Noncontact power supply system, power transmission device, and power reception device

Abstract

To provide a power transmission non-contact power supply system in which a power transmission device can stop power transmission after a power reception device stops power reception.SOLUTION: In a non-contact power supply system 1 for supplying power from a power transmission device 10 to a power reception device 80 in a non-contact manner, the power reception device includes: a secondary side resonance circuit 81 having a secondary side coil L2 and a secondary side capacitor C2; a rectifier circuit 83; an immittance circuit 82; a load device 83; a protection switch for bringing the secondary side resonance circuit into a non-resonance state by being brought into a conduction state or a non-conduction state; and a secondary side control circuit 85 for switching a state of the protection switch between the conduction state and the non-conduction state. A primary side control circuit causes the power reception device to transition from a power transmission state to a standby state by changing impedance of a variable impedance element by using a detection value of a primary side detection circuit that changes when the protection switch is switched to the conductive state or the non-conductive state.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a contactless power supply device, a power transmitting device, and a power receiving device. [Background technology]

[0002] Conventionally, there is a technology for protecting a load to which received power is supplied when an abnormality occurs in a power receiving device that receives power from a power transmitting device in a non-contact manner (for example, Patent Document 1). In Patent Document 1, a transistor included in a rectifier is turned on, and then a relay arranged in a current path from a resonator coil to the rectifier is opened to protect the load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2022-533250 Summary of the Invention [Problem to be solved by the invention]

[0004] Since the power transmitting device continues transmitting power even after the power receiving device stops receiving power, a power loss may occur in the power transmitting device. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] According to a first embodiment of the present disclosure, there is provided a contactless power supply system (1, 101-401) that contactlessly supplies power from a power transmitting device (10, 210-410) to a power receiving device (80, 280-480). The power transmitting device includes a primary resonant circuit (12, 212, 312) having a primary coil (L1) and a primary capacitor (C1), an AC power source (11) that applies AC power of a predetermined operating frequency to the primary resonant circuit, an impedance variable element (C1, SW21, SW31) that is connected between the primary coil and the AC power source and switches the state of the power transmitting device between a power transmitting state and a standby state, a primary control circuit (13) that changes the impedance of the impedance variable element, and a primary detection circuit (14, M1) that detects either the magnitude of a magnetic flux linking the primary coil or the magnitude of a magnetic flux in the vicinity of the primary coil. The power receiving device includes a secondary resonant circuit (81) having a secondary coil (L2) for magnetically coupling with the primary coil and secondary capacitors (C2, C3), a rectifier circuit (83, 283, 483) for rectifying AC power output from the secondary resonant circuit, an immittance circuit (82, 282) connected between the rectifier circuit and the secondary resonant circuit, and a load device (83) to which DC power output from the rectifier circuit is supplied, and a load device (83) that controls the secondary resonant circuit by being in either a conductive state or a non-conductive state. The power receiving device includes protection switches (SW1, TR, RE, SW41, SW42) for achieving a non-resonant state, and a secondary side control circuit (85) for setting the state of the protection switches to either the conductive state or the non-conductive state, and the primary side control circuit transitions the power receiving device from the power transmitting state to the standby state by changing the impedance of the impedance variable element using the detection value of the primary side detection circuit that changes when the protection switches are set to either the conductive state or the non-conductive state.

[0007] According to this embodiment, since the power receiving device has a protection switch, when the power receiving device is in an abnormal state, the protection switch can be used to reduce the current supplied to the load device to protect the load device. Furthermore, when the magnetic flux near the primary coil becomes small in the power transmitting state, the primary control circuit increases the impedance of the primary resonant circuit to transition to a standby state. This makes it possible to suppress power consumption that does not contribute to power supply in the power transmitting device.

[0008] According to a second embodiment of the present disclosure, there is provided a contactless power feeding system (501) that wirelessly feeds power from a power transmitting device (210) to a power receiving device (580).The power transmitting device includes a primary side resonant circuit (212) having a primary side coil (L1) and a primary side capacitor (C1), an AC power source (11) that applies AC power of a predetermined operating frequency to the primary side resonant circuit, an impedance variable element (SW21) that is connected between the primary side coil and the AC power source and switches the state of the power transmitting device between a power transmitting state and a standby state, a primary side control circuit (13) that changes the impedance of the impedance variable element, and a control circuit (14) that controls the magnitude of the magnetic flux linking the primary side coil and the magnitude of the magnetic flux in the vicinity of the primary side coil. and a primary-side detection circuit (M1) for detecting either one of the primary-side and secondary-side resonant circuits, and the power receiving device includes a secondary-side resonant circuit (81) having a secondary-side coil (L2) for magnetically coupling with the primary-side coil and secondary-side capacitors (C2, C3), a rectifier circuit (283) for rectifying AC power output from the secondary-side resonant circuit, the rectifier circuit having switches (Q1, Q2) in at least one of a lower arm and an upper arm, an immittance circuit (282) connected between the rectifier circuit and the secondary-side resonant circuit, and a secondary-side detection circuit (M2) for detecting either one of the primary-side and secondary-side resonant circuits. the secondary-side control circuit (85) sets the state of the protection switch to either the conductive state or the non-conductive state, and a state detection circuit (87) for detecting the state of the power transmitting device, and when the secondary-side control circuit receives a power supply stop signal, the secondary-side control circuit performs a first process (S11) of setting the protection switch to the conductive state before setting the protection switch to the conductive state, and after the first process When the state of the power transmission device detected by the state detection circuit is the power transmission state, the protection switch is set to the conductive state, and the primary side control circuit transitions the power receiving device from the power transmission state to the standby state by changing the impedance of the impedance variable element using at least one of the detection value of the primary side detection circuit that changes when the switch is set to the conductive state and the detection value of the primary side detection circuit that changes when the protection switch is set to either the conductive state or the non-conductive state.

[0009] According to this embodiment, since the power receiving device has a protection switch and a rectifier circuit having a switch, when the power receiving device is in an abnormal state, the protection switch or the switch of the rectifier circuit can be used to reduce the current supplied to the load device to protect the load device. Furthermore, when the magnetic flux near the primary coil becomes small in the power transmitting state, the primary control circuit increases the impedance of the primary resonant circuit to transition to a standby state. This makes it possible to suppress power consumption that does not contribute to power supply in the power transmitting device.

[0010] According to a third embodiment of the present disclosure, there is provided a power transmitting device (10, 210-410) that wirelessly supplies power to a power receiving device (80, 280-480). The power transmitting device includes a primary resonant circuit (12, 212, 312) having a primary coil (L1) and a primary capacitor (C1), an AC power source (11) that applies AC power of a predetermined operating frequency to the primary resonant circuit, an impedance variable element (C1, SW21, SW31) that is connected between the primary coil and the AC power source and switches the state of the power transmitting device between a power transmitting state and a standby state, a primary control circuit (13) that changes the impedance of the impedance variable element, and a primary detection circuit (14, M1) that detects either the magnitude of a magnetic flux linking the primary coil or the magnitude of a magnetic flux in the vicinity of the primary coil. The power receiving device includes a secondary side resonant circuit (81) having a secondary side coil (L2) for magnetically coupling with the primary side coil and secondary side capacitors (C2, C3), a rectifier circuit (83, 283, 483) for rectifying AC power output from the secondary side resonant circuit, an immittance circuit (82, 282) connected between the rectifier circuit and the secondary side resonant circuit, a load device (83) to which DC power output from the rectifier circuit is supplied, protection switches (SW1, TR, RE, SW41, SW42) for putting the secondary side resonant circuit into a non-resonant state by being in either a conductive state or a non-conductive state, and a secondary side control circuit (85) for setting the state of the protection switch to either the conductive state or the non-conductive state. The primary side control circuit transitions the power receiving device from the power transmitting state to the standby state by changing the impedance of the impedance variable element using the detection value of the primary side detection circuit, which changes when the protection switch is set to either the conductive state or the non-conductive state.

[0011] According to this embodiment, since the power receiving device has a protection switch, when the power receiving device is in an abnormal state, the protection switch can be used to reduce the current supplied to the load device to protect the load device. Furthermore, when the magnetic flux near the primary coil becomes small in the power transmitting state, the primary control circuit increases the impedance of the primary resonant circuit to transition to a standby state. This makes it possible to suppress power consumption that does not contribute to power supply in the power transmitting device.

[0012] According to a fourth embodiment of the present disclosure, there is provided a power receiving device (80, 280 to 480) that receives power contactlessly from a power transmitting device (10, 210 to 410). The power transmitting device includes a primary resonant circuit (12, 212, 312) having a primary coil (L1) and a primary capacitor (C1), an AC power source (11) that applies AC power of a predetermined operating frequency to the primary resonant circuit, an impedance variable element (C1, SW21, SW31) that is connected between the primary coil and the AC power source and switches the state of the power transmitting device between a power transmitting state and a standby state, a primary control circuit (13) that changes the impedance of the impedance variable element, and a primary detection circuit (14, M1) that detects either the magnitude of a magnetic flux linking the primary coil or the magnitude of a magnetic flux in the vicinity of the primary coil. the secondary side resonant circuit (81) having a secondary side coil (L2) for magnetically coupling with the secondary side resonant circuit and secondary side capacitors (C2, C3); a rectifier circuit (83, 283, 483) for rectifying AC power output from the secondary side resonant circuit; an immittance circuit (82, 282) connected between the rectifier circuit and the secondary side resonant circuit; a load device (83) to which DC power output from the rectifier circuit is supplied; protection switches (SW1, TR, RE, SW41, SW42) for putting the secondary side resonant circuit in a non-resonant state by being in either a conductive state or a non-conductive state; and a secondary side control circuit (85) for setting the state of the protection switch to either the conductive state or the non-conductive state. The primary side control circuit transitions the power receiving device from the power transmitting state to the standby state by changing the impedance of the impedance variable element using the detection value of the primary side detection circuit, which changes when the protection switch is set to either the conductive state or the non-conductive state.

[0013] According to this embodiment, since the power receiving device has a protection switch, when the power receiving device is in an abnormal state, the protection switch can be used to reduce the current supplied to the load device to protect the load device. Furthermore, when the magnetic flux near the primary coil becomes small in the power transmitting state, the primary control circuit increases the impedance of the primary resonant circuit to transition to a standby state. This makes it possible to suppress power consumption that does not contribute to power supply in the power transmitting device. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram of a contactless power supply system. [Diagram 2] FIG. 1 is a circuit diagram of a contactless power supply system according to a first embodiment. [Diagram 3] FIG. 4 is a diagram for explaining a power supply sequence according to the first embodiment. [Figure 4] FIG. 11 is a circuit diagram of a non-contact power supply system according to a second embodiment. [Diagram 5] FIG. 11 is a diagram illustrating a power supply sequence according to the second embodiment. [Figure 6] FIG. 11 is a circuit diagram of a contactless power supply system according to a third embodiment. [Figure 7] FIG. 11 is a diagram illustrating a power supply sequence according to the third embodiment. [Figure 8] FIG. 13 is a circuit diagram of a contactless power supply system according to a fourth embodiment. [Figure 9] FIG. 13 is a circuit diagram of a contactless power supply system according to a fifth embodiment. [Figure 10] FIG. 13 is a diagram illustrating a power supply sequence according to the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A. First embodiment: A1. Configuration of the wireless power supply system: As shown in FIG. 1, the contactless power supply system 1 includes a power transmission device 10 and a power receiving device 80. In this embodiment, the power transmission device 10 is buried under a road RS. The power receiving device 80 is mounted on a vehicle VE as a moving body that travels on the road RS. When the vehicle VE is traveling, power is supplied to the power receiving device 80 from the power transmission device 10. Here, traveling includes a case where the vehicle VE is moving and a case where the vehicle is stopped, such as waiting at a traffic light. The vehicle VE is configured as, for example, an electric vehicle or a hybrid vehicle.

[0016] The power transmission device 10 includes a primary resonant circuit 12 having a primary coil L1, and an AC power source 11 that supplies power to the primary resonant circuit 12. The AC power source 11 supplies power to the multiple primary resonant circuits 12. The multiple primary coils L1 are arranged along the extension direction of the road RS.

[0017] The moving body on which the power receiving device 80 is mounted is not limited to a vehicle VE traveling on the road RS, and may be, for example, an AGV (automated guided vehicle), a traveling robot, etc. The power transmitting device 10 may be installed not under the road RS, but on a sidewalk or parking lot adjacent to the road RS, or on a route along which the AGV travels.

[0018] The power receiving device 80 includes a battery 84 as a load device, an auxiliary battery 94, a rectifier circuit 83, a secondary resonant circuit 81 having a secondary coil L2 for magnetically coupling with the primary coil L1, a DC / DC converter 92, an inverter 91, a motor generator 93, an auxiliary 95, and a power receiving side control unit 96. In this embodiment, the secondary coil L2 is provided on the underside of the vehicle VE, in a position opposite to the primary coil L1.

[0019] A rectifier circuit 83 is connected to the secondary resonant circuit 81. In a power receiving state, the rectifier circuit 83 rectifies the AC power received by the secondary resonant circuit 81, and supplies the rectified DC power to a battery 84, a DC / DC converter 92, and an inverter 91.

[0020] Battery 84 is a secondary battery that is charged by the supplied DC power. Inverter 91 drives motor generator 93 using the supplied DC power. Motor generator 93 operates as a three-phase AC motor and generates driving force for traveling. In addition, motor generator 93 operates as a generator when vehicle VE decelerates and regenerates power. The regenerated three-phase AC power is converted to DC power by inverter 91 and used to charge battery 84.

[0021] The DC / DC converter 92 steps down the DC power supplied from the rectifier circuit 83, and supplies the stepped-down DC power to an auxiliary battery 94 and auxiliary equipment 95. The auxiliary equipment 95 includes an air conditioner for the vehicle VE, an electric power steering device, peripheral devices such as headlights, blinkers, and wipers, and accessories for the vehicle VE. The auxiliary battery 94 is a secondary battery for driving the auxiliary equipment 95.

[0022] The power receiving side control unit 96 controls each unit such as the inverter 91 in the power receiving device 80. The power receiving side control unit 96 is realized by including an ECU (engine control unit). The ECU may be realized by one microcontroller or may be realized by including multiple microcontrollers. The case where multiple microcontrollers are included is the case where, for example, a microcontroller that controls mechanisms related to the drive of the vehicle VE, such as the motor generator 93, and a microcontroller that controls mechanisms related to the battery 84, such as the rectifier circuit 83, are included.

[0023] A2.Circuit configuration of the non-contact power supply system: As shown in Fig. 2, in addition to the above configuration, the power transmitting device 10 includes a primary side capacitor C1 which is a variable capacitance capacitor, a primary side control circuit 13, and a magnetic flux detection circuit 14 which serves as a primary side detection circuit. Note that, in Fig. 2, of the multiple primary side resonant circuits 12 connected to the AC power supply 11, only one primary side resonant circuit 12 is shown, and the other primary side resonant circuits 12 are not shown.

[0024] The AC power source 11 applies AC power of a predetermined operating frequency to the primary resonant circuit 12. In this embodiment, the operating frequency is 85 kHz. The primary capacitor C1 as an impedance variable element has a function of putting the primary resonant circuit 12 in a resonant state at the operating frequency and putting the primary resonant circuit 12 in a non-resonant state at the operating frequency. The primary capacitor C1 is connected between the primary coil L1 and the AC power source 11. The primary capacitor C1 switches the state of the power transmitting device 10 between a standby state and a power transmitting state, which will be described later.

[0025] In this embodiment, the primary side capacitor C1 is configured to be switchable between a first capacitance value and a second capacitance value smaller than the first capacitance value. The capacitance value of the primary side capacitor C1 is switched between the first capacitance value and the second capacitance value by a switching signal Sig1 output from the primary side control circuit 13. When the primary side coil L1 and the secondary side coil L2 are magnetically coupled and the primary side capacitor C1 has the first capacitance value, the primary side resonant circuit 12 is in a resonant state at the operating frequency. That is, the first capacitance value of the primary side capacitor C1 is set to a value at which the resonant frequency of the primary side resonant circuit 12 coincides with the operating frequency. On the other hand, when the primary side capacitor C1 has the second capacitance value, the resonant frequency of the primary side resonant circuit 12 deviates from the operating frequency, so that the primary side resonant circuit 12 is in a non-resonant state at the operating frequency.

[0026] A primary coil L1 and a primary capacitor C1 are connected in series to form a primary resonant circuit 12. A magnetic flux detection circuit 14 detects the magnitude of magnetic flux near the primary coil L1. Specifically, the magnetic flux detection circuit 14 incorporates a detection coil Lsp arranged near the secondary coil L2, and detects the magnitude of magnetic flux density using a change in current flowing through the detection coil Lsp. The magnetic flux detection circuit 14 outputs a signal indicating the magnitude of the detected magnetic flux density to the primary control circuit 13.

[0027] The primary side control circuit 13 uses a signal output from the magnetic flux detection circuit 14 to output a switching signal Sig1 to the primary side capacitor C1.

[0028] The primary side detection circuit is not limited to the magnetic flux detection circuit 14 that detects the magnitude of the magnetic flux density, but may be a sensor that can detect the magnitude of the magnetic flux linking the primary side coil L1. Specifically, the primary side detection circuit may be a current sensor that detects the current flowing through the primary side coil L1, or a voltage sensor that detects the voltage of the primary side coil L1. Note that "detecting the magnitude of the magnetic flux linking the primary side coil L1" does not only include the case where all of the magnetic flux linking the primary side coil L1 is detected, but also includes the case where a part of the magnetic flux linking the primary side coil L1 is detected, as in this embodiment.

[0029] In addition to the above configuration, the power receiving device 80 has secondary side capacitors C2 and C3, an immittance circuit 82, a secondary side control circuit 85, and an abnormality detection circuit 86. The secondary side capacitor C2 is connected in series to one terminal of the secondary side coil L2, and the secondary side capacitor C3 is connected in series to the other terminal of the secondary side coil L2 to form a secondary side resonant circuit 81. As another embodiment of the secondary side resonant circuit 81, the secondary side resonant circuit 81 may have either the secondary side capacitor C2 or the secondary side capacitor C3.

[0030] The immittance circuit 82 is connected between the secondary resonant circuit 81 and the rectifier circuit 83. When AC power having the resonant frequency of the immittance circuit 82 is input to the immittance circuit 82, the immittance circuit 82 functions as an impedance-admittance converter. When AC power having a frequency other than the resonant frequency of the immittance circuit 82 is input to the immittance circuit 82, the immittance circuit 82 functions as a low-pass filter.

[0031] In this embodiment, the immittance circuit 82 includes coils L3 to L6 and a capacitor C4. The coils L3 and L4 are connected in series to a first power supply line N1 connected to one terminal of the secondary coil L2. The coils L5 and L6 are connected in series to a second power supply line N2 connected to the other terminal of the secondary coil L2. The capacitor C4 is connected to the connection point between the coils L3 and L4 and the connection point between the coils L5 and L6, and is connected in parallel to the secondary coil L2.

[0032] The secondary resonant circuit 81 further includes a protection switch SW1. The protection switch SW1 is connected in parallel to the secondary coil L2. This allows the power loss to be reduced and the current rating of the protection switch SW1 to be smaller than when the protection switch SW1 is connected in series to the secondary coil L2, i.e., inserted in the first power feed line N1 or the second power feed line N2. The protection switch SW1 puts the secondary resonant circuit 81 into a non-resonant state by being in a conductive state. In this embodiment, the protection switch SW1 is realized by a bidirectional switch that is two MOSFETs with their respective source terminals connected to each other. This allows the size of the protection switch SW1 to be reduced.

[0033] The secondary-side control circuit 85 switches the state of the protection switch SW1 between a conductive state and a non-conductive state. In this embodiment, the secondary-side control circuit 85 changes the voltage value of the signal Sig2 input to the gate terminals of the two MOSFETs that configure the protection switch SW1 to switch the state of the protection switch SW1.

[0034] The rectifier circuit 83 is realized by a diode bridge.

[0035] The abnormality detection circuit 86 detects an abnormal state in the power receiving device 80. Specifically, the abnormality detection circuit 86 has a voltage sensor (not shown) that detects the voltage of the battery 84, and when the voltage of the battery 84 is outside a predetermined voltage range, the abnormality detection circuit 86 determines that an abnormal state has occurred and outputs an abnormality signal to the secondary side control circuit 85.

[0036] When prohibiting power supply from the secondary-side resonant circuit 81 to the battery 84, the power receiving-side control unit 96 outputs a stop signal to the secondary-side control circuit 85. The power receiving-side control unit 96 outputs the stop signal, for example, when the state of the battery 84 is not suitable for charging.

[0037] When the primary coil L1 and the secondary coil L2 are magnetically coupled, the resonant frequency of the primary resonant circuit 12 and the resonant frequency of the secondary resonant circuit 81 are set to be substantially the same. This allows contactless power supply to the power receiving device 80 by magnetic field resonance between the primary coil L1 and the secondary coil L2. As described above, the DC power output from the secondary resonant circuit 81 is rectified by the rectifier circuit 83 and supplied to the battery 84.

[0038] A3. Power supply sequence: The primary coils L1 are arranged in the direction in which the road RS extends, and the secondary coils L2 receive contactless power supply from the nearest primary coil L1.

[0039] In a standby state, the power transmitting device 10 causes a standby current to flow through the primary coil L1, thereby generating magnetic flux from the primary coil L1. When the secondary coil L2 approaches the primary coil L1, the power receiving device 80 detects the magnetic flux generated by the primary coil L1 using a secondary detection circuit (not shown). When the power receiving device 80 detects the magnetic flux generated by the primary coil L1, the power receiving device 80 generates a start magnetic flux in step S1 shown in FIG. 3. Specifically, the power receiving device 80 applies AC power to a magnetic flux generating coil (not shown). This causes the magnetic flux generating coil to generate magnetic flux.

[0040] The method for the power receiving device 80 to detect the nearest primary coil L1 is not limited to the above. For example, the power receiving device 80 may detect the nearest primary coil L1 by using a camera of the power receiving device 80 to capture an image of an identifier displayed in the vicinity of the primary coil L1.

[0041] When the primary side control circuit 13 determines that the magnetic flux density indicated by the signal output from the magnetic flux detection circuit 14 is greater than the threshold value, the primary side control circuit 13 changes the impedance of the primary side capacitor C1 as an impedance variable element in step S3 of FIG. 3. Specifically, the primary side control circuit 13 outputs a switching signal Sig1 to the primary side capacitor C1. As a result, the capacitance value of the primary side capacitor C1 is switched from the second capacitance value to the first capacitance value. As a result, the primary side resonant circuit 12 enters a resonant state at the operating frequency, transitions to a power transmission state in which a power transmission current flows through the primary side coil L1, and power supply is started. In this way, when an increase in the magnetic flux near the primary side coil L1 is detected by the magnetic flux detection circuit 14, the power transmitting device 10 transitions from a standby state to a power transmitting state. At the time when the capacitance value of the primary side capacitor C1 is switched, the power transmitting device 10 transitions from a standby state to a power transmitting state. Similarly, at the time when the capacitance value of the primary side capacitor C1 is switched, the power receiving device 80 transitions from a non-power receiving state to a power receiving state. When the power receiving device 80 is in a power receiving state, the protection switch SW1 is set to a non-conducting state.

[0042] 3, after starting power reception, the secondary-side control circuit 85 of the power receiving device 80 determines in step S5 whether a stop signal has been input as a power supply stop signal. If it is determined that a stop signal has been input, the secondary-side control circuit 85 determines in step S7 whether an abnormality signal has been input as a power supply stop signal. If it is determined that an abnormality signal has not been input, the secondary-side control circuit 85 returns the process to step S5.

[0043] On the other hand, when it is determined in step S5 that a stop signal has been input, and when it is determined in step S7 that an abnormality signal has been input, the secondary side control circuit 85 sets the protection switch SW1 to a conductive state in step S15. In detail, the secondary side control circuit 85 switches the protection switch SW1 from a non-conductive state to a conductive state. Specifically, the secondary side control circuit 85 outputs a high level signal Sig2 to the protection switch SW1. As a result, the protection switch SW1 is in a conductive state, and one terminal and the other terminal of the secondary side coil L2 are short-circuited. As a result, the impedance of the secondary side resonant circuit 81 increases, and the current flowing through the secondary side coil L2 decreases. Therefore, the current supplied to the battery 84 decreases, and the battery 84 can be protected. Also, by shorting one terminal and the other terminal of the secondary side coil L2, the secondary side coil L2 can function as a cancel coil that cancels the magnetic flux generated by the primary side coil L1.

[0044] In detail, if the inductance of the secondary coil L2 is "L", the capacitance of the secondary capacitor C2 is "C / 2", the capacitance of the secondary capacitor C3 is "C / 2", and the resistance of the resistance component of the secondary resonant circuit 81 is "r", the impedance "Z" of the secondary resonant circuit 81 when the protection switch SW1 is in a non-conducting state is expressed by equation (1). Z = r + j(ωL-1 / ωC) (1) In addition, in the formula (1), j represents an imaginary unit, and ω represents an angular frequency. The frequency at which the imaginary part of equation (1) becomes zero is the resonant frequency. When the protection switch SW1 is in a conductive state, the impedance of the secondary resonant circuit 81 becomes a value different from that of equation (1). Therefore, when AC power of the resonant frequency is input to the secondary resonant circuit 81, the imaginary part of equation (1) does not become zero, and the impedance of the secondary resonant circuit 81 becomes large. Therefore, the current flowing through the secondary coil L2 is smaller than the current flowing through the secondary coil L2 when the protection switch SW1 is in a non-conductive state.

[0045] As the impedance of the secondary resonant circuit 81 increases, the input impedance of the primary resonant circuit 12 increases. As a result, the current flowing through the primary coil L1 decreases, and the magnetic flux density detected by the magnetic flux detection circuit 14 decreases. When the primary control circuit 13 determines in step S17 that the detected magnetic flux density value Bd indicated by the signal output from the magnetic flux detection circuit 14 is smaller than the reference magnetic flux density Bth, the primary control circuit 13 outputs a switching signal Sig1 to switch the primary capacitor C1 to the second capacitance value in step S19. As a result, the primary resonant circuit 12 is in a non-resonant state at the operating frequency, and power transmission is stopped. Therefore, when the power receiving device 80 stops receiving power, the power transmission in the power transmitting device 10 can be stopped without a separate communication. As a result, power consumption that does not contribute to power supply in the power transmitting device 10 can be suppressed.

[0046] According to the first embodiment described above, the power receiving device 80 has a protection switch SW1. Therefore, when the power receiving device 80 is in an abnormal state, the protection switch SW1 can be used to reduce the current flowing through the secondary coil L2 to protect the battery 84. When the magnetic flux near the primary coil L1 becomes small in the power transmitting state, the primary control circuit 13 changes the capacitance value of the primary capacitor C1 to increase the impedance of the primary resonant circuit 12 and transition to a standby state. This makes it possible to suppress power consumption that does not contribute to power supply in the power transmitting device 10.

[0047] B. Second embodiment: 4, the contactless power supply system 201 according to this embodiment differs from the first embodiment in the circuit configuration of the primary side resonant circuit 212, the circuit configuration of the immittance circuit 282, the circuit configuration of the rectifier circuit 283, the means for realizing the protection switch, and the power supply sequence. The same configurations and processing steps as those in the first embodiment are denoted by the same reference numerals, and detailed explanations will be omitted as appropriate.

[0048] The primary side resonant circuit 212 includes a first capacitor C21, a second capacitor C22, and a primary side coil L1. The first capacitor C21 and the second capacitor C22 are connected in series to the primary side coil L1. The capacitance value of the first capacitor C21 is smaller than the capacitance value of the second capacitor C22. The power transmitting device 210 further includes a switch SW21 that bypasses the first capacitor C21. In a power transmitting state of the power transmitting device 210, the switch SW21 as an impedance variable element is set to a conductive state. In a standby state of the power transmitting device 210, the switch SW21 is set to a non-conductive state. When the switch SW21 is set to a conductive state, the capacitance value of the second capacitor C22 is set to a value that causes the primary side coil L1 to resonate at the operating frequency. When the switch SW21 is set to a non-conductive state, the impedance of the primary side resonant circuit 212 increases, and a standby current smaller than the power transmission current flows through the primary side coil L1.

[0049] In this embodiment, a voltage sensor M1 is provided as a primary side detection circuit instead of the magnetic flux detection circuit 14 of the first embodiment. The voltage sensor M1 is used to detect the magnitude of the magnetic flux linking the primary side coil. Specifically, the voltage sensor M1 detects the voltage of the second capacitor C22 and outputs a signal indicating the detection value to the primary side control circuit 13. The detection value of the voltage sensor M1 increases as the current value flowing through the primary side coil L1 increases. Therefore, similar to the first embodiment, a decrease in the current flowing through the secondary side coil L2 in the power receiving device 280 can be detected.

[0050] The immittance circuit 282 according to this embodiment differs from the first embodiment in that it does not have the coils L3 and L5 of the immittance circuit 82 according to the first embodiment. In this embodiment, the leakage inductance of the secondary coil L2 is used as the coils L3 and L5 of the immittance circuit 82 according to the first embodiment. In other words, the immittance circuit 282 functions as an immittance circuit by the leakage inductance of the secondary coil L2, the coils L4 and L6, and the capacitor C4.

[0051] The rectifier circuit 283 according to this embodiment is configured by using two switching elements instead of two of the four diodes of the diode bridge. Specifically, the rectifier circuit 283 has diodes D1 and D2 and switching elements Q1 and Q2 as switches. The diodes D1 and D2 configure an upper arm connected to a positive supply line N3 connected to a positive terminal of the battery 84. The switching elements Q1 and Q2 configure a lower arm connected to a negative supply line N4 connected to a negative terminal of the battery 84. The switching elements Q1 and Q2 are driven complementarily to each other. A control signal output from the secondary side control circuit 85 is input to each gate terminal of the switching elements Q1 and Q2. In this embodiment, the switching elements Q1 and Q2 are MOSFETs.

[0052] In this embodiment, a triac TR is provided as a protection switch. A signal output from a secondary side control circuit 85 is input to a gate terminal of the triac TR.

[0053] As shown in FIG. 5, when it is determined in step S5 that a stop signal is input, and when it is determined in step S7 that an abnormality signal is input, the secondary side control circuit 85 sets the switching elements Q1 and Q2 of the rectifier circuit 283 to a conductive state in step S11. As a result, the first power supply line N1 and the second power supply line N2 are short-circuited via the switching elements Q1 and Q2, so that the current supplied to the battery 84 can be reduced. Therefore, application of an overcurrent or an overvoltage to the battery 84 is suppressed, and the battery 84 can be protected. Since the immittance circuit 282 is a constant current source when viewed from the output side, even if the switching elements Q1 and Q2 are set to a conductive state and the two output nodes of the immittance circuit 282 are short-circuited, an excessive current is suppressed from flowing, unlike a constant voltage source. Therefore, it is possible to protect the battery 84 while avoiding application of an excessive current or voltage to the switching elements Q1 and Q2.

[0054] In step S15, the secondary control circuit 85 switches the triac TR, which serves as a protection switch, to a conductive state. This allows the current flowing through the secondary coil L2 to be reduced, as in the first embodiment. By setting the switching elements Q1 and Q2 to a conductive state before switching the triac TR to a conductive state, the battery 84 can be protected early.

[0055] When the primary side control circuit 13 determines in step S17 that the voltage value Vd indicated by the signal output from the voltage sensor M1 is smaller than the reference voltage Vth, it outputs a high-level signal to the switch SW21 to set the switch SW21 to a conductive state in step S19. This causes the primary side resonant circuit 212 to enter a non-resonant state at the operating frequency, and power transmission is stopped.

[0056] According to the second embodiment described above, the same effects as those of the first embodiment can be obtained. In addition, by setting the switching elements Q1 and Q2 of the rectifier circuit to the conductive state while switching the protection switch SW1 to the conductive state, the battery 84 can be protected early.

[0057] C. Third embodiment: 6, the contactless power supply system 301 according to this embodiment differs from the above-described embodiments in the circuit configuration of the primary-side resonant circuit 312 of the power transmitting device 310, the circuit configuration of the power receiving device 380, the means for realizing the protection switch, and the power supply sequence. The same configurations and processing steps as those of the above-described embodiments are denoted by the same reference numerals, and detailed explanations will be omitted as appropriate.

[0058] In the primary side resonant circuit 312 according to this embodiment, a primary side capacitor C31 is connected in parallel to a primary side coil L1. The power transmitting device 310 according to this embodiment further includes a resistor R1. The resistor R1 is connected in series to the primary side coil L1.

[0059] In this embodiment, a voltage sensor M1 serving as a primary side detection circuit detects the voltage of resistor R1 and outputs a signal indicating the detection value to the primary side control circuit 13. The detection value of the voltage sensor M1 increases as the current value flowing through the primary side coil L1 increases. Therefore, as in the first embodiment, a decrease in the current flowing through the secondary side coil L2 in the power receiving device 280 can be detected. Note that the power transmitting device 310 may have a coil instead of resistor R1. In this case, the voltage sensor M1 detects the voltage of the coil.

[0060] In this embodiment, a switch SW31 serving as an impedance variable element is connected in series with the primary coil L1. When the switch SW31 is turned off, the impedance of the switch SW31 increases, and the primary resonant circuit 312 is turned off.

[0061] The power receiving device 380 has a semiconductor relay RE as a protection switch. In this embodiment, the semiconductor relay RE bypasses the secondary capacitor C3. The semiconductor relay RE may be connected to bypass the secondary capacitor C2 instead of the secondary capacitor C3.

[0062] As shown in FIG. 7, when it is determined in step S5 that a stop signal has been input, or when it is determined in step S7 that an abnormality signal has been input, the secondary-side control circuit 85 sets the switching elements Q1 and Q2 of the rectifier circuit 283 to a non-conductive state in step S13. The secondary-side control circuit 85 switches the semiconductor relay RE to a conductive state in step S15. Since the semiconductor relay RE is connected in parallel with the secondary-side capacitor C3, if the semiconductor relay RE is switched to a conductive state while the switching elements Q1 and Q2 of the rectifier circuit 283 are in a conductive state, an excessive current may flow through the secondary-side coil L2. Therefore, by switching the semiconductor relay RE to a conductive state while the switching elements Q1 and Q2 of the rectifier circuit 283 are in a non-conductive state, damage to the secondary-side coil L2 can be avoided.

[0063] According to the third embodiment described above, the same effects as those of the above-mentioned embodiments can be obtained, and by switching the switching elements Q1 and Q2 of the rectifier circuit 283 to a non-conductive state and the semiconductor relay RE to a conductive state, damage to the secondary coil L2 can be avoided.

[0064] D. Fourth embodiment: 8, the contactless power supply system 401 according to this embodiment differs from the above-described embodiments in the circuit configuration of the power transmitting device 410 and the circuit configuration of the power receiving device 480. The same configurations and processing steps as those of the above-described embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.

[0065] The power transmitting device 410 has a characteristic change circuit 15. The characteristic change circuit 15 is a closed circuit in which a coil L41 and a capacitor C42 are connected in series. The coil L41 is disposed at a position where it can be magnetically coupled to the primary coil L1. The resonant frequency of the characteristic change circuit 15 is higher than the operating frequency.

[0066] The characteristic change circuit 15 has a function of reducing the current flowing through the primary coil L1 when the distance between the primary coil L1 and the secondary coil L2 is long and the coupling coefficient between the primary coil L1 and the secondary coil L2 is small. More specifically, the capacitance value of the primary capacitor C1 is set to a value that provides a resonant state at the operating frequency when the coupling coefficient between the primary coil L1 and the secondary coil L2 is a target value. Here, the target value of the coupling coefficient is the coupling coefficient when the distance between the primary coil L1 and the secondary coil L2 is short and the target distance allows contactless power supply. When the coupling coefficient between the primary coil L1 and the secondary coil L2 is small, the inductance of the primary resonant circuit 12 increases and the current flowing through the primary coil L1 decreases.

[0067] The power receiving device 480 has two protection switches SW41 and SW42. The protection switches SW41 and SW42 are semiconductor switching elements. In this embodiment, the protection switches SW41 and SW42 are one MOSFET. The protection switch SW41 is inserted in the first power supply line N1. The protection switch SW42 is inserted in the second power supply line N2.

[0068] As another embodiment of the protection switches SW41 and SW42, a bidirectional switch having two MOSFETs may be used. Also, a protection switch may be inserted in only one of the first power supply line N1 and the second power supply line N2.

[0069] The rectifier circuit 483 has two diodes constituting a lower arm, and two switching elements Q1, Q2 constituting an upper arm.

[0070] As in the first embodiment, when it is determined that a stop signal is input, or when it is determined that an abnormality signal is input, the secondary-side control circuit 85 sets the protection switches SW41 and SW42 from a conductive state to a non-conductive state. This cuts off the power supply to the battery 84, thereby protecting the battery 84.

[0071] When the protection switches SW41 and SW42 are set to the non-conductive state, the secondary resonant circuit 81 is in a non-resonant state, and the current flowing through the secondary coil L2 decreases. In this case, the secondary coil L2 can be regarded as not being present from the perspective of the primary resonant circuit 12, and the current I 1 is expressed by equation (2). I 1 =r 3 / (ω 2 L 13 3 )·V 1 (2) In formula (2), r 3 is the winding resistance of coil L41, and L 13 is the mutual inductance between the primary coil L1 and the coil L41, and V 1is the output voltage of the AC power source 11. In the formula (2), the numerator "r 3 ", the denominator "ω 2 L 13 3 " is large enough that the current I 1 is approximately zero amperes.

[0072] According to the fourth embodiment described above, the same effects as those of the above embodiments are achieved.

[0073] E. Fifth embodiment: 9, the contactless power supply system 501 according to this embodiment differs from the second embodiment in that the power receiving device 580 has a state detection circuit 87. The same configurations and processing steps as those in the above embodiments are denoted by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0074] The state detection circuit 87 detects whether the state of the power transmitting device 210 is a standby state or a power transmitting state. The state detection circuit 87 has a temperature sensor M4. The temperature sensor M4 is arranged in the vicinity of the immittance circuit 282. The temperature sensor M4 may be arranged in the vicinity of the switching elements Q1 and Q2 instead of in the vicinity of the immittance circuit 282 to detect the temperature in the vicinity of the switching elements Q1 and Q2.

[0075] The state detection circuit 87 detects the temperature with the immittance circuit 282, and outputs a signal indicating that the power transmitting device 210 is in a power transmitting state to the secondary side control circuit 85 when the detected temperature Td is higher than a predetermined reference temperature Tth.

[0076] As shown in FIG. 10, in step S11 as a first process, the secondary side control circuit 85 sets the switching elements Q1, Q2 of the rectifier circuit 283 to a conductive state, and then, in step S14, if it is determined that the detected temperature Td of the temperature sensor M4 is greater than a predetermined reference temperature Tth, in step S15, the secondary side control circuit 85 switches the triac TR as a protection switch to a conductive state.

[0077] In step S11, when the switching elements Q1 and Q2 of the rectifier circuit 283 are set to the conductive state, the current flowing through the secondary coil L2 decreases as described above. However, when the circuit constant of the primary resonant circuit 212 deviates from the design value, the current flowing through the primary coil L1 may not be smaller than the reference voltage as detected by the voltage sensor M1. In this case, the power transmitting device 210 does not transition to the standby state, and the same current as in the power receiving state flows through the primary coil L1, so the temperature of the immittance circuit 282 does not decrease. Therefore, when the secondary control circuit 85 determines in step S14 that the detected temperature Td of the temperature sensor M4 is higher than the reference temperature Tth, it switches the triac TR to the conductive state. As a result, when the switching elements Q1 and Q2 of the rectifier circuit 283 are set to the conductive state but the power transmitting device 210 does not transition to the standby state, the triac TR can be switched to the conductive state to transition the power transmitting device 210 to the standby state. In addition, when it is determined that the detected temperature Td of the temperature sensor M4 is not greater than the reference temperature Tth, the power transmission device 210 has already transitioned to a standby state after the switching elements Q1 and Q2 of the rectifier circuit 283 are set to a conductive state, and therefore the secondary side control circuit 85 does not switch the protection switch SW1 to a conductive state.

[0078] The fifth embodiment described above has the same effects as the above-mentioned embodiments. In addition, when the temperature detected by the temperature sensor M4 is higher than the reference temperature Tth and the current continues to flow through the secondary coil L2 during power supply, the triac TR is switched to a non-conducting state in step S15, so that the power transmitting device 210 can be shifted to a standby state.

[0079] F. Other Embodiments: (F1) In the first embodiment, the primary side resonant circuit 12 has a primary side capacitor C1 connected in series to the primary side coil L1, and the secondary side resonant circuit 81 has a secondary side capacitor C2 connected in series to the secondary side coil L2, which is a so-called SS type circuit configuration. The circuit configuration of the primary side resonant circuit 12 and the circuit configuration of the secondary side resonant circuit 81 are not limited to the SS type. (a) For example, the primary side resonant circuit 12 may have a so-called PS type circuit configuration in which the primary side capacitor C1 is connected in parallel to the primary side coil L1, and the secondary side resonant circuit 81 may have a secondary side capacitor C2 connected in series to the secondary side coil L2. (b) Also, in addition to the primary side capacitor C1 connected in series to the primary side coil L1, a capacitor connected in parallel to the primary side coil L1 is provided, and the secondary side resonant circuit 81 may have a so-called P-SS type circuit configuration in which two secondary side capacitors C2 are connected in series to each of both terminals of the secondary side coil L2. (c) The primary resonant circuit 12 may also include a closed circuit in which a coil and a capacitor are connected in series. The coil of this closed circuit is arranged at a position where it can be magnetically coupled to the secondary coil L2 when the primary coil L1 and secondary coil L2 are magnetically coupled. (d) The capacitor of the closed circuit may also be connected in parallel to the coil, not in series. (e) The primary resonant circuit 12 may also include a coil connected in series to the primary coil L1, and a capacitor connected in parallel to the coil. The coil is arranged at a position where it can be magnetically coupled to the secondary coil L2 when the primary coil L1 and secondary coil L2 are magnetically coupled.

[0080] (F2) In the second embodiment, the switching elements Q1 and Q2 of the rectifier circuit 83 are realized by MOSFETs. In another embodiment, the switching elements Q1 and Q2 may be realized by other semiconductor elements, for example, an IGBT (Insulated Gate Bipolar Transistor) connected to a freewheeling diode.

[0081] (F3) In the second embodiment, the lower arm of the rectifier circuit 283 is configured with switching elements Q1 and Q2, and the upper arm is configured with a diode. As another embodiment, the rectifier circuit 283 may be realized with a synchronous rectifier circuit in which both the upper arm and the lower arm are configured with switching elements. In this case, the synchronous rectifier circuit can be used to apply AC power from the battery 84 to the secondary coil L2. Therefore, in step S1, the secondary coil L2 may function as a magnetic flux generating coil by applying AC power to the secondary coil L2.

[0082] (F4) In the above fifth embodiment, the state detection circuit 87 detects the temperature with the immittance circuit 282, and when the detected temperature Td is higher than a predetermined reference temperature Tth, outputs a signal indicating that the power transmitting device 210 is in a power transmitting state to the secondary side control circuit 85. As another embodiment of the state detection circuit 87, the detected temperature Td of the temperature sensor M4 in step S11 may be stored as a reference temperature, and when the difference between the reference temperature and the current detected temperature is within a predetermined reference range, the state detection circuit 87 may output a signal indicating that the power transmitting device 210 is in a power transmitting state to the secondary side control circuit 85.

[0083] (F5) In the above-described fifth embodiment, the state detection circuit 87 detects the state of the power transmitting device 210 by detecting the temperature of the immittance circuit 282. As another embodiment, a sensor for detecting the current flowing through the secondary coil L2 or the voltage of the secondary coil L2 may be provided, and it may be determined that the power transmitting device 210 is in the power transmitting state when the current flowing through the secondary coil L2 or the voltage of the secondary coil L2 does not decrease.

[0084] The present disclosure is not limited to the above-mentioned embodiments and modifications, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features in the embodiments and modifications corresponding to the technical features in each aspect described in the Summary of the Invention column can be appropriately replaced or combined in order to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0085] Other forms: The features of the present disclosure are as follows: (Form 1) A contactless power supply system (1, 101 to 401) that supplies power from a power transmitting device (10, 210 to 410) to a power receiving device (80, 280 to 480) in a contactless manner, The power transmitting device is A primary side resonant circuit (12, 212, 312) having a primary side coil (L1) and a primary side capacitor (C1); an AC power source (11) that applies AC power of a predetermined operating frequency to the primary side resonant circuit; variable impedance elements (C1, SW21, SW31) connected between the primary coil and the AC power source for switching a state of the power transmitting device between a power transmitting state and a standby state; A primary side control circuit (13) that changes the impedance of the impedance variable element; a primary side detection circuit (14, M1) for detecting either the magnitude of the magnetic flux interlinked with the primary side coil or the magnitude of the magnetic flux in the vicinity of the primary side coil; The power receiving device is a secondary-side resonant circuit (81) having a secondary-side coil (L2) for magnetically coupling with the primary-side coil and secondary-side capacitors (C2, C3); a rectifier circuit (83, 283, 483) that rectifies the AC power output from the secondary side resonant circuit; an immittance circuit (82, 282) connected between the rectifier circuit and the secondary side resonant circuit; a load device (83) to which the DC power output from the rectifier circuit is supplied; protection switches (SW1, TR, RE, SW41, SW42) for putting the secondary resonant circuit into a non-resonant state by being in either a conductive state or a non-conductive state; a secondary side control circuit (85) that sets the state of the protection switch to either the conductive state or the non-conductive state, The primary side control circuit includes: A contactless power supply system which transitions the power receiving device from the power transmitting state to the standby state by changing the impedance of the impedance variable element using the detection value of the primary side detection circuit, which changes when the protection switch is set to either the conductive state or the non-conductive state. (Form 2) The wireless power supply system according to aspect 1, the secondary capacitor is connected in series with the secondary coil; The protection switch is connected in parallel with the secondary coil, The secondary side control circuit sets the protection switch to the conductive state when a power supply stop signal is received. (Form 3) The wireless power supply system according to aspect 2, The contactless power transfer system, wherein the protection switch is any one of a bidirectional switch using two MOSFETs, a semiconductor relay, and a triac. (Form 4) The wireless power supply system according to aspect 2 or 3, the rectifier circuit has a switch (Q1, Q2) in at least one of a lower arm and an upper arm, When the secondary side control circuit receives a power supply stop signal, the secondary side control circuit sets the switch to the conductive state before setting the protection switch to the conductive state. (Form 5) The wireless power supply system according to aspect 1, the secondary capacitor is connected in series with the secondary coil; The protection switch is connected in parallel with the secondary capacitor; The secondary side control circuit sets the protection switch to the conductive state when a power supply stop signal is received. (Form 6) The wireless power supply system according to aspect 5, The contactless power transfer system, wherein the protection switch is any one of a bidirectional switch using two MOSFETs, a semiconductor relay, and a triac. (Form 7) The wireless power supply system according to aspect 5 or 6, the rectifier circuit has a switch (Q1, Q2) in at least one of a lower arm and an upper arm, The secondary side control circuit includes: a contactless power supply system that, when receiving a power supply stop signal, sets the switch to the non-conductive state and then sets the protection switch to the conductive state. (Form 8) The wireless power supply system according to aspect 1, the secondary capacitor is connected in series with the secondary coil; The protection switch is a semiconductor switching element and is connected in series with the secondary coil between the secondary capacitor and the rectifier circuit, The secondary side control circuit switches the protection switch to the non-conductive state when a power supply stop signal is received. (Form 9) The wireless power supply system according to aspect 8, The contactless power transfer system, wherein the protection switch is a bidirectional switch using two MOSFETs. (Form 10) The wireless power supply system according to aspect 8, The contactless power transfer system, wherein the protection switch is a MOSFET. (Form 11) A contactless power supply system (501) for supplying power from a power transmitting device (210) to a power receiving device (580) in a contactless manner, The power transmitting device is a primary side resonant circuit (212) having a primary side coil (L1) and a primary side capacitor (C1); an AC power source (11) that applies AC power of a predetermined operating frequency to the primary side resonant circuit; a variable impedance element (SW21) connected between the primary coil and the AC power supply for switching a state of the power transmitting device between a power transmitting state and a standby state; A primary side control circuit (13) that changes the impedance of the impedance variable element; a primary detection circuit (M1) for detecting either the magnitude of the magnetic flux interlinked with the primary coil or the magnitude of the magnetic flux in the vicinity of the primary coil; The power receiving device is a secondary-side resonant circuit (81) having a secondary-side coil (L2) for magnetically coupling with the primary-side coil and secondary-side capacitors (C2, C3); a rectifier circuit (283) for rectifying the AC power output from the secondary resonant circuit, the rectifier circuit having a switch (Q1, Q2) in at least one of a lower arm and an upper arm; an immittance circuit (282) connected between the rectifier circuit and the secondary side resonant circuit; a load device (84) to which the DC power output from the rectifier circuit is supplied; a protection switch (TR) for putting the secondary side resonant circuit into a non-resonant state by being in either a conductive state or a non-conductive state; a secondary side control circuit (85) that sets the state of the protection switch to either the conductive state or the non-conductive state; A state detection circuit (87) for detecting a state of the power transmitting device, The secondary side control circuit includes: When a power supply stop signal is received, before the protection switch is set to the conductive state, a first process (S11) is performed to set the switch to the conductive state; When the state of the power transmitting device detected by the state detection circuit after the first process is the power transmitting state, the protection switch is set to the conductive state; The primary side control circuit includes: A contactless power supply system in which the power receiving device is transitioned from the power transmission state to the standby state by changing the impedance of the impedance variable element using at least one of the detection value of the primary side detection circuit, which changes when the switch is set to the conductive state, and the detection value of the primary side detection circuit, which changes when the protection switch is set to either the conductive state or the non-conductive state. (Form 12) 12. The wireless power supply system according to claim 11, The state detection circuit detects the temperature of at least one of the switch and the immittance circuit, and when the detected temperature is greater than a predetermined reference temperature (Tth), outputs a signal indicating that the power transmission device is in the power transmission state to the secondary side control circuit. (Form 13) A power transmitting device (10, 210 to 410) that wirelessly supplies power to a power receiving device (80, 280 to 480), The power transmitting device is A primary side resonant circuit (12, 212, 312) having a primary side coil (L1) and a primary side capacitor (C1); an AC power source (11) that applies AC power of a predetermined operating frequency to the primary side resonant circuit; variable impedance elements (C1, SW21, SW31) connected between the primary coil and the AC power source for switching a state of the power transmitting device between a power transmitting state and a standby state; A primary side control circuit (13) that changes the impedance of the impedance variable element; a primary side detection circuit (14, M1) for detecting either the magnitude of the magnetic flux interlinked with the primary side coil or the magnitude of the magnetic flux in the vicinity of the primary side coil; The power receiving device is a secondary-side resonant circuit (81) having a secondary-side coil (L2) for magnetically coupling with the primary-side coil and secondary-side capacitors (C2, C3); a rectifier circuit (83, 283, 483) that rectifies the AC power output from the secondary side resonant circuit; an immittance circuit (82, 282) connected between the rectifier circuit and the secondary side resonant circuit; a load device (83) to which the DC power output from the rectifier circuit is supplied; protection switches (SW1, TR, RE, SW41, SW42) for putting the secondary resonant circuit into a non-resonant state by being in either a conductive state or a non-conductive state; a secondary side control circuit (85) that sets the state of the protection switch to either the conductive state or the non-conductive state, The primary side control circuit includes: A power transmitting device that transitions the power receiving device from the power transmitting state to the standby state by changing the impedance of the impedance variable element using the detection value of the primary side detection circuit, which changes when the protection switch is set to either the conductive state or the non-conductive state. (Form 14) A power receiving device (80, 280 to 480) that receives power contactlessly from a power transmitting device (10, 210 to 410), The power transmitting device is A primary side resonant circuit (12, 212, 312) having a primary side coil (L1) and a primary side capacitor (C1); an AC power source (11) that applies AC power of a predetermined operating frequency to the primary side resonant circuit; variable impedance elements (C1, SW21, SW31) connected between the primary coil and the AC power source for switching a state of the power transmitting device between a power transmitting state and a standby state; A primary side control circuit (13) that changes the impedance of the impedance variable element; a primary side detection circuit (14, M1) for detecting either the magnitude of the magnetic flux interlinked with the primary side coil or the magnitude of the magnetic flux in the vicinity of the primary side coil; The power receiving device is a secondary-side resonant circuit (81) having a secondary-side coil (L2) for magnetically coupling with the primary-side coil and secondary-side capacitors (C2, C3); a rectifier circuit (83, 283, 483) that rectifies the AC power output from the secondary side resonant circuit; an immittance circuit (82, 282) connected between the rectifier circuit and the secondary side resonant circuit; a load device (83) to which the DC power output from the rectifier circuit is supplied; protection switches (SW1, TR, RE, SW41, SW42) for putting the secondary resonant circuit into a non-resonant state by being in either a conductive state or a non-conductive state; a secondary side control circuit (85) that sets the state of the protection switch to either the conductive state or the non-conductive state, The primary side control circuit includes: The power receiving device transitions the power receiving device from the power transmitting state to the standby state by changing the impedance of the impedance variable element using the detection value of the primary side detection circuit, which changes when the protection switch is set to either the conductive state or the non-conductive state. [Explanation of symbols]

[0086] 1,201,301,401,501...Non-contact power supply system, 10,210,310,410...Power transmission device, 11...AC power source, 12,212,312...Primary side resonant circuit, 13...Primary side control circuit, 14...Magnetic flux detection circuit, 80,280,380,480,580...Power receiving device, 81...Secondary side resonant circuit, 82,282...Immitance circuit, 83,283,483... Rectifier circuit, 84... battery, 85... secondary control circuit, 87... state detection circuit, C1, C31... primary capacitor, C2, C3... secondary capacitor, L1... primary coil, L2... secondary coil, M1... voltage sensor, M4... temperature sensor, Q1, Q2... switching element, RE... semiconductor relay, SW1, SW41, SW42... protection switch, TR... triac

Claims

1. A contactless power supply system (1, 101 to 401) that supplies power from a power transmitting device (10, 210 to 410) to a power receiving device (80, 280 to 480) in a contactless manner, The power transmitting device is A primary-side resonant circuit (12, 212, 312) having a primary-side coil (L1) and a primary-side capacitor (C1); an AC power source (11) that applies AC power having a predetermined operating frequency to the primary side resonant circuit; an impedance variable element (C1, SW21, SW31) connected between the primary coil and the AC power source for switching a state of the power transmitting device between a power transmitting state and a standby state; A primary side control circuit (13) that changes the impedance of the impedance variable element; a primary side detection circuit (14, M1) for detecting either the magnitude of the magnetic flux interlinked with the primary side coil or the magnitude of the magnetic flux in the vicinity of the primary side coil; The power receiving device is a secondary-side resonant circuit (81) having a secondary-side coil (L2) for magnetically coupling with the primary-side coil and secondary-side capacitors (C2, C3); a rectifier circuit (83, 283, 483) that rectifies the AC power output from the secondary side resonant circuit; an immittance circuit (82, 282) connected between the rectifier circuit and the secondary side resonant circuit; A load device (83) to which the DC power output from the rectifier circuit is supplied; protection switches (SW1, TR, RE, SW41, SW42) for putting the secondary resonant circuit into a non-resonant state by being in either a conductive state or a non-conductive state; a secondary side control circuit (85) that sets the state of the protection switch to either the conductive state or the non-conductive state; The primary side control circuit includes: a detection value of the primary side detection circuit, which changes when the protection switch is set to either the conductive state or the non-conductive state, is used to change the impedance of the impedance variable element, thereby transitioning the power receiving device from the power transmitting state to the standby state; the secondary capacitor is connected in series with the secondary coil, The protection switch is connected in parallel with the secondary coil, The rectifier circuit has a switch (Q1, Q2) in at least one of a lower arm and an upper arm, The secondary side control circuit includes: When a power supply stop signal is received, the protection switch is set to the conductive state; When the power supply stop signal is received, the switch is set to the conductive state before the protection switch is set to the conductive state.

2. The non-contact power supply system according to claim 1, The non-contact power supply system, wherein the protection switch is any one of a bidirectional switch using two MOSFETs, a semiconductor relay, and a triac.

3. A contactless power supply system (1, 101 to 401) that supplies power from a power transmitting device (10, 210 to 410) to a power receiving device (80, 280 to 480) in a contactless manner, The power transmitting device is A primary-side resonant circuit (12, 212, 312) having a primary-side coil (L1) and a primary-side capacitor (C1); an AC power source (11) that applies AC power having a predetermined operating frequency to the primary side resonant circuit; an impedance variable element (C1, SW21, SW31) connected between the primary coil and the AC power source for switching a state of the power transmitting device between a power transmitting state and a standby state; A primary side control circuit (13) that changes the impedance of the impedance variable element; a primary side detection circuit (14, M1) for detecting either the magnitude of the magnetic flux interlinked with the primary side coil or the magnitude of the magnetic flux in the vicinity of the primary side coil; The power receiving device is a secondary-side resonant circuit (81) having a secondary-side coil (L2) for magnetically coupling with the primary-side coil and secondary-side capacitors (C2, C3); a rectifier circuit (83, 283, 483) that rectifies the AC power output from the secondary side resonant circuit; an immittance circuit (82, 282) connected between the rectifier circuit and the secondary side resonant circuit; A load device (83) to which the DC power output from the rectifier circuit is supplied; protection switches (SW1, TR, RE, SW41, SW42) for putting the secondary resonant circuit into a non-resonant state by being in either a conductive state or a non-conductive state; a secondary side control circuit (85) that sets the state of the protection switch to either the conductive state or the non-conductive state; The primary side control circuit includes: a detection value of the primary side detection circuit, which changes when the protection switch is set to either the conductive state or the non-conductive state, is used to change the impedance of the impedance variable element, thereby transitioning the power receiving device from the power transmitting state to the standby state; the secondary capacitor is connected in series with the secondary coil, The protection switch is connected in parallel with the secondary capacitor, The rectifier circuit has a switch (Q1, Q2) in at least one of a lower arm and an upper arm, The secondary side control circuit includes: When a power supply stop signal is received, the protection switch is set to the conductive state; when the power supply stop signal is received, the switch is set to the non-conductive state, and then the protection switch is set to the conductive state.

4. The non-contact power supply system according to claim 3, The non-contact power supply system, wherein the protection switch is any one of a bidirectional switch using two MOSFETs, a semiconductor relay, and a triac.

5. A contactless power supply system (501) for contactlessly supplying power from a power transmitting device (210) to a power receiving device (580), The power transmitting device is A primary resonant circuit (212) having a primary coil (L1) and a primary capacitor (C1); an AC power source (11) that applies AC power having a predetermined operating frequency to the primary side resonant circuit; an impedance variable element (SW21) connected between the primary coil and the AC power supply for switching a state of the power transmitting device between a power transmitting state and a standby state; A primary side control circuit (13) that changes the impedance of the impedance variable element; a primary detection circuit (M1) for detecting either the magnitude of a magnetic flux interlinked with the primary coil or the magnitude of a magnetic flux in the vicinity of the primary coil; The power receiving device is a secondary-side resonant circuit (81) having a secondary-side coil (L2) for magnetically coupling with the primary-side coil and secondary-side capacitors (C2, C3); A rectifier circuit (283) for rectifying AC power output from the secondary resonant circuit, the rectifier circuit having switches (Q1, Q2) in at least one of a lower arm and an upper arm; an immittance circuit (282) connected between the rectifier circuit and the secondary side resonant circuit; A load device (84) to which the DC power output from the rectifier circuit is supplied; a protection switch (TR) for putting the secondary side resonant circuit into a non-resonant state by being in either a conductive state or a non-conductive state; a secondary side control circuit (85) that sets the state of the protection switch to either the conductive state or the non-conductive state; A state detection circuit (87) for detecting a state of the power transmitting device, The secondary side control circuit includes: When a power supply stop signal is received, before the protection switch is set to the conductive state, a first process (S11) is performed to set the switch to the conductive state; When the state of the power transmitting device detected by the state detection circuit after the first process is the power transmitting state, the protection switch is set to the conductive state; The primary side control circuit includes: A contactless power supply system in which the power receiving device is transitioned from the power transmission state to the standby state by changing the impedance of the impedance variable element using at least one of the detection value of the primary side detection circuit, which changes when the switch is set to the conductive state, and the detection value of the primary side detection circuit, which changes when the protection switch is set to either the conductive state or the non-conductive state.

6. The non-contact power supply system according to claim 5, The state detection circuit detects the temperature of at least one of the switch and the immittance circuit, and when the detected temperature is greater than a predetermined reference temperature (Tth), outputs a signal indicating that the power transmission device is in the power transmission state to the secondary side control circuit.

7. A power transmitting device (10, 210 to 410) that wirelessly supplies power to a power receiving device (80, 280 to 480), The power transmitting device is A primary-side resonant circuit (12, 212, 312) having a primary-side coil (L1) and a primary-side capacitor (C1); an AC power source (11) that applies AC power having a predetermined operating frequency to the primary side resonant circuit; an impedance variable element (C1, SW21, SW31) connected between the primary coil and the AC power source for switching a state of the power transmitting device between a power transmitting state and a standby state; A primary side control circuit (13) that changes the impedance of the impedance variable element; a primary side detection circuit (14, M1) for detecting either the magnitude of the magnetic flux interlinked with the primary side coil or the magnitude of the magnetic flux in the vicinity of the primary side coil; The power receiving device is a secondary-side resonant circuit (81) having a secondary-side coil (L2) for magnetically coupling with the primary-side coil and secondary-side capacitors (C2, C3); a rectifier circuit (83, 283, 483) that rectifies the AC power output from the secondary side resonant circuit; an immittance circuit (82, 282) connected between the rectifier circuit and the secondary side resonant circuit; A load device (83) to which the DC power output from the rectifier circuit is supplied; protection switches (SW1, TR, RE, SW41, SW42) for putting the secondary resonant circuit into a non-resonant state by being in either a conductive state or a non-conductive state; a secondary side control circuit (85) that sets the state of the protection switch to either the conductive state or the non-conductive state; The primary side control circuit includes: a detection value of the primary side detection circuit, which changes when the protection switch is set to either the conductive state or the non-conductive state, is used to change the impedance of the impedance variable element, thereby transitioning the power receiving device from the power transmitting state to the standby state; the secondary capacitor is connected in series with the secondary coil, The protection switch is connected in parallel with the secondary coil, The rectifier circuit has a switch (Q1, Q2) in at least one of a lower arm and an upper arm, The secondary side control circuit includes: When a power supply stop signal is received, the protection switch is set to the conductive state; The power transmitting device, upon receiving the power supply stop signal, sets the switch to the conductive state before setting the protection switch to the conductive state.

8. A power receiving device (80, 280 to 480) that receives power contactlessly from a power transmitting device (10, 210 to 410), The power transmitting device is A primary-side resonant circuit (12, 212, 312) having a primary-side coil (L1) and a primary-side capacitor (C1); an AC power source (11) that applies AC power having a predetermined operating frequency to the primary side resonant circuit; an impedance variable element (C1, SW21, SW31) connected between the primary coil and the AC power source for switching a state of the power transmitting device between a power transmitting state and a standby state; A primary side control circuit (13) that changes the impedance of the impedance variable element; a primary side detection circuit (14, M1) for detecting either the magnitude of the magnetic flux interlinked with the primary side coil or the magnitude of the magnetic flux in the vicinity of the primary side coil; The power receiving device is a secondary-side resonant circuit (81) having a secondary-side coil (L2) for magnetically coupling with the primary-side coil and secondary-side capacitors (C2, C3); a rectifier circuit (83, 283, 483) that rectifies the AC power output from the secondary side resonant circuit; an immittance circuit (82, 282) connected between the rectifier circuit and the secondary side resonant circuit; A load device (83) to which the DC power output from the rectifier circuit is supplied; protection switches (SW1, TR, RE, SW41, SW42) for putting the secondary resonant circuit into a non-resonant state by being in either a conductive state or a non-conductive state; a secondary side control circuit (85) that sets the state of the protection switch to either the conductive state or the non-conductive state; The primary side control circuit includes: a detection value of the primary side detection circuit, which changes when the protection switch is set to either the conductive state or the non-conductive state, is used to change the impedance of the impedance variable element, thereby transitioning the power receiving device from the power transmitting state to the standby state; the secondary capacitor is connected in series with the secondary coil, The protection switch is connected in parallel with the secondary coil, The rectifier circuit has a switch (Q1, Q2) in at least one of a lower arm and an upper arm, The secondary side control circuit includes: When a power supply stop signal is received, the protection switch is set to the conductive state; When the power supply stop signal is received, the power receiving device sets the switch to the conductive state before setting the protection switch to the conductive state.

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