmission side filter circuit may be disposed at other locations such as between the power transmission side rectifier circuit 41 and the converter circuit 42.

[0027] The power transmission side resonance circuit 44 includes a power transmission coil 45 and a power transmission side resonance capacitor 46. When current flows, the power transmission coil 45 generates a magnetic field for non-contact power transmission. The power transmission coil 45 and the power transmission side resonance capacitor 46 constitute a resonator. The various parameters of the power transmission coil 45 and the power transmission side resonance capacitor 46 (such as the outer diameter and inner diameter of the power transmission coil 45, the number of turns of the power transmission coil 45, the capacitance of the power transmission side resonance capacitor 46, etc.) are determined such that the resonance frequency of the power transmission unit 32 becomes a specified set value. The specified set value is, for example, 10 kHz to 100 GHz, and preferably 85 kHz determined according to the SAE TIR J2954 standard as a frequency band for non-contact power transmission. In addition, in the present embodiment, all the power transmission side resonance circuits 44 are configured such that the various parameters of the power transmission coil 45 and the power transmission side resonance capacitor 446 are the same for each other. In other words, all the power transmission units 32 have the same configuration.

[0028] The controller 33 is, for example, a general-purpose computer and performs various controls of the on-ground power supply device 1. In particular, the controller 33 functions as a control device for controlling the power supply device. For example, the controller 33 is electrically connected to the converter circuit 42 of the power transmission unit 32 and controls the converter circuit 42 in order to control the power transmission through the power transmission unit 32. Specifically, for example, the controller 33 determines the power transmission unit 32 on which the vehicle 5 is located based on the output from an arbitrary sensor (not shown), and controls the converter circuit 42 so as to supply power to the determined power transmission unit 32. The controller 33 includes a processor that executes various processes, a memory that stores programs for causing the processor to execute various processes, and various data used by the processor when executing various processes.

[0029] In addition, the power transmission coil 45 and the power transmission side resonance capacitor 46 of the power transmission unit 32 are buried underground. In particular, the power transmission coil 45 is disposed such that its center is located at the center of the charging zone. Alternatively, the power transmission coil 45 is disposed such that its center is located at the center of the lane. On the other hand, the power transmission side filter circuit 43 of the power transmission unit 32 and the converter circuit 42 of the power supply unit 31 may be buried underground or may be provided on the ground.

[0030] In the non-contact power supply system 100 configured as described above, as in Figure 1When the power receiving coil 22 of the power receiving side resonance circuit 21 of the vehicle 5 shown faces the power transmission coil 45 of the power transmission side resonance circuit 44 of the ground power supply device 1, AC power is supplied to the power transmission side resonance circuit 44, and an alternating magnetic field is generated through the power transmission coil 45. After generating the alternating magnetic field in this way, the vibration of the alternating magnetic field is transmitted to the power receiving coil 22. As a result, an induced current flows through the power receiving coil 22 due to electromagnetic induction, and an induced electromotive force is generated in the power receiving side resonance circuit 21 through the induced current. That is, power is transmitted from the power transmission unit 32 including the power transmission side resonance circuit 44 to the power receiving unit 14 including the power receiving side resonance circuit 21.

[0031] <Description of the circuit> Next, with reference to Figure 2 , the circuits in the power supply unit 31 and the power transmission unit 32 will be described. Figure 2 is a diagram schematically showing the configuration of the circuits in the power supply unit 31 and the power transmission unit 32. As described above, the power supply unit 31 has a converter circuit 42, and the power transmission unit 32 has a power transmission side filter circuit 43 and a power transmission side resonance circuit 44.

[0032] As Figure 2 shown, the converter circuit 42 has four switching transistors 51 to 54 and a smoothing capacitor 55. The four switching transistors 51 to 54 form an H-bridge circuit. The first switching transistor 51 and the third switching transistor 53 are connected in series, and the second switching transistor 52 and the fourth switching transistor 54 are connected in series. The two sets of switching transistors 51 to 54 connected in series are connected to the positive line 56 connected to the positive electrode of the power supply unit 31 and the negative line 57 connected to the negative electrode of the power supply unit 31.

[0033] Specifically, the first switching transistor 51 and the second switching transistor 52 are connected to the positive line 56. On the other hand, the third switching transistor 53 and the fourth switching transistor 54 are connected to the negative line 57. In addition, between the first switching transistor 51 and the second switching transistor 52 is connected to the first output terminal 58 of the converter circuit 42 (i.e., the first output terminal of the power supply device). On the other hand, between the third switching transistor 53 and the fourth switching transistor 54 is connected to the second output terminal 59 of the converter circuit 42 (i.e., the second output terminal of the power supply device). Therefore, the first switching transistor 51 is provided between the positive line 56 and the first output terminal 58, and the second switching transistor 52 is provided between the positive line 56 and the second output terminal 59. In addition, the third switching transistor 43 is provided between the negative line 57 and the first output terminal 58, and the fourth switching transistor 54 is provided between the negative line 57 and the second output terminal 59. These switching transistors 51 to 54 are connected to the controller 33, and the on / off is controlled by the controller 33.

[0034] The smoothing capacitor 55 is provided between the positive line 56 and the negative line 57. The smoothing capacitor 55 is used to smooth the current rectified by the rectifying circuit on the power transmission side of the power supply unit 31.

[0035] In addition, as described above, a power transmission side filter circuit can also be provided between the converter circuit 42 and the power transmission side rectifying circuit 41. Specifically, an X capacitor, a Y capacitor, a common mode choke coil, etc. disposed between the positive line 56 and the negative line 57 can be provided between the converter circuit 42 and the power transmission side rectifying circuit 41. Through these power transmission side filter circuits, the normal mode noise and common mode noise generated in the power supply unit 31 and the power transmission unit 32 can be reduced. In addition, the power transmission side filter circuit 43 may not be provided.

[0036] As Figure 2 shown, the power transmission side filter circuit 43 has various filter elements for reducing noise. Specifically, in the present embodiment, the power transmission side filter circuit 43 has a Y capacitor 61, an X capacitor 62, a normal mode choke coil 63, and a common mode choke coil 64.

[0037] The Y capacitor 61 has a first capacitor 61a and a second capacitor 61b connected in series. In addition, the first capacitor 61a is connected to the first line 65 connected to the first output terminal 58 of the converter circuit 42. Similarly, the second capacitor 61b is connected to the second line 66 connected to the second output terminal 59 of the converter circuit 42. In addition, the ground is connected between the first capacitor 61a and the second capacitor 61b. Thus, one end of the first capacitor 61a is connected to the first line 65 and the other end is grounded. One end of the second capacitor 61b is connected to the second line 66 and the other end is grounded. The Y capacitor 61 can reduce the common mode noise generated in the power transmission unit 32.

[0038] The X capacitor 62 is a capacitor provided between the first line 65 and the second line 66. The X capacitor 62 can reduce the normal mode noise generated in the power transmission unit 32. The normal mode choke coil 63 is a coil connected in series with the first line 65 and the second line 66. The normal mode choke coil 63 can reduce the normal mode noise generated in the power transmission unit 32. In addition, the common mode choke coil 64 is a filter element having a structure in which a wire connected in series with the first line 65 and a wire connected in series with the second line 66 are wound around one core material. The common mode choke coil 64 can reduce the common mode noise.

[0039] In addition, in the present embodiment, the power transmission side filter circuit 43 includes a Y capacitor 61, an X capacitor 62, a common mode choke coil 63, and a differential mode choke coil 64. However, it is sufficient to have a part of these filter elements, and it is not necessary to have all of the above filter elements. In addition, the power transmission side filter circuit 43 may also have other filter elements such as a filter element capable of returning the common mode current. Furthermore, the filter element may also have Figure 3 a fourth-order filter 67 as shown in Figure 4 a band-pass filter 68 as shown in

[0040] As described above, the power transmission side resonance circuit 44 includes a power transmission coil 45 and a power transmission side resonance capacitor 46. One end of the power transmission coil 45 is connected to the first line 65, and the other end is connected to the second line 66. Thus, the first output terminal 58 of the converter circuit 42 and the first capacitor 61a are connected to one end of the power transmission coil 45. On the other hand, the second output terminal 59 of the converter circuit 42 and the second capacitor 61b are connected to the other end of the power transmission coil 45. In addition, in the present embodiment, two power transmission side resonance capacitors 46 are respectively connected in series with the first line 65 and the second line 66. In addition, as long as the power transmission side resonance capacitor 46 forms a resonator together with the power transmission coil 45, it can be arranged in any manner. Thus, the power transmission side resonance capacitor 46 may be connected in series with only one of the first line 65 and the second line 66, or may be connected in parallel with the power transmission coil 45 between the first line 65 and the second line 66.

[0041] In addition, in the present embodiment, a plurality of ammeters 71 to 74 are provided for the power transmission unit 32. Specifically, the first ammeter 71 is provided on the first line 65 close to the first output terminal 58 of the converter circuit 42. The first ammeter 71 detects the current flowing through the first output terminal 58 of the converter circuit 42. In addition, the second ammeter 72 is provided on the second line 66 close to the second output terminal 59 of the converter circuit 42. The second ammeter 72 detects the current flowing through the second output terminal 59 of the converter circuit 42. In addition, as long as these ammeters can detect the current flowing through the first output terminal 58 or the second output terminal 59 of the converter circuit 42, they may also be arranged at positions other than the above positions such as the positive line 56 or the negative line 57.

[0042] In addition, a third ammeter 73 is disposed on the first line 65 between the power transmission side filter circuit 43 and the power transmission side resonance circuit 44. The third ammeter 73 detects the current flowing from the power transmission side filter circuit 43 through the first line 65 to the power transmission coil 45. A fourth ammeter 74 is disposed on the second line 66 between the power transmission side filter circuit 43 and the power transmission side resonance circuit 44. The fourth ammeter 74 detects the current flowing from the power transmission side filter circuit 43 through the second line 66 to the power transmission coil 45. In addition, as long as these ammeters can detect the current flowing through the power transmission coil 45, the current flowing through the power transmission side resonance capacitor 46, or the current flowing from the power transmission side filter circuit 43 to the power transmission coil 45, they may also be disposed at positions other than the above-mentioned positions.

[0043] <Operation during power transmission> Next, with reference to Figure 5 , the operations of the power supply unit 31 and the power transmission unit 32 during power transmission will be described. Figure 5 It is a diagram for explaining the operations of the power supply unit 31 and the power transmission unit 32 during power transmission.

[0044] During power transmission, the switching transistors 51 to 54 of the converter circuit 42 are selectively connected, and AC power is output from the output terminals 58 and 59 of the converter circuit 42. Specifically, in the converter circuit 42, the first connection state and the second connection state are intermittently and alternately repeated to output AC power.

[0045] In the first connection state, as shown in (A) of Figure 5 , the first switching transistor 51 and the fourth switching transistor 54 are turned on, and the second switching transistor 52 and the third switching transistor 53 are turned off. In this case, the positive line 56 is connected to the first output terminal 58, and thus connected to the first line 65. On the other hand, the negative line 57 is connected to the second output terminal 59, and thus connected to the second line 66.

[0046] In addition, in the second connection state, as shown in (B) of Figure 5 , the second switching transistor 52 and the third switching transistor 53 are turned on, and the first switching transistor 51 and the fourth switching transistor 54 are turned off. In this case, the positive line 56 is connected to the second output terminal 59, and thus connected to the second line 66. On the other hand, the negative line 57 is connected to the first output terminal 58, and thus connected to the first line 65.

[0047] When power is supplied, in the converter circuit 42, the first connection state and the second connection state as described above are intermittently and alternately repeated, whereby AC power is output from the output terminals 58 and 59 of the converter circuit 42. When AC power is output from the converter circuit 42 in this way, the AC power is supplied to the power transmission side resonance circuit 44 via the power transmission side filter circuit 43. As a result, an alternating magnetic field is generated in the power transmission coil 45. That is, in the present embodiment, when power is transmitted, the controller 33 controls the power supply unit 31 including the converter circuit 42 to apply an AC voltage to the power transmission coil 45.

[0048] <Detection of leakage> Accidental leakage may occur in the power transmission side resonance circuit 44 including the power transmission coil 45. If such leakage occurs, power cannot be efficiently transmitted from the ground power supply device 1 to the vehicle 5. Therefore, in the present embodiment, leakage in the power transmission side resonance circuit 44 is detected.

[0049] Refer to Figures 6 - 8 , and the detection of leakage in the power transmission side resonance circuit 44 will be described. Figure 6 is a diagram schematically showing the state of the circuit when no leakage occurs in the power transmission side resonance circuit 44.

[0050] In the present embodiment, when detecting leakage in the power transmission side resonance circuit 44, as Figure 6 shown, the controller 33 switches the first switching transistor 51 and the second switching transistor 52 from off to on and then maintains them in the on state. On the other hand, the third switching transistor 53 and the fourth switching transistor 54 are maintained in the off state. As a result, both the first output terminal 58 and the second output terminal 59 of the converter circuit 42 are connected to the positive line 56 and are maintained at the same potential different from the ground potential. Thus, in the present embodiment, when detecting leakage in the power transmission side resonance circuit 44, the controller 33 controls the power supply device to maintain the two output terminals 58 and 59 of the power supply device at the same potential different from the ground potential.

[0051] In addition, when detecting leakage in the power transmission side resonance circuit 44, the controller 33 can also switch the third switching transistor 53 and the fourth switching transistor 54 from off to on and then maintain them in the on state, and maintain the first switching transistor 51 and the second switching transistor 52 in the off state. However, this method is limited to the case where the negative line 57 is at a potential different from the ground potential. When the switching transistors 51 to 54 are maintained in this way, both the first output terminal 58 and the second output terminal 59 of the converter circuit 42 are connected to the negative line 57 and are maintained at the same potential different from the ground potential.

[0052] Furthermore, in the present embodiment, the leakage in the power transmission side resonance circuit 44 is detected based on the current detected by the current meters 71 to 74 when the two output terminals 58 and 59 are maintained at the same potential different from the ground potential.

[0053] Here, consider a case where, in a state where no leakage occurs in the power transmission side resonance circuit 44, starting from a state where all the switching transistors 51 to 54 are set to the cut-off state, only the first switching transistor 51 and the second switching transistor 52 are switched to the on state and maintained. Figure 6 It is a diagram schematically showing the current flow in the power supply unit 31 and the power transmission unit 32 in this case. In particular, Figure 6 (A) of shows the current flow immediately after the first switching transistor 51 and the second switching transistor 52 are switched to the on state. On the other hand, Figure 6 (B) of shows the current flow after a certain amount of time has passed since the first switching transistor 51 and the second switching transistor 52 were switched to the on state.

[0054] As Figure 6 shown in (A) of, immediately after the first switching transistor 51 and the second switching transistor 52 are switched to the on state, in the first capacitor 61a and the second capacitor 61b that constitute the Y capacitor 61, the voltages on both sides thereof are different. Therefore, a current flows to accumulate charges in these capacitors 61a and 61b. As a result, immediately after the first switching transistor 51 and the second switching transistor 52 are switched to the on state, as Figure 6 shown in (A) of, the current flows from the first output terminal 58 and the second output terminal 59 toward the grounded portion of the Y capacitor 61.

[0055] On the other hand, after a certain amount of time has passed since the first switching transistor 51 and the second switching transistor 52 were switched to the on state, charges corresponding to the potential difference between both ends thereof are accumulated in the first capacitor 61a and the second capacitor 61b. As a result, after a certain amount of time has passed, as Figure 6 shown in (B) of, no current flows in the power supply unit 31 and the power transmission unit 32.

[0056] Next, with reference to Figure 7 , consider a case where, in a state where leakage occurs in the power transmission side resonance circuit 44, starting from a state where all the switching transistors 51 to 54 are set to the cut-off state, only the first switching transistor 51 and the second switching transistor 52 are switched to the on state and maintained. Figure 7 It is a diagram schematically showing the state of the circuit in the case where leakage occurs in the power transmission side resonance circuit 44. In particular, in Figure 7 , the portions where leakage occurs are denoted as X1, X2, and X3. In addition, in Figure 7In the figure, the leakage occurs at three locations X1, X2, and X3. However, the following describes the case where the leakage occurs at one of these locations.

[0057] In a state where leakage occurs at any one of X1, X2, or X3 in the power supply side resonance circuit 44, immediately after the first switching transistor 51 and the second switching transistor 52 are switched to the on state, as Figure 7 shown in (A), current flows to accumulate charges in the first capacitor 61a and the second capacitor 61b that constitute the Y capacitor 61. Furthermore, in this case, due to the occurrence of leakage, current also flows from the power supply side filter circuit 43 to the power supply side resonance circuit 44.

[0058] Figure 8 A graph showing the change in the current detected by the ammeter 71 (i.e., the current flowing through the first output terminal 58) immediately after the first switching transistor 51 and the second switching transistor 52 are switched to the on state. The dashed line in the graph represents the change in the current when no leakage occurs, and the solid line represents the change in the current when leakage occurs. As Figure 8 shown, when leakage occurs, compared to the case where no leakage occurs, current also flows from the power supply side filter circuit 43 to the power supply side resonance circuit 44, so the rising speed of the current becomes faster.

[0059] Therefore, in the present embodiment, when the first switching transistor 51 and the second switching transistor 52 are switched to the on state, that is, when the two output terminals 58 and 59 of the converter circuit 42 are switched to the same potential different from the ground potential, the presence or absence of leakage is detected based on the rising speed of the current detected by the ammeters 71 and 72. Specifically, in the present embodiment, based on whether the time taken for the current detected by the first ammeter 71 or the second ammeter 72 to reach a specified reference current Iref after the first switching transistor 51 and the second switching transistor 52 are switched to the on state is equal to or greater than a reference time, the presence or absence of leakage is detected. In the Figure 8 example shown, when no leakage occurs, the time t2 for the current detected by the ammeters 71 and 72 to reach the reference current Iref is greater than the reference time. Thus, in this case, the controller 33 connected to the ammeters 71 and 72 determines that no leakage has occurred. On the other hand, when leakage occurs, the time t1 for the current detected by the ammeters 71 and 72 to reach the reference current Iref is less than the reference time. Thus, in this case, the controller 33 connected to the ammeters 71 and 72 determines that leakage has occurred.

[0060] In addition, in the present embodiment, the presence or absence of leakage is detected based on the time it takes for the current detected by the current meters 71 and 72 to reach the reference current. However, as long as it is substantially based on whether the rising speed of the current detected by the current meters 71 and 72 is equal to or higher than a specified speed, the presence or absence of leakage can also be detected by other methods. Specifically, the rising speed can be calculated based on the outputs of the current meters 71 and 72, and the presence or absence of leakage can be detected based on the calculated rising speed. Alternatively, the presence or absence of leakage can be detected based on the current values detected by the current meters 71 and 72 when a specified time has elapsed since the first switching transistor 51 and the second switching transistor 52 were switched to the conducting state.

[0061] In addition, in a state where leakage occurs at any one of X1, X2, or X3 in the power transmission side resonant circuit 44, only after a certain amount of time has elapsed since the first switching transistor 51 and the second switching transistor 52 were switched to the conducting state, as Figure 7 (B) shown, no current flows through the first capacitor 61a and the second capacitor 61b that constitute the Y capacitor 61. On the other hand, in this case, due to the occurrence of leakage, current flows from the power transmission side filter circuit 43 to the power transmission side resonant circuit 44. That is, for the current detected by the third current meter 73 or the fourth current meter 74, in the case of no leakage, it becomes zero after a certain amount of time has elapsed since the switching of the switching transistors 51 and 52, whereas in the case of leakage, it does not become zero even after a certain amount of time has elapsed since the switching of the switching transistors 51 and 52, but remains at a specified value.

[0062] Therefore, in the present embodiment, after a certain amount of time has elapsed since the first switching transistor 51 and the second switching transistor 52 were switched to the conducting state, that is, after a certain amount of time has elapsed since the two output terminals 58 and 59 of the converter circuit 42 were set to the same potential different from the ground potential, the presence or absence of leakage is detected based on the current detected by the current meters 73 and 74. Specifically, when the current detected by the current meters 73 and 74 when the reference time has elapsed since the first switching transistor 51 and the second switching transistor 52 were switched to the conducting state is equal to or higher than a specified reference value (a value close to zero), that is, when the current is not zero, the controller 33 determines that leakage has occurred in the power transmission side resonant circuit 44. On the other hand, when the current detected by the current meters 73 and 74 when the reference time has elapsed since the first switching transistor 51 and the second switching transistor 52 were switched to the conducting state is less than the specified reference value, that is, when the current is zero (including substantially zero), the controller 33 determines that no leakage has occurred in the power transmission side resonant circuit 44. In addition, the reference time is the time that usually elapses until the current detected by the current meters 71 to 74 converges after the two output terminals 58 and 59 are set to the same potential different from the ground potential.

[0063] As described above, according to the present embodiment, leakage is detected based on the electrical characteristics of the ground power supply device 1 when the first switching transistor 51 and the second switching transistor 52 are switched on or after a certain period of time has passed since the switching. As a result, leakage in the power transmission side resonance circuit 44 can be detected relatively accurately.

[0064] In the present embodiment, when leakage is detected in the power transmission side resonance circuit 44, the controller 33 may prohibit the supply of electric power for power transmission to the power transmission side resonance circuit 44 so as not to use the power transmission side resonance circuit 44 for power transmission. In addition, when leakage is detected in the power transmission side resonance circuit 44, the controller 33 may notify the administrator (user) of the ground power supply device 1 that leakage has occurred. Specifically, the controller 33 displays the leakage on a display device such as a display connected to the controller 33, or plays a sound indicating the leakage from a speaker connected to the controller 33.

[0065] <Modification> In the above embodiment, leakage is detected in the power transmission side resonance circuit 44. However, leakage in the first line 65 and the second line 66 other than the power transmission side filter circuit 43 and the power transmission side resonance circuit 44 may be detected in the same manner.

[0066] In the above embodiment, the power transmission side filter circuit 43 may be omitted. However, in this case, no current flows through the power transmission side resonance circuit 44. Figure 6 Thus, in this case, the presence or absence of leakage is determined based on whether the current detected by the ammeters 71 to 74 is above a reference value close to zero immediately after the first switch transistor 51 and the second switch transistor 52 are switched on. In addition, in this case, the presence or absence of leakage is not detected based on the rising speed of the current immediately after the first switch transistor 51 and the second switch transistor 52 are switched on.

[0067] In the above embodiment, one transmission-side resonance circuit 44 is connected to one converter circuit 42. Figure 9 As shown, a plurality of power-transmitting-side resonant circuits 44 are connected to one converter circuit 42 . Figure 9 The diagram schematically shows the configuration of the circuits in the power supply unit 31 and the power transmission unit 32 when a plurality of power transmission-side resonant circuits 44 are connected to one converter circuit 42. Figure 2 Same picture.

[0068] exist Figure 9In the example shown, three power transmission side resonance circuits 44, namely a first power transmission side resonance circuit 44-1 to a third power transmission side resonance circuit 44-3, are connected to a converter circuit 42. A power transmission side filter circuit 43 is arranged between the converter circuit 42 and each power transmission side resonance circuit 44. Further, a changeover switch 69 (the first changeover switch 69-1 to the third changeover switch 69-3 in the example shown in Figure 9 ) is provided between the converter circuit 42 and each power transmission side resonance circuit 44. When power is transmitted to the vehicle 5, the changeover switch 69 closes the changeover switch 69 corresponding to the power transmission side resonance circuit 44 on which the vehicle 5 is located, and opens the changeover switches 69 corresponding to the other power transmission side resonance circuits 44.

[0069] On the other hand, when detecting leakage in the power transmission side resonance circuit 44, the power transmission side resonance circuits 44 are connected to the converter circuit 42 one by one through the changeover switch 69, and leakage in each power transmission side resonance circuit 44 being connected is detected. That is, in a state where one changeover switch 69 is closed and the remaining changeover switches 69 are open, both the first output terminal 58 and the second output terminal 59 of the converter circuit 42 are connected to the positive line 56 and are maintained at the same potential different from the ground potential. And when leakage is determined to occur in a state where one changeover switch 69 (the changeover switch 69 corresponding to one power transmission side resonance circuit 44) is closed and the remaining changeover switches 69 are open (that is, a state where only one power transmission side resonance circuit 44 is connected to the converter circuit 42), and leakage is not determined to occur in a state where the other changeover switches are closed and the remaining changeover switches are open (that is, a state where a power transmission side resonance circuit 44 other than the above one power transmission side resonance circuit 44 is connected to the converter circuit 42), it is determined that leakage occurs in the one power transmission side resonance circuit 44 connected to the above one changeover switch 69.

[0070] On the other hand, when it is determined that leakage occurs in all cases when all the changeover switches 69 are closed one by one and the remaining changeover switches 69 are open (that is, a state where all the power transmission side resonance circuits 44 are connected to the converter circuit 42 one by one), it is determined that leakage occurs in a circuit on the converter circuit 42 side compared with the changeover switch 69 (for example, a part of the power transmission side filter circuit 43). Further, when leakage is detected in a state where all the changeover switches 69 are open, it is also determined that leakage occurs in a circuit on the converter circuit 42 side compared with the changeover switch 69 (for example, a part of the power transmission side filter circuit 43).

[0071] Second Embodiment Next, refer to Figure 10, the above-ground power supply device 1 according to the second embodiment will be described. The configuration of the above-ground power supply device 1 according to the second embodiment is basically the same as that of the above-ground power supply device 1 according to the first embodiment. The following description will focus on the differences from the above-ground power supply device 1 according to the first embodiment.

[0072] Figure 10 is a diagram that schematically shows the circuit configuration in the power supply unit 31 and the power transmission unit 32 according to the second embodiment, and is the same as Figure 2 the same figure. As Figure 10 shown, the power transmission unit 32 according to the present embodiment has a voltmeter 75 connected in parallel with the power transmission side resonance capacitor 46. The voltmeter 75 detects the voltage between both ends of the power transmission side resonance capacitor 46.

[0073] Here, in the above-ground power supply device 1 configured in this way, when there is no leakage in the power transmission side resonance circuit 44, if the first switching transistor 51 and the second switching transistor 52 are maintained in the on state, that is, if the two output terminals 58 and 59 are maintained at the same potential different from the ground potential, the potentials at both ends of the power transmission side resonance capacitor 46 are equal. Thus, in this case, the voltage detected by the voltmeter 75 is approximately zero.

[0074] On the other hand, when there is leakage in the power transmission side resonance circuit 44, even if the first switching transistor 51 and the second switching transistor 52 are maintained in the on state, the potentials at both ends of the power transmission side resonance capacitor 46 are different. Thus, in this case, the voltage detected by the voltmeter 75 is not zero, but is maintained at a specified value different from zero.

[0075] Therefore, in the present embodiment, after a certain period of time has elapsed since the first switching transistor 51 and the second switching transistor 52 are switched to the on state, that is, after a certain period of time has elapsed since the two output terminals 58 and 59 of the converter circuit 42 are set to the same potential different from the ground potential, the presence or absence of leakage is detected based on the voltage detected by the voltmeter 75. Specifically, when the voltage detected by the voltmeter 75 is equal to or higher than a specified reference value (a value close to zero), that is, when the voltage is not zero (including approximately zero), after the reference time has elapsed since the first switching transistor 51 and the second switching transistor 52 are switched to the on state, the controller 33 determines that there is leakage in the power transmission side resonance circuit 44. On the other hand, when the voltage detected by the voltmeter 75 is less than the specified reference value after the reference time has elapsed since the first switching transistor 51 and the second switching transistor 52 are switched to the on state, that is, when the voltage is zero (including approximately zero), the controller 33 determines that there is no leakage in the power transmission side resonance circuit 44.

[0076] In this manner, according to the present embodiment, leakage is detected based on the electrical characteristics of the ground power supply device 1 when the first switching transistor 51 and the second switching transistor 52 are switched on. As a result, leakage in the power transmission side resonance circuit 44 can be detected relatively accurately.

[0077] In addition, in the second embodiment, not only can leakage in the power transmission side resonance circuit 44 be detected based on the voltmeter 75, but also leakage in the power transmission side resonance circuit 44 can be detected based on the ammeters 71 to 74 according to the first embodiment. By detecting leakage using multiple methods in this way, leakage can be detected with high precision.

[0078] Third Embodiment Next, with reference to Figure 11 , the ground power supply device 1 according to the third embodiment will be described. The configuration of the ground power supply device 1 according to the third embodiment is basically the same as the configurations of the ground power supply devices 1 according to the first embodiment and the second embodiment. Hereinafter, the description will focus on the differences from the ground power supply devices 1 according to the first embodiment and the second embodiment.

[0079] Figure 11 is a diagram similar to Figure 2 schematically showing the circuit configuration in the power supply unit 31 and the power transmission unit 32 according to the third embodiment. As Figure 11 shown, the power transmission unit 32 according to the present embodiment has a resistor 76 and a fifth ammeter 77 connected in parallel with the power transmission side resonance capacitor 46. The fifth ammeter 77 is connected in series with the resistor 76 and detects the current flowing through the resistor 76. The resistor 76 has a large resistance value so that a large current does not flow.

[0080] Here, in the ground power supply device 1 configured in this way, when there is no leakage in the power transmission side resonance circuit 44, if the first switching transistor 51 and the second switching transistor 52 are maintained in the on state, that is, if the two output terminals 58 and 59 are maintained at the same potential different from the ground potential, the potentials at both ends of the power transmission side resonance capacitor 46 are equal. Thus, in this case, no current flows through the resistor 76 connected in parallel with the power transmission side resonance capacitor 46, and thus the current detected by the fifth ammeter 77 is substantially zero.

[0081] On the other hand, when there is leakage in the power transmission side resonance circuit 44, even if the first switching transistor 51 and the second switching transistor 52 are maintained in the on state, the potentials at both ends of the power transmission side resonance capacitor 46 are different. Thus, in this case, a current flows through the resistor 76 connected in parallel with the power transmission side resonance capacitor 46, and thus the current detected by the fifth ammeter 77 is not zero but is maintained at a specified value different from zero.

[0082] Therefore, in the present embodiment, after a certain period of time has elapsed since the first switching transistor 51 and the second switching transistor 52 are switched to the on state, that is, after a certain period of time has elapsed since the two output terminals 58 and 59 of the converter circuit 42 are set to the same potential different from the ground potential, the presence or absence of leakage is detected based on the current detected by the fifth ammeter 77. Specifically, when the current detected by the fifth ammeter 77 when a reference time has elapsed since the first switching transistor 51 and the second switching transistor 52 are switched to the on state is equal to or greater than a specified reference value (a value close to zero), that is, when the current is not zero (including approximately zero), the controller 33 determines that leakage has occurred in the power transmission side resonance circuit 44. On the other hand, when the current detected by the fifth ammeter 77 when a reference time has elapsed since the first switching transistor 51 and the second switching transistor 52 are switched to the on state is less than the specified reference value, that is, when the current is zero (including approximately zero), the controller 33 determines that no leakage has occurred in the power transmission side resonance circuit 44.

[0083] In this way, according to the present embodiment, the leakage is also detected based on the electrical characteristics of the ground power supply device 1 when the first switching transistor 51 and the second switching transistor 52 are switched to the on state. As a result, the leakage in the power transmission side resonance circuit 44 can be detected relatively accurately.

[0084] In addition, in the third embodiment, not only can the leakage in the power transmission side resonance circuit 44 be detected based on the fifth ammeter 77, but also the leakage in the power transmission side resonance circuit 44 can be detected based on the ammeters 71 to 74 in the first embodiment or the voltmeter 75 according to the second embodiment. By detecting the leakage using multiple methods in this way, the leakage can be detected with high precision.

[0085] Fourth Embodiment Next, with reference to Figures 12 - 15 , the vehicle 5 according to the fourth embodiment will be described. The configuration of the vehicle 5 according to the fourth embodiment is basically the same as the configuration of the vehicle 5 according to the first to third embodiments. The following description will focus on the differences from the vehicle 5 according to the first to third embodiments.

[0086] Figure 12 is a diagram schematically showing the configuration of the circuit in the power receiving unit 14. As described above, the power receiving unit 14 includes a power receiving side resonance circuit 21 and a power receiving side rectifying circuit 24. In addition, the power receiving unit 14 includes a power receiving side filter circuit 26 disposed between the power receiving side resonance circuit 21 and the power receiving side rectifying circuit 24. In addition, in Figure 12 , the circuit configuration of the charging circuit 25 is omitted. In addition, the power receiving unit 14 may not include the power receiving side filter circuit 26.

[0087] In the present embodiment, as Figure 12 shown, the power receiving side rectifier circuit 24 has four switching transistors 91 to 94 each connected in parallel with a diode, and a smoothing capacitor 95. As the switching transistors 91 to 94, for example, a reversely conductive field effect transistor such as a MOSFET is used. The four switching transistors 91 to 94 are configured to form an H-bridge circuit in the same manner as in the first embodiment. In the present embodiment, a first switching transistor 91 is also provided between the positive line 96 connected to the positive electrode of the battery 12 and the first input terminal 98 (which functions as the first output terminal when supplying power from the battery 12 to the power receiving side resonant circuit 21). Similarly, a second switching transistor 92 is provided between the positive line 96 and the second input terminal 99 (which functions as the second output terminal when supplying power from the battery 12 to the power receiving side resonant circuit 21). In addition, a third switching transistor 93 is provided between the negative line 97 connected to the negative electrode of the battery 12 and the first input terminal 98, and a fourth switching transistor 94 is provided between the negative line 97 and the second input terminal 99. These switching transistors 91 to 94 are connected to the ECU 15 and are controlled to be turned on / off by the ECU 15.

[0088] The power receiving side filter circuit 26 removes the noise generated in the power receiving unit 14, particularly common mode noise and differential mode noise. In the present embodiment, the power receiving side filter circuit 26 is disposed between the power receiving side resonant circuit 21 and the power receiving side rectifier circuit 24. As Figure 12 shown, the power receiving side filter circuit 26 has various filter elements for reducing noise. Specifically, in the present embodiment, the power receiving side filter circuit 26 has an X capacitor 81, a common mode choke coil 82, and a differential mode choke coil 83. In addition, the power receiving side filter circuit 26 may have only a part of these multiple filter elements. Further, the power receiving side filter circuit 26 may also have other filter elements such as a Y capacitor, a fourth-order filter, or a band-pass filter.

[0089] As described above, the power receiving side resonant circuit 21 has a power receiving coil 22 and a power receiving side resonant capacitor 23. One end of the power receiving coil 22 is connected to the first line 84 connected to the first input terminal 98 of the power receiving side rectifier circuit 24, and the other end is connected to the second line 85 connected to the second input terminal 99 of the power receiving side rectifier circuit 24. In addition, in the present embodiment, two power receiving side resonant capacitors 23 are respectively connected in series with the first line 84 and the second line 85. Further, the power receiving side resonant capacitor 23 only needs to form a resonator together with the power receiving coil 22 and can be arranged in any manner.

[0090] In addition, in the present embodiment, a plurality of ammeters 86 to 89 are provided for the power receiving unit 14. Specifically, the first ammeter 86 is provided on the first line 84 close to the first input terminal 98 of the power receiving side rectifier circuit 24. The second ammeter 87 is provided on the second line 85 close to the second input terminal 99 of the power receiving side rectifier circuit 24. In addition, the third ammeter 88 is provided on the first line 84 between the power receiving side filter circuit 26 and the power receiving side resonance circuit 21. The fourth ammeter 89 is provided on the second line 85 between the power receiving side filter circuit 26 and the power receiving side resonance circuit 21. In addition, as long as these ammeters can detect the current flowing through the power receiving coil 22, the current flowing through the power receiving side resonance capacitor 23, or the current flowing from the power receiving side filter circuit 26 to the power receiving coil 22, they may also be arranged at positions other than the above-mentioned positions.

[0091] Next, with reference to Figure 13 and Figure 14 , the operation of the power receiving unit 14 of the vehicle 5 configured as described above during power reception will be described. Figure 13 FIG. is a diagram for explaining the operation of the power receiving unit 14 during power reception.

[0092] During power reception, the switching transistors 91 to 94 of the power receiving side rectifier circuit 24 are selectively connected, and the AC power supplied to the power receiving side rectifier circuit 24 is converted into DC power. Specifically, in the power receiving side rectifier circuit 24, the first connection state and the second connection state are alternately switched to output DC power.

[0093] In the first connection state, as shown in (A) of Figure 13 , the first switching transistor 91 and the fourth switching transistor 94 are turned on, and the second switching transistor 92 and the third switching transistor 93 are turned off. In this case, the positive line 96 is connected to the first input terminal 98, and thus is connected to the first line 84. On the other hand, the negative line 97 is connected to the second input terminal 99, and thus is connected to the second line 85.

[0094] In addition, in the second connection state, as shown in (B) of Figure 13 , the second switching transistor 92 and the third switching transistor 93 are turned on, and the first switching transistor 91 and the fourth switching transistor 94 are turned off. In this case, the positive line 96 is connected to the second input terminal 99, and thus is connected to the second line 85. On the other hand, the negative line 97 is connected to the first input terminal 98, and thus is connected to the first line 84.

[0095] Figure 14 FIG. is a timing chart of the input current to the power receiving side rectifier circuit 24, the states of the switching transistors 91 to 94, and the output current from the power receiving side rectifier circuit 24. As shown in Figure 14As shown, during power reception, in the power reception side rectifier circuit 24, the first connection state and the second connection state are alternately switched corresponding to the direction of the alternating current generated by the power reception coil 22. Specifically, when the direction of the input current is in one direction (time t1 to t2), the power reception side rectifier circuit 24 is set to the first connection state. On the other hand, when the direction of the input current is in the direction opposite to the above-mentioned one direction (time t2 to t3), the power reception side rectifier circuit 24 is set to the second connection state. Thus, as Figure 14 shown, the output current from the power reception side rectifier circuit 24 becomes a direct current. Thus, direct current power is supplied to the battery 12. Thus, in the present embodiment, the power reception side rectifier circuit 24 is controlled to charge the battery 12 after rectifying the alternating current power received by the power reception coil 22 into direct current power.

[0096] Figure 15 The detection of leakage in the power reception side resonance circuit 21 will be described. Figure 15 FIG. is a diagram for explaining the operation of the power reception unit 14 when detecting leakage in the power reception side resonance circuit 21. As Figure 15 shown, when detecting leakage in the power reception side resonance circuit 21, when the vehicle 5 is not located on the power transmission coil 45, the power of the battery 12 is used. Thus, the battery 12 and the power reception side rectifier circuit 24 act as a power supply device capable of supplying power to the power reception coil 22. Thus, in the present embodiment, the power supply device is charged by the power received by the power reception coil 22.

[0097] Specifically, when detecting leakage in the power reception side resonance circuit 21, when the vehicle 5 is not located on the power transmission coil 45, as Figure 15 shown, the first switching transistor 91 and the second switching transistor 92 are turned on, and the third switching transistor 93 and the fourth switching transistor 94 are turned off. Thus, when detecting leakage in the power reception side resonance circuit 21, the switching transistors 91 to 94 of the power reception side rectifier circuit 24 are controlled in the same manner as in the first embodiment so that the two input terminals 98 and 99 of the power reception side rectifier circuit 24 (the two output terminals of the power supply device) are maintained at the same potential different from the ground potential.

[0098] Then, in the same manner as in the first embodiment, after a certain period of time has elapsed since the first switching transistor 91 and the second switching transistor 92 are switched to the on state, it is determined whether there is a leakage in the power receiving side resonance circuit 21 based on the currents detected by the ammeters 88 and 89. Further, when the Y capacitors are included in the power receiving side filter circuit 26, it is also possible to determine whether there is a leakage in the power receiving side resonance circuit 21 based on the rising speed of the currents detected by the ammeters 88 and 89 when the first switching transistor 91 and the second switching transistor 92 are switched to the on state, in the same manner as in the first embodiment. Thus, it is possible to detect a leakage in the vehicle 5, particularly a leakage in the power receiving side resonance circuit 21 or the power receiving unit 14 of the vehicle 5.

[0099] In the present embodiment, when it is detected that a leakage has occurred in the power receiving side resonance circuit 21, the ECU 15 may prohibit the use of the power receiving side resonance circuit 21 of the vehicle 5 so that power is not received using the power receiving side resonance circuit 21. Additionally, the ECU 15 may be configured to not send a power transmission request to the ground power supply device 1 when it is detected that a leakage has occurred in the power receiving side resonance circuit 21. Further, when the vehicle 5 is configured to be capable of autonomous driving, it may be that the ECU 15 drives the vehicle 5 in such a way that it does not travel in the lane in which the power transmission coil 45 is buried when it is detected that a leakage has occurred in the power receiving side resonance circuit 21. Additionally, when it is detected that a leakage has occurred in the power receiving side resonance circuit 21, the ECU 15 may notify the user of the vehicle 5 of the occurrence of the leakage. Specifically, the ECU 15 displays the content of the occurrence of the leakage on a display device such as a display connected to the ECU 15, or plays a sound of the content of the occurrence of the leakage from a speaker connected to the ECU 15.

[0100] In addition, in the above-described embodiment, the detection of the leakage in the power receiving side resonance circuit 21 is performed when the vehicle 5 is not located on the power transmission coil 45. However, the detection of the leakage in the power receiving side resonance circuit 21 may also be performed after the power supply of the vehicle 5 is turned on and before the vehicle 5 starts to travel (before the motor 11 operates). Specifically, the detection of the leakage in the power receiving side resonance circuit 21 is performed, for example, when the door of the vehicle 5 is unlocked by the smart key, or when the user gets into the vehicle 5 and presses the start / stop button. Alternatively, the detection of the leakage in the power receiving side resonance circuit 21 may also be performed after the power supply of the vehicle 5 is turned off. Specifically, the detection of the leakage in the power receiving side resonance circuit 21 is performed, for example, when the user presses the start / stop button before getting out of the vehicle 5.

[0101] The preferred embodiments related to the present disclosure have been described above, but the present disclosure is not limited to these embodiments, and various modifications and changes can be made within the scope of the claims.

Claims

1. A power transmission device having: a coil for non - contact power transmission or reception; a power supply device connected to the coil and applying a voltage to the coil; a control device for controlling the power supply device, wherein, When detecting the leakage of the power transmission device, the control device controls the power supply device to maintain the two output terminals of the power supply device at the same potential different from the ground potential, and detects the leakage based on the electrical characteristics in the power transmission device at this time.

2. The power transmission device according to claim 1, wherein, The electrical characteristics include the current flowing through the output terminals of the power supply device.

3. The power transmission device according to claim 1, wherein, It also has a filter circuit provided between the coil and the power supply device. The electrical characteristics include the current flowing between the filter circuit and the coil.

4. The power transmission device according to claim 2 or 3, wherein, When the control device detects that the current is not zero when controlling the power supply device to maintain the two output terminals of the power supply device at the same potential different from the ground potential, it determines that leakage has occurred in the power transmission device.

5. The power transmission device according to any one of claims 1 to 4, wherein, It also has a filter circuit provided between the coil and the power supply device. The filter circuit has a plurality of capacitors. One capacitor of the capacitors has one end connected to one end of the coil and the other end grounded, and the other capacitor of the capacitors has one end connected to the other end of the coil and the other end grounded. The control device detects the leakage based on the rising speed of the current flowing through the output terminals of the power supply device when the two output terminals are made to have the same potential different from the ground potential.

6. The power transmission device according to any one of claims 1 to 5, wherein, It also has a resonant capacitor connected in series with the coil. The electrical characteristics include the voltage between the two ends of the resonant capacitor.

7. The power transmission device according to claim 6, wherein, When the control device detects that the voltage between the two ends of the resonant capacitor is not zero when controlling the power supply device to maintain the two output terminals of the power supply device at the same potential different from the ground potential, it determines that leakage has occurred in the power transmission device.

8. The power transmission device according to any one of claims 1 to 7, wherein, It also has a resonant capacitor connected in series with the coil and a resistor connected in parallel with the resonant capacitor. The electrical characteristics include the current flowing through the resistor.

9. The power transmission device according to claim 8, wherein, When the control device detects that the current flowing through the resistor is not zero when controlling the power supply device to maintain the two output terminals of the power supply device at the same potential different from the ground potential, it determines that leakage has occurred in the power transmission device.

10. The power transmission device according to any one of claims 1 to 9, wherein, When the control device determines that leakage has occurred in the power transmission device, it notifies the user of the occurrence of leakage.

11. The power transmission device according to any one of claims 1 to 10, wherein, The coil is a power transmission coil for non-contact power transmission. When the power transmission coil performs non-contact power transmission, the control device controls the power supply device to supply AC power to the power transmission coil.

12. The power transmission device according to claim 11, wherein, When the control device determines that leakage has occurred in association with the power transmission coil constituting the power transmission device, it prohibits the power supply to the power transmission coil.

13. The power transmission device according to claim 11 or 12, wherein, The power transmission device has a plurality of power transmission coils, and the plurality of power transmission coils are respectively connected to one power supply device via a changeover switch. When detecting the leakage of the power transmission device, the control device controls the power supply device to maintain the two output terminals of the power supply device at the same potential different from the ground potential in a state where one changeover switch is turned on and the remaining changeover switches are turned off, and detects the leakage based on the electrical characteristics in the power transmission device at this time.

14. The power transmission device according to any one of claims 11 to 13, wherein, When the control device determines that a leakage has occurred only when one change-over switch is turned on and the remaining change-over switches are turned off, and does not determine that a leakage has occurred when other change-over switches are respectively turned on and the remaining change-over switches are turned off, it determines that a leakage has occurred in the resonance circuit including the power transmission coil connected to the one change-over switch.

15. The power transmission device according to any one of claims 1 to 10, wherein, The coil is a power receiving coil that receives power non-contactingly, and the power supply device is configured to be charged by the power received in the power receiving coil. When the power receiving coil receives power non-contactingly, the control device controls the power supply device to charge the power after rectifying the received AC power into DC power.

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