Power receiver and wireless power transfer system comprising protection circuit to perform short-circuit control to cut off the power supply to the power supply target

Abstract

A power receiver coil (110) of a power receiver (100) includes a main power receiver coil (110a) that supplies power received from a power transmitter coil (22) to a high-voltage storage battery (300), and a sub power receiver coil (110b) that receives power from the power transmitter coil when the main power receiver coil is receiving power from the power transmitter coil. The power receiver also includes a rectifier circuit (200) capable of performing short-circuit control to short-circuit the main power receiver coil, a short-circuit control circuit (360) that controls the rectifier circuit, and a communication unit (400) that can transmit a power supply stop signal. The short-circuit control circuit performs the short-circuit control when receiving operating power only from the sub power receiver coil.

Description

POWER RECEIVER AND WIRELESS POWER TRANSFER SYSTEM COMPRISING PROTECTION CIRCUIT TO PERFORM SHORT-CIRCUIT CONTROL TO CUT OFF THE POWER SUPPLY TO THE POWER SUPPLY TARGETCross Reference

[0001] This application is based on Japanese Patent Application No. 2024-207999 filed on November 29, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a power receiver and a wireless power transfer system.

[0003] Patent Literature 1 discloses a system for executing wireless power transfer from a ground-based power transmitter to a power receiver installed in an electric vehicle. The power transmitter includes a power transmitter coil and a controller that energizes the power transmitter coil. The power receiver includes a power receiver coil that is supplied with power wirelessly from the power transmitter coil.

[0004] The power transmitter and the power receiver include communication coils for narrow area wireless communication. The power receiver supplies a power supply request signal to the communication coil of the power receiver. The power transmitter determines whether there is a power supply request based on an output signal from the communication coil of the power transmitter. When the power transmitter determines that there is a power supply request, the power transmitter energizes the power transmitter coil.

[0005] JP 2024-008088 A

[0006] Even when the vehicle is being started or stopped and is not in a state to receive power, noise or signals from other vehicles, etc., may cause the power transmitter to erroneously determine that there is a power request, and power may be erroneously transmitted from the power transmitter. In this case, it is necessary to short-circuit the power receiver coil using a protection circuit so as to cut off the power supply from the power receiver coil and prevent overvoltage.

[0007] However, when the vehicle is being started or stopped, the power supply from a low-voltage battery, which is generally an operating power source, is also stopped, and this poses a problem in that the protection circuit cannot be driven. In addition, when the vehicle is being started or stopped, a control device such as an ECU is also stopped, and therefore a command to stop power transmission cannot be issued to the power transmitter.

[0008] The present disclosure has been made in consideration of the above circumstances, and it is a main object to provide a power receiver and a wireless power transfer system that are capable of operating even when power supply from an operating power source is cut off.

[0009] According to an aspect of the present disclosure, a first power receiver includes a power receiving antenna, a protection circuit, a short-circuit control unit, and a power converter. The power receiving antenna is configured to receive power wirelessly transmitted from a power transmitting antenna of a power transmitter. The power receiving antenna is configured to supply the power received from the power transmitting antenna to a power supply target device. The protection circuit is configured to short one of paths from the power receiving antenna to the power supply target device to cut off power supply from the power receiving antenna to the power supply target device. The short-circuit control unit is configured to control the protection circuit. The power converter is configured to receive, convert, and output a portion of the power transmitted from the power transmitting antenna during the power receiving antenna receiving the power from the power transmitting antenna. The short-circuit control unit is connected to an operating power source via a power switch, and configured to receive operating power supplied from the operating power source when the power switch is turned on. The short-circuit control unit is connected to the power converter, and configured to receive operating power output from the power converter. The short-circuit control unit is configured to control the protection circuit to perform short-circuit control to cut off the power supply to the power supply target device when operating power from the power converter is supplied to the short-circuit control unit and operating power from the operating power source is not being supplied to the short-circuit control unit.

[0010] According to this, the protection circuit can be operated even if power is transmitted erroneously while power supply from the operating power source is cut off.

[0011] According to an aspect of the present disclosure, a second power receiver includes a power receiving antenna, a protection circuit, a short-circuit control unit, and a power converter. The power receiving antenna is configured to receive power wirelessly transmitted from a power transmitting antenna of a power transmitter. The power receiving antenna is configured to supply the power received from the power transmitting antenna to a power supply target device. The protection circuit is configured to short one of paths from the power receiving antenna to the power supply target device to cut off power supply from the power receiving antenna to the power supply target device. The short-circuit control unit is configured to control the protection circuit. The power converter is configured to receive, convert, and output a portion of the power transmitted from the power transmitting antenna during the power receiving antenna receiving the power from the power transmitting antenna. The short-circuit control unit is connected to an operating power source via a power switch, and configured to receive operating power supplied from the operating power source when the power switch is turned on. The short-circuit control unit is connected to the power converter, and configured to receive operating power output from the power converter. The second power receiver further comprises a determination unit configured to determine whether operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit. The determination unit is configured to determine that an abnormality has occurred when the determination unit determines that operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit.

[0012] According to this, an occurrence of an abnormality can be determined even if power is transmitted erroneously while power supply from the operating power source is cut off.

[0013] According to an aspect of the present disclosure, a third power receiver includes a power receiving antenna, a protection circuit, a short-circuit control unit, a power converter, and a communication unit. The power receiving antenna is configured to receive power wirelessly transmitted from a power transmitting antenna of a power transmitter. The power receiving antenna is configured to supply the power received from the power transmitting antenna to a power supply target device. The protection circuit is configured to short one of paths from the power receiving antenna to the power supply target device to cut off power supply from the power receiving antenna to the power supply target device. The short-circuit control unit is configured to control the protection circuit. The power converter is configured to receive, convert, and output a portion of the power transmitted from the power transmitting antenna during the power receiving antenna receiving the power from the power transmitting antenna. The communication unit is configured to transmit a power supply stop signal to command the power transmitter to stop power transmission. The short-circuit control unit is connected to an operating power source via a power switch, and configured to receive operating power supplied from the operating power source when the power switch is turned on. The short-circuit control unit is connected to the power converter, and configured to receive operating power output from the power converter. The communication unit is configured to transmit the power supply stop signal when operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit.

[0014] According to this, power transmission can be stopped even if power is transmitted erroneously from the power transmitter while power supply from the operating power source is cut off.

[0015] According to an aspect of the present disclosure, a first wireless power transfer system includes a power transmitter having a power transmitting antenna, and a power receiver having a power receiving antenna. The power transmitting antenna is configured to wirelessly supply power to the power receiving antenna. The power receiving antenna is configured to supply the power received from the power transmitting antenna to a power supply target device. The power receiver includes a protection circuit, a short-circuit control unit and a power converter. The protection circuit is configured to short one of paths from the power receiving antenna to the power supply target device to cut off power supply from the power receiving antenna to the power supply target device. The short-circuit control unit is configured to control the protection circuit. The power converter is configured to receive, convert, and output a portion of the power transmitted from the power transmitting antenna during the power receiving antenna receiving the power from the power transmitting antenna. The short-circuit control unit is connected to an operating power source via a power switch, and configured to receive operating power supplied from the operating power source when the power switch is turned on. The short-circuit control unit is connected to the power converter, and configured to receive operating power output from the power converter. The short-circuit control unit is configured to control the protection circuit to perform short-circuit control to cut off the power supply to the power supply target device when operating power from the power converter is supplied to the short-circuit control unit and operating power from the operating power source is not being supplied to the short-circuit control unit.

[0016] According to this, the protection circuit can be operated even if power is transmitted erroneously while power supply from the operating power source is cut off.

[0017] According to an aspect of the present disclosure, a second wireless power transfer system includes a power transmitter having a power transmitting antenna, and a power receiver having a power receiving antenna. The power transmitting antenna is configured to wirelessly supply power to the power receiving antenna. The power receiving antenna is configured to supply the power received from the power transmitting antenna to a power supply target device. The power receiver includes a protection circuit, a short-circuit control unit and a power converter. The protection circuit is configured to short one of paths from the power receiving antenna to the power supply target device to cut off power supply from the power receiving antenna to the power supply target device. The short-circuit control unit is configured to control the protection circuit. The power converter is configured to receive, convert, and output a portion of the power transmitted from the power transmitting antenna during the power receiving antenna receiving the power from the power transmitting antenna. The short-circuit control unit is connected to an operating power source via a power switch, and configured to receive operating power supplied from the operating power source when the power switch is turned on. The short-circuit control unit is connected to the power converter, and configured to receive operating power output from the power converter. The second power receiver further comprises a determination unit configured to determine whether operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit. The determination unit is configured to determine that an abnormality has occurred when the determination unit determines that operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit.

[0018] According to this, an occurrence of an abnormality can be determined even if power is transmitted erroneously while power supply from the operating power source is cut off.

[0019] According to an aspect of the present disclosure, a third wireless power transfer system includes a power transmitter having a power transmitting antenna, and a power receiver having a power receiving antenna. The power transmitting antenna is configured to wirelessly supply power to the power receiving antenna. The power receiving antenna is configured to supply the power received from the power transmitting antenna to a power supply target device. The power receiver includes a protection circuit, a short-circuit control unit, a power converter, and a communication unit. The protection circuit is configured to short one of paths from the power receiving antenna to the power supply target device to cut off power supply from the power receiving antenna to the power supply target device. The short-circuit control unit is configured to control the protection circuit. The power converter is configured to receive, convert, and output a portion of the power transmitted from the power transmitting antenna during the power receiving antenna receiving the power from the power transmitting antenna. The communication unit is configured to transmit a power supply stop signal to command the power transmitter to stop power transmission. The short-circuit control unit is connected to an operating power source via a power switch, and configured to receive operating power supplied from the operating power source when the power switch is turned on. The short-circuit control unit is connected to the power converter, and configured to receive operating power output from the power converter. The communication unit is configured to transmit the power supply stop signal when operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit. The power transmitter is configured to stop power transmission when the power transmitter receives the power supply stop signal.

[0020] According to this, power transmission can be stopped even if power is transmitted erroneously from the power transmitter while power supply from the operating power source is cut off.

[0021] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.FIG. 1 is an overall configuration diagram of a wireless power transfer system according to a first embodiment.FIG. 2 is an overall configuration diagram of the wireless power transfer system.FIG. 3 is a diagram illustrating a power transmitter and a power receiver.FIG. 4 is a diagram illustrating an electrical circuit of the power receiver.FIG. 5 is a flowchart illustrating a flow a short-circuit process.FIG. 6 is a diagram illustrating an electric circuit of a power receiver according to a second embodiment.FIG. 7 is a flowchart illustrating a flow of a short-circuit process according to the second embodiment.FIG. 8 is a diagram illustrating a protection circuit according to a modification.FIG. 9 is a diagram illustrating a protection circuit according to a modification.FIG. 10 is a diagram illustrating a protection circuit according to a modification.FIG. 11 is a diagram illustrating a protection circuit according to a modification.FIG. 12 is a diagram illustrating a protection circuit according to a modification.FIG. 13 is a diagram illustrating a protection circuit according to a modification.FIG. 14 is a diagram illustrating a protection circuit according to a modification.FIG. 15 is a diagram illustrating a power converter according to a modification.FIG. 16 is a diagram illustrating a power converter according to a modification.FIG. 17 is a diagram illustrating a power converter according to a modification.FIG. 18 is a diagram illustrating a power converter according to a modification.FIG. 19 is a diagram illustrating a power converter according to a modification.FIG. 20 is a diagram illustrating a power converter according to a modification.

[0022] Multiple embodiments will be described with reference to the drawings. In the embodiments, parts that functionally and / or structurally correspond to or are associated with each other may be assigned the same reference numeral, or reference numerals different in digit in the hundreds or higher place. The corresponding and / or associated parts may refer to the explanation in the other embodiments.

[0023] First EmbodimentA first embodiment of a wireless power transfer system and a power receiver of the present disclosure will be described below with reference to the drawings.

[0024] First, an overall configuration of the wireless power transfer system will be described. As shown in FIGS. 1 to 4, the wireless power transfer system 10 includes a power transmitter 20 and a power receiver 100. The power receiver 100 is mounted on a vehicle 11 as a moving object that travels on a road RS, and is a vehicle-side device. The vehicle 11 is, for example, an electric automobile or a hybrid vehicle. The power is supplied from the power transmitter 20 to the power receiver 100 while the vehicle 11 is travelling or stopped. The wireless power transfer system 10 executes wireless power transfer from the power transmitter 20 to the power receiver 100 through magnetic field resonance coupling (magnetic field resonance). The wireless power transfer system 10 is also referred to as a dynamic wireless power transfer (D-WPT) system.

[0025] The power transmitter 20 is a ground-side device and has a power-transmitter coil unit 21 and a power-transmitter power supply unit 51 that supplies power to the power-transmitter coil unit 21. The power transmitter 20 is, for example, a stationary device. The power-transmitter coil unit 21 is installed (for example, buried) in the road RS, a parking lot, or the like. The power-transmitter power supply unit 51 is installed, for example, on the side of the road RS. The power-transmitter coil unit 21 is connected to the power-transmitter power supply unit 51. The power-transmitter power supply unit 51 is connected to an AC power source 15 and supplies AC (alternating-current) power from the AC power source 15 to the power-transmitter coil unit 21. The AC power source 15 is, for example, a commercial power source. Multiple power-transmitter coil units 21 are arranged along the lanes of the road RS. FIG. 2 shows an example of four power-transmitter coil units 21 aligned along the road RS and connected to one power-transmitter power supply unit 51. In other words, one power-transmitter power supply unit 51 is provided for each of the four power-transmitter coil units 21.

[0026] The configuration is not limited to one power-transmitter power supply unit 51 for each of the multiple power-transmitter coil units 21, but one power-transmitter power supply unit 51 may be provided for each power-transmitter coil unit 21.

[0027] The power-transmitter power supply unit 51 includes a PFC (Power Factor Correction) circuit 61, an inverter 60, and a filter circuit 52. The PFC circuit 61 includes an AC / DC converter and is connected to the AC power source 15. The PFC circuit 61 includes switching elements (e.g., IGBTs or MOSFETs) that are switched and controlled to convert the input AC power to DC (direct current) power and improve a power factor of the AC power input from the AC power source 15. IGBT is an abbreviation of Insulated Gate Bipolar Transistor. MOSFET is an abbreviation of Metal-Oxide-Semiconductor Field-Effect Transistor.

[0028] The inverter 60 is connected to the PFC circuit 61. The inverter 60 includes switching elements (e.g., IGBTs or MOSFETs) that are switched and controlled to convert the DC power input from the PFC circuit 61 to AC power.

[0029] The filter circuit 52 removes noise contained in the AC current input from the inverter 60 and supplies the AC current from which noise has been removed to the power-transmitter coil unit 21. The filter circuit 52 is, for example, an LC filter that includes a coil and a capacitor. Circuits having various configurations can be used as the filter circuit 52, and, for example, a T-type filter circuit is used as the filter circuit 52.

[0030] The power-transmitter coil unit 21 includes a power transmitter coil 22 (corresponding to power transmitting antenna), a power-transmitter resonant circuit 30, and a power-transmitter communication coil 40. The power-transmitter resonant circuit 30 supplies the AC power supplied by the filter circuit 52 to the power transmitter coil 22.

[0031] The power receiver 100 includes a power-receiver coil unit 101 and a power-receiver power supply unit 181. The power-receiver coil unit 101 includes a power- receiver coil 110. Although described in detail below, the power receiver coil 110 has a main power receiver coil 110a (corresponding to a "power receiving antenna") and a sub power receiver coil 110b. Hereinafter, the main power receiver coil 110a and the sub power receiver coil 110b will be collectively referred to as the power receiver coil 110.

[0032] The power-receiver coil unit 101 is located at the bottom of the vehicle body of the vehicle 11. The power-receiver coil unit 101 is located at the bottom of the vehicle body to face the ground surface. When the vehicle 11 travels on the road RS where the power transmitter coil 22 is buried, the power transmitter coil 22 on the ground side and the power receiver coil 110 of the vehicle 11 face each other in the vertical direction.

[0033] The power receiver 100 includes a power-receiver resonant circuit 140. The main power receiver coil 110a of the power receiver coil 110 is connected to the power-receiver resonant circuit 140. The main power receiver coil 110a of the power-receiver coil 110 is supplied with power from the power transmitter coil 22. The main power receiver coil 110a of the power receiver coil 110 supplies the received power to the power-receiver resonant circuit 140. The sub power receiver coil 110b is provided near the main power receiver coil 110a so as to receive power from the power transmitter coil 22 when the main power receiver coil 110a is receiving power from the power transmitter coil 22. The main power receiver coil 110a and the sub power receiver coil 110b share a common core.

[0034] The power receiver 100 includes a filter circuit 182 and a rectifier circuit 200 that also functions as a "protection circuit." In this embodiment, the rectifier circuit 200 corresponds to a "protection circuit."

[0035] The configurations of the power-receiver resonant circuit 140, the filter circuit 182, and the rectifier circuit 200 will be described. As shown in FIG. 4, the power-receiver resonant circuit 140 includes a first resonant capacitor 141 and a second resonant capacitor 142. The power-receiver resonant circuit 140 is not limited to the circuit shown in FIG. 4, but various circuits can be employed.

[0036] The rectifier circuit 200 is a circuit that converts the input AC current into a DC current and outputs the DC current. The rectifier circuit 200 is a full bridge circuit and includes a first upper arm switch QH1, a first lower arm switch QL1, a second upper arm switch QH2, and a second lower arm switch QL2. In this embodiment, each switch QH1, QL1, QH2, QL2 is a semiconductor switching device, and specifically, is an N-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). Each switch QH1, QL1, QH2, QL2 has a body diode DH1, DL1, DH2, DL2.

[0037] The rectifier circuit 200 is also referred to as an ERB (Electronic Rectification Box). The rectifier circuit 200 may includes an IGBT (Insulated Gate Bipolar Transistor) instead of the N-channel MOSFET. In this case, a freewheel diode may be connected in inverse parallel to the IGBT.

[0038] The source of the first upper arm switch QH1, which is the low potential terminal of the first upper arm switch QH1, and the drain of the first lower arm switch QL1, which is the high potential terminal of the first lower arm switch QL1, are connected to one end of the first resonant capacitor 141. The other end of the first resonant capacitor 141 is connected to a first end of the main power receiver coil 110a. The source of the second upper arm switch QH2 and the drain of the second lower arm switch QL2 are connected to one end of the second resonant capacitor 142. The second resonant capacitor 142 is connected to a second end of the main power receiver coil 110a. The drains of the first and second upper arm switches QH1, QH2 are connected to a high potential path H1, and the sources of the first and second lower arm switches QL1, QL2 are connected to a low potential path L1.

[0039] The filter circuit 182 removes noise contained in the current input from the rectifier circuit 200 and supplies the current from which noise has been removed toward a high-voltage storage battery 300. The filter circuit 182 is an LC filter (low-pass filter) that includes a reactor 183 and a capacitor 185. The filter circuit 182 is not limited to the circuit shown in FIG. 4, but various circuits can be employed.

[0040] The power receiver 100 includes a smoothing capacitor 210 between the filter circuit 182 and the high-voltage storage battery 300. One end of the smoothing capacitor 210 is connected to the high potential path H1, and the other end of the smoothing capacitor 210 is connected to the low potential path L1.

[0041] The vehicle 11 includes a high potential main switch 301H, a low potential main switch 301L, and a high-voltage storage battery 300 (corresponding to "power supply target device") as a power storage unit. The high potential main switch 301H and the low potential main switch 301L are, for example, relays (specifically, mechanical relays). A positive terminal of the high-voltage storage battery 300 is connected to the high potential path H1 via a high potential main switch 301H. A negative terminal of the high-voltage storage battery 300 is connected to the low potential path L1 via a low potential main switch 301L. The high-voltage storage battery 300 is a secondary battery that can be charged and discharged and has a rated voltage of several hundred volts, for example. The high-voltage storage battery 300 is, for example, a lithium-ion storage battery or a nickel-metal hydride storage battery.

[0042] The vehicle 11 includes a travelling inverter 310 and a rotary electric machine 320. The travelling inverter 310 is a 3-phase inverter and is connected to the high-voltage storage battery 300 via the high potential main switch 301H and the low potential main switch 301L. The armature windings of the rotary electric machine 320 are connected to the upper and lower arm switches that constitute the travelling inverter 310. By switching control of the upper and lower arm switches of the travelling inverter 310 while the high potential main switch 301H and the low potential main switch 301L are turned on, the travelling inverter 310 converts the DC power supplied from the high-voltage storage battery 300 into AC power and supplies it to the armature winding. This causes the rotor of the rotary electric machine 320 to rotate, and the rotational power of the rotor rotates drive wheels of the vehicle 11. As a result, the vehicle 11 travels.

[0043] As shown in FIG. 3, the power-transmitter power supply unit 51, which constitutes the power transmitter 20, includes a power-transmitter control unit 70. The power-transmitter control unit 70 includes a power-transmitter controller 71. The power-transmitter controller 71 is an electronic control unit (ECU) that executes various controls of the power transmitters 20 and includes a processor as hardware, a storage unit, and a communication bus connecting the processor and storage unit.

[0044] The storage unit includes a memory and a storage as hardware. The memory is a storage device for storing data used in the processing of the power-transmitter controller 71. The memory, for example, provides the processor with a work area for temporary use when the processor performs processing. The memory includes, for example, RAM and ROM. The storage is a storage device that stores various programs and data to be read and executed by the processor and is a non-transitory tangible storage medium. The storage includes, for example, HDD or flash memory. The storage contains program information and other information for various processes.

[0045] For example, the program information stored on the non-transitory tangible storage medium is installed in the storage unit. The storage medium is, for example, a USB memory, CD-ROM or DVD. In addition, the program information transmitted over a communication network, such as OTA (Over The Air), for example, is installed in the storage unit.

[0046] The power-receiver power supply unit 181, which constitutes the power receiver 100, includes a power-receiver control unit 230. The power-receiver control unit 230 includes a power-receiver controller 231. The power-receiver controller 231 is an ECU that performs various controls of the power receiver 100. The power-receiver controller 231, as shown in FIG. 4, includes a processor 232 as hardware, a storage unit 233, and a communication bus 234 that connects the processor 232 and storage unit 233.

[0047] The storage unit 233 includes a memory and a storage as hardware. The memory is a storage device for storing data used in the processing of the power-receiver controller 231. The memory, for example, provides the processor 232 with a work area for temporary use when the processor 232 performs processing. The memory includes, for example, RAM and ROM. The storage is a storage device that stores various programs and data to be read and executed by the processor 232 and is a non-transitory tangible storage medium. The storage includes, for example, HDD or flash memory. The storage contains program information and other information for various processes.

[0048] For example, the program information stored on the non-transitory tangible storage medium is installed in the storage unit 233. The storage medium is, for example, a USB memory, CD-ROM or DVD. In addition, the program information transmitted over a communication network, such as OTA (Over The Air), for example, is installed in the storage unit 233.

[0049] The power-transmitter controller 71 executes a switching control of the PFC circuit 61 and a switching control of the inverter 60. Through the switching control of the inverter 60, a high-frequency AC voltage is applied to the power transmitter coil 22. This causes a high-frequency current to flow in the power transmitter coils 22 and a magnetic field for power transmission is generated in the power transmitter coils 22.

[0050] In this embodiment, the power-transmitter controller 71 switches and controls the inverter 60 so that the frequency of the high-frequency voltage applied to the power transmitter coil 22 is becomes a first specified frequency between 10 kHz and 100 GHz, specifically, 85 kHz. The resonant frequencies of the power-transmitter resonant circuit 30 and the power-receiver resonant circuit 140 are set at the same frequency or close to the first specified frequency.

[0051] When the magnetic field generated in the power transmitter coil 22 links with the power receiver coil 110 (i.e., the main power receiver coil 110a and the sub power receiver coil 110b) of the vehicle 11, a high-frequency current flows in the power receiver coil 110, varying with the frequency of the high-frequency current flowing in the power transmitter coil 22. The high-frequency current flowing in the main power receiver coil 110a is supplied to the rectifier circuit 200 through the power-receiver resonant circuit 140.

[0052] The power-receiver controller 231 converts the supplied AC current into DC current by executing switching control (i.e., synchronous rectification control) of each of the switches QH1, QL1, QH2, and QL2 and outputs it.

[0053] While the high potential main switch 301H and the low potential main switch 301L are turned on, the output current of the rectifier circuit 200 is supplied to the high-voltage storage battery 300 or the travelling inverter 310 through the filter circuit 182.

[0054] The high potential main switch 301H and the low potential main switch 301L can actually be controlled by a different controller than the power-receiver controller 231. For convenience, however, the high potential main switch 301H and the low potential main switch 301L are controlled by the power-receiver controller 231.

[0055] The vehicle 11 is equipped with a low-voltage storage battery 302 as an "operating power source." The rated voltage of the low-voltage storage battery 302 is lower than the rated voltage of the high-voltage storage battery 300, and is, for example, 12V. The low-voltage storage battery 302 is, for example, a lead-acid battery. The power supplied from the low-voltage storage battery 302 to the power-receiver controller 231 enables the power-receiver controller 231 to operate.

[0056] The vehicle 11 includes a voltage sensor 330, a current sensor 340, and a temperature sensor 350. A voltage sensor detects voltages of various in-vehicle devices of the vehicle 11 (specifically, components of the power receiver 100), and the voltage sensor 330 of the present embodiment detects, for example, a voltage of the smoothing capacitor 210. A current sensor detects currents flowing in various in-vehicle devices of the vehicle 11 (specifically, the components of the power receiver 100). The current sensor 340 of the present embodiment detects current flowing through the high potential path H1. A temperature sensor detects temperatures of the various in-vehicle devices of the vehicle 11 (specifically, components of the power receiver 100), and the temperature sensor 350 of the present embodiment detects, for example, temperatures of the smoothing capacitor 210 and the rectifier circuit 200. The detected values of each sensor 330, 340, 350 are input to the power-receiver controller 231.

[0057] The power receiver 100 and the power transmitter 20 each have a configuration for communication between the power receiver 100 and the power transmitter 20. In detail, the power-receiver coil unit 101, which constitutes the power receiver 100, includes a power-receiver communication coil 170 as a wireless communication antenna. A power-receiver control unit 230 includes a signal transmitter 240.

[0058] The power-transmitter coil unit 21, which constitutes the power transmitter 20, includes the power-transmitter communication coil 40. The power-transmitter control unit 70 includes a signal receiver 80. The power-receiver communication coil 170 and the power-transmitter communication coil 40 are communication coils (communication antennas) for narrow area wireless communication. Narrow area wireless communications are those with a communication distance of less than 10 meters (e.g., a maximum of about 3 meters). Narrow area wireless communication is a communication with a shorter communication distance than wide area wireless communication.

[0059] Various short-range wireless communications can be used as the narrow area wireless communication. For example, communications compliant with any communication standards established by IEEE, ISO, and IEC can be used. Specifically, for example, Wi-Fi (registered trademark), Bluetooth (registered trademark), ZigBee (registered trademark), RFID (Radio Frequency Identification), or DSRC (Dedicated Short Range Communication) can used as the narrow area wireless communication.

[0060] Communication networks used in wide area wireless communication include, for example, a WAN (Wide Area Network), which is a public communication network such as the Internet, a telephone communication network for a mobile phone, an information and communication network for ETC, and an information and communication network for a Vehicle Information and Communication System (VICS (registered trademark)). Wide area wireless communication is a communication with a longer communication distance than the narrow area wireless communication. Wide area wireless communication is communication with a communication distance of, for example, 10 meters to 10 kilometers. Examples of the wide area wireless communication include 3GPP (registered trademark), 4G, LTE, 5G, and WiMAX (registered trademark) developed by IEEE.

[0061] The signal transmitter 240 is connected to the power-receiver controller 231. The signal transmitter 240 is connected to the power-receiver communication coil 170. A communication unit 400 of the power-receiver controller 231 controls the signal transmitter 240 to supply an electric signal to the power-receiver communication coil 170. The electric signal corresponds to various information such as a power supply request signal. The power supply request signal is a signal requesting the power transmitter coil 22 near the vehicle 11 to transmit power to the power receiver coil 110. The functions of the communication unit 400 are realized by the processor 232 implementing the program stored in the storage unit 233.

[0062] The power-receiver control unit 230 controls the signal transmitter 240 so that information including the power supply request signal is included in one frame and wirelessly transmitted from the power-receiver communication coil 170. In this embodiment, the power supply request signal includes ID information of the vehicle 11 and a requested power Weq that is a requested value of power to be supplied to the vehicle 11. This control causes a high-frequency signal to be supplied from the signal transmitter 240 to the power-receiver communication coil 170. Consequently, a high-frequency current flows in the power-receiver communication coil 170, and a magnetic field for information communication is generated in the power-receiver communication coil 170.

[0063] When the power-receiver coil unit 101 of the vehicle 11 approaches the power-transmitter coil unit 21 on the ground side, the generated magnetic field links to the power-transmitter communication coil 40, and a high-frequency current flows through the power-transmitter communication coil 40. This high-frequency current is input to the signal receiver 80. The signal receiver 80 recognizes the presence or absence of a power supply request and ID information based on the input signal from the power-transmitter communication coil 40. The signal receiver 80 also acquires the required power Weq for the vehicle 11 with the recognized ID information, based on the signal from the power-transmitter communication coil 40. The information recognized by the signal receiver 80 and the requested power Weq are input to the power-transmitter controller 71.

[0064] In this embodiment, the power-receiver controller 231 controls the signal transmitter 240 so that the frequency of the high-frequency voltage applied to the power-receiver communication coil 170 becomes a second specified frequency between 10 kHz and 100 GHz. In this embodiment, the second specified frequency is a frequency that deviates from the first specified frequency above, specifically a frequency higher than the first specified frequency (e.g., 13.56 MHz).

[0065] When the power-transmitter controller 71 determines that there is a power supply request based on input information from the signal receiver 80, the power-transmitter controller 71 applies high-frequency voltage to the power transmitter coil 22 by controlling the inverter 60 and the PFC circuit 61. This results in a wireless power transmission from the power transmitter coil 22 to the power receiver coil 110.

[0066] In the present embodiment, the rectifier circuit 200 functions as a protection circuit that shorts the power receiver coil 110 and cuts off the supply of power from the power receiver coil 110 to the high-voltage storage battery 300 if an abnormality occurs in the power receiver 100. To explain in more detail, when the voltage sensor 330 detects an overvoltage, when the current sensor 340 detects an overcurrent, or when the temperature sensor 350 detects an abnormal temperature, the power-receiver controller 231 turns on switches QL1 and QL2 of the rectifier circuit 200 to perform short-circuit control. This function as a protection circuit can cut off the current from the main power receiver coil 110a and prevent, for example, an overvoltage from being applied to the high-voltage storage battery 300 or the travelling inverter 310.

[0067] However, even when the vehicle 11 is being started or stopped and is not in a state to receive power, noise or signals from other vehicles, etc., may cause the power transmitter 20 to erroneously determine that "there is a power request," and power may be erroneously transmitted from the power transmitter 20. In this case, it is necessary to short-circuit the main power receiver coil 110a using the rectifier circuit 200 so as to cut off the power supply from the main power receiver coil 110a and prevent overvoltage.

[0068] However, when the vehicle 11 is being started or stopped, the power supply from the low-voltage storage battery 302 (operating power source) to the power-receiver controller 231 is generally also stopped, which may pose a problem that the rectifier circuit 200 cannot be driven. In addition, when the vehicle 11 is being started or stopped, the power-receiver controller 231 is also not started, and therefore a command to stop power transmission cannot be issued to the power transmitter 20.

[0069] Therefore, in the power receiver 100 of this embodiment, the following configurations are adopted so that the rectifier circuit 200 is operated and power transmission from the power transmitter 20 is stopped even when the vehicle 11 is being started or stopped. This will be described below in detail.

[0070] The power-receiver power supply unit 181 has a short-circuit control circuit 360. The short-circuit control circuit 360 is a circuit that, when a voltage equal to or greater than a voltage threshold Vth is applied from the low-voltage storage battery 302 or the like, turns on the switches QL1 and QL2 of the rectifier circuit 200 to perform short-circuit control. The short-circuit control circuit 360 may be provided for each of the switches QL1 and QL2. The voltage threshold Vth is a voltage lower than the rated voltage (12V) of the low-voltage storage battery 302, and is, for example, 10V. The short-circuit control circuit 360 is connected to the low-voltage storage battery 302 via a power switch 370. The power switch 370 is controlled to be turned on and off by a determination circuit 361, which will be described later.

[0071] As shown in FIG. 4, the power switch 370 is connected to the short-circuit control circuit 360 via a first diode D11. More specifically, one end of the power switch 370 is connected to the low-voltage storage battery 302, and the other end of the power switch 370 is connected to the anode side of the first diode D11. The cathode of the first diode D11 is connected to the short-circuit control circuit 360. In other words, the first diode D11 is provided on an electrical path between the power switch 370 and the short-circuit control circuit 360 so that a voltage is applied from the low-voltage storage battery 302 to the short-circuit control circuit 360 when the power switch 370 is turned on.

[0072] The sub power receiver coil 110b is connected to a self-generating circuit 362. The sub power receiver coil 110b, together with the main power receiver coil 110a, receives power from the power transmitter coil 22 in a non-contact manner. When the magnetic field generated in the power transmitter coil 22 links with the sub power receiver coil 110b, a high-frequency current flows in the sub power receiver coil 110b, varying with the frequency of the high-frequency current flowing in the power transmitter coil 22. In other words, when the power transmitter coil 22 is transmitting power, the sub power receiver coil 110b is capable of receiving a portion of the power transmitted from the power transmitter coil 22. The high-frequency current flowing through the sub power receiver coil 110b is supplied to the self-generating circuit 362.

[0073] The self-generating circuit 362 is a type of regulator, and is a circuit (AC-DC converter) for receiving an input of a high-frequency current (AC current) and outputting a DC current of a predetermined voltage. To explain in more detail, the self-generating circuit 362 is a circuit that rectifies the input high-frequency current (AC current) to convert it to DC current, then smooths it to suppress fluctuations in the voltage of the DC current, stabilizes the voltage, and outputs the DC current at a predetermined voltage. The output voltage (applied voltage) of the self-generating circuit 362 is lower than the rated voltage (12 V) of the low-voltage storage battery 302 and higher than the voltage threshold Vth (10 V), for example, 11 V. In this embodiment, the sub power receiver coil 110b and the self-generating circuit 362 correspond to a power converter that receives, converts, and outputs a portion of the power from the power transmitter coil 22 during power transmission.

[0074] As shown in FIG. 4, the self-generating circuit 362 is connected to the short-circuit control circuit 360 via a second diode D12. More specifically, the self-generating circuit 362 is connected to the anode side of the second diode D12. The cathode of the second diode D12 is connected to the cathode of the first diode D11, and the short-circuit control circuit 360 is connected to a connection point P11 provided on the electrical path connecting the cathode of the first diode D11 and the cathode of the second diode D12.

[0075] In other words, the first diode D11 and the second diode D12 are provided so that the application of current and voltage from the self-generating circuit 362 to the short-circuit control circuit 360 is permitted, while the application of current and voltage from the self-generating circuit 362 to the low-voltage storage battery 302 is regulated. At the same time, the first diode D11 and the second diode D12 are provided so that the application of current and voltage from the low-voltage storage battery 302 to the short-circuit control circuit 360 is permitted, while the application of current and voltage from the low-voltage storage battery 302 to the self-generating circuit 362 is regulated.

[0076] The power-receiver power supply unit 181 also includes a determination circuit 361 that receives an input of a first voltage V11 on the anode side of the first diode D11 and an input of a second voltage V12 on the anode side of the second diode D12 and determines whether the second voltage V12 is higher than the first voltage V11. The first voltage V11 is the voltage between the first diode D11 and the power switch 370, and the second voltage V12 is the voltage between the second diode D12 and the self-generating circuit 362.

[0077] When the second voltage V12 is higher than the first voltage V11, i.e., when the voltage from the low-voltage storage battery 302 (voltage of 12 V) is not being applied and only the voltage from the self-generating circuit 362 (voltage of 11 V) is being applied, the determination circuit 361 controls the power switch 370 to be switched from off to on. In addition, when the second voltage V12 is higher than the first voltage V11, the determination circuit 361 starts the power-receiver controller 231 and instructs the power-receiver controller 231 to send a power supply stop signal (STOP-COMM) to the power transmitter 20 to command the power transmitter 20 to stop transmitting power.

[0078] On the other hand, when the second voltage V12 is lower than the first voltage V11, the power switch 370 is turned on and voltage is applied from the low-voltage storage battery 302, or no power is being transmitted from the power transmitter coil 22 to the sub power receiver coil 110b. The determination circuit 361 is configured to be operate by power supplied from the self-generating circuit 362. That is, even when the vehicle 11 is being stopped or started, the sub power receiver coil 110b can operate when power is being transmitted from the power transmitter coil 22 to the sub power receiver coil 110b.

[0079] A cooling fan 390 is provided near the main power receiver coil 110a to blow air toward the main power receiver coil 110a and cool the main power receiver coil 110a. The cooling fan 390 is driven by power supplied from the low-voltage storage battery 302 or the self-generating circuit 362.

[0080] Next, a flow of a short-circuit process when power is transmitted from the power transmitter 20 while the vehicle 11 is being started or stopped will be described with reference to FIG. 5. When, for some reason, power is transmitted from the power transmitter coil 22 to the power receiver coil 110 (the main power receiver coil 110a and the sub power receiver coil 110b) while the vehicle 11 is being started or stopped, the self-generating circuit 362 receives an input AC current from the sub power receiver coil 110b, converts it to a predetermined DC voltage, and applies the predetermined DC voltage to the short-circuit control circuit 360 (step S101). As a result, the short-circuit control circuit 360 turns on the switches QL1 and QL2 to short-circuit the main power receiver coil 110a. This makes it possible to prevent an overvoltage from being applied from the main power receiver coil 110a to the power receiver 100.

[0081] Next, the determination circuit 361 determines whether power is being fed only from the sub power receiver coil 110b (step S102). Specifically, the determination circuit 361 receives the first voltage V11 and the second voltage V12, and determines whether the second voltage V12 is higher than the first voltage V11.

[0082] When this determination result is negative, the power switch 370 is on and voltage is being applied from the low-voltage storage battery 302, so the process ends. On the other hand, when the determination result in step S102 is affirmative, the determination circuit 361 controls the power switch 370 to switch from off to on (step S103).

[0083] The determination circuit 361 also starts up the power-receiver controller 231, and instructs the power-receiver controller 231 to transmit a power supply stop signal (STOP-COMM) commanding the power transmitter 20 to stop power transmission (step S104). When the power-receiver controller 231 is started up, the communication unit 400 controls the signal transmitter 240 to transmit a power supply stop signal (STOP-COMM) based on an instruction from the determination circuit 361. That is, the power supply stop signal is transmitted to the power transmitter 20 via narrow area wireless communication. Furthermore, the communication unit 400 of the power-receiver controller 231 transmits the power supply stop signal to the power transmitter 20 by using wide area wireless communication (for example, communication via a cloud).

[0084] Furthermore, the power-receiver controller 231 starts the cooling fan 390 to cool the main power receiver coil 110a (step S105). The determination circuit 361 may start the cooling fan 390.

[0085] According to the first embodiment, the sub power receiver coil 110b receives power from the power transmitter coil 22 when the main power receiver coil 110a is receiving power from the power transmitter coil 22. Even if the power switch 370 is turned off and no power is being supplied from the low-voltage storage battery 302, the short-circuit control circuit 360 receives an input of operating power from the sub power receiver coil 110b, turns off switches QL1 and QL2, and performs the short-circuit control. As a result, even when the vehicle 11 is being started or stopped, the short-circuit control can be performed to prevent an overvoltage from being applied to the power receiver 100.

[0086] In addition, when operating power is supplied to the short-circuit control circuit 360 from the sub power receiver coil 110b while no operating power is supplied to the short-circuit control circuit 360 from the low-voltage storage battery 302, the determination circuit 361 activates the power-receiver controller 231 and instructs it to transmit a power supply stop signal. When the power-receiver controller 231 is started up, the power-receiver controller 231 transmits the power supply stop signal to the power transmitter 20 based on the instruction. As a result, even if power transmission from the power transmitter 20 occurs due to some malfunction while the vehicle 11 is being started or stopped, the power transmission can be stopped.

[0087] In addition, when the determination circuit 361 determines that operating power is not being supplied to the short-circuit control circuit 360 from the low-voltage storage battery 302 and that operating power is being supplied to the short-circuit control circuit 360 only from the sub power receiver coil 110b, the determination circuit 361 turns on the power switch 370. Accordingly, operating power can be supplied from the low-voltage storage battery 302 to the short-circuit control circuit 360, and the short-circuit control can be continued.

[0088] The determination circuit 361 compares the first voltage V11 on the anode side of the first diode D11 with the second voltage V12 on the anode side of the second diode D12, and when the second voltage V12 is higher than the first voltage V11, the determination circuit 361 determines that operating power is being supplied to the short-circuit control circuit 360 only from the sub power receiver coil 110b. This makes it possible to determine, with a simple configuration, whether operating power is being supplied only from the sub power receiver coil 110b.

[0089] The power-receiver controller 231 transmits a power supply stop signal via narrow area wireless communication and wide area wireless communication. Therefore, even if either the narrow area wireless communication or the wide area wireless communication is not working properly, the power supply stop signal can be transmitted reliably.

[0090] When the determination circuit 361 determines that operating power is not being supplied to the short-circuit control circuit 360 from the low-voltage storage battery 302 and that operating power is being supplied to the short-circuit control circuit 360 only from the sub power receiver coil 110b, the determination circuit 361 starts the cooling fan 390. This allows the main power receiver coil 110a to be cooled, thereby suppressing heat generation due to overvoltage.

[0091] In addition, in the first embodiment described above, when the power-receiver controller 231 detects an abnormality (overvoltage, etc.) in the power receiver 100 during startup of the vehicle 11, the power-receiver controller 231 turns on the switches QL1 and QL2 of the rectifier circuit 200 to perform the short-circuit control. However, the power switch 370 may be turned on and the short-circuit control circuit 360 perform the short-circuit control.

[0092] Second EmbodimentA second embodiment in which the configuration of the power receiver 100 of the first embodiment is partially modified will be described below. In the second embodiment, the function of the short-circuit control circuit 360 and the function of the determination circuit 361 are provided in the power-receiver controller 231. This will be described in detail below with reference to FIG. 6.

[0093] As shown in FIG. 6, a processor 232 of a power-receiver controller 231 has a function as a short-circuit control unit 401 and a function as a determination unit 402. These functions are realized by the processor 232 implementing the program stored in a storage unit 233.

[0094] As shown in FIG. 6, a power switch 470 is connected to the power-receiver controller 231 via a first diode D21. More specifically, one end of the power switch 470 is connected to the low-voltage storage battery 302, and the other end of the power switch 470 is connected to the anode side of the first diode D21. The cathode of the first diode D21 is connected to the power-receiver controller 231. In other words, when the power switch 470 is turned on, the first diode D21 is provided on the electrical path between the power switch 470 and the power-receiver controller 231 so that voltage is applied and power is supplied from the low-voltage storage battery 302 to the power-receiver controller 231. During startup of the vehicle 11, for example when an ignition switch is turned on, the power switch 470 is turned on together with the main switches 301H, 301L, etc.

[0095] The sub power receiver coil 110b is connected to a self-generating circuit 362. The sub power receiver coil 110b and the self-generating circuit 362 are the same as those in the first embodiment, and therefore description thereof will be omitted. As shown in FIG. 6, the self-generating circuit 362 is connected to the power-receiver controller 231 via a second diode D22. More specifically, the self-generating circuit 362 is connected to the anode side of the second diode D22. The cathode of the second diode D22 is connected to the cathode of the first diode D21, and the power-receiver controller 231 is connected to a connection point P21 provided on the electrical path connecting the cathode of the first diode D21 and the cathode of the second diode D22.

[0096] Next, various functions of the power-receiver controller 231 will be described. The power-receiver controller 231 includes an abnormality determination unit that determines whether the power receiver 100 is abnormal. For example, the power-receiver controller 231 determines that an abnormality has occurred in the power receiver 100 when a voltage sensor 330 detects an overvoltage, when a current sensor 340 detects an overcurrent, or when a temperature sensor 350 detects an abnormal temperature. When an abnormality in the power receiver 100 is detected, the short-circuit control unit 401 turns on the switches QL1 and QL2 of the rectifier circuit 200 to perform short-circuit control. Furthermore, when the determination unit 402 described later determines that power is being supplied only from the sub power receiver coil 110b, the short-circuit control unit 401 performs the short-circuit control.

[0097] When the power-receiver controller 231 is stopped (or in a sleep state) and a voltage equal to or greater than a voltage threshold Vth is applied to the power-receiver controller 231 from the low-voltage storage battery 302 or the self-generating circuit 362, the power-receiver controller 231 starts up and performs the function of the determination unit 402. The voltage threshold Vth is a voltage lower than the rated voltage (12V) of the low-voltage storage battery 302 and the voltage applied from the self-generating circuit 362, and is, for example, 10V.

[0098] The determination unit 402 receives a first voltage V21 on the anode side of the first diode D21 and a second voltage V22 on the anode side of the second diode D22, and determines whether the second voltage V22 is higher than the first voltage V21. The first voltage V21 is the voltage between the first diode D21 and the power switch 470, and the second voltage V22 is the voltage between the second diode D22 and the self-generating circuit 362.

[0099] When the second voltage V22 is higher than the first voltage V21, that is, when the voltage from the low-voltage storage battery 302 (voltage of 12 V) is not being applied and only the voltage from the self-generating circuit 362 (voltage of 11 V) is being applied, the determination unit 402 determines that power is being transmitted from the power transmitter 20 and that an abnormality has occurred. In this case, the determination unit 402 controls the power switch 470 to switch from off to on. Furthermore, when the second voltage V22 is higher than the first voltage V21, the determination unit 402 notifies the short-circuit control unit 401 and the communication unit 400 of that the second voltage V22 is higher than the first voltage V21.

[0100] When the short-circuit control unit 401 receives a notification from the determination unit 402 that the second voltage V22 is higher than the first voltage V21, the short-circuit control unit 401 performs the short-circuit control. In other words, when the determination unit 402 determines that power is being supplied only from the sub power receiver coil 110b, i.e., when it is determined that power is being transmitted during the vehicle being started or stopped and that there is an abnormality, the short-circuit control unit 401 performs the short-circuit control. Furthermore, when the communication unit 400 receives the notification from the determination unit 402, the communication unit 400 controls the signal transmitter 240 to transmit a power supply stop signal (STOP-COMM) to the power transmitter 20 to command the power transmitter 20 to stop transmitting power. Furthermore, the communication unit 400 transmits the power supply stop signal (STOP-COMM) to the power transmitter 20 by wide area wireless communication. Furthermore, the power-receiver controller 231 drives a cooling fan 390 when the determination unit 402 determines that the second voltage V22 is higher than the first voltage V21.

[0101] Next, a flow of a short-circuit process when power is transmitted from the power transmitter 20 while the vehicle 11 is being started or stopped will be described with reference to FIG. 7. When, for some reason, power is transmitted from the power transmitter coil 22 to the power receiver coil 110 (the main power receiver coil 110a and the sub power receiver coil 110b) while the vehicle 11 is being started or stopped, the self-generating circuit 362 receives an input AC current from the sub power receiver coil 110b, converts it to a predetermined DC voltage, and applies the predetermined DC voltage to the power-receiver controller 231 (step S201). As a result, the power-receiver controller 231 is started up. Then, the determination unit 402 of the power-receiver controller 231 determines whether power is being fed only from the sub power receiver coil 110b (step S202). Specifically, the determination unit 402 receives the first voltage V11 and the second voltage V12, and determines whether the second voltage V12 is higher than the first voltage V11.

[0102] When this determination result is negative, the power switch 470 is on and voltage is being applied from the low-voltage storage battery 302, so the process ends. In this case, the power-receiver controller 231 then performs normal startup processing.

[0103] On the other hand, when the determination result of step S202 is affirmative, the determination unit 402 determines that power is being transmitted during the vehicle being started or stopped, i.e., that there is an abnormality, and the determination unit 402 notifies the short-circuit control unit 401 and the communication unit 400 that power is being supplied only from the sub power receiver coil 110b (step S203). Furthermore, when the determination unit 402 determines that power is being fed only from the sub power receiver coil 110b, the power-receiver controller 231 controls the power switch 470 to switch from off to on (step S204).

[0104] When the determination unit 402 determines that power is being fed only from the sub power receiver coil 110b, the short-circuit control unit 401 turns on the switches QL1 and QL2 to perform the short-circuit control to short circuit the main power receiver coil 110a (step S205). This makes it possible to prevent an overvoltage from being applied from the main power receiver coil 110a to the power receiver 100.

[0105] In addition, when the determination unit 402 determines that power is being supplied only from the sub power receiver coil 110b, the communication unit 400 transmits a power supply stop signal (STOP-COMM) to the power transmitter 20 using narrow area wireless communication and wide area wireless communication (step S206).

[0106] Furthermore, the power-receiver controller 231 starts the cooling fan 390 to cool the main power receiver coil 110a (step S207).

[0107] The effects of the second embodiment is described. Even when power is not being supplied from the low-voltage storage battery 302 to the power-receiver controller 231, the power-receiver controller 231 is started up by receiving power from the sub power receiver coil 110b. When the determination unit 402 determines that power is being supplied only from the sub power receiver coil 110b, the determination unit 402 determines that power is being transmitted during the vehicle being stopped or started, and that an abnormality has occurred. In this case, the short-circuit control unit 401 turns off the switches QL1 and QL2 to perform the short-circuit control. As a result, even when the vehicle 11 is being started or stopped, an overvoltage can be prevented from being applied to the power receiver 100.

[0108] In addition, when the determination unit 402 determines that power is not being supplied from the low-voltage storage battery 302 to the power-receiver controller 231 and power is being supplied from the sub power receiver coil 110b to the power-receiver controller 231, that is, when power is being transmitted during the vehicle is being started or stopped and an abnormality is detected, the determination unit 402 instructs the communication unit 400 to send a power supply stop signal. As a result, even if power transmission from the power transmitter 20 occurs due to some malfunction while the vehicle 11 is being started or stopped, the power transmission can be stopped.

[0109] In addition, when power from the low-voltage storage battery 302 is not being supplied to the power-receiver controller 231 and power from the sub power receiver coil 110b is being supplied to the power-receiver controller 231, the power-receiver controller 231 turns on the power switch 470. This allows power to be supplied from the low-voltage storage battery 302 to the power-receiver controller 231, and makes it possible to continue the short-circuit control even if the power from the sub power receiver coil 110b is cut off.

[0110] The determination unit 402 compares the first voltage V21 on the anode side of the first diode D21 with the second voltage V22 on the anode side of the second diode D22, and when the second voltage V22 is higher than the first voltage V21, the determination unit 402 determines that power is being supplied only from the sub power receiver coil 110b. This makes it possible to determine, with a simple configuration, whether power is being supplied only from the sub power receiver coil 110b.

[0111] ModificationsIn the above embodiments, the cooling fan 390 does not have to be driven. Also, the cooling fan 390 does not need to be provided.

[0112] In the above embodiments, another cooling unit may be provided in place of the cooling fan 390. For example, a water-cooling type cooling unit may be provided.

[0113] In the above embodiments, the communication unit 400 may transmit the power supply stop signal by only one of the narrow area wireless communication and the wide area wireless communication.

[0114] The first embodiment and the second embodiment may be combined. For example, in the second embodiment, the determination circuit 361 may be provided in place of the determination unit 402. Also, instead of the short-circuit control unit 401, the short-circuit control circuit 360 may be provided.

[0115] In the short-circuit control of the above embodiments, the upper arm switches QH1, QH2 may be turned on, and the lower arm switches QL1, QL2 may be turned off.

[0116] In the above embodiments, the positions of the rectifier circuit 200 and the filter circuit 182 may be interchanged.

[0117] In the above embodiments, the protection circuit may have any circuit configuration as long as it can short-circuit the power receiver coil 110. In addition, a protection circuit may be provided separately from the rectifier circuit 200.

[0118] In the above embodiments, the rectifier circuit 200 functions as a protection circuit. However, the rectifier circuit 200 and the protection circuit may be provided separately. For example, as shown in FIGS. 8 to 11, a protection circuit 500 includes a bidirectional switch in which two semiconductor switches 501 and 502 are connected in series. The protection circuit 500 is disposed between the high potential path H1 and the low potential path L1. The layout of the protection circuit 500 may be changed arbitrarily. For example, as shown in FIG. 8, the protection circuit 500 may be located inside the power-receiver coil unit 101, between the power receiver coil 110 and the power-receiver resonant circuit 140. Alternatively, as shown in FIG. 9, the protection circuit 500 may be located inside the power-receiver coil unit 101, between the power-receiver resonant circuit 140 and the filter circuit 182. Alternatively, as shown in FIG. 10, the protection circuit 500 may be located inside the power-receiver power supply unit 181, between the power-receiver resonant circuit 140 and the filter circuit 182. Alternatively, as shown in FIG. 11, the protection circuit 500 may be located inside the power-receiver power supply unit 181, between the filter circuit 182 and the rectifier circuit 200.

[0119] The configuration of the protection circuit is not limited to the bidirectional switch, and a protection circuit 1000 including a rectifier circuit 200a and a semiconductor switch SW10 may be adopted. The rectifier circuit 200a includes diodes D31 to D34 as shown in FIG. 12, and the semiconductor switch SW10 is connected in parallel to the rectifier circuit 200a. The position of the protection circuit 1000 may be changed arbitrarily. For example, the protection circuit 1000 may be used instead of the protection circuit 500 shown in FIGS. 8 to 11.

[0120] In the above embodiments, the rectifier circuit 200 may employ rectifier circuits 200b and 200c that includes diodes D31 to D34 as shown in FIGS. 13 and 14. In this case, as shown in FIG. 13, semiconductor switches SW13 and SW14 may be connected in parallel to diodes D33 and D34 constituting the lower arm, thereby allowing the rectifier circuit 200b to function as a protection circuit. Furthermore, as shown in FIG. 14, semiconductor switches SW11 and SW12 may be connected in parallel to diodes D31 and D32 constituting the upper arm, thereby allowing the rectifier circuit 200c to function as a protection circuit.

[0121] In the above embodiments, the magnetic field generated in the power transmitter coil 22 links with the sub power receiver coil 110b, thereby causing the sub power receiver coil 110b to receive power. However, other configurations may be used as long as a portion of the power transmitted from the power transmitter coil 22 can be input. For example, when a high-frequency current flows through the main power receiver coil 110a due to power reception from the power transmitter coil 22, the sub power receiver coil 110b may be provided so as to link with a magnetic field generated in the main power receiver coil 110a. This allows the sub power receiver coil 110b to indirectly receive a portion of the power transmitted from the power transmitter coil 22 via the main power receiver coil 110a.

[0122] Similarly, as shown in FIGS. 15 and 16, a sub power receiver coil 110b may be arranged so as to link with the magnetic field generated in a coil 183, 186 provided between the main power receiver coil 110a and the rectifier circuit 200. The coil provided between the main power receiver coil 110a and the rectifier circuit 200 is, for example, the reactor 183 of the filter circuit 182. When a high-frequency current flows through main power receiver coil 110a as a result of receiving power from power transmitter coil 22, the high-frequency current also flows through these coils 183, 186, generating a magnetic field. As a result, a high-frequency current also flows through the sub power receiver coil 110b arranged as shown in FIGS. 15 and 16. Therefore, the sub power receiver coil 110b shown in FIGS. 15 and 16 can also indirectly receive a portion of the power transmitted from the power transmitter coil 22 via the main power receiver coil 110a and other components.

[0123] In the above embodiments, the sub power receiver coil 110b is used to input a portion of the power transmitted from the power transmitter coil 22, but the configuration may also be such that a portion of the current (power) flowing between the main power receiver coil 110a and the rectifier circuit 200 is directly input. For example, as shown in FIG. 17, a self-generating circuit 362 may be connected across a capacitor, such as resonant capacitors 141 and 142, connected in series with the main power receiver coil 110a between the main power receiver coil 110a and the rectifier circuit 200. This self-generating circuit 362 is configured to receive AC current flowing from the main power receiver coil 110a, convert it into DC current of a predetermined voltage, and output it to the short-circuit control circuit 360 and the power-receiver controller 231.

[0124] Furthermore, for example, as shown in FIGS. 18 and 19, a self-generating circuit 362 may be connected between the main power receiver coil 110a and the rectifier circuit 200. In detail, the self-generating circuit 362 in FIG. 18 is connected between the filter circuit 182 and the rectifier circuit 200 to a first electrical path H11 and a second electrical path L11. The first electrical path is connected to one end of the main power receiver coil 110a, and the second electrical path L11 is connected to the other end of the main power receiver coil 110a. The self-generating circuit 362 in FIG. 19 is connected to the first electrical path H11 and the second electrical path L11 between the main power receiver coil 110a and the filter circuit 182. The self-generating circuit 362 in FIGS. 18 and 19 is configured to receive AC current flowing from the main power receiver coil 110a to the rectifier circuit 200, convert it into DC current of a predetermined voltage, and output it to the short-circuit control circuit 360 and the power-receiver controller 231.

[0125] Also, for example, as shown in FIG. 20, a self-generating circuit 362 may be connected between the rectifier circuit 200 and the main switches 301H, 301L. In detail, the self-generating circuit 362 in FIG. 20 is connected at one end to the high potential path H1 and at the other end to the low potential path L1 between the rectifier circuit 200 and the main switches 301H, 301L. The self-generating circuit 362 in FIG. 20 is configured to receive DC current from the rectifier circuit 200, convert it into DC current of a predetermined voltage, and output it to the short-circuit control circuit 360 and the power-receiver controller 231. In other words, the self-generating circuit 362 in FIG. 20 is a DC-DC converter. In FIGS. 17 to 20, the self-generating circuit 362 corresponds to the power converter.

[0126] In the above embodiments, the positions of the rectifier circuit 200 and the filter circuit 182 may be interchanged.

[0127] In the above embodiments, the operating power source may be a power source other than the low-voltage storage battery 302, for example, may be a switching power source.

[0128] The method of wireless power transmission by the power transmitting antenna and the power receiving antenna in the above embodiments is not limited to the magnetic field resonance method, and may be an electric field coupling method. In this case, a power transmitting antenna and a power receiving antenna that are different in form from coils and use an electric field coupling method may be used.

[0129] In the above embodiments, the power supply target device to be supplied with power is not limited to the high-voltage storage battery 300, and may be an electric load connected to the power receiver 100, such as the travelling inverter 310 and the rotary electric machine 320.

[0130] In the above embodiments, the wireless power transfer system may have a second function of wirelessly supplying power from the vehicle-side device to the ground-side device, in addition to the first function of wirelessly supplying power from the ground-side device to the vehicle-side device. In this case, the in-vehicle power receiver 100 has a power transmitting function in addition to the power receiving function. Moreover, the power transmitter 20 on the ground side has a power receiving function in addition to the power transmitting function. The second function will be described below with reference to FIG. 3.

[0131] The power-receiver controller 231 applies a high frequency AC voltage to the main power receiver coil 110a by controlling the switching of the rectifier circuit 200. This causes a high-frequency current to flow in the main power receiver coil 110a and a magnetic field for power transmission is generated in the main power receiver coil 110a.

[0132] When the magnetic field generated in the main power receiver coil 110a links with the power transmitter coil 22, a high-frequency current flows in the power transmitter coil 22, varying with the frequency of the high-frequency current flowing in the main power receiver coil 110a. The high-frequency current flowing through the power transmitter coil 22 is supplied to the AC power source 15 via the power-transmitter resonant circuit 30, the filter circuit 52, the inverter 60 and the PFC circuit 61. In this case, the power-transmitter controller 71 controls the switching of the inverter 60 and the PFC circuit 61.

[0133] In the wireless power transfer system having the second function, for example, the power transmitter 20 may include a signal transmitter that supplies a power supply request signal to the power-transmitter communication coil 40. Furthermore, the power receiver 100 may include a signal receiver that receives the power supply request signal received by the power-receiver communication coil 170 and inputs the information to the power-receiver controller 231.

[0134] The wireless power transfer system of the above embodiments may have the function of wirelessly supplying power from the vehicle-side device to the ground-side device, instead of the function of wirelessly supplying power from the ground-side device to the vehicle-side device.

[0135] In the above embodiments, the power-receiver communication antenna and the power-transmitter communication antenna are not limited to communication coils, and may employ various antennas. For example, the communication antenna is a dipole antenna or a monopole antenna.

[0136] In the above embodiments, the vehicle on which the power receiver 100 is mounted is not limited to a vehicle traveling on the road RS, but may be, for example, an AGV (Automated Guided Vehicle) or a traveling robot. In this case, the power-transmitter coil unit 21 is not buried in the road RS, but may be installed on a sidewalk adjacent to the road RS, in a parking lot, or in the path along which the AGV travels.

[0137] While the present disclosure has been described with reference to various exemplary embodiments thereof, it is to be understood that the disclosure is not limited to the disclosed embodiments and constructions. To the contrary, the disclosure is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the disclosure are shown in various combinations and configurations, which are exemplary, other various combinations and configurations, including more, less or only a single element, are also within the spirit of the disclosure.

Claims

A power receiver (100) comprising:a power receiving antenna (110a) configured to receive power wirelessly transmitted from a power transmitting antenna (22) of a power transmitter (20), the power receiving antenna being configured to supply the power received from the power transmitting antenna to a power supply target device (300);a protection circuit (200) configured to short one of paths from the power receiving antenna to the power supply target device to cut off power supply from the power receiving antenna to the power supply target device;a short-circuit control unit (360, 401) configured to control the protection circuit; anda power converter (110b, 362) configured to receive, convert, and output a portion of the power transmitted from the power transmitting antenna during the power receiving antenna receiving the power from the power transmitting antenna, whereinthe short-circuit control unit is connected to an operating power source (302) via a power switch (370, 470), and configured to receive operating power supplied from the operating power source when the power switch is turned on,the short-circuit control unit is connected to the power converter, and configured to receive operating power output from the power converter, andthe short-circuit control unit is configured to control the protection circuit to perform short-circuit control to cut off the power supply to the power supply target device when operating power from the power converter is supplied to the short-circuit control unit and operating power from the operating power source is not being supplied to the short-circuit control unit.The power receiver according to claim 1, further comprisinga determination unit (361, 402) configured to determine whether operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit, whereinthe determination unit is configured to turn on the power switch to supply the operating power from the operating power source to the short-circuit control unit and continue the short-circuit control when the determination unit determines that operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit.The power receiver according to claim 1, whereinthe operating power source is connected to an anode side of a first diode (D11, D21) via the power switch,the power converter is connected to an anode side of a second diode (D12, D22),a cathode of the first diode is connected to a cathode of the second diode,the short-circuit control unit is connected to a connection point (P11, P12) provided on an electrical path connecting the cathode of the first diode and the cathode of the second diode,a voltage applied from the operating power source is higher than a voltage applied from the power converter,the power receiver further comprises a determination unit (361, 402) configured tocompare a first voltage (V11) on the anode side of the first diode with a second voltage (V12) on the anode side of the second diode, anddetermine, when the second voltage is higher than the first voltage, that operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit, andthe determination unit is configured to turn on the power switch to supply the operating power from the operating power source to the short-circuit control unit and continue the short-circuit control when the determination unit determines that operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit.The power receiver according to any one of claims 1 to 3, further comprisinga communication unit (400) configured to transmit a power supply stop signal to command the power transmitter to stop power transmission, whereinthe communication unit is configured to transmit the power supply stop signal when operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit.The power receiver according to claim 4, whereinthe communication unit includes a wireless communication antenna (170) for narrow area wireless communication, andthe communication unit is configured to transmit the power supply stop signal using the wireless communication antenna by narrow area wireless communication.The power receiver according to claim 4 or 5, whereinthe communication unit is configured to transmit the power supply stop signal by using a wide area wireless communication device.The power receiver according to any one of claims 1 to 6, further comprisingan abnormality determination unit configured to determine an abnormality in the power receiver, whereinthe short-circuit control unit is configured to perform the short-circuit control when the abnormality determination unit determines that an abnormality has occurred in the power receiver in a state where the power switch is on and operating power is being supplied from the operating power source to the short-circuit control unit.The power receiver according to any one of claims 1 to 7, whereinthe short-circuit control unit is a short-circuit control circuit configured cause the protection circuit to perform the short-circuit control when the short-circuit control circuit receives operating power.The power receiver according to any one of claims 1 to 8, further comprisinga cooling unit (390) configured to cool the power receiving antenna based on receiving of power supply from the power converter when operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit.A power receiver (100) comprising:a power receiving antenna (110a) configured to receive power wirelessly transmitted from a power transmitting antenna (22) of a power transmitter (20), the power receiving antenna being configured to supply the power received from the power transmitting antenna to a power supply target device (300);a protection circuit (200) configured to short one of paths from the power receiving antenna to the power supply target device to cut off power supply from the power receiving antenna to the power supply target device;a short-circuit control unit (360, 401) configured to control the protection circuit; anda power converter (110b, 362) configured to receive, convert, and output a portion of the power transmitted from the power transmitting antenna during the power receiving antenna receiving the power from the power transmitting antenna, whereinthe short-circuit control unit is connected to an operating power source (302) via a power switch (370, 470), and configured to receive operating power supplied from the operating power source when the power switch is turned on,the short-circuit control unit is connected to the power converter, and configured to receive operating power output from the power converter,the power receiver further comprises a determination unit (361, 402) configured to determine whether operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit, andthe determination unit is configured to determine that an abnormality has occurred when the determination unit determines that operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit.The power receiver according to claim 10, whereinthe short-circuit control unit is configured to control the protection circuit to perform short-circuit control to cut off the power supply to the power supply target device when the determination unit determines that an abnormality has occurred.The power receiver according to claim 10 or 11, further comprisinga communication unit (400) configured to transmit a power supply stop signal to command the power transmitter to stop power transmission, whereinthe communication unit is configured to transmit the power supply stop signal when the determination unit determines that an abnormality has occurred.A power receiver (100) comprising:a power receiving antenna (110a) configured to receive power wirelessly transmitted from a power transmitting antenna (22) of a power transmitter (20), the power receiving antenna being configured to supply the power received from the power transmitting antenna to a power supply target device (300);a protection circuit (200) configured to short one of paths from the power receiving antenna to the power supply target device to cut off power supply from the power receiving antenna to the power supply target device;a short-circuit control unit (360, 401) configured to control the protection circuit;a power converter (110b, 362) configured to receive, convert, and output a portion of the power transmitted from the power transmitting antenna during the power receiving antenna receiving the power from the power transmitting antenna; anda communication unit (400) configured to transmit a power supply stop signal to command the power transmitter to stop power transmission, whereinthe short-circuit control unit is connected to an operating power source (302) via a power switch (370, 470), and configured to receive operating power supplied from the operating power source when the power switch is turned on,the short-circuit control unit is connected to the power converter, and configured to receive operating power output from the power converter, andthe communication unit is configured to transmit the power supply stop signal when operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit.A wireless power transfer system (10) comprising:a power transmitter (20) having a power transmitting antenna (22); anda power receiver (100) having a power receiving antenna (110a), whereinthe power transmitting antenna is configured to wirelessly transfer power to the power receiving antenna,the power receiving antenna is configured to supply the power received from the power transmitting antenna to a power supply target device (300),the power receiver includesa protection circuit (200) configured to short one of paths from the power receiving antenna to the power supply target device to cut off power supply from the power receiving antenna to the power supply target device,a short-circuit control unit (360, 401) configured to control the protection circuit, anda power converter (110b, 362) configured to receive, convert, and output a portion of the power transmitted from the power transmitting antenna during the power receiving antenna receiving the power from the power transmitting antenna,the short-circuit control unit is connected to an operating power source (302) via a power switch (370, 470), and configured to receive operating power supplied from the operating power source when the power switch is turned on,the short-circuit control unit is connected to the power converter, and configured to receive operating power output from the power converter, andthe short-circuit control unit is configured to control the protection circuit to perform short-circuit control to cut off the power supply to the power supply target device when operating power from the power converter is supplied to the short-circuit control unit and operating power from the operating power source is not being supplied to the short-circuit control unit.A wireless power transfer system (10) comprising:a power transmitter (20) having a power transmitting antenna (22); anda power receiver (100) having a power receiving antenna (110a), whereinthe power transmitting antenna is configured to wirelessly transfer power to the power receiving antenna,the power receiving antenna is configured to supply the power received from the power transmitting antenna to a power supply target device (300),the power receiver includesa protection circuit (200) configured to short one of paths from the power receiving antenna to the power supply target device to cut off power supply from the power receiving antenna to the power supply target device,a short-circuit control unit (360, 401) configured to control the protection circuit, anda power converter (110b, 362) configured to receive, convert, and output a portion of the power transmitted from the power transmitting antenna during the power receiving antenna receiving the power from the power transmitting antenna,the short-circuit control unit is connected to an operating power source (302) via a power switch (370, 470), and configured to receive operating power supplied from the operating power source when the power switch is turned on,the short-circuit control unit is connected to the power converter, and configured to receive operating power output from the power converter,the power receiver further comprises a determination unit (361, 402) configured to determine whether operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit, andthe determination unit is configured to determine that an abnormality has occurred when the determination unit determines that operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit.A wireless power transfer system (10) comprising:a power transmitter (20) having a power transmitting antenna (22); anda power receiver (100) having a power receiving antenna (110a), whereinthe power transmitting antenna is configured to wirelessly transfer power to the power receiving antenna,the power receiving antenna is configured to supply the power received from the power transmitting antenna to a power supply target device (300),the power receiver includesa protection circuit (200) configured to short one of paths from the power receiving antenna to the power supply target device to cut off power supply from the power receiving antenna to the power supply target device,a short-circuit control unit (360, 401) configured to control the protection circuit,a power converter (110b, 362) configured to receive, convert, and output a portion of the power transmitted from the power transmitting antenna during the power receiving antenna receiving the power from the power transmitting antenna, anda communication unit (400) is configured to transmit a power supply stop signal to command the power transmitter to stop power transmission,the short-circuit control unit is connected to an operating power source (302) via a power switch (370, 470), and configured to receive operating power supplied from the operating power source when the power switch is turned on,the short-circuit control unit is connected to the power converter, and configured to receive operating power output from the power converter,the communication unit is configured to transmit the power supply stop signal when operating power from the operating power source is not being supplied to the short-circuit control unit and operating power from the power converter is being supplied to the short-circuit control unit, andthe power transmitter is configured to stop power transmission when the power transmitter receives the power supply stop signal.

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