Wireless power transfer system, program, control method for wireless power transfer system, and power transmitter

Abstract

A power-transmitter control unit (70) calculates an intensity of a power supply request signal based on an output signal of a power-transmitter communication coil (40), and energizes a power transmitter coil (22) when determining that the calculated intensity exceeds a determination threshold. The power-transmitter control unit calculates a determination period, which is a period from when the calculated intensity exceeds the determination threshold until it falls below the determination threshold, calculates a ratio between the calculated determination period and an energization period of the power transmitter coil, and diagnoses a communication function of a power transmitter (20) based on the calculated ratio.

Description

WIRELESS POWER TRANSFER SYSTEM, PROGRAM, CONTROL METHOD FOR WIRELESS POWER TRANSFER SYSTEM, AND POWER TRANSMITTERCross Reference

[0001] This application is based on Japanese Patent Application No. 2024-208032 filed on November 29, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a wireless power transfer system, a program, a control method for a wireless power transfer system, 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] The receiving sensitivity of the power transmitter for receiving the power supply request signal may change due to factors such as differences in the shape of the power-transmitter communication antenna among power transmitters and individual variations in the shape of the power-transmitter communication antenna. For example, if the receiving sensitivity increases, the power transmitter coil that does not need to be energized may be energized. For this reason, a technique capable of diagnosing the communication function of the power transmitter is desired. Such a technique is also desired when the power transmitter is a vehicle-side device and the power receiver is a ground-side device.

[0007] It is a main object of the present disclosure is to provide a wireless power transfer system, a program, a control method for a wireless power transfer system, and a power transmitter that are capable of diagnosing a communication function of the power transmitter.

[0008] According to an aspect of the present disclosure, a wireless power transfer system includes a power transmitter having a power transmitting antenna, and a power receiver having a power receiving antenna. The power transmitting antenna is configured to wirelessly supply power to the power receiving antenna. One of the power receiver and the power transmitter is mounted on a vehicle. The other of the power receiver and the power transmitter is a ground-side device. The power receiver includes a power-receiver communication antenna, and a power-receiver control unit configured to perform energization control of the power-receiver communication antenna to supply a power supply request signal, which indicates power supply request to the power transmitting antenna, to the power-receiver communication antenna. The power transmitter includes a power-transmitter communication antenna and a power-transmitter control unit. The power-transmitter communication antenna is configured to perform wireless communication with the power-receiver communication antenna. The power-transmitter control unit is configured to calculate an intensity of the power supply request signal based on an output signal of the power-transmitter communication antenna, and energize the power transmitting antenna when determining that the calculated intensity exceeds a determination threshold. The wireless power transfer system includes a period calculation unit and a diagnostic unit. The period calculation unit is configured to calculate a determination period that is a period from when the calculated intensity exceeds the determination threshold until the calculated intensity falls below the determination threshold. The diagnostic unit is configured to diagnose a communication function of the power transmitter based on the calculated determination period.

[0009] The determination period, which is the period from when the intensity of the power supply request signal exceeds the determination threshold until when it falls below the determination threshold, is a parameter for grasping the state of the communication function of the power transmitter. Therefore, the communication function of the power transmitter can be diagnosed.

[0010] 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 configuration of wide area wireless communication between the power transmitter and a vehicle.FIG. 5 is a diagram illustrating a signal transmitter and its peripheral configuration.FIG. 6 is a diagram illustrating a signal receiver and its peripheral configuration.FIG. 7 is a flowchart illustrating a process executed by the power transmitter.FIG. 8 is a time chart illustrating definitions of a determination period and an energization period.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 and a server according to a third embodiment.FIG. 11 is a flowchart illustrating a process executed by a power transmitter according to a fourth embodiment.FIG. 12 is a diagram illustrating a deviation degree of a vehicle according to a fifth embodiment.FIG. 13 is a graph showing a calculation result of influence on the deviation degree during an energization period.FIG. 14 is a graph showing a calculation result of influence on the deviation degree during an energization period.FIG. 15 is a flowchart illustrating a process executed by a power transmitter.

[0011] 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.

[0012] First Embodiment A first embodiment of a wireless power transfer system of the present disclosure will be described below with reference to the drawings.

[0013] 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.

[0014] The power transmitter 20 is a ground-side device and has a power-transmitter coil unit 21 and a power-transmitter power supply unit 51 that supplies power to the power-transmitter coil unit 21. The power transmitter 20 is, for example, a stationary device. The power-transmitter coil unit 21 is installed (for example, buried) in the road RS, a parking lot, or the like. The power-transmitter power supply unit 51 is installed, for example, on the side of the road RS. The power-transmitter coil unit 21 is connected to the power-transmitter power supply unit 51. The power-transmitter power supply unit 51 is connected to an AC power source 15 and supplies AC (alternating-current) power from the AC power source 15 to the power-transmitter coil unit 21. The AC power source 15 is, for example, a commercial power source. Multiple power-transmitter coil units 21 are arranged along the lanes of the road RS. FIG. 2 shows an example of four power-transmitter coil units 21 aligned along the road RS and connected to one power-transmitter power supply unit 51. In other words, one power-transmitter power supply unit 51 is provided for each of the four power-transmitter coil units 21.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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).

[0024] 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.

[0025] 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 wheels 12 (drive wheels) of the vehicle 11. As a result, the vehicle 11 travels.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] The power-receiver control unit 230 includes information containing the power supply request signal COMM and a traveling speed of the vehicle 11 into one frame, and supplies the frame to the power-receiver communication coil 170. As a result, a high-frequency voltage is 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. In this embodiment, the power supply request signal includes ID information of the vehicle 11 (corresponding to "identification information") and requested power Weq, which is a requested value of power to be supplied to the vehicle 11.

[0039] 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. 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.

[0040] 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).

[0041] 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.

[0042] FIG. 4 is a schematic diagram for explaining wide area wireless communication in the wireless power transfer system 10. In the wireless power transfer system 10, each vehicle 11 is capable of communicating with each power transmitter 20 via a communication network 16. The communication network 16 includes, for example, a WAN (Wide Area Network), which is a public communication network such as the Internet, a telephone communication network for a mobile phone, an information and communication network for ETC, and an information and communication network for a Vehicle Information and Communication System (VICS (registered trademark)). Wide area wireless communication is a communication with a longer communication distance than the narrow area wireless communication. Wide area wireless communication is communication with a communication distance of, for example, 10 meters to 10 kilometers. Examples of the wide area wireless communication include 3GPP (registered trademark), 4G, LTE, 5G, and WiMAX (registered trademark) developed by IEEE.

[0043] The vehicle 11 is equipped with a position sensor 330, a navigation device 331, and a communication unit 332. The position sensor 330 is a sensor that detects the current position of the vehicle, and is, for example, a GPS sensor. A storage unit (for example, storage) of the navigation device 331 stores map information including road information. The navigation device 331 receives information on the current position of the vehicle detected by the position sensor 330 and weather information. The power-transmitter control unit 70 of the power transmitter 20 includes a communication unit 90. The communication unit 332 of the vehicle 11 and the communication unit 90 of the power-transmitter control unit 70 perform wide area wireless communication via the communication network 16.

[0044] The wireless power transfer system 10 includes a server 400. The server 400 is, for example, a cloud server, and includes a server controller 401 and a communication unit 402. The server controller 401 is an electronic control unit (ECU) that executes various controls of the server 400 and includes a processor as hardware, a storage unit, and a communication bus connecting the processor and storage unit. 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 server controller 401. 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.

[0045] The server controller 401 is connected to the communication unit 402. The server controller 401 performs wide area wireless communication with the communication unit 332 of the vehicle 11 and the communication unit 90 of the power-transmitter control unit 70 via the communication unit 402 and the communication network 16.

[0046] 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, power-transmitter controller 71, and the server controller401. The storage medium is, for example, a USB memory, CD-ROM or DVD. In addition, program information transmitted over a communication network 16, such as OTA (Over The Air), is installed in the storage units.

[0047] Next, the signal transmitter 240 and its peripheral configuration will be described with reference to FIG. 5.

[0048] 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.

[0049] 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.

[0050] The signal receiver 80 and its peripheral configuration will be described with reference to FIG. 6.

[0051] The signal receiver 80 includes a power-transmitter amplifier 81. The power-transmitter amplifier 81 amplifies a high-frequency signal (high-frequency current signal or high-frequency 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] The signal receiver 80 includes a detection circuit 82. The output signal of the power-transmitter amplifier 81 is input to the detection circuit 82. 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 power-transmitter controller 71.

[0053] The power-transmitter controller 71 determines whether there is a power supply request to the power transmitter coil 22 based on the input intensity Intd. Specifically, when the power-transmitter controller 71 determines that the intensity Intd exceeds a determination threshold Ijde, the power-transmitter controller 71 determines that there is a power supply request. On the other hand, when the power-transmitter controller 71 determines that the intensity Intd is lower than the determination threshold Ijde, the power-transmitter controller 71 determines that there is no power supply request.

[0054] When the power-transmitter controller 71 determines that there is no power supply request, the power-transmitter controller 71 stops the switching control of the PFC circuit 61 and the inverter 60. As a result, the switches of the PFC circuit 61 and the inverter 60 are kept off, and the power transmitter coil 22 is not energized.

[0055] On the other hand, when it is determined that there is a power supply request, 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 for a predetermined period of time. This causes a high-frequency current to flow through the power transmitter coil 22 for a predetermined period of time. 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. After energizing the power transmitter coil 22 for a predetermined period of time, the power-transmitter controller 71 does not energize the power transmitter coil 22 until it determines next time that there is a power supply request.

[0056] The receiving sensitivity of the power-transmitter communication coil 40 for receiving the power supply request signal may change due to factors such as differences in the shape of the power-transmitter communication coil 40 among power transmitters 20 and individual variations in the shape of the power-transmitter communication coil 40 and the power-transmitter amplifier 81. For example, if the receiving sensitivity increases, a power transmitter coil 22 that does not need to be energized may be energized.

[0057] Therefore, the wireless power transfer system 10 has a configuration for diagnosing the communication function of the power transmitter 20. In this embodiment, the power transmitter 20 is provided with a configuration for performing diagnosis.

[0058] FIG. 7 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.

[0059] In step S10, the power-transmitter controller 71 acquires the intensity Intd of the power supply request signal and the ID information of the vehicle from the detection circuit 82.

[0060] In step S11, the power-transmitter controller 71 determines whether there is a power supply request based on the acquired intensity Intd. When the power-transmitter controller 71 determines that there is no power supply request, it proceeds to step S12 and does not energize the power transmitter coil 22 that is a target of energization control by the power-transmitter controller 71. In other words, the power-transmitter controller 71 does not perform switching control of the inverter 60 and the PFC circuit 61 that are targets of energization control by the power-transmitter controller 71, and keeps the switches of the inverter 60 and the PFC circuit 61 turned off.

[0061] On the other hand, when the power-transmitter controller 71 determines that there is a power supply request, it proceeds to step S13 and energizes the power transmitter coil 22 that is the target of the energization control by the power-transmitter controller 71. That is, the power-transmitter controller 71 performs switching control of the inverter 60 and the PFC circuit 61 that are targets of energization control by the power-transmitter controller 71. The power-transmitter controller 71 performs the above switching control for a predetermined period of time after it determines that there is a power supply request.

[0062] In step S14, the power-transmitter controller 71 determines whether the ID information acquired in step S10 is ID information of an inspection vehicle. The inspection vehicle is a vehicle in which the adjustment of the transmission intensity of the power supply request signal has been completed. The completion of the adjustment of the transmission intensity refers, for example, to the completion of the adjustment of the gain of the power-receiver amplifier 242. The process of step S14 can improve the accuracy of calculation of the determination period Tjde in step S15 described later. The ID information of the inspection vehicle is stored, for example, in a storage unit of the server 400. The power-transmitter controller 71 may, for example, acquire the ID information of the inspection vehicle from the server 400 by wide area wireless communication, and the power-transmitter controller 71 may store the acquired ID information in its own storage unit.

[0063] The ID information of the inspection vehicle may be, for example, ID information of a vehicle used exclusively for inspection and owned by an operating company of the wireless power transfer system 10, or it may be ID information of a general vehicle whose transmission intensity has been adjusted at a repair shop of a vehicle dealer.

[0064] When the power-transmitter controller 71 determines that the ID information is of an inspection vehicle, it proceeds to step S15 and calculates the determination period Tjde based on the intensity Intd of the power supply request signal. The processing of step S15 corresponds to a "period calculation unit".

[0065] The determination period Tjde and an energization period Te will be described with reference to FIG. 8. In FIG. 8, (a) shows a transition of the transmission state of the power supply request signal from the power receiver 100. (b) shows a transition of the energization state of the power receiver coil 102. (c) shows a transition of the intensity of the power supply request signal received by the power transmitter 20. (d) shows a transition of the energization state of the power transmitter coil 22.

[0066] At time t1, the intensity of the power supply request signal starts to increase, and at time t2, the intensity exceeds the determination threshold Ijde. As a result, it is determined that there is a power supply request, and switching control of the inverter 60 is executed for a predetermined period, thereby energizing the power transmitter coil 22 from t3 to t4. The period from t3 to t4 is the above-mentioned predetermined period and the energization period Te. The energization period Te is, in other words, the period from when the switching control of the inverter 60 is started until it is ended, and is the duration of the switching control.

[0067] The power-transmitter controller 71 may set the above-mentioned predetermined period as the energization period Te, or may calculate the energization period Te based on the detection value of a current sensor (not shown) that detects the current flowing through the power transmitter coil 22.

[0068] The energization of the power transmitter coil 22 causes the current to flow through the power receiver coil 102 from time t3 to t4 as shown by (b) in FIG. 8. Thereafter, the intensity starts to decrease, and at time t5, the intensity falls below the determination threshold Ijde. The period from t2 to t5 during which the calculated intensity exceeds the determination threshold Ijde until it falls below the determination threshold Ijde is the determination period Tjde. After that, at time t6, the intensity becomes 0.

[0069] In step S16, the power-transmitter controller 71 calculates a ratio Rr between the calculated determination period Tjde and the energization period Te. Specifically, the power-transmitter controller 71 calculates the ratio Rr by dividing the energization period Te by the calculated determination period Tjde.

[0070] In steps S17 to S20 and S22, the power-transmitter controller 71 diagnoses the communication function of the power transmitter 20 based on the calculated ratio Rr. The processes in steps S16 to S20 and S22 correspond to a "diagnostic unit."

[0071] The closer the calculated ratio Rr (= Te / Tjde) is to 1, the higher the communication sensitivity. This is because the higher the communication sensitivity, the faster the rate of change in the intensity of the power supply request signal shown in FIG. 8 (c) becomes, and the determination period Tjde becomes shorter and approaches the energization period Te. On the other hand, the smaller the ratio Rr becomes from 1, the lower the communication sensitivity is. This is because the lower the communication sensitivity, the slower the rate of change in the intensity of the power supply request signal shown in FIG. 8 (c) becomes, and the longer the determination period Tjde becomes. The higher the traveling speed of a vehicle traveling near the power transmitter coil 22, the shorter the determination period Tjde. On the other hand, the ratio Rr is a value obtained by dividing a parameter having a time dimension by a parameter having a time dimension, and is therefore dimensionless information. Therefore, by using the ratio Rr, the influence of the vehicle's traveling speed on the diagnosis of the communication function can be suppressed.

[0072] In step S17, the power-transmitter controller 71 determines whether the calculated ratio Rr is smaller than or equal to an upper threshold TthH and greater than or equal to a lower threshold TthL. The lower threshold TthL is a value smaller than the upper threshold TthH. The upper threshold TthH is a value smaller than 1. The range of "TthL ≦ Rr ≦ TthH" is the range of communication sensitivity that is assumed when the communication sensitivity of the power transmitter 20 is normal.

[0073] When the power-transmitter controller 71 determines that "TthL ≦ Rr ≦ TthH", it proceeds to step S18 and determines that the communication sensitivity is normal, meaning that the communication function is normal.

[0074] On the other hand, when the power-transmitter controller 71 makes a negative determination in step S17, it proceeds to step S19 and determines whether "TthH < Rr < 1". When the power-transmitter controller 71 determines that "TthH < Rr < 1", it proceeds to step S20 and diagnoses that the communication sensitivity is outside the assumed sensitivity range on the high-sensitivity side.

[0075] In step S21, the power-transmitter controller 71 decreases the gain of the power-transmitter amplifier 81. This reduces the receiving sensitivity of the power transmitter 20.

[0076] On the other hand, when the power-transmitter controller 71 determines in step S19 that "Rr < TthL", it proceeds to step S22 and diagnoses that the communication sensitivity is outside the assumed sensitivity range on the low-sensitivity side.

[0077] In step S23, the power-transmitter controller 71 increases the gain of the power-transmitter amplifier 81. This increases the receiving sensitivity of the power transmitter 20. By the process of step S23 or S21, the receiving sensitivity can be adjusted to an appropriate sensitivity.

[0078] Note that, when the power-transmitter controller 71 determines that the calculated ratio Rr is below an abnormality threshold that is lower than the lower limit threshold TthL, the power-transmitter controller 71 may determine that an abnormality has occurred in the communication function of the power transmitter 20. In this case, the power-transmitter controller 71 may execute the process of step S22 and may also perform a process of notifying the server 400 via wide area wireless communication that an abnormality has occurred.

[0079] According to the present embodiment described above, the communication function of the power transmitter 20 can be diagnosed.

[0080] Modification of First Embodiment The power-transmitter controller 71 may calculate a ratio Rr (= Tjde / Te) by dividing the calculated determination period Tjde by the energization period Te. In this case, the closer the ratio Rr (= Te / Tjde) is to 1, the higher the communication sensitivity. The further the ratio Rr deviates upward from 1, the lower the communication sensitivity. In this case, the lower limit threshold TthL and the upper limit threshold TthH are greater than 1. In this case, the process of step S19 may be modified to be a process of determining whether "1 < Rr <TthL".

[0081] 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, the communication function of the power transmitter 20 is diagnosed based on multiple calculated ratios.

[0082] 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.

[0083] After step S16, in step S24, the power-transmitter controller 71 calculates an average value Rave of multiple ratios Rr that have been calculated in step S16 so far. Then, in steps S25 and S26, the power-transmitter controller 71 uses the average value Rave instead of the ratio Rr. Therefore, an accuracy of diagnosing the communication function of the power transmitter 20 can be improved.

[0084] Modification of Second Embodiment In step S24, the power-transmitter controller 71 may calculate the median of the multiple ratios Rr that have been calculated in step S16 so far, instead of the average value Rave. The median is used in steps S25 and S26.

[0085] Third Embodiment A third embodiment will be described below with reference to the drawings mainly in terms of differences from the first embodiment. In this embodiment, the diagnostic function is provided in the server 400.

[0086] FIG. 10 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 in cooperation with the server 400.

[0087] In step S30, the power-transmitter controller 71 transmits information on the determination period Tjde calculated in step S15 to the server 400 by wide area wireless communication.

[0088] In step S40, the server controller 401 determines whether the transmitted information on the determination period Tjde has been received.

[0089] When the server controller 401 determines that the information has been received, it performs the processes of steps S41 to S46. The processes of steps S41 to S46 are similar to the processes of steps S16 to S20 and S22 in FIG. 7, and therefore a detailed description thereof will be omitted.

[0090] In step S47, the server controller 401 transmits information on the diagnosis result in step S43, S45, or S46 to the power transmitter 20 by wide area wireless communication.

[0091] In step S31, the power-transmitter controller 71 determines whether information on the diagnosis result transmitted from the server 400 has been received.

[0092] When the power-transmitter controller 71 determines that the diagnosis result has been received, the power-transmitter controller 71 proceeds to step S32 and determines whether the received diagnosis result indicates that the communication sensitivity is outside the assumed sensitivity range on the high-sensitivity side. When the power-transmitter controller 71 makes an affirmative determination in step S32, the power-transmitter controller 71 executes the process of step S21.

[0093] On the other hand, when the power-transmitter controller 71 makes a negative determination in step S32, it proceeds to step S33 and determines whether the received diagnosis result indicates that the communication sensitivity is outside the assumed sensitivity range on the low-sensitivity side. When the power-transmitter controller 71 makes an affirmative determination in step S33, it executes the process of step S23. When a negative determination is made in step S33, the power-transmitter controller 71 determines that the communication function is normal.

[0094] According to the above present embodiment, the similar effects as those of the first embodiment can be obtained.

[0095] Fourth Embodiment Hereinafter, a fourth embodiment will be described with reference to the drawings, focusing on differences from the first embodiment. In the present embodiment, preliminary energization is performed before main energization of the power transmitter coil 22.

[0096] FIG. 11 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.

[0097] When the power-transmitter controller 71 determines in step S11 that there is a power supply request, it proceeds to step S50 and executes a tracking process (corresponding to a "preliminary energization process") prior to main energization. Specifically, the power-transmitter controller 71 performs the switching control of the inverter 60 and the PFC circuit 61 to set the frequency of the voltage applied to the power transmitter coil 22 to multiple different frequencies sequentially from the higher frequency side to the lower frequency side or from lower frequency side to higher frequency side. The power-transmitter controller 71 may initially set the frequency of the voltage applied to the power transmitter coil 22 to a frequency that is different from the resonant frequency of the power-transmitter resonant circuit 30, for example.

[0098] The power-transmitter controller 71 changes the frequency of the voltage applied to the power transmitter coil 22 through the switching control, while calculating the phase difference between the current of the power transmitter coil 22 and the voltage applied to the power transmitter coil 22. The power-transmitter controller 71 sets the frequency of the high-frequency current to be supplied to the power transmitter coil 22 to a frequency among the multiple set frequencies of the applied voltage at which the calculated phase difference is below a phase difference threshold. The phase difference threshold may be, for example, a value at which a power supply efficiency from the power transmitter coil 22 to the power receiver coil 102 becomes greater than a predetermined efficiency, and may be set in advance based on tests or simulations. Furthermore, the power-transmitter controller 71 may calculate the phase difference based on, for example, a detection value of a current sensor that detects a current flowing through the power transmitter coil 22 and a detection value of a voltage sensor that detects a voltage of the power transmitter coil 22. Instead of the phase difference, another parameter, such as a detected value of the current flowing through the power transmitter coil 22, may be used.

[0099] In step S51, the power-transmitter controller 71 determines during the tracking process whether the relative positional relationship between the power transmitter coil 22 and the power receiver coil 102 of the vehicle 11 traveling near the power transmitter coil 22 is an appropriate positional relationship for performing wireless power transfer. For example, the power-transmitter controller 71 calculates a ratio (Pout / Pin) of an output power Pout (effective power) of the inverter 60 to an input power Pin (apparent power) from the PFC circuit 61 to the inverter 60, and determines that the positional relationship is appropriate when the calculated ratio exceeds a predetermined ratio. This determination method is based on the consideration that as the relative positional relationship approaches the appropriate positional relationship, the coupling coefficient between the power transmitter coil 22 and the power receiver coil 102 increases, and the ratio becomes larger. In addition, the power-transmitter controller 71 may, for example, calculate the above ratio based on the detected values from current and voltage sensors that detect the input current and input voltage to the inverter 60, as well as the detected values from current and voltage sensors that detect the output current and output voltage of the inverter 60. In addition, in the determination process of step S51, other parameters such as a detected value of a current flowing through the power transmitter coil 22 may be used in addition to the power.

[0100] When the power-transmitter controller 71 determines in step S51 that the positional relationship is not appropriate, it proceeds to step S12 and stops the energization (preliminary energization) of the power transmitter coil 22 by stopping the switching control of the PFC circuit 61 and the inverter 60.

[0101] On the other hand, when the power-transmitter controller 71 determines in step S51 that the positional relationship is appropriate, the process proceeds to step S13. In step S13, the power-transmitter controller 71, using the frequency set during the tracking process in step S50, performs the switching control of the PFC circuit 61 and the inverter 60 to energize the power transmitter coil 22 for the above-mentioned predetermined period in order to perform main energization with a larger transmission power than the energization during the tracking process (corresponding to the "preliminary energization").

[0102] After that, in step S16, the power-transmitter controller 71 uses the energization period Te of the power transmitter coil 22 during execution of the main energization to calculate the ratio Rr.

[0103] According to the present embodiment described above, main energization is performed in a state where the degree of magnetic coupling between the power receiver coil 102 and the power transmitter coil 22 is set to an appropriate degree for wireless power transfer. This makes it possible to improve the efficiency of wireless power transfer.

[0104] Modification of Fourth Embodiment The configuration of the fourth embodiment can also be applied to the second and third embodiments.

[0105] Fifth Embodiment Hereinafter, a fifth embodiment will be described with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, the power-transmitter controller 71 further uses a deviation degree to diagnose the communication function of the power transmitter 20. As shown in FIG. 12, when the vehicle 11 travels on lane LL, the deviation degree is the distance D2 in the vehicle width direction between the central position in the vehicle width direction of the power-receiver coil unit 101 (e.g., power-receiver communication coil 170) and the central position in the vehicle width direction of the power-transmitter coil unit 21 (e.g., power-transmitter communication coil 40). The power-transmitter controller 71 may calculate the deviation degree D2 based on the current position information of the vehicle 11 detected by the position sensor 330 and road information which has been received via wide area wireless communication, for example.

[0106] As shown in FIG. 12, the communication range of the power-receiver communication coil 170 may be, for example, an elliptical communication range 500 as indicated by the dashed dotted line. That is, in this case, the communication range in the vehicle width direction becomes narrower toward the front or rear end of the vehicle 11 in the vehicle length direction. In other words, the communication range in the vehicle length direction becomes narrower toward ends of the vehicle 11 in the vehicle width direction. In this case, even if the transmission intensity of the power supply request signal from the power-receiver communication coil 170 is the same, the energization period Te changes according to the deviation degree D2. Specifically, the larger the deviation degree D2, the shorter the energization period Te. FIGS. 13 and 14 show calculation results of supply power during the transmission period of the power supply request signal COMM when the deviation degree D2 is 0 and when the deviation degree D2 is K (>0). In FIGS. 13 and 14, the horizontal axis indicates the relative position in the vehicle length direction between the central position in the vehicle length direction of the power-receiver coil unit 101 (i.e., power-receiver communication coil 170) and the central position in the vehicle length direction of the power-transmitter coil unit 21 (i.e., power-transmitter communication coil 40). One scale unit on the horizontal axis is K. The vertical axis of the supply power in FIGS. 13 and 14 corresponds to the energization period Te. One scale unit on the vertical axis is P. When the deviation degree D2 increases, the ratio of the power supply continuation period (i.e., the energization period Te) to the transmission period of the power supply request signal decreases. If the energization period Te during which the deviation degree D2 is large is used to calculate the ratio Rr, there is a concern that the accuracy of diagnosing the communication function of the power transmitter 20 may decrease.

[0107] Therefore, the power-transmitter controller 71 further uses the acquired deviation degree D2 to diagnose the communication function of the power transmitter 20.

[0108] FIG. 15 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.

[0109] After completing step S15, in step S52, the power-transmitter controller 71 calculates the deviation degree D2.

[0110] In step S53, the power-transmitter controller 71 corrects the energization period Te based on the calculated deviation degree D2. Specifically, the power-transmitter controller 71 corrects the energization period Te to be longer as the deviation degree D2 increases. The power-transmitter controller 71 may calculate the corrected energization period Te based on map information or formula information in which the deviation degree D2 and the corrected energization period Te are associated with each other, for example.

[0111] In step S16, the power-transmitter controller 71 uses the energization period Te corrected in step S53 to calculate the ratio Rr.

[0112] According to the present embodiment described above, the deviation degree D2 of the vehicle 11 can be taken into consideration, so that the accuracy of diagnosing the communication function of the power transmitter 20 can be improved.

[0113] Modification of Fifth Embodiment The configuration of the fifth embodiment can also be applied to the second to fourth embodiment embodiments.

[0114] The power-transmitter controller 71 may correct the ratio Rr calculated in step S16, instead of the energization period Te, based on the calculated deviation degree D2. Specifically, the power-transmitter controller 71 may perform correction so that the ratio Rr increases as the deviation degree D2 increases.

[0115] Other Embodiments The above embodiments may be changed and carried out as follows.

[0116] In steps S17 and S19 in FIG. 7, steps S25 and S26 in FIG. 9, and steps S42 and S44 in FIG. 10, the determination period Tjde may be used instead of the ratio Rr or the average value Rave. Using FIG. 7 as an example, the process of step S17 is a process of determining whether "PLth ≦ Tjde ≦ PHth" is true. The lower limit period PLth is a value smaller than the upper limit period PHth. The lower limit period PLth and the upper limit period PHth are set to be smaller as the vehicle traveling speed increases. The information on the traveling speed used here may be acquired through narrow area wireless communication in the process of step S10. Moreover, the process of step S19 is a process of determining whether "Tjde < PLth" is satisfied. The lower limit period PLth is a threshold for diagnosing that the communication sensitivity is outside the assumed sensitivity range on the high-sensitivity side. The upper limit period PHth is a threshold for diagnosing that the communication sensitivity is outside the assumed sensitivity range on the low-sensitivity side.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] Characteristic configurations extracted from the above embodiments will be described below. A program for a power transmitter applied to a wireless power transfer system (10). 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 requesting power supply 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 receives the power supply request signal. The power transmitter includes a power-transmitter communication antenna (40) and a power-transmitter control unit (70). The power-transmitter communication antenna is configured to receive the power supply request signal wirelessly transmitted from a power-receiver communication antenna (170) provided in the power receiver. The program configured to cause the power-transmitter control unit to carry out calculating an intensity of the power supply request signal based on an output signal of the power-transmitter communication antenna, energizing the power transmitting antenna when determining that the calculated intensity exceeds a determination threshold, and calculating a determination period that is a period from when the calculated intensity exceeds the determination threshold until the calculated intensity falls below the determination threshold. The wireless power transfer system includes a diagnostic unit (70) configured to diagnose a communication function of the power transmitter based on the calculated determination period. A control method for a power transmitter applied to a wireless power transfer system (10). 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 requesting power supply 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 receives the power supply request signal. The power transmitter includes a power-transmitter communication antenna (40) and a power-transmitter control unit (70). The power-transmitter communication antenna is configured to receive the power supply request signal wirelessly transmitted from a power-receiver communication antenna (170) provided in the power receiver. The control method includes causing the power-transmitter control unit to carry out calculating an intensity of the power supply request signal based on an output signal of the power-transmitter communication antenna, energizing the power transmitting antenna when determining that the calculated intensity exceeds a determination threshold, and calculating a determination period that is a period from when the calculated intensity exceeds the determination threshold until the calculated intensity falls below the determination threshold. The wireless power transfer system includes a diagnostic unit (70) configured to diagnose a communication function of the power transmitter based on the calculated determination period.

[0128] 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 wireless power transfer system (10) comprising: a power transmitter (20) having a power transmitting antenna (22); and a power receiver (100) having a power receiving antenna (102), wherein the power transmitting antenna is configured to wirelessly supply power to the power receiving antenna, one of the power receiver and the power transmitter is mounted on a vehicle (11), the other of the power receiver and the power transmitter is a ground-side device, the power receiver includes a power-receiver communication antenna (170), and a power-receiver control unit (230) configured to perform energization control of the power-receiver communication antenna to supply a power supply request signal, which indicates power supply request to the power transmitting antenna, to the power-receiver communication antenna, the power transmitter includes a power-transmitter communication antenna (40) configured to perform wireless communication with the power-receiver communication antenna, and a power-transmitter control unit (70), the power-transmitter control unit is configured to calculate an intensity of the power supply request signal based on an output signal of the power-transmitter communication antenna, and energize the power transmitting antenna when determining that the calculated intensity exceeds a determination threshold, and the wireless power transfer system comprises: a period calculation unit (70) configured to calculate a determination period that is a period from when the calculated intensity exceeds the determination threshold until the calculated intensity falls below the determination threshold; and a diagnostic unit (70, 400) configured to diagnose a communication function of the power transmitter based on the calculated determination period.

2. The wireless power transfer system according to claim 1, wherein the diagnostic unit is configured to calculate a ratio between the calculated determination period and an energization period of the power transmitting antenna, and diagnose the communication function of the power transmitter based on the calculated ratio.

3. The wireless power transfer system according to claim 2, wherein the diagnostic unit is configured to increase a receiving sensitivity of the power transmitter when diagnosing that a communication sensitivity of the power transmitter is outside an assumed sensitivity range on a low-sensitivity side based on the calculated ratio, and decrease the receiving sensitivity of the power transmitter when diagnosing that the communication sensitivity of the power transmitter is outside the assumed sensitivity range on a high-sensitivity side based on the calculated ratio.

4. The wireless power transfer system according to claim 2 or 3, wherein the diagnostic unit is configured to calculate the ratio for multiple vehicles, and diagnose the communication function of the power transmitter based on calculated ratios corresponding to the multiple vehicles.

5. The wireless power transfer system according to any one of claims 1 to 3, wherein the power receiver is mounted on the vehicle, the power transmitter is the ground-side device, the power transmitter includes the period calculation unit, and the period calculation unit is configured to calculate the determination period on condition that the period calculation unit determines that the vehicle corresponding to the calculated intensity is an inspection vehicle in which adjustment of a transmission intensity of the power supply request signal has been completed.

6. The wireless power transfer system according to any one of claims 1 to 3, wherein the power transmitter includes the period calculation unit and the diagnostic unit.

7. The wireless power transfer system according to any one of claims 1 to 3, further comprising a server (400), wherein the power transmitter includes the period calculation unit, the server includes the diagnostic unit, the power-transmitter control unit is configured to transmit the calculated determination period to the server, and the diagnostic unit of the server is configured to diagnose the communication function of the power transmitter based on the received determination period.

8. The wireless power transfer system according to claim 2 or 3, wherein the power-transmitter control unit is configured to execute a preliminary energization process performing preliminary energization of the power transmitting antenna when determining that the calculated intensity exceeds the determination threshold, determine, during execution of the preliminary energization process, whether a relative positional relationship between the power transmitting antenna and the power receiving antenna is appropriate, and execute main energization of the power transmitting antenna on condition that the relative positional relationship is determined to be appropriate, the main energization being larger in transmission power than the preliminary energization, and the diagnostic unit is configured to calculate a ratio between the calculated determination period and an energization period of the power transmitting antenna during execution of the main energization.

9. The wireless power transfer system according to claim 2 or 3, wherein the power receiver is mounted on the vehicle, the power transmitter is the ground-side device, the power transmitting antenna is one of power transmitting antennas arranged at predetermined intervals along a lane, and the diagnostic unit is configured to acquire a deviation degree of the vehicle in a vehicle width direction relative to the power transmitting antenna when the vehicle is traveling on the lane, and diagnose the communication function of the power transmitter using the acquired deviation degree.

10. A program for a wireless power transfer system (10), the system including a power transmitter (20) having a power transmitting antenna (22), and a power receiver (100) having a power receiving antenna (102), the power transmitting antenna being configured to wirelessly supply power to the power receiving antenna, one of the power receiver and the power transmitter being mounted on a vehicle (11), the other of the power receiver and the power transmitter being a ground-side device, the power receiver including a power-receiver communication antenna (170), and a power-receiver control unit (230) configured to perform energization control of the power-receiver communication antenna to supply a power supply request signal, which indicates power supply request to the power transmitting antenna, to the power-receiver communication antenna, the power transmitter including a power-transmitter communication antenna (40) configured to perform wireless communication with the power-receiver communication antenna, and a power-transmitter control unit (70), the program configured to cause the power-transmitter control unit to carry out: calculating an intensity of the power supply request signal based on an output signal of the power-transmitter communication antenna; and performing energization of the power transmitting antenna when determining that the calculated intensity exceeds a determination threshold, the program configured to cause the wireless power transfer system to carry out: calculating a determination period that is a period from when the calculated intensity exceeds the determination threshold until the calculated intensity falls below the determination threshold; and diagnosing a communication function of the power transmitter based on the calculated determination period.

11. A control method for a wireless power transfer system (10), the system including a power transmitter (20) having a power transmitting antenna (22), and a power receiver (100) having a power receiving antenna (102), the power transmitting antenna being configured to wirelessly supply power to the power receiving antenna, one of the power receiver and the power transmitter being mounted on a vehicle (11), the other of the power receiver and the power transmitter being a ground-side device, the power receiver including a power-receiver communication antenna (170), and a power-receiver control unit (230) configured to perform energization control of the power-receiver communication antenna to supply a power supply request signal, which indicates power supply request to the power transmitting antenna, to the power-receiver communication antenna, the power transmitter includes a power-transmitter communication antenna (40) configured to perform wireless communication with the power-receiver communication antenna, and a power-transmitter control unit (70), the control method comprising: causing the power-transmitter control unit to carry out calculating an intensity of the power supply request signal based on an output signal of the power-transmitter communication antenna, and performing energization of the power transmitting antenna when determining that the calculated intensity exceeds a determination threshold; and causing the wireless power transfer system to carry out calculating a determination period that is a period from when the calculated intensity exceeds the determination threshold until the calculated intensity falls below the determination threshold; and diagnosing a communication function of the power transmitter based on the calculated determination period.

12. 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 requesting power supply 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 receives the 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) of the power receiver; and a power-transmitter control unit (70), wherein the power-transmitter control unit is configured to calculate an intensity of the power supply request signal based on an output signal of the power-transmitter communication antenna, energize the power transmitting antenna when determining that the calculated intensity exceeds a determination threshold, and calculate a determination period that is a period from when the calculated intensity exceeds the determination threshold until the calculated intensity falls below the determination threshold, and the wireless power transfer system includes a diagnostic unit (70) configured to diagnose a communication function of the power transmitter based on the calculated determination period.

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