Power receiver, program, control method for power receiver, and power transmitter

Abstract

A power-transmitter control unit (70) energizes a power transmitter coil (22) when determining that there is a power supply request based on an output signal of a power-transmitter communication coil (40), and stop energization of the power transmitter coil when determining that there is no power supply request. The power-transmitter control unit stops energization of the power transmitter coil when determining that a stop request signal is input based on the output signal of the power-transmitter communication coil. The stop request signal is a signal requesting for stop of power supply from a power transmitter coil (22) to a power receiver coil (102). The power-receiver control unit (230) supplies the stop request signal to a power-receiver communication coil (170) when determining that a start condition is satisfied.

Description

POWER RECEIVER, PROGRAM, CONTROL METHOD FOR POWER RECEIVER, AND POWER TRANSMITTERCross Reference

[0001] This application is based on Japanese Patent Application No. 2024-208025 filed on November 29, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a power receiver, a program, a control method for a power receiver, and a power transmitter.

[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 antennas for narrow area wireless communication. The power receiver supplies a power supply request signal to a power-receiver communication antenna of the power receiver. The power transmitter determines whether there is a power supply request based on an output signal from a power-transmitter communication antenna of the power transmitter. When the power transmitter determines that there is a power supply request, the power transmitter energizes the power transmitter coil. On the other hand, when the power transmitter determines that there is no power supply request, the power transmitter stops energization of the power transmitter coil.

[0005] JP 2024-008088 A

[0006] Herein, in some cases, the intensity of the power supply request signal supplied to the power-receiver communication antenna of the vehicle becomes excessively large, and a communication range of the power supply request signal transmitted from the vehicle may be excessively expanded.

[0007] In this case, even though no power supply request signal is supplied to the power-receiver communication antenna, a nearby power transmitter coil in another vehicle near the vehicle with the excessively expanded communication range may be energized. As a result, the power transmitter coil may transmit power to the power receiver coil of the vehicle even though there is no power supply request from the vehicle. Such a problem may also occur when the power transmitter is a vehicle-side device and the power receiver is a ground-side device.

[0008] It is a main objective of the present disclosure is to provide a power receiver, a program, a control method for a power receiver, and a power transmitter, which are capable of suppressing an occurrence of a situation in which power is transmitted from a nearby power transmitting antenna to a power receiving antenna of the power receiver even when there is no power supply request from the power receiver.

[0009] According to an aspect of the present disclosure, a power receiver is applied to a wireless power transfer system. The system includes a ground-side device and a vehicle-side device. One of the ground-side device and the vehicle-side device is a power transmitter having a power transmitting antenna. The other of the ground-side device and the vehicle-side device is the power receiver having a power receiving antenna. The power receiver is configured to transmit a power supply request signal for a power supply request to the power transmitter. The power transmitter is configured to energize the power transmitting antenna to perform wireless power transfer to the power receiving antenna on condition that the power transmitter determines that there is the power supply request based on the received power supply request signal. The power receiver includes a power-receiver communication antenna and a power-receiver control unit. The power-receiver communication antenna is configured to wirelessly transmit the power supply request signal to a power-transmitter communication antenna provided in the power transmitter. The power-receiver control unit is configured to control energization of the power-receiver communication antenna to supply the power supply request signal to the power-receiver communication antenna. The power transmitter is configured to stop energization of the power transmitting antenna when determining, based on an output signal of the power-transmitter communication antenna, that a stop request signal for requesting stop of power supply from the power transmitting antenna to the power receiving antenna has been input. The power-receiver control unit is configured to supply the stop request signal to the power-receiver communication antenna when a transmission start condition for starting transmission of the stop request signal is satisfied.

[0010] When the stop request signal is input from the power-receiver communication antenna to the power-transmitter control unit via the power-transmitter communication antenna, energization of the power transmitting antenna is stopped. Accordingly, it is possible to reduce an occurrence of a situation in which power is transmitted from the power transmitting antenna present near the power receiver, in which there is no power supply request, to the power receiving antenna of the power receiver.

[0011] 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 a power-receiver control unit and its peripheral configuration.FIG. 5 is a flowchart showing a transmission process of a power supply request signal executed by the power receiver.FIG. 6 is a diagram showing a state in which erroneous power supply occurs due to a vehicle with an expanded communication range.FIG. 7 is a flowchart of a transmission process of a stop request signal, executed by the power receiver.FIG. 8 is a flowchart of a power transmitter coil energization control process executed by the power transmitter.FIG. 9 is a flowchart of a transmission process of a stop request signal, executed by a power receiver according to a second embodiment.FIG. 10 is a diagram illustrating a signal transmitter and its peripheral configuration, according to a third embodiment.FIG. 11 is a flowchart of a diagnostic process for a signal-transmitting function, executed by a power receiver.FIG. 12 is a diagram illustrating a signal transmitter and its peripheral configuration, according to a modification of the third embodiment.FIG. 13 is a diagram illustrating a signal transmitter and its peripheral configuration, according to a modification of the third embodiment.FIG. 14 is a diagram illustrating a signal receiver and its peripheral configuration, according to a fourth embodiment.FIG. 15 is a flowchart of a diagnostic process for a signal-receiving function, executed by a power transmitter.FIG. 16 is a diagram illustrating a signal receiver and its peripheral configuration, according to a fifth embodiment.FIG. 17 is a diagram illustrating a signal receiver and its peripheral configuration, according to a sixth embodiment.

[0012] 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.

[0013] First Embodiment A first embodiment of a wireless power transfer system of the present disclosure will be described below with reference to the drawings.

[0014] First, an overall configuration of the wireless power transfer system will be described. As shown in FIGS. 1, 2, and 3, 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.

[0015] 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, and 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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. The power-transmitter resonant circuit 30 can employ various well-known resonant circuits such as a circuit including a resonant capacitor.

[0021] 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 102 (corresponding to a "power receiving antenna"). 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 102 of the vehicle 11 face each other in the vertical direction.

[0022] The power receiver 100 includes a power-receiver resonant circuit 140. The power receiver coil 102 is connected to the power-receiver resonant circuit 140. The power receiver coil 102 is supplied with power from the power transmitter coil 22. The power receiver coil 102 supplies the received power to the power-receiver resonant circuit 140. The power-receiver resonant circuit 140 can employ various well-known resonant circuits such as a circuit including a resonant capacitor.

[0023] The power receiver 100 includes a filter circuit 182, a rectifier circuit 200 that functions as a DC-AC conversion circuit, and a smoothing capacitor 210. The filter circuit 182 removes noise contained in the AC current input from the power-receiver resonant circuit 140 and supplies the AC current from which noise has been removed to the rectifier circuit 200. The filter circuit 182 of the present embodiment is, for example, an LC filter that includes reactor and a capacitor.

[0024] The rectifier circuit 200 converts the input AC current into a DC current and outputs the DC current. The rectifier circuit 200 is, for example, a full-bridge circuit including semiconductor switching elements, or a diode rectifier circuit. A first end of the smoothing capacitor 210 is connected to a high potential side output terminal of the rectifier circuit 200. A second end of the smoothing capacitor 210 is connected to a low potential side output terminal of the rectifier circuit 200. The rectifier circuit 200 is also referred to as an ERB (Electronic Rectification Box).

[0025] The vehicle 11 includes a high potential main switch 301H, a low potential main switch 301L, and a high-voltage storage battery 300 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). The high potential side output terminal of the rectifier circuit 200 is connected to a positive terminal of the high-voltage storage battery 300 via the high potential main switch 301H. The low potential side output terminal of the rectifier circuit 200 is connected to a negative terminal of the high-voltage storage battery 300 via the 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.

[0026] 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.

[0027] 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.

[0028] 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 the processes described below.

[0029] The power-receiver power supply unit 181, which constitutes the power receiver 100, includes a power-receiver controller 231. The power-receiver controller 231 is an ECU that executes various controls of the power receiver 100, and includes a processor as hardware, a storage unit, and a communication bus that connects the processor and storage unit.

[0030] 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-receiver controller 231. 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 the processes described below.

[0031] For example, the program information stored on the non-transitory tangible storage medium is installed in the storage units of the power-receiver controller 231 and power-transmitter controller 71. 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.

[0032] 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.

[0033] 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.

[0034] When the magnetic field generated in the power transmitter coil 22 links with the power receiver coil 102 of the vehicle 11, a high-frequency current flows in the power receiver coil 102, varying with the frequency of the high-frequency current flowing in the power transmitter coil 22. The high-frequency current flowing in the power receiver coil 102 is supplied to the rectifier circuit 200 through the power-receiver resonant circuit 140 and the filter circuit 182. The rectifier circuit 200 converts the supplied AC current into a DC current and outputs the DC current. 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 and the travelling inverter 310.

[0035] The vehicle 11 includes a low-voltage storage battery 302. The rated voltage of the low-voltage storage battery 302 is lower than the rated voltage of the high-voltage storage battery 300. 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.

[0036] The power receiver 100 includes a voltage sensor 330, a current sensor 340, and an intensity sensor 350 (corresponding to an "intensity detection unit"). The voltage sensor 330 detects voltages of various in-vehicle devices of the vehicle 11 (specifically, components of the power receiver 100), for example, a voltage of the smoothing capacitor 210. The current sensor 340 detects currents flowing in various in-vehicle devices of the vehicle 11 (specifically, the components of the power receiver 100), for example, currents flowing in the power receiver coil 102 and the rectifier circuit 200. The intensity sensor 350 detects an intensity of signal transmitted from another vehicle present around the vehicle 11 via narrow area wireless communication. The intensity sensor 350 can be a variety of sensors, such as, for example, a magnetoresistive sensor or a Hall effect sensor. The detected values of the sensors 330, 340, 350 are input to the power-receiver controller 231.

[0037] 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 (corresponding to a power-receiver communication antenna). A power-receiver control unit 230 includes a signal transmitter 240.

[0038] The power-transmitter coil unit 21, which constitutes the power transmitter 20, includes a power-transmitter communication coil 40 (corresponding to a power-transmitter communication antenna). 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 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 3 meters). Narrow area wireless communication is a communication with a shorter communication distance than wide area wireless communication.

[0039] 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.

[0040] 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. The power-receiver controller 231 controls the signal transmitter 240 to supply a power supply request signal COMM to the power-receiver communication coil 170. The power supply request signal COMM is a signal requesting the power transmitter coil 22 near the vehicle 11 to transmit power to the power receiver coil 102.

[0041] The power-receiver control unit 230 controls the signal transmitter 240 to supply a vehicle-side signal including a power supply request signal COMM in one frame to 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 voltage to be applied 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.

[0042] When the power-receiver coil unit 101 of the vehicle 11 approaches the power-transmitter coil unit 21 on the ground side, the magnetic field generated by the power-receiver communication coil 170 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 shown in FIG. 3. 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 requested 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.

[0043] 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).

[0044] The power-transmitter controller 71 determines whether to energize the power transmitter coil 22 based on the input signal from the signal receiver 80. In detail, when the power-transmitter controller 71 determines that there is a power supply request based on the input signal from the signal receiver 80, the power-transmitter controller 71 applies high-frequency voltage to the power transmitter coil 22 by performing switching control of the inverter 60 and the PFC circuit 61. This results in a wireless power transfer from the power transmitter coil 22 to the power receiver coil 102. In addition, when the power-transmitter controller 71 determines that there is a power supply request, it actually performs a coupling determination process prior to executing the switching control of the inverter 60 and the PFC circuit 61 to determine whether the degree of magnetic coupling between the power receiver coil 102 and the power transmitter coil 22 is appropriate for power transmission. The power-transmitter controller 71 executes the switching control of the inverter 60 and the PFC circuit 61 on condition that the power-transmitter controller 71 has determined that the degree of magnetic coupling between the power receiver coil 102 and the power transmitter coil 22 is appropriate. As a result, the power transmitter coil 22 is energized while the power receiver coil 102 and the power transmitter coil 22 are in close proximity to each other.

[0045] The signal transmitter 240 and its peripheral configuration will be described with reference to FIG. 4.

[0046] The signal transmitter 240 includes a generating circuit 241, and a power-receiver amplifier 242. The generating circuit 241 is connected to the power-receiver controller 231 and the power-receiver amplifier 242. The generating circuit 241 generates a vehicle-side signal, which is a high-frequency signal including a power supply request signal, based on a command from the power-receiver controller 231. The frequency of the vehicle-side signal is the second specified frequency. The power-receiver amplifier 242 amplifies the high-frequency signal generated by the generating circuit 241 and supplies the amplified signal to the power-receiver communication coil 170.

[0047] The power-receiver controller 231 instructs the generating circuit 241 to generate a vehicle-side signal. The high-frequency signal output from the generating circuit 241 is amplified by the power-receiver amplifier 242. The amplified signal is supplied to the power-receiver communication coil 170.

[0048] FIG. 5 shows a flowchart of a transmission process of the power supply request signal executed by the power receiver 100.

[0049] In step S10, the power-receiver controller 231 determines whether there is a power supply request. When determining that there is the power supply request, the process proceeds to step S11 in which the power-receiver controller 231 instructs the generating circuit 241 to generate a vehicle-side signal including a power supply request signal. As a result, the vehicle-side signal from the generating circuit 241 is input to the power-receiver amplifier 242. The power-receiver amplifier 242 amplifies the input vehicle-side signal and supplies the amplified signal to the power-receiver communication coil 170.

[0050] On the other hand, when determining that there is no power supply request, the process proceeds to step S12, in which the power-receiver controller 231 instructs the generating circuit 241 to stop generating the vehicle-side signal. This causes the generating circuit 241 to stop outputting the vehicle-side signal. As a result, the supply of the vehicle-side signal to the power-receiver communication coil 170 is stopped.

[0051] Returning to FIG. 3, the signal receiver 80 amplifies the high-frequency signal (high-frequency current or voltage signal) output from the power-transmitter communication coil 40. The high-frequency signal output from the power-transmitter communication coil 40 contains a frequency component that fluctuates at the second specified frequency.

[0052] Based on the high-frequency signal input from the power-transmitter amplifier 81, the signal receiver 80 calculates an intensity Intd which is an amplitude or effective value of the input high-frequency signal. The signal receiver 80 determines whether there is a power supply request to the power transmitter coil 22 based on the calculated intensity Intd. Specifically, when determining that the intensity Intd exceeds a determination threshold Ijde, the signal receiver 80 determines that there is the power supply request. On the other hand, when determining that the intensity Intd is lower than the determination threshold Ijde, the signal receiver 80 determines that there is no power supply request. The determination result information of the signal receiver 80 is input to the power-transmitter controller 71.

[0053] When the power-transmitter controller 71 determines that there is no power supply request based on the input determination result information, the power-transmitter controller 71 stops the switching control of the PFC circuit 61 and the inverter 60. As a result, no current is applied to the power transmitter coil 22.

[0054] On the other hand, when determining that there is a power supply request based on the determination result information, the power-transmitter controller 71 applies a high frequency voltage to the power transmitter coil 22 by performing switching control of the PFC circuit 61 and the inverter 60. This causes a high-frequency current to flow through the power transmitter coil 22. In this case, wireless power transfer from the power transmitter coil 22 to the power receiver coil 102 that faces the power transmitter coil 22 in the vertical direction is performed.

[0055] Herein, in some cases, the intensity of the power supply request signal supplied to the power-receiver communication coil 170 of the vehicle may become excessively large, and a communication range of the power supply request signal transmitted from the vehicle may be excessively expanded. In FIG. 6, the reference numeral 500 indicates a vehicle with an excessively expanded communication range.

[0056] In another vehicle 11 present near the vehicle 500 with the excessively expanded communication range, the power-transmitter communication coil 40 present nearby would receive the power supply request signal, even though the power supply request signal is not supplied to the power-receiver communication coil 170. As a result, the nearby power transmitter coil 22 is energized, and power is transmitted from the power transmitter coil 22 to the power receiver coil 102 of the vehicle 11, even though there is no power supply request from the vehicle 11.

[0057] In addition to the case where the vehicle 500 with the expanded communication range and the other vehicle 11 are stopped, this issue may occur in a case where the vehicle 500 with the expanded communication range and the other vehicle 11 are traveling, and the relative speed between the vehicle 500 with the extended communication range and the other vehicle 11 is close to zero.

[0058] In order to address such issues, the power-receiver control unit 230 supplies a stop request signal STOPCOMM to the power-receiver communication coil 170, when determining that a transmission start condition for the stop request signal is satisfied. The stop request signal is a signal requesting a stop of power supply from the power transmitter coil 22 to the power receiver coil 102. The power-transmitter control unit 70 stops energization of the power transmitter coil 22, when determining that the stop request signal has been input based on the output signal of the power-transmitter communication coil 40.

[0059] FIG. 7 is a flowchart of a transmission process for the stop request signal executed by the power-receiver control unit 230.

[0060] In step S20, the power-receiver controller 231 determines whether the transmission start condition is satisfied. The transmission start condition is a condition for detecting the presence of the vehicle 500 with the excessively expanded communication range around the vehicle 11. The transmission start condition is, for example, any one of the following conditions (A1) to (A4).

[0061] A condition (A1) is a condition that the power-receiver controller 231 determines that the vehicle 11 has switched from a state where there is a power supply request to a state where there is no power supply request. That is, in the process of FIG. 5, the condition (A1) is satisfied when a state where the determination in step S10 is affirmative is switched to a state where the determination is negative. According to the condition (A1), when there is no power supply request from the vehicle 11, energization of the power transmitter coil 22 present near the vehicle 11 is stopped.

[0062] A condition (A2) is a condition that there is no power supply request from the vehicle 11 and a current is flowing through the power receiver coil 102. The state in which a current flows through the power receiver coil 102 even though there is no power supply request from the vehicle 11 is a state where there is a high possibility that the vehicle 500, with the excessively expanded communication range for the power supply request signal, is present nearby. The transmission start condition (A2) allows for an accurate determination of such a state. It may be determined whether a current flows through the power receiver coil 102 based on, for example, a current value of the power receiver coil 102 or the rectifier circuit 200 detected by the current sensor 340, or a voltage value of the power receiver coil 102 or the rectifier circuit 200 detected by the voltage sensor 330.

[0063] A condition (A3) is a condition that an intensity ILoud detected by the intensity sensor 350 exceeds an intensity threshold ILth. A state in which the intensity ILoud detected by the intensity sensor 350 becomes excessively large and exceeds the intensity threshold ILth is a state in which there is a high possibility that the vehicle 500 with the excessively expanded communication range for the power supply request signal is present nearby. The transmission start condition (A3) allows accurate determination of such a state. The intensity threshold ILth is, for example, a value larger than the determination threshold Ijde.

[0064] A condition (A4) is a condition that the intensity ILoud detected by the intensity sensor 350 exceeds the intensity threshold ILth and there is no power supply request in the vehicle 11. The transmission start condition (A4) allows more accurate determination that the vehicle 500 with the excessively expanded communication range is highly likely to be present near the vehicle 11.

[0065] When determining in step S20 that the transmission start condition is satisfied, the process proceeds to step S21 in which the power-receiver controller 231 instructs the generating circuit 241 to generate the stop request signal, which is a high-frequency signal. As a result, the stop request signal generated by the generating circuit 241 is input to the power-receiver amplifier 242. The stop request signal amplified by the power-receiver amplifier 242 is supplied to the power-receiver communication coil 170. This causes the power-receiver communication coil 170 to transmit the stop request signal.

[0066] Regardless of the result of the determination of the presence or absence of the power supply request in the process of FIG. 5, when determining that the transmission start condition is satisfied, the power-receiver controller 231 instructs the generating circuit 241 to stop generating the power supply request signal.

[0067] The stop request signal is a signal different from the power supply request signal.

[0068] For example, the stop request signal is a signal having a greater intensity than the power supply request signal. A large intensity means that the amplitude or effective value of the signal is large. In this case, the frequency of the stop request signal may be, for example, the same as the frequency of the power supply request signal.

[0069] For example, the stop request signal is a signal having a different bit length from the power supply request signal. In this case, the frequency of the stop request signal may be, for example, the same as the frequency of the power supply request signal. For example, the stop request signal is a signal having a different frequency from the power supply request signal.

[0070] The stop request signal may be, for example, a signal having a greater intensity than the power supply request signal and a different frequency than the power supply request signal, a signal having a greater intensity than the power supply request signal and a different bit length than the power supply request signal, or a signal having a different frequency than the power supply request signal and a different bit length than the power supply request signal.

[0071] Such stop request signal allows the power-transmitter control unit 70 to appropriately distinguish between the power supply request signal and the stop request signal.

[0072] When the stop request signal is a signal having a different bit length from the power supply request signal, the stop request signal may be a signal having a shorter bit length than the power supply request signal. Therefore, an energization stop request to the power transmitter coil 22 can be notified to the power-transmitter control unit 70 as early as possible.

[0073] When determining in step S20 that the transmission start condition is not satisfied, the process proceeds to step S22 where the power-receiver controller 231 instructs the generating circuit 241 to stop generating the stop request signal, and the process proceeds to step S20. As a result, the generating circuit 241 does not output the stop request signal.

[0074] After completing step S21, in step S23, the power-receiver controller 231 determines whether a stop condition for stopping the transmission of the stop request signal is satisfied.

[0075] For example, when the transmission start condition is the condition (A1), the stop condition may be a condition that a state where there is no power supply request is switched to a state where there is a power supply request. That is, in the process of FIG. 5, the stop condition is satisfied when a state where the determination in step S10 is negative is switched to a state where the determination is affirmative.

[0076] For example, when the transmission start condition is the condition (A2), the stop condition may be a condition that a current no longer flows through the power receiver coil 102. It may be determined whether a current flows through the power receiver coil 102 based on, for example, a current value of the power receiver coil 102 or the rectifier circuit 200 detected by the current sensor 340, or a voltage value of the power receiver coil 102 or the rectifier circuit 200 detected by the voltage sensor 330.

[0077] For example, when the transmission start condition is the condition (A3) or (A4), the stop condition may be a condition that the intensity ILoud detected by the intensity sensor 350 is lower than the intensity threshold ILth. Accordingly, supply of the stop request signal can be stopped when the narrow area wireless communication of the vehicle 500 with the excessively expanded communication range no longer reaches the vehicle 11.

[0078] When it is determined in step S23 that the stop condition is satisfied, the process proceeds to step S24 where the power-receiver controller 231 instructs the generating circuit 241 to stop generating the stop request signal. When determination in step S23 is affirmative in a state where there is the power supply request in the process shown in the flowchart of FIG. 5, the power-receiver controller 231 instructs the generating circuit 241 to start generating the power supply request signal.

[0079] FIG. 8 is a flowchart of an energization control process for the power transmitter coil 22, executed by the power-transmitter control unit 70.

[0080] In step S30, the power-transmitter controller 71 acquires determination result of whether there is the power supply request from the signal receiver 80. The power-transmitter controller 71 determines whether there is the power supply request based on the determination result.

[0081] In step S30, when the power-transmitter controller 71 determines that there is the power supply request, the process proceeds to step S31. In step S31, the power-transmitter controller 71 acquires from the signal receiver 80 the determination result of whether the stop request signal has been received. The signal receiver 80 determines whether the stop request signal has been received based on the high-frequency signal input from the power-transmitter amplifier 81.

[0082] When determining in step S31 that the stop request signal has not been received, the process proceeds to step S32 where the power-transmitter controller 71 sets a flag F to 0. In the following step S33, the power-transmitter controller 71 performs the switching control of the inverter 60 and the PFC circuit 61 to energize the power transmitter coil 22.

[0083] On the other hand, when determining in step S31 that the stop request signal has been received, the process proceeds to step S34 where the power-transmitter controller 71 sets the flag F to 1. In the following step S35, the power-transmitter controller 71 stops the switching control of the inverter 60 and the PFC circuit 61 to stop energization of the power transmitter coil 22. The power-transmitter controller 71 executes the process of step S35 also when determination in step S30 is negative.

[0084] When the stop request signal is a signal having a different frequency from the power supply request signal, a carrier frequency and a modulation frequency for generating the stop request signal may be different from each other. In digital communication using a subcarrier, for example, in a case where the modulation frequency is normally set to 3.3 kHz, the power-transmitter control unit 70 may determine that the stop request signal has been received, when a modulation frequency of 1 kHz has been received by the power-transmitter control unit 70.

[0085] In step S36, the power-transmitter controller 71 determines whether the flag F is 1. When determining that the flag F is 0, the power-transmitter controller 71 determines that the stop request signal has not been received, and the process proceeds to step S30.

[0086] On the other hand, when determining that the flag F is 1, the power-transmitter controller 71 determines that the stop request signal has been received, and the process proceeds to step S37. In step S37, the power-transmitter controller 71 determines whether a release condition for releasing energization stop of the power transmitter coil 22 is satisfied. The release condition is, for example, the following condition (B1) or (B2).

[0087] A condition (B1) is a condition in which it is determined that the stop request signal has not been received, and the intensity Intd of the power supply request signal is lower than a detection threshold Ith. The detection threshold Ith is a value for determining whether the vehicle 500 with the excessively expanded communication range is present near the vehicle 11, and is, for example, a value larger than the determination threshold Ijde. Specifically, for example, the detection threshold Ith is set to be in the range "2×Ijde ≦ Ith ≦ 3×Ijde". According to the release condition (B1), it is possible to accurately determine a state in which the likelihood of the vehicle 500, with the excessively expanded communication range for the power supply request signal, being present nearby has decreased.

[0088] A condition (B2) is a condition that a predetermined period has elapsed since it was determined that the stop request signal has not been received. The predetermined period is, for example, a period on the order of several seconds to several minutes. For example, the condition (B2) is used when the vehicle 11 is stopped.

[0089] When the power-transmitter controller 71 determines in step S37 that the release condition is not satisfied, the process proceeds to step S30. On the other hand, when the power-transmitter controller 71 determines that the release condition is satisfied, the process proceeds to step S38, and the power-transmitter controller 71 releases energization stop of the power transmitter coil 22. As a result, when determining that there is the power supply request, the power-transmitter controller 71 performs the switching control of the inverter 60 and the PFC circuit 61 to energize the power transmitter coil 22.

[0090] In the present embodiment described above, when the stop request signal is input from the power-receiver communication coil 170 to the power-transmitter control unit 70 via the power-transmitter communication coil 40, energization of the power transmitter coil 22 is stopped. Therefore, an occurrence of a situation in which power is transmitted from the power transmitter coil 22 present near the vehicle 11 to the power receiver coil 102 of the vehicle 11 even though there is no power supply request in the vehicle 11.

[0091] Second Embodiment A second embodiment will be described below with reference to the drawings mainly in terms of differences from the first embodiment. In this embodiment, as shown in FIG. 9, the transmission process of the stop request signal is modified. In addition, in step S20 of this embodiment, when it is determined that the above condition (A1) or (A2) is satisfied, the process of FIG. 7 is executed.

[0092] In step S20, when determining that the transmission start condition is satisfied, the process proceeds to step S25 where the power-receiver controller 231 determines whether there is the power supply request from the vehicle 11. When the power-receiver controller 231 determines that there is no power supply request, the process proceeds to step S22.

[0093] On the other hand, when determining that there is the power supply request, the process proceeds to step S26 where the power-receiver controller 231 determines whether a received power Wr of the power receiver coil exceeds the requested power Weq. The received power Wr of the power receiver coil 102 may be calculated, for example, based on the current value of the power receiver coil 102 or the rectifier circuit 200 detected by the current sensor 340, or the voltage value of the power receiver coil 102 or the rectifier circuit 200 detected by the voltage sensor 330.

[0094] When determining that the received power Wr is lower than the requested power Weq, the process proceeds to step S22 where the power-receiver controller 231 instructs the generating circuit 241 to stop generating the stop request signal. As a result, power is transmitted from the power transmitter coil 22 to the power receiver coil 102 of the vehicle 11 in response to the power supply request signal transmitted from the vehicle 11.

[0095] On the other hand, when determining that the received power Wr exceeds the requested power Weq, the process proceeds to step S21 where the power-receiver controller 231 instructs the generating circuit 241 to stop generating the power supply request signal and to start generating the stop request signal.

[0096] According to the present embodiment described above, when the vehicle 11 can accept the received power, wireless power transfer to the vehicle 11 can be continued, even when it is determined that the transmission start condition is satisfied.

[0097] Third Embodiment Hereinafter, the third embodiment will be described with reference to the drawings, focusing on the differences from the above-described embodiments. In this embodiment, the power-receiver control unit 230 acquires the intensity of the stop request signal transmitted from the power-receiver communication coil 170, and adjusts the transmission intensity of the stop request signal based on the acquired intensity.

[0098] First, the signal transmitter 240 and its peripheral configuration will be described with reference to FIG. 10.

[0099] The power-receiver coil unit 101 includes a detection antenna 401 as a signal detection unit. The detection antenna 401 of this embodiment is a detection coil that detects a magnetic field signal generated by the power-receiver communication coil 170 as a high-frequency voltage signal or high-frequency current signal. The detection signal of the detection antenna 401 is input to the power-receiver controller 231. The signal detection unit is not limited to a coil.

[0100] FIG. 11 is a flowchart illustrating a procedure of a diagnostic process for the signal-transmitting function of the power receiver 100. The process is executed by the power-receiver control unit 230.

[0101] In step S40, the power-receiver controller 231 determines whether an execution condition of the diagnostic process for the signal-transmitting function of the power receiver 100 is satisfied. The execution condition is, for example, that a specified period of time has elapsed since the previous diagnosis, or that a preset diagnosis time has arrived.

[0102] When it is determined that the execution condition is satisfied, the power-receiver controller 231 proceeds to step S41 and controls the signal transmitter 240 to supply a diagnostic signal from the power-receiver amplifier 242 to the power-receiver communication coil 170. The diagnostic signal is a stop request signal that fluctuates at the second specified frequency.

[0103] When a diagnostic signal is input to the power-receiver communication coil 170, a high-frequency current that fluctuates at the second specified frequency flows through the power-receiver communication coil 170. This causes a magnetic field to be generated in the power-receiver communication coil 170. When the generated magnetic field links with the detection antenna 401, a high-frequency current flows through the detection antenna 401. This high-frequency current is input to the power-receiver controller 231.

[0104] In step S42, the power-receiver controller 231 acquires the detection signal of the detection antenna 401, and calculates a diagnostic intensity Ir which is the amplitude or effective value of the output signal of the detection antenna 401 based on the acquired signal.

[0105] In step S43, the power-receiver controller 231 determines whether the calculated diagnostic intensity Ir is below a lower limit threshold ILlimit indicating an abnormality in the signal-transmitting function of the power receiver 100.

[0106] When a negative determination is made in step S43, the power-receiver controller 231 determines in step S46 whether the calculated diagnostic intensity Ir exceeds an upper limit threshold IHlimit indicating an abnormality in the signal-transmitting function of the power receiver 100. The upper threshold IHlimit is a value greater than the lower threshold ILlimit. The upper threshold IHlimit and the lower threshold ILlimit are values that are determined in advance by, for example, experiment or calculation.

[0107] When the power-receiver controller 231 makes a positive determination in step S43 or S46, the power-receiver controller 231 proceeds to step S44 and determines that an abnormality has occurred in the signal-transmitting function of the power receiver 100. The abnormality in the signal-transmitting function includes an abnormality in any one of the power-receiver communication coil 170, the power-receiver amplifier 242, or the generating circuit 241.

[0108] In step S45, the power-receiver controller 231 prevents energization of the power-receiver communication coil 170. As a result, a vehicle-side signal including a power supply request signal, and a stop request signal are not transmitted. Accordingly, the signal-transmitting function of the power receiver 100 can be prevented from being used continuously in an undesirable state.

[0109] When a negative determination is made in step S46, the power-receiver controller 231 proceeds to step S47. In step S47, the power-receiver controller 231 determines whether the calculated diagnostic intensity Ir is greater than an upper limit value IHth of an expected intensity range. The upper limit value IHth is lower than the upper limit threshold IHlimit and is greater than the lower limit threshold ILlimit (IHlimit > IHth > ILlimit).

[0110] When the power-receiver controller 231 determines in step S47 that the diagnostic intensity Ir is greater than the upper limit value IHth, the power-transmitter controller 71 proceeds to step S48. In step S48, the power-receiver controller 231 performs a process of decreasing the gain of the power-receiver amplifier 242. As a result, the transmission intensity of the stop request signal and the transmission intensity of the vehicle-side signal including the power supply request signal can be reduced.

[0111] When a negative determination is made in step S47, the power-receiver controller 231 proceeds to step S49. In step S49, the power-receiver controller 231 determines whether the calculated diagnostic intensity Ir is lower than a lower limit value ILth of the expected intensity range. The lower limit value ILth is lower than the upper limit value IHth and is greater than the lower threshold ILlimit (IHlimit > IHth > ILth > ILlimit).

[0112] When the power-receiver controller 231 determines in step S49 that the diagnostic intensity Ir is lower than the lower limit value ILth, the power-receiver controller 231 proceeds to step S50. In step S50, the power-receiver controller 231 performs a process of increasing the gain of the power-receiver amplifier 242. As a result, the transmission intensity of the stop request signal and the transmission intensity of the vehicle-side signal including the power supply request signal can be increased.

[0113] Due to deterioration of the power receiver 100 over time, the intensity of the transmission signal from the power receiver 100 may deviate from the expected intensity range. Even in this case, the processing in steps S48 and S50 can adjust the gain of the power-receiver amplifier 242 so that the intensity of the transmission signal falls within the expected intensity range.

[0114] Modification of Third Embodiment In the process of FIG. 11, the parameters described below can be used instead of the diagnostic intensity Ir.

[0115] (A) Instead of the diagnostic intensity Ir, the amplitude or effective value of the current flowing through the power-receiver communication coil 170 detected by the current sensor 340 may be used.

[0116] (B) Although not shown in FIG. 10, the signal transmitter 240 includes resonant capacitors 500 as shown in FIG. 12. The resonant capacitors 500 are connected in series to the power-receiver communication coil 170. The power-receiver communication coil 170 and the power-receiver amplifier 242 are connected via the resonant capacitors 500.

[0117] The signal transmitter 240 includes a capacitor voltage sensor 250 (corresponding to a "signal detection unit") that detects the voltage of a resonant capacitor 500 as a correlation value of the magnetic field signal generated by the power-receiver communication coil 170. When a high-frequency signal is output from the power-receiver amplifier 242 to the resonant capacitor 500, the frequency of the detection signal from the capacitor voltage sensor 250 is the second specified frequency. A detection signal from the capacitor voltage sensor 250 is input to the power-receiver controller 231.

[0118] In the process of FIG. 11, the amplitude or effective value of the detection signal of the capacitor voltage sensor 250 may be used instead of the diagnostic intensity Ir. The resonant capacitors 500 have a high-pass filter characteristic. Therefore, the detection signal of the voltage sensor 250 is a signal that contains relatively few noise frequency components other than the second specified frequency.

[0119] (C) As shown in FIG. 13, the power receiver 100 (for example, the power-receiver coil unit 101) includes a sub power receiver coil 103. In this embodiment, the power receiver coil 102 is referred to as a main power receiver coil 102.

[0120] The sub power receiver coil 103 is magnetically coupled to the main power receiver coil 102 and is capable of receiving power from the power transmitter coil 22 when the main power receiver coil 102 is receiving power from the power transmitter coil 22.

[0121] The power receiver 100 includes a conversion circuit 510, a first diode 511, a second diode 512, and a power switch 513. The input portion of the conversion circuit 510 is connected to the sub power receiver coil 103, and the output portion of the conversion circuit 510 is connected to the anode of the first diode 511. The conversion circuit 510 converts the AC current output from the sub power receiver coil 103 into a DC current and outputs it from the output portion. The direct current output from the output portion of the conversion circuit 510 is supplied to the power-receiver controller 231 via the first diode 511. The power-receiver controller 231 is connected to the low-voltage storage battery 302 via the second diode 512 and the power switch 513. For example, when the power switch 513 is turned off, the sub power receiver coil 103 and the conversion circuit 510 serve as a power source for the power-receiver controller 231.

[0122] The power receiver 100 includes a current sensor 252 as a signal detection unit that detects the output current of the conversion circuit 510. A detection signal from the current sensor 252 is input to the power-receiver controller 231.

[0123] In the process of FIG. 11, the amplitude or effective value of the detection signal of the current sensor 252 may be used instead of the diagnostic intensity Ir.

[0124] Fourth Embodiment Hereinafter, a fourth embodiment will be described with reference to the drawings, focusing on differences from the third embodiment. In this embodiment, the power transmitter 20 adjusts the reception intensity of the stop request signal.

[0125] First, the power-transmitter control unit 70 and its peripheral configuration will be described with reference to FIG. 14.

[0126] The signal receiver 80 includes a power-transmitter amplifier 81, a detection circuit 82 and a determination circuit 83. The power-transmitter amplifier 81 amplifies the high-frequency signal (high frequency current or voltage signal) output from the power-transmitter communication coil 40 and supplies the amplified signal to the detection circuit 82. The high-frequency signal output from the power-transmitter communication coil 40 contains a frequency component that fluctuates at the second specified frequency.

[0127] The detection circuit 82 detects the high-frequency signal input from the power-transmitter amplifier 81, and calculates an intensity Intd which is an amplitude or effective value of the input high-frequency signal. The calculated intensity Intd is input to the determination circuit 83.

[0128] The determination circuit 83 determines whether there is a power supply request to the power transmitter coil 22 based on the input intensity Intd. Specifically, when determining that the intensity Intd exceeds a determination threshold Ijde, the determination circuit 83 determines that there is a power supply request. On the other hand, when determining that the intensity Intd is lower than the determination threshold Ijde, the determination circuit 83 determines that there is no power supply request. The determination result information of the determination circuit 83 is input to the power-transmitter controller 71.

[0129] The power transmitter 20 has a configuration for diagnosing the signal-receiving function of the power transmitter 20.

[0130] The power-transmitter coil unit 21 includes a test communication coil 600 (corresponding to a "test communication antenna"). The test communication coil 600 is provided near the power-transmitter communication coil 40. The test communication coil 600 is a coil for performing wireless communication with the power-transmitter communication coil 40.

[0131] The power-transmitter control unit 70 includes a test transmission circuit 610 connected to the test communication coil 600. The test transmission circuit 610 receives a command from the power-transmitter controller 71 to supply the test communication coil 600 with a diagnostic stop request signal. The test transmission circuit 610 generates the diagnostic stop request signal that fluctuates at the second specified frequency and supplies the signal to the test communication coil 600. In this embodiment, the test communication coil 600 and the test transmission circuit 610 correspond to a "test signal transmitter."

[0132] When a diagnostic stop request signal is input to the test communication coil 600, a high-frequency current that fluctuates at the second specified frequency flows through the test communication coil 600. This causes a magnetic field to be generated in the test communication coil 600. When the generated magnetic field links with the power-transmitter communication coil 40, a high frequency current flows through the power-transmitter communication coil 40, similar to the case where a magnetic field from the power-receiver communication coil 170 links with the power-transmitter communication coil 40. This high-frequency current is input to the power-transmitter amplifier 81.

[0133] The high-frequency signal input to the power-transmitter amplifier 81 is amplified and input to the detection circuit 82. The detection circuit 82 detects the high-frequency signal input from the power-transmitter amplifier 81, and calculates a diagnostic intensity Itr, which is the intensity (specifically, for example, amplitude or effective value) of the received stop request signal. The calculated diagnostic intensity Itr is input to the power-transmitter controller 71. The power-transmitter controller 71 diagnoses the signal-receiving function of the power transmitter 20 based on the input diagnostic intensity Itr.

[0134] FIG. 15 is a flowchart illustrating a procedure of a diagnostic process for the signal-receiving function of the power transmitter 20. The process is executed by the power-transmitter control unit 70.

[0135] In step S60, the power-transmitter controller 71 determines whether an execution condition of the diagnostic process is satisfied. The execution condition is, for example, that a specified period of time has elapsed since the previous diagnosis, or that a preset diagnosis time has arrived.

[0136] In step S61, the power-transmitter controller 71 instructs the test transmission circuit 610 to supply a diagnostic stop request signal to the test communication coil 600.

[0137] In step S62, when the diagnostic stop request signal is being supplied to the test communication coil 600, the detection circuit 82 detects a high-frequency signal input from the power-transmitter amplifier 81, thereby calculating the diagnostic intensity Itr. The calculated diagnostic intensity Itr is input to the power-transmitter controller 71.

[0138] In step S63, the power-transmitter controller 71 determines whether the acquired diagnostic intensity Itr is below a lower limit threshold ItLlimit indicating an abnormality in the signal-receiving function of the power transmitter 20.

[0139] When a negative determination is made in step S63, the power-transmitter controller 71 determines in step S66 whether the acquired diagnostic intensity Itr exceeds an upper limit threshold ItHlimit indicating an abnormality in the signal-receiving function of the power transmitter 20. The upper threshold ItHlimit is a value greater than the lower threshold ItLlimit. The upper threshold ItHlimit and the lower threshold ItLlimit are values that are determined in advance by, for example, experiment or calculation.

[0140] When the power-transmitter controller 71 makes an affirmative determination in step S63 or S66, the power-transmitter controller 71 proceeds to step S64 and determines that an abnormality has occurred in the signal-receiving function of the power transmitter 20. The abnormality in the signal-receiving function of the power transmitter 20 includes an abnormality in any one of the power-transmitter communication coil 40, the power-transmitter amplifier 81, or the detection circuit 82.

[0141] In step S65, the power-transmitter controller 71 prevents energization of the power transmitter coil 22. Specifically, the power-transmitter controller 71 prevents switching control of the inverter 60 and the PFC circuit 61 from being performed. As a result, the power transmitter coil 22 is not energized. Accordingly, the power transmitter 20 can be prevented from being used continuously in an undesirable state.

[0142] When a negative determination is made in step S66, the power-transmitter controller 71 proceeds to step S67. In step S67, the power-transmitter controller 71 determines whether the acquired diagnostic intensity Itr is greater than an upper limit value ItHth of an expected intensity range. The upper limit value ItHth is lower than the upper limit threshold ItHlimit and is greater than the lower limit threshold ItLlimit (ItHlimit > ItHth > ItLlimit).

[0143] When the power-transmitter controller 71 determines in step S67 that the diagnostic intensity Itr is greater than the upper limit value ItHth, the power-transmitter controller 71 proceeds to step S68. In step S68, the power-transmitter controller 71 decreases the gain of the power-transmitter amplifier 81. As a result, the reception intensity of the vehicle-side signal including the power supply request signal and the reception intensity of the stop request signal can be reduced.

[0144] When a negative determination is made in step S67, the power-transmitter controller 71 proceeds to step S69. In step S69, the power-transmitter controller 71 determines whether the acquired diagnostic intensity Itr is lower than a lower limit value ItLth of the expected intensity range. The lower limit value ItLth is lower than the upper limit value ItHth and is greater than the lower threshold ItLlimit (ItHlimit > ItHth > ItLth > ItLlimit).

[0145] When the power-transmitter controller 71 determines in step S69 that the diagnostic intensity Itr is lower than the lower limit value ItLth, the power-transmitter controller 71 proceeds to step S70. In step S70, the power-transmitter controller 71 increases the gain of the power-transmitter amplifier 81. As a result, the reception intensity of the vehicle-side signal including the power supply request signal and the reception intensity of the stop request signal can be increased.

[0146] Due to deterioration of the power transmitter 20 over time, the intensity of the received signal may deviate from the expected intensity range. Even in this case, the processing in steps S68 and S70 can adjust the gain of the power-transmitter amplifier 81 so that the intensity of the received signal falls within the expected intensity range.

[0147] The determination threshold Ijde used by the determination circuit 83 to determine the presence or absence of a power supply request may be a value that is smaller than the lower limit value ItLth of the expected intensity range and larger than the lower limit threshold ItLlimit, for example.

[0148] Fifth Embodiment A fifth embodiment will be described below with reference to the drawings mainly in terms of differences from the fourth embodiment. As shown in FIG. 16, the power transmitter 20 does not have to include the test communication coil 600. The test transmission circuit 610 is connected to the power-transmitter communication coil 40. In the diagnostic process, the power-transmitter controller 71 may instruct the test transmission circuit 610 to supply a diagnostic stop request signal to the power-transmitter communication coil 40. When the diagnostic stop request signal is supplied to the power-transmitter communication coil 40, the power-transmitter controller 71 may diagnose the signal-receiving function of the power transmitter 20 based on the output signal of the power-transmitter amplifier 81 in a manner similar to that shown in FIG. 11.

[0149] Sixth Embodiment Hereinafter, a sixth embodiment will be described with reference to the drawings, focusing on differences from the fifth embodiment. As shown in FIG. 17, the test transmission circuit 610 is connected to an input portion of the power-transmitter amplifier 81 (more specifically, an input portion to which the output signal of the power-transmitter communication coil 40 is input). In the diagnostic process, the power-transmitter controller 71 may instruct the test transmission circuit 610 to supply a diagnostic stop request signal to the input portion of the power-transmitter amplifier 81. When the diagnostic stop request signal is supplied to the input portion of the power-transmitter amplifier 81, the power-transmitter controller 71 may diagnose the signal-receiving function of the power transmitter 20 based on the output signal of the power-transmitter amplifier 81 in a manner similar to that shown in FIG. 11.

[0150] Other Embodiments The above embodiments may be changed and carried out as follows.

[0151] The wireless power transfer system may have the first function of wirelessly supplying power from the vehicle-side device to the ground-side device, in addition to the second 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.

[0152] The power-receiver controller 231 applies a high frequency AC voltage to the power receiver coil 102 by controlling the switching of the rectifier circuit 200. This causes a high-frequency current to flow in the power receiver coil 102 and a magnetic field for power transmission is generated in the power receiver coil 102.

[0153] When the magnetic field generated in the power receiver coil 102 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 power receiver coil 102. 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.

[0154] 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.

[0155] The wireless power transfer system 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.

[0156] 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.

[0157] The method of wireless power transmission by the power transmitting antenna and the power receiving antenna 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.

[0158] The vehicle identification information used in the processes of the above embodiments is not limited to vehicle ID information, and may be, for example, a token or credit card information of a vehicle user.

[0159] 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.

[0160] The control units and methods thereof described in the present disclosure may be implemented by a dedicated computer including a processor programmed to execute one or more functions embodied by a computer program and a memory. Alternatively, the control units and methods thereof described in the present disclosure may be implemented using a dedicated computer with a processor consisting of one or more dedicated hardware logic circuits. Alternatively, the controller and method described in the present disclosure may be implemented using one or more dedicated computers, which include a combination of a processor consisting of one or more hardware logic circuits, and a processor and memory programmed to perform one or more functions. The computer programs may be stored, as instructions to be executed by a computer, in a tangible non-transitory computer-readable medium.

[0161] 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

1. A power receiver (100) applied to a wireless power transfer system, the system including a ground-side device and a vehicle-side device, one of the ground-side device and the vehicle-side device being a power transmitter (20) having a power transmitting antenna (22), the other of the ground-side device and the vehicle-side device being the power receiver having a power receiving antenna (102), the power receiver being configured to transmit a power supply request signal for a power supply request to the power transmitter, the power transmitter being configured to energize the power transmitting antenna to perform wireless power transfer to the power receiving antenna on condition that the power transmitter determines that there is the power supply request based on the received power supply request signal, the power receiver comprising: a power-receiver communication antenna (170) configured to wirelessly transmit the power supply request signal to a power-transmitter communication antenna (40) provided in the power transmitter; and a power-receiver control unit (230) configured to control energization of the power-receiver communication antenna to supply the power supply request signal to the power-receiver communication antenna, wherein the power transmitter is configured to stop energization of the power transmitting antenna when determining, based on an output signal of the power-transmitter communication antenna, that a stop request signal for requesting stop of power supply from the power transmitting antenna to the power receiving antenna has been input, and the power-receiver control unit is configured to supply the stop request signal to the power-receiver communication antenna when a transmission start condition for starting transmission of the stop request signal is satisfied.

2. The power receiver according to claim 1, wherein the transmission start condition is a condition that the power receiver has switched from a state where there is the power supply request to a state where there is no power supply request.

3. The power receiver according to claim 1, wherein the transmission start condition is a condition that there is no power supply request in the power receiver and a current is flowing through the power receiving antenna.

4. The power receiver according to claim 1, further comprising an intensity detection unit (350) configured to detect an intensity of a signal transmitted via narrow area wireless communication from another power receiver different from the power receiver, wherein the transmission start condition is a condition that the intensity detected by the intensity detection unit is higher than an intensity threshold.

5. The power receiver according to claim 4, wherein the transmission start condition is a condition that the intensity detected by the intensity detection unit is higher the intensity threshold and there is no power supply request in the power receiver.

6. The power receiver according to any one of claims 1 to 5, wherein when the transmission start condition is satisfied and there is the power supply request in the power receiver, the power-receiver control unit is configured to stop supply of the stop request signal to the power-receiver communication antenna based on a received power of the power receiving antenna being lower than a requested power of the power receiver, and supply the stop request signal to the power-receiver communication antenna based on the received power of the power receiving antenna being higher than the requested power.

7. The power receiver according to claim 2, wherein the power-receiver control unit is configured to stop supply of the stop request signal to the power-receiver communication antenna when the power-receiver control unit determines that a stop condition is satisfied after starting the supply of the stop request signal to the power-receiver communication antenna, and the stop condition is a condition that the state where there is no power supply request has been switched to the state where there is the power supply request.

8. The power receiver according to claim 3, wherein the power-receiver control unit is configured to stop supply of the stop request signal to the power-receiver communication antenna when the power-receiver control unit determines that a stop condition is satisfied after starting the supply of the stop request signal to the power-receiver communication antenna, and the stop condition is a condition that a current is not flowing through the power receiving antenna.

9. The power receiver according to claim 4 or 5, wherein the power-receiver control unit is configured to stop supply of the stop request signal to the power-receiver communication antenna when the power-receiver control unit determines that a stop condition is satisfied after starting the supply of the stop request signal to the power-receiver communication antenna, and the stop condition is a condition that the intensity detected by the intensity detection unit becomes lower than the intensity threshold.

10. The power receiver according to any one of claims 1 to 9, wherein the stop request signal is a signal greater in intensity than the power supply request signal, a signal different in bit length from the power supply request signal, or a signal different in frequency from the power supply request signal.

11. The power receiver according to any one of claims 1 to 9, wherein the stop request signal is shorter in bit length than the power supply request signal.

12. The power receiver according to any one of claims 1 to 11, wherein the power-receiver control unit is configured to obtain an intensity of the stop request signal, perform a process of increasing a transmission intensity of the stop request signal when determining that the acquired intensity is lower than a lower limit value of an expected intensity range, and perform a process of decreasing the transmission intensity of the stop request signal when determining that the acquired intensity is higher than a higher limit value of the expected intensity range.

13. A program for a power receiver applied to a wireless power transfer system, the system including a ground-side device and a vehicle-side device, one of the ground-side device and the vehicle-side device being a power transmitter (20) having a power transmitting antenna (22), the other of the ground-side device and the vehicle-side device being the power receiver (100) having a power receiving antenna (102), the power receiver being configured to transmit a power supply request signal for a power supply request to the power transmitter, the power transmitter being configured to energize the power transmitting antenna to perform wireless power transfer to the power receiving antenna on condition that the power transmitter determines that there is the power supply request based on the received power supply request signal, the power receiver including a power-receiver communication antenna (170) configured to wirelessly transmit the power supply request signal to a power-transmitter communication antenna (40) provided in the power transmitter, the power receiver including a power-receiver control unit (230) configured to control energization of the power-receiver communication antenna to supply the power supply request signal to the power-receiver communication antenna, the power transmitter being configured to stop energization of the power transmitting antenna when determining, based on an output signal of the power-transmitter communication antenna, that a stop request signal for requesting stop of power supply from the power transmitting antenna to the power receiving antenna has been input, the program executed by the power-receiver control unit to perform: supplying the stop request signal to the power-receiver communication antenna when a transmission start condition for starting transmission of the stop request signal is satisfied.

14. A control method for a power receiver applied to a wireless power transfer system including a ground-side device and a vehicle-side device, one of the ground-side device and the vehicle-side device being a power transmitter (20) having a power transmitting antenna (22), the other of the ground-side device and the vehicle-side device being the power receiver (100) having a power receiving antenna (102), the power receiver being configured to transmit a power supply request signal for a power supply request to the power transmitter, the power transmitter being configured to energize the power transmitting antenna to perform wireless power transfer to the power receiving antenna on condition that the power transmitter determines that there is the power supply request based on the received power supply request signal, the power receiver including a power-receiver communication antenna (170) configured to wirelessly transmit the power supply request signal to a power-transmitter communication antenna (40) provided in the power transmitter, and the power receiver including a power-receiver control unit (230) configured to control energization of the power-receiver communication antenna to supply the power supply request signal to the power-receiver communication antenna, the power transmitter being configured to stop energization of the power transmitting antenna when determining, based on an output signal of the power-transmitter communication antenna, that a stop request signal for requesting stop of power supply from the power transmitting antenna to the power receiving antenna has been input, the control method, executed by the power-receiver control unit, comprising: supplying the stop request signal to the power-receiver communication antenna when a transmission start condition for starting transmission of the stop request signal is satisfied.

15. A power transmitter (20) applied to a wireless power transfer system, the system including a ground-side device and a vehicle-side device, one of the ground-side device and the vehicle-side device being the power transmitter having a power transmitting antenna (22), the other of the ground-side device and the vehicle-side device being a power receiver (100) having a power receiving antenna (102), the power receiver being configured to transmit a power supply request signal for a power supply request to the power transmitter, the power transmitter being configured to energize the power transmitting antenna to perform wireless power transfer to the power receiving antenna on condition that the power transmitter determines that there is the power supply request based on the received power supply request signal, the power transmitter comprising: a power-transmitter communication antenna (40) configured to receive the power supply request signal wirelessly transmitted from a power-receiver communication antenna (170) provided in the power receiver, wherein the power receiver is configured to supply the power-receiver communication antenna with a stop request signal requesting stop of power supply from the power transmitting antenna to the power receiving antenna when determining that a transmission start condition for starting transmission of the stop request signal is satisfied; a power-transmitter control unit (70) configured to stop energization of the power transmitting antenna when determining that the stop request signal has been input based on an output signal of the power-transmitter communication antenna; and a test signal transmitter (600, 610).

16. The power transmitter according to claim 15, wherein the test signal transmitter includes a test communication antenna (600) provided near the power-transmitter communication antenna and configured to perform wireless communication with the power-transmitter communication antenna, and a test transmission circuit (610) connected to the test communication antenna, and the power-transmitter control unit is configured to control the test transmission circuit to supply a diagnostic stop request signal from the test transmission circuit to the test communication antenna, acquire the stop request signal received by the power-transmitter communication antenna when the diagnostic stop request signal is supplied to the test communication antenna, perform a process of increasing a reception intensity of the stop request signal when determining that an intensity of the acquired stop request signal is lower than a lower limit value of an expected intensity range, and perform a process of decreasing the reception intensity of the stop request signal when determining that the intensity of the acquired stop request signal is higher than a higher limit value of the expected intensity range.

17. The power transmitter according to claim 15, wherein the test signal transmitter includes a test transmission circuit (610) connected to the power-transmitter control unit, the power-transmitter control unit is configured to control the test transmission circuit to supply a diagnostic stop request signal from the test transmission circuit to the power-transmitter control unit, acquire the stop request signal received by a communication device (80) of the power-transmitter control unit when the diagnostic stop request signal is supplied to the power-transmitter control unit, perform a process of increasing a reception intensity of the stop request signal when determining that an intensity of the acquired stop request signal is lower than a lower limit value of an expected intensity range, and perform a process of decreasing the reception intensity of the stop request signal when determining that the intensity of the acquired stop request signal is higher than a higher limit value of the expected intensity range.

18. The power transmitter according to claim 15, wherein the power-transmitter control unit includes a power-transmitter amplifier (81) configured to amplify a signal received by the power-transmitter communication antenna, the test signal transmitter includes a test transmission circuit (610) connected to the power-transmitter amplifier, and the power-transmitter control unit is configured to control the test transmission circuit to supply a diagnostic stop request signal from the test transmission circuit to the power-transmitter amplifier, acquire the stop request signal output from the power-transmitter amplifier when the diagnostic stop request signal is supplied to the power-transmitter amplifier, perform a process of increasing a reception intensity of the stop request signal when determining that an intensity of the acquired stop request signal is lower than a lower limit value of an expected intensity range, and perform a process of decreasing the reception intensity of the stop request signal when determining that the intensity of the acquired stop request signal is higher than a higher limit value of the expected intensity range.

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