Power transmitter, program, and control method for 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. A power-receiver control unit (230) supplies a stop request signal to a power-receiver communication coil (170), when determining that a start condition is satisfied. The stop request signal is a signal requesting a stop of power supply from the power transmitter coil to a power receiver coil (102). The power-transmitter control unit stops energization of the power transmitter coil, when determining that the stop request signal has been input based on the output signal of the power-transmitter communication coil.

Description

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

[0001] This application is based on Japanese Patent Application No. 2024-208026 filed on November 29, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a power transmitter, a program, and a control method for 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 transmitter, a program, and a control method for 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 even when there is no power supply request from a power receiver.

[0009] According to an aspect of the present disclosure, a power transmitter 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 the power transmitter having a power transmitting antenna. The other of the ground-side device and the vehicle-side device is a 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 transmitter includes a power-transmitter communication antenna and a power-transmitter control unit. The power-transmitter communication antenna is configured to receive the power supply request signal wirelessly transmitted from a power-receiver communication antenna provided in the power receiver. The power-transmitter control unit is configured to control energization of the power transmitting antenna to perform the wireless power transfer to the power receiving antenna. 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. The power-transmitter control unit is configured to stop energization of the power transmitting antenna when the power-transmitter control unit determines that the stop request signal has been input based on an output signal of the power-transmitter communication antenna.

[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, 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.

[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 illustrating a transmission process for 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 illustrating a process executed by a power transmitter according to a second embodiment.FIG. 10 is a flowchart illustrating a process executed by a power transmitter.FIG. 11 is a diagram illustrating an example of information transmission in each power transmitter.FIG. 12 is a diagram illustrating an example of information transmission in each power transmitter.FIG. 13 is a diagram illustrating an example of information transmission in each power transmitter.FIG. 14 is a flowchart illustrating a process executed by a power transmitter according to a third 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 transmitter coil 22 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, on condition that 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 communication coil 40, 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, the power transmitter coil 22 is not energized.

[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 predetermined transmission start condition 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 a power-transmitter communication coil 40.

[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 higher than the determination threshold 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 the present embodiment, when the power-transmitter control unit 70 determines that the intensity Intd of the power supply request signal exceeds a detection threshold Ith, it transmits information on a target ID (corresponding to a "identification information"), which is an ID of a vehicle corresponding to the intensity Intd that exceeds the detection threshold Ith, to a power-transmitter control unit 70 of another power transmitter 20. The vehicle identified by the target ID is a vehicle whose communication range has been excessively expanded, and is hereinafter referred to as a target vehicle. The power-transmitter control unit 70 that has received the information of the target ID prevents energization of the power transmitter coil 22 even when the target vehicle is present near the power transmitter coil 22 that is a target controlled by the power-transmitter control unit 70.

[0092] FIG. 9 is a flowchart of the process executed by the power-transmitter control unit 70 of each power-transmitter power supply unit 51 installed on the ground.

[0093] In step S40, based on the high-frequency signal input from the power-transmitter communication coil 40, the power-transmitter controller 71 calculates an intensity Intd which is an amplitude or effective value of the input high-frequency signal. The power-transmitter controller 71 determines whether the calculated intensity Intd is higher than the detection threshold Ith. Furthermore, the power-transmitter controller 71 acquires information on the target ID that is an ID of a vehicle corresponding to the calculated intensity Intd, based on the high-frequency signal input from the power-transmitter communication coil 40.

[0094] When the power-transmitter controller 71 determines that the calculated intensity Intd exceeds the detection threshold Ith, the power-transmitter controller 71 proceeds to step S41 and transmits information on the target ID to a power-transmitter control unit 70 of another power transmitter 20. As a result, the information on the target ID is shared among power-transmitter control units 70 of multiple power transmitters 20. The power-transmitter control unit 70 that has received the information on the target ID executes the process shown in FIG. 10.

[0095] Specifically, in step S50, the power-transmitter controller 71 determines, based on the high-frequency signal input from the power-transmitter communication coil 40, whether the input high-frequency signal is a signal transmitted from the target vehicle.

[0096] When the power-transmitter controller 71 determines that the signal is transmitted from the vehicle of the target ID, the power-transmitter controller 71 proceeds to step S51 and calculates an intensity Intd, which is an amplitude or effective value of the input high-frequency signal input.

[0097] In step S52, the power-transmitter controller 71 determines whether the intensity Intd calculated in step S51 exceeds the determination threshold Ijde.

[0098] When the power-transmitter controller 71 determines that the intensity Intd exceeds the determination threshold Ijde, the power-transmitter controller 71 proceeds to step S53 and does not energize the power transmitter coil 22 that is the control target by the power-transmitter controller 71. That is, the power-transmitter controller 71 does not performs switching control of the inverter 60 and the PFC circuit 61 that are control targets by the power-transmitter controller 71.

[0099] According to the present embodiment described above, even when the target vehicle is traveling or stopped near the power transmitter coil 22, the power-transmitter controller 71 can ignore a power supply request of the target vehicle. Therefore, an unintended power transfer to other vehicles present near the target vehicle can be reduced.

[0100] The information communication in step S41 in FIG. 9 and step S50 in FIG. 10 can use, for example, wide area wireless communication (for example, communication via a cloud) or the configurations in the FIGS. 11 to 13 described below.

[0101] As shown in FIG. 11, the wireless power transfer system 10 includes a higher-level unit 400 that is an ECU controlling information communication between two power-transmitter power supply units 51. Accordingly, the higher-level unit 400 can act as a bridge to share information on the target ID among the power-transmitter control units 70 of the power-transmitter power supply units 51.

[0102] As shown in FIG. 12, the wireless power transfer system 10 includes a subunit 420. The subunit 420 is an ECU that controls information communication between a part (one in FIG. 12) of a group of a predetermined number (four in FIG. 12) of power-transmitter communication coils 40 corresponding to a certain power-transmitter power supply unit 51, and a part (one in FIG. 12) of a group of the predetermined number of power-transmitter communication coils 40 corresponding to another power-transmitter power supply unit 51. This allows the subunit 420 to act as a bridge for information.

[0103] As shown in FIG. 13, the wireless power transfer system 10 includes a higher-level unit 430 that is an ECU controlling information communication between all power-transmitter power supply units 51. This allows the higher-level unit 430 to act as a bridge for information.

[0104] Third Embodiment Hereinafter, a third embodiment will be described with reference to the drawings, focusing on differences from the second embodiment. In this embodiment, when the power-transmitter control unit 70 determines that the intensity Intd of the power supply request signal is higher than the detection threshold Ith, the power-transmitter control unit 70 transmits information, indicating that the intensity Intd is higher than the detection threshold Ith, to the power receiver 100 of the vehicle corresponding to the intensity Intd that exceeds the detection threshold Ith.

[0105] FIG. 14 is a flowchart of the process executed by the power-transmitter control unit 70 of each power-transmitter power supply unit 51 installed on the ground.

[0106] In step S60, based on the high-frequency signal input from the power-transmitter communication coil 40, the power-transmitter controller 71 calculates an intensity Intd which is an amplitude or effective value of the input high-frequency signal. The power-transmitter controller 71 determines whether the calculated intensity Intd is higher than the detection threshold Ith. Furthermore, the power-transmitter controller 71 acquires information on the target ID that is an ID of a vehicle corresponding to the calculated intensity Intd, based on the high-frequency signal input from the power-transmitter communication coil 40.

[0107] When the power-transmitter controller 71 determines that the calculated intensity Intd exceeds the detection threshold Ith, it proceeds to step S61 and transmits abnormality information, indicating that the intensity Intd exceeds the detection threshold Ith, to the power receiver 100 of the target vehicle. Furthermore, the power-transmitter controller 71 stops the switching control of the inverter 60 and the PFC circuit 61 which are control targets by the power-transmitter controller 71, in order to stop energization of the power transmitter coil 22 which is a control target by the power-transmitter controller 71. The information communication in step S61 may use, for example, wide area wireless communication or road-to-vehicle communication.

[0108] In the power receiver 100 that has received the abnormality information, 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 power supply request signal can be reduced in the target vehicle. As a result, an unintended power transfer to other vehicles present near the target vehicle can be reduced.

[0109] Other Embodiments The above embodiments may be changed and carried out as follows.

[0110] In the wireless power transfer system 10, the transmission process for the stop request signal, the reception process for the stop request signal, and the processes associated with the reception process are not essential.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] Characteristic configurations extracted from the above embodiments will be described below. A program for a power transmitter 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 the power transmitter (20) having a power transmitting antenna (22). The other of the ground-side device and the vehicle-side device is a power receiver (100) having a power receiving antenna (102). 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 transmitter includes a power-transmitter communication antenna and a power-transmitter control unit. The power-transmitter communication antenna (40) is configured to receive the power supply request signal wirelessly transmitted from a power-receiver communication antenna (170) provided in the power receiver. The power-transmitter control unit (70) is configured to control energization of the power transmitting antenna to perform wireless power transfer to the power receiving antenna. The program is configured to cause the power-transmitter control unit to carry out determining whether an intensity of the power supply request signal calculated based on an output signal of the power-transmitter communication antenna exceeds a detection threshold, transmitting target identification information, which is identification information of a power receiver corresponding to the intensity exceeding the detection threshold, to a power-transmitter control unit of another power transmitter when the power-transmitter control unit determines that the intensity exceeds the detection threshold, and preventing energization of the power transmitting antenna when receiving the target identification information, even though the power receiver identified by the target identification information is present near the power transmitting antenna. A control method for a power transmitter 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 the power transmitter (20) having a power transmitting antenna (22). The other of the ground-side device and the vehicle-side device is a power receiver (100) having a power receiving antenna (102). 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 transmitter includes a power-transmitter communication antenna and a power-transmitter control unit. The power-transmitter communication antenna (40) is configured to receive the power supply request signal wirelessly transmitted from a power-receiver communication antenna (170) provided in the power receiver. The power-transmitter control unit (70) is configured to control energization of the power transmitting antenna to perform wireless power transfer to the power receiving antenna. The control method includes causing the power-transmitter control unit to carry out determining whether an intensity of the power supply request signal calculated based on an output signal of the power-transmitter communication antenna exceeds a detection threshold, transmitting target identification information, which is identification information of a power receiver corresponding to the intensity exceeding the detection threshold, to a power-transmitter control unit of another power transmitter when the power-transmitter control unit determines that the intensity exceeds the detection threshold, and preventing energization of the power transmitting antenna when receiving the target identification information, even though the power receiver identified by the target identification information is present near the power transmitting antenna. A program for a power transmitter 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 the power transmitter (20) having a power transmitting antenna (22). The other of the ground-side device and the vehicle-side device is a power receiver (100) having a power receiving antenna (102). 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 transmitter includes a power-transmitter communication antenna and a power-transmitter control unit. The power-transmitter communication antenna (40) is configured to receive the power supply request signal wirelessly transmitted from a power-receiver communication antenna (170) provided in the power receiver. The power-transmitter control unit (70) is configured to control energization of the power transmitting antenna to perform wireless power transfer to the power receiving antenna. The program is configured to cause the power-transmitter control unit to carry out determining whether an intensity of the power supply request signal calculated based on the output signal of the power-transmitter communication antenna exceeds a detection threshold, and transmitting information indicating that the intensity exceeds the detection threshold to a power receiver corresponding to the intensity exceeding the detection threshold when the power-transmitter control unit determines that the intensity exceeds the detection threshold. A control method for a power transmitter 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 the power transmitter (20) having a power transmitting antenna (22). The other of the ground-side device and the vehicle-side device is a power receiver (100) having a power receiving antenna (102). 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 transmitter includes a power-transmitter communication antenna and a power-transmitter control unit. The power-transmitter communication antenna (40) is configured to receive the power supply request signal wirelessly transmitted from a power-receiver communication antenna (170) provided in the power receiver. The power-transmitter control unit (70) is configured to control energization of the power transmitting antenna to perform wireless power transfer to the power receiving antenna. The control method includes causing the power-transmitter control unit to carry out determining whether an intensity of the power supply request signal calculated based on the output signal of the power-transmitter communication antenna exceeds a detection threshold, and transmitting information indicating that the intensity exceeds the detection threshold to a power receiver corresponding to the intensity exceeding the detection threshold when the power-transmitter control unit determines that the intensity exceeds the detection threshold.

[0122] 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 transmitter (20) 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 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; and a power-transmitter control unit (70) configured to control energization of the power transmitting antenna to perform the wireless power transfer to the power receiving antenna, 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 the power receiver determines that a transmission start condition for starting transmission of the stop request signal is satisfied, and the power-transmitter control unit is configured to stop energization of the power transmitting antenna when the power-transmitter control unit determines that the stop request signal has been input based on an output signal of the power-transmitter communication antenna.

2. The power transmitter according to claim 1, wherein the power receiver is configured to supply the stop request signal to the power-receiver communication antenna during a period from when the power receiver determines that the transmission start condition is satisfied until the power receiver determines that a stop condition is satisfied, and the power-transmitter control unit is configured to continue to stop the energization of the power transmitting antenna until the power-transmitter control unit determines that a release condition is satisfied, after the power-transmitter control unit determines that the stop request signal has been input.

3. The power transmitter according to claim 2, wherein the release condition is a condition that: it is determined that the stop request signal has not been input based on the output signal of the power-transmitter communication antenna; and an intensity of the power supply request signal calculated based on the output signal of the power-transmitter communication antenna is lower than a detection threshold.

4. The power transmitter according to claim 2, wherein the release condition is a condition that a predetermined period has elapsed since it was determined, based on the output signal of the power-transmitter communication antenna, that the stop request signal has not been input.

5. The power transmitter according to any one of claims 2 to 4, wherein the power-transmitter control unit is configured to determine whether an intensity of the power supply request signal calculated based on the output signal of the power-transmitter communication antenna exceeds a detection threshold, transmit target identification information, which is identification information of a power receiver corresponding to the intensity exceeding the detection threshold, to a power-transmitter control unit of another power transmitter when the power-transmitter control unit determines that the intensity exceeds the detection threshold, and prevent energization of the power transmitting antenna when receiving the target identification information, even though the power receiver identified by the target identification information is present near the power transmitting antenna.

6. The power transmitter according to any one of claims 2 to 5, wherein the power-transmitter control unit is configured to determine whether an intensity of the power supply request signal calculated based on the output signal of the power-transmitter communication antenna exceeds a detection threshold, and transmit information, indicating that the intensity exceeds the detection threshold, to a power receiver corresponding to the intensity exceeding the detection threshold when the power-transmitter control unit determines that the intensity exceeds the detection threshold.

7. The power transmitter according to any one of claims 1 to 6, 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.

8. The power transmitter according to any one of claims 1 to 6, 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.

9. The power transmitter according to any one of claims 1 to 6, wherein the power receiver includes 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, and the transmission start condition is a condition that the intensity detected by the intensity detection unit is higher than an intensity threshold.

10. The power transmitter according to claim 9, wherein the transmission start condition is a condition that the intensity detected by the intensity detection unit exceeds the intensity threshold and there is no power supply request in the power receiver.

11. The power transmitter according to any one of claims 1 to 4, wherein the power receiver is configured to stop supply of the stop request signal to the power-receiver communication antenna when the power receiver 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 state where there is no power supply request has been switched to a state where there is the power supply request.

12. The power transmitter according to claim 8, wherein the power receiver is configured to stop supply of the stop request signal to the power-receiver communication antenna when the power receiver 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.

13. The power transmitter according to claim 9 or 10, wherein the power receiver is configured to stop supply of the stop request signal to the power-receiver communication antenna when the power receiver 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.

14. The power transmitter according to any one of claims 1 to 13, 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.

15. A power transmitter (20) 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 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; and a power-transmitter control unit (70) configured to control energization of the power transmitting antenna to perform the wireless power transfer to the power receiving antenna, wherein the power-transmitter control unit is configured to determine whether an intensity of the power supply request signal calculated based on an output signal of the power-transmitter communication antenna exceeds a detection threshold, transmit target identification information, which is identification information of a power receiver corresponding to the intensity exceeding the detection threshold, to a power-transmitter control unit of another power transmitter when the power-transmitter control unit determines that the intensity exceeds the detection threshold, and prevent energization of the power transmitting antenna when receiving the target identification information, even though the power receiver identified by the target identification information is present near the power transmitting antenna.

16. A power transmitter (20) 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 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; and a power-transmitter control unit (70) configured to control energization of the power transmitting antenna to perform the wireless power transfer to the power receiving antenna, wherein the power-transmitter control unit is configured to determine whether an intensity of the power supply request signal calculated based on an output signal of the power-transmitter communication antenna exceeds a detection threshold, and transmit information indicating that the intensity exceeds the detection threshold to a power receiver corresponding to the intensity exceeding the detection threshold when the power-transmitter control unit determines that the intensity exceeds the detection threshold.

17. A program for a power transmitter (20) 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 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 including 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, and a power-transmitter control unit (70) configured to control energization of the power transmitting antenna to perform wireless power transfer to the power receiving antenna, the power receiver being 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, the program configured to cause the power-transmitter control unit to carry out stopping 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.

18. A control method for a power transmitter (20) 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 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 including 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, and a power-transmitter control unit (70) configured to control energization of the power transmitting antenna to perform wireless power transfer to the power receiving antenna, the power receiver being 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, the control method comprising causing the power-transmitter control unit to carry out stopping 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.

Images