Power receiver, program, and control method

Abstract

A wireless power transfer system (10) includes a power transmitter (20) having a power transmitter circuit (400) including a power transmitter coil (22), and a power receiver (100) having a power receiver circuit (500) including a power receiver coil (102), and energizes the power transmitter coil (22) to perform wireless power transfer to the power receiver coil (102). The power receiver circuit (500) includes a power-receiver resonant circuit (140) and a rectifier circuit (200). The power receiver (100) includes a power-receiver communication device (240) that acquires power-transmitter information including at least information related to an output characteristic of the power transmitter circuit (400), and a power-receiver control unit (230) that controls the rectifier circuit (200). The power-receiver control unit (230) changes an amplitude of an output voltage of the power-receiver resonant circuit (140) input to the rectifier circuit (200) based on the information related to the output characteristic of the power transmitter circuit (400) acquired by the power-receiver communication device (240).

Description

POWER RECEIVER, PROGRAM, AND CONTROL METHODCross Reference

[0001] This application is based on Japanese Patent Application No. 2025-019567 filed on February 7, 2025, the contents of which are incorporated herein by reference.

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

[0003] Conventionally, as described in, for example, Patent Literature 1, a wireless power transfer system is known, which includes a power transmitter circuit having a power transmitter coil arranged along the travel path of a vehicle, and a power receiver circuit provided in the vehicle and having a power receiver coil, wherein wireless power transfer is performed from the power transmitter coil to the power receiver coil.

[0004] JP 2024-008088 A

[0005] There are various types of power transmitter coils and power transmitter circuit topologies in a power transmitter on the ground side, and depending on a combination with a power receiver circuit on the vehicle side, stable power supply may not be possible in some cases.

[0006] An object of the present disclosure is to provide a power receiver, a program, and a control method, which are capable of suppressing an occurrence of disadvantages caused by differences in combinations.

[0007] According to an aspect of the present disclosure, a power receiver is for a wireless power transfer system including a vehicle-side device and a ground-side device. One of the vehicle-side device and the ground-side device is a power transmitter having a power transmitting antenna and a power transmitter circuit. Another of the vehicle-side device and the ground-side device is the power receiver having a power receiving antenna and a power receiver circuit. The power transmitting antenna is configured to be energized to perform wireless power transfer to the power receiving antenna. The power receiver circuit includes a power-receiver resonator configured to resonate with the power receiving antenna, and a power converter configured to convert power received by the power receiving antenna to correspond to power required by a power supply target device. The power receiver includes an information acquisition unit configured to acquire power-transmitter information including at least information related to an output characteristic of the power transmitter circuit, and a power-receiver control unit configured to control the power converter. The power-receiver control unit is configured to change an amplitude of an output voltage of the power-receiver resonator input to the power converter, based on the information related to the output characteristic of the power transmitter circuit acquired by the information acquisition unit.

[0008] According to the above configuration, even when combination of the power receiver circuit and the power transmitter circuit is not appropriate, the information related to the output characteristic of the power transmitter circuit can be acquired in advance, and control related to wireless power transfer can be changed, thereby suppressing occurrence of the aforementioned disadvantages.

[0009] According to an aspect of the present disclosure, a program is for a power receiver to be applied to a wireless power transfer system including a vehicle-side device and a ground-side device. One of the vehicle-side device and the ground-side device is a power transmitter having a power transmitting antenna and a power transmitter circuit. Another of the vehicle-side device and the ground-side device is the power receiver having a power receiving antenna and a power receiver circuit. The power transmitting antenna is configured to be energized to perform wireless power transfer to the power receiving antenna. The power receiver circuit includes a power-receiver resonator configured to resonate with the power receiving antenna, and a power converter configured to convert power received by the power receiving antenna to correspond to power required by a power supply target device. The program is configured to perform an information acquisition step of acquiring power-transmitter information including at least information related to an output characteristic of the power transmitter circuit, and a power-receiver control step of controlling the power converter. The power-receiver control step includes changing an amplitude of an output voltage of the power-receiver resonator input to the power converter, based on the information related to the output characteristic of the power transmitter circuit acquired by the information acquisition step.

[0010] According to the above configuration, even when combination of the power receiver circuit and the power transmitter circuit is not appropriate, the information related to the output characteristic of the power transmitter circuit can be acquired in advance, and control related to wireless power transfer can be changed, thereby suppressing occurrence of the aforementioned disadvantages.

[0011] According to an aspect of the present disclosure, a control method is for a power receiver to be applied to a wireless power transfer system including a vehicle-side device and a ground-side device. One of the vehicle-side device and the ground-side device is a power transmitter having a power transmitting antenna and a power transmitter circuit. Another of the vehicle-side device and the ground-side device is the power receiver having a power receiving antenna and a power receiver circuit. The power transmitting antenna is configured to be energized to perform wireless power transfer to the power receiving antenna. The power receiver circuit includes a power-receiver resonator configured to resonate with the power receiving antenna, and a power converter configured to convert power received by the power receiving antenna to correspond to power required by a power supply target device. The control method includes an information acquisition step of acquiring power-transmitter information including at least information related to an output characteristic of the power transmitter circuit, and a power-receiver control step of controlling the power converter. The power-receiver control step includes changing an amplitude of an output voltage of the power-receiver resonator input to the power converter, based on the information related to the output characteristic of the power transmitter circuit acquired by the information acquisition step.

[0012] According to the above configuration, even when combination of the power receiver circuit and the power transmitter circuit is not appropriate, the information related to the output characteristic of the power transmitter circuit can be acquired in advance, and control related to wireless power transfer can be changed, thereby suppressing occurrence of the aforementioned disadvantages.

[0013] 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 an example of an appropriate combination of a power transmitter circuit and a power receiver circuit in an SS topology.FIG. 6 is a diagram illustrating an example of an appropriate combination of the power transmitter circuit and the power receiver circuit in a Double-LCC topology.FIG. 7 is a diagram illustrating an example in which the combination of the power transmitter circuit and the power receiver circuit is not an appropriate combination.FIG. 8 is a flowchart of a power-transfer start process.FIG. 9 is a flowchart of an adjustment process.FIG. 10 is a configuration diagram of a power receiver circuit according to a second embodiment.FIG. 11 is a flowchart of a power-transfer start process according to a second embodiment.FIG. 12 is a block diagram of an information acquisition unit according to a modification.FIG. 13 is a diagram illustrating a switching pattern of a rectifier.FIG. 14 is a diagram illustrating a switching pattern of a rectifier.FIG. 15 is a diagram illustrating a switching pattern of a rectifier.FIG. 16 is a diagram illustrating a switching pattern of a rectifier.

[0014] Multiple embodiments will be described with reference to the drawings. In the embodiments, functionally and / or structurally corresponding and / or associated parts may be assigned the same reference numerals. The corresponding and / or associated parts may refer to the explanation in the other embodiments.

[0015] First Embodiment 　　　　　　 A first embodiment of a wireless power transfer system of the present disclosure will be described below with reference to the drawings.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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. In the present embodiment, the PFC circuit 61 functions as a direct-current voltage source.

[0020] The inverter 60 is connected to the PFC circuit 61. By controlling switching of the switching elements (e.g., IGBT or MOSFET) S1H, S1L, S2H, S2L provided in the inverter 60, the DC power input from the PFC circuit 61 is converted into AC power.

[0021] 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 may be used as the filter circuit 52.

[0022] 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. In the present embodiment, the inverter 60, the filter circuit 52, and the power-transmitter resonant circuit 30 constitute the power transmitter circuit 400.

[0023] 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.

[0024] The power receiver 100 includes a power-receiver resonant circuit 140 (power-receiver resonator). 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.

[0025] 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.

[0026] 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). In the present embodiment, the power-receiver resonant circuit 140, the filter circuit 182, and the rectifier circuit 200 constitute the power receiver circuit 500. The rectifier circuit 200 of the present embodiment is configured as a full-bridge circuit including a semiconductor switching element.

[0027] 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.

[0028] 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. In the present embodiment, the high-voltage storage battery 300 corresponds to a "power supply target device."

[0029] The power-transmitter power supply unit 51, which constitutes the power transmitter 20, is provided with 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.

[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-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.

[0031] The power-receiver power supply unit 181, which constitutes the power receiver 100, includes a power-receiver control unit 230. The power-receiver control unit 230 includes a power-receiver controller 231. The power-receiver controller 231 is an ECU that 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.

[0032] 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.

[0033] The power-transmitter controller 71 performs switching control of the PFC circuit 61 and 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 transfer is generated in the power transmitter coils 22.

[0034] 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.

[0035] 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.

[0036] 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.

[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). The power-receiver control unit 230 includes a power-receiver communication device 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 power-transmitter communication device 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 communication is communication 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 power-receiver communication device 240 is connected to the power-receiver controller 231. The power-receiver communication coil 170 is connected to the power-receiver communication device 240. The power-receiver controller 231 controls the power-receiver communication device 240 to supply a signal to the power-receiver communication coil 170 when transmitting a signal. For example, the power-receiver controller 231 controls the power-receiver communication device 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 includes a vehicle-side signal, which contains the power supply request signal COMM, 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 power-receiver communication device 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 the present embodiment, the power supply request signal includes ID information for identifying the vehicle 11 and a requested power Weq that is a requested value of power to be supplied to the vehicle 11.

[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 power-transmitter communication device 80. The power-transmitter communication device 80 recognizes information based on the signal input from the power-transmitter communication coil 40. For example, the power-transmitter communication device 80 recognizes the presence or absence of a power supply request and the ID information based on the power supply request signal COMM input from the power-transmitter communication coil 40. Further, the power-transmitter communication device 80 acquires the requested power Weq of the vehicle 11 corresponding to the recognized ID information based on the power supply request signal COMM. The information recognized by the power-transmitter communication device 80 is input to the power-transmitter controller 71.

[0043] In the present embodiment, the power-receiver controller 231 controls the power-receiver communication device 240 so that, when transmitting a signal, 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 is capable of determining whether to energize the power transmitter coil 22 based on the input signal from the power-transmitter communication device 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 power-transmitter communication device 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.

[0045] Specifically, 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 switching elements of the PFC circuit 61 and the inverter 60 are kept off, and the power transmitter coil 22 is not energized.

[0046] 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.

[0047] When applying a high-frequency voltage to the power transmitter coil 22, the power-transmitter controller 71 performs frequency control. The frequency control adjusts an effective power Wact supplied from the inverter 60 to the filter circuit 52 by adjusting an output voltage frequency fout from the inverter 60 to the filter circuit 52. Based on the requested power Weq, the power-transmitter controller 71 alternately turns on the pair of the first upper arm switch S1H and the second lower arm switch S2L, and the pair of the first lower arm switch S1L and the second upper arm switch S2H, in order to adjust the output voltage frequency fout.

[0048] The power-receiver communication device 240 has a signal-receiving function similar to that of the power-transmitter communication device 80, and the power-transmitter communication device 80 has a signal-transmitting function similar to that of the power-receiver communication device 240. The power-transmitter communication device 80 is capable of transmitting signals, and the signals (information) transmitted from the power-transmitter communication device 80 can be received by the power-receiver communication device 240.

[0049] FIG. 4 is a schematic diagram for explaining wide area wireless communications 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.

[0050] 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 11, 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 11 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.

[0051] The wireless power transfer system 10 includes a server 410. The server 410 is, for example, a cloud server, and includes a server controller 411 and a communication unit 412. The server controller 411 is an electronic control unit (ECU) that executes various controls of the server 410 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 411. 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.

[0052] The server controller 411 is connected to the communication unit 412. The server controller 411 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 412 and the communication network 16.

[0053] 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 controller 411. The storage medium is, for example, a USB memory, a CD-ROM, or a DVD. In addition, program information transmitted over a communication network 16, such as OTA (Over The Air), is installed in the storage units.

[0054] An output characteristic of the power transmitter circuit 400 and an output characteristic of the power transmitter circuit 400 required by the power receiver circuit 500 will be described. The output characteristic refers to a property indicating what kind of current or voltage is used to supply power to power transfer target (such as a power supply target device) that receives the electric power. The output characteristic includes, for example, a current source characteristic, in which power is supplied at a constant current to the power transfer target that is the power supply destination, and a voltage source characteristic, in which power is supplied at a constant voltage to the power transfer target. There is also a characteristic intermediate between the current source characteristic and the voltage source characteristic. This intermediate characteristic can generally be classified as being closer to either the current source characteristic or the voltage source characteristic. In the present embodiment, a circuit having the current source characteristic and a circuit having a characteristic close to the current source characteristic are collectively referred to as a "current source," while a circuit having the voltage source characteristic and a circuit having a characteristic close to the voltage source characteristic are collectively referred to as a "voltage source."

[0055] In order to identify the output characteristic, the current and voltage may be measured while varying the load during power supply. To identify the output characteristic of the power transmitter circuit 400, the current and voltage supplied from the power transmitter circuit 400 to the power transmitter coil 22 may be measured. In addition, the output characteristic of the power receiver coil 102 between the power receiver coil 102 and the power receiver circuit 500 at the time of wireless power transfer may be obtained by measuring a current and a voltage flowing from the power receiver coil 102 to the power receiver circuit 500 (in the present embodiment, the power-receiver resonant circuit 140). Also, to identify the output characteristic of the power receiver circuit 500, the current and voltage supplied from the power transmitter circuit 400 to the high-voltage storage battery 300 may be measured . The output characteristic can also be identified based on the circuit configuration. In addition, when the output characteristic of the power transmitter circuit 400 required by the power receiver circuit 500 match the output characteristic of the power transmitter circuit 400, the combination of the power transmitter circuit 400 and the power receiver circuit 500 is appropriate, indicating that the power receiver circuit 500 is compatible with the output characteristic of the power transmitter circuit 400. When the compatibility is present, the power receiver circuit 500 is able to appropriately receive power from the power transmitter circuit 400.

[0056] Next, the combination of the output characteristic of the power transmitter circuit 400 and the output characteristic of the power receiver circuit 500 will be explained. FIGS. 5 and 6 show examples of typical combinations.

[0057] FIG. 5 illustrates a wireless power transfer system 10 employing an SS (Series-Series) topology. The power transmitter circuit 400 of this system includes a band-pass filter as the filter circuit 52. The band-pass filter includes a parallel capacitor 53A connected in parallel to the power transmitter coil 22, series capacitors 53B connected in series to the power transmitter coil 22, and inductors 53C connected in series to the series capacitors 53B. In addition, the power transmitter circuit 400 includes two series capacitors 23 as the power-transmitter resonant circuit 30. A first terminal of each series capacitor 23 is connected an end of the power transmitter coil 22. A second terminal of each series capacitor 23 is connected to the parallel capacitor 53A of the band-pass filter. Further, in this embodiment, the output characteristic of the power transmitter circuit 400 is a characteristic of output from the power-transmitter resonant circuit 30 to the power transmitter coil 22 (i.e., output characteristic between the power-transmitter resonant circuit 30 and the power transmitter coil 22).

[0058] The power receiver circuit 500 of the wireless power transfer system 10 having the SS topology includes a band-pass filter as the filter circuit 182. The band-pass filter includes a parallel capacitor 183A connected in parallel with the power receiver coil 102, series capacitors 183B connected in series with the power receiver coil 102, and inductors 183C connected in series with the series capacitors 183B. In addition, the power receiver circuit 500 includes two series capacitors 141 as the power-receiver resonant circuit 140. A first end of each series capacitor 141 is connected to an end of the power receiver coil 102. A second end of each series capacitor 141 is connected to the parallel capacitor 183A of the band-pass filter.

[0059] The rectifier circuit 200 of the power receiver circuit 500 includes a pair consisting of a first upper arm switch S11H and a second lower arm switch S12L, and a pair consisting of a first lower arm switch S11L and a second upper arm switch S12H. The rectifier circuit 200 includes switching elements (e.g., IGBT or MOSFET) S11H, S12L, S12H, S12L that are controlled to be switched for converting the AC power input from the power receiver coil 102 into DC power. In the present embodiment, the rectifier circuit 200 corresponds to a power converter.

[0060] In the wireless power transfer system 10 having the SS topology, the inverter 60 is supplied with power from the PFC circuit 61, which functions as a voltage source, and, switching control is performed so that the output characteristic of the inverter 60 functions as the voltage source for the filter circuit 52. The filter circuit 52 does not have a function as an immittance converter that performs immittance conversion. Therefore, when the inverter 60 serves as a voltage source, the output characteristic of the filter circuit 52 functions as the voltage source for the power-transmitter resonant circuit 30 which is a power transmission destination. The immittance conversion refers to impedance-admittance conversion; in the present embodiment, if the power transmission source is a current source, it is converted to a voltage source, and if the power transmission source is a voltage source, it is converted to a current source.

[0061] Since the power-transmitter resonant circuit 30 only includes the two series capacitors 23, when the output characteristic of the filter circuit 52 functions as the voltage source, the output characteristic of the power-transmitter resonant circuit 30 (that is, the output characteristic of the power transmitter circuit 400) functions as the voltage source for the power transmitter coil 22 which is an power transmission destination.

[0062] In addition, in the present embodiment, since the power transmitter coil 22 and the power receiver coil 102 have the function of the immittance converter, the output characteristic (i.e., the output characteristic of the power receiver coil 102) functions as the current source for the power-receiver resonant circuit 140 which is a power transmission destination. Further, in the present embodiment, since the power-receiver resonant circuit 140 only includes two series capacitors 141, when the output characteristic of the power receiver coil 102 functions as the current source, the output characteristic of the power-receiver resonant circuit 140 functions as the current source for the filter circuit 182 which is a power transmission destination.

[0063] Since the filter circuit 182 does not have a function as the immittance converter, the output characteristic of the filter circuit 182 functions as the current source for the rectifier circuit 200 which is a power transmission destination. As a result, the output characteristic for the rectifier circuit 200 and the high-voltage storage battery 300 becomes the current source. In a normal state, switching control is performed in the rectifier circuit 200 so that its output characteristic for the high-voltage storage battery 300 is not converted. That is, the output characteristic of the rectifier circuit 200 for the high-voltage storage battery 300 (i.e., the output characteristic of the power receiver circuit 500) functions as the current source.

[0064] In the present embodiment, the output characteristic of the power transmitter circuit 400 required by the power receiver circuit 500 allows the current power receiver circuit 500 to appropriately receive power from the power transmitter circuit 400. The output characteristic of the power transmitter circuit 400 is determined by the circuit configuration of the power receiver circuit 500, the control by the power-receiver controller 231, and the power supply target device to which power is supplied from the power receiver circuit 500. When the high-voltage storage battery 300 is being charged, it requires the current source as the output characteristic of a power supply. In the power receiver circuit 500 shown in FIG. 5, the output characteristic of the power transmitter circuit 400 is converted to supply power to the high-voltage storage battery 300. Therefore, the power receiver circuit 500 shown in FIG. 5 requires the output characteristic of the power transmitter circuit 400 to function as the voltage source. Whether the power receiver circuit 500 converts the output characteristic of the power transmitter circuit 400 to supply power to the power supply target device (such as the high-voltage storage battery 300) depends on the circuit configuration of the power receiver circuit 500 and the control content of the power-receiver control unit 230 that controls the power receiver circuit 500.

[0065] In FIG. 5, the power transmitter circuit 400 may not be provided with the filter circuit 52, and the power receiver circuit 500 may not be provided with the filter circuit 182.

[0066] FIG. 6 illustrates a wireless power transfer system 10 employing the Double-LCC (Double-sided inductor-capacitor-capacitor) topology. The power transmitter circuit 400 of this system includes an immittance filter as the filter circuit 52. The immittance filter includes first inductors 54A connected in series with the power transmitter coil 22, second inductors 54C connected in series with the first inductors 54A, and a capacitor 54B. The capacitor 54B is connected to the connection points between the first inductors 54A and the second inductors 54C. In addition, the power transmitter circuit 400 includes two series capacitors 23 as the power-transmitter resonant circuit 30, in the same manner as in FIG. 5.

[0067] The power receiver circuit 500 of the wireless power transfer system 10 having the Double-LCC topology includes an immittance filter as the filter circuit 182. The immittance filter includes first inductors 184A connected in series with the power receiver coil 102, second inductors 184C connected in series with the first inductors 184A, and a capacitor 184B. The capacitor 184B is connected to the connection points between the first inductors 184A and the second inductors 184C. In addition, the power receiver circuit 500 includes two series capacitors 141 as the power-receiver resonant circuit 140, in the same manner as in FIG. 5.

[0068] The rectifier circuit 200 of the power receiver circuit 500 includes a pair consisting of a first upper arm switch S11H and a second lower arm switch S12L, and a pair consisting of a first lower arm switch S11L and a second upper arm switch S12H. The rectifier circuit 200 includes switching elements (e.g., IGBT or MOSFET) S11H, S12L, S12H, S12L that are controlled to be switched for converting the AC power input from the power receiver coil 102 into DC power. In the present embodiment, the rectifier circuit 200 corresponds to a power converter.

[0069] In the wireless power transfer system 10 having the Double-LCC topology, the filter circuit 52 has a function as the immittance converter. Therefore, when the inverter 60 serves as a voltage source, the output characteristic of the filter circuit 52 (i.e., the output characteristic of the power transmitter circuit 400) functions as the current source for the power-transmitter resonant circuit 30 which is a power transmission destination.

[0070] Since the power-transmitter resonant circuit 30 only includes the two series capacitors 23, when the output characteristic of the filter circuit 52 functions as the current source, the output characteristic of the power-transmitter resonant circuit 30 functions as the current source for the power transmitter coil 22 which is an power transmission destination.

[0071] In addition, in the present embodiment, since the power transmitter coil 22 and the power receiver coil 102 have the function of the immittance converter, the output characteristic (i.e., the output characteristic of the power receiver coil 102) functions as the voltage source for the power-receiver resonant circuit 140 which is a power transmission destination. Further, in the present embodiment, since the power-receiver resonant circuit 140 only includes two series capacitors 141, when the output characteristic of the power receiver coil 102 functions as the voltage source, the output characteristic of the power-receiver resonant circuit 140 functions as the voltage source for the filter circuit 182 which is a power transmission destination.

[0072] Since the filter circuit 182 has a function as the immittance converter, the output characteristic of the filter circuit 182 becomes the current source characteristic with respect to the rectifier circuit 200 which is a power transmission destination. As a result, the power supply to the rectifier circuit 200 and the high-voltage storage battery 300 becomes the current source. In the normal state, switching control is performed in the rectifier circuit 200 so that its output characteristic for the high-voltage storage battery 300 is not converted. That is, the output characteristic of the rectifier circuit 200 for the high-voltage storage battery 300 (i.e., the output characteristic of the power receiver circuit 500) functions as the current source.

[0073] When the high-voltage storage battery 300 is being charged, it requires the current source as the output characteristic of a power supply. In the power receiver circuit 500 shown in FIG. 6, the output characteristic of the power transmitter circuit 400 is conveyed as it is to the high-voltage storage battery 300. Therefore, the power receiver circuit 500 shown in FIG. 6 requires the output characteristic of the power transmitter circuit 400 to function as the current source.

[0074] In FIG. 6, the first inductors 54A in the filter circuit 52 of the power transmitter circuit 400, connected to the power transmitter coil 22, may be omitted. The function of the first inductors 54A may instead be substituted by the inductance of the power transmitter coil 22. Further, the first inductors 184A in the filter circuit 182 of the power receiver circuit 500, connected to the power receiver coil 102, may be omitted. The function of the first inductors 184A may instead be substituted by the inductance of the power receiver coil 102.

[0075] As illustrated in FIGS. 5 and 6, the output characteristic of the power receiver circuit 500 functions as the current source for the high-voltage storage battery 300. On the other hand, there may be multiple specifications set for the power transmitter circuit 400 that is distributed in the market. Additionally, there may be multiple specifications set for the power receiver circuit 500 that is distributed in the market. In this case, the combination of the power transmitter circuit 400 and the power receiver circuit 500 may not be appropriate, i.e., the output characteristic of the power transmitter circuit 400 required by the power receiver circuit 500 may not match the actual output characteristic of the power transmitter circuit 400. FIG. 7 illustrates an example in which the combination is not appropriate, wherein the power transmitter circuit 400 has the Double-LCC type topology (e.g., the power transmitter circuit 400 of FIG. 6), and the filter circuit 182 of the power receiver circuit 500 is a band-pass filter (e.g, the power receiver circuit 500 of FIG. 5) rather than an immittance filter.

[0076] In this case shown in FIG. 7, the output characteristic of the power transmitter circuit 400 functions as the current source, while the power receiver circuit 500 requires the output characteristic of the power transmitter circuit 400 to function as the voltage source; therefore, the combination is not appropriate. When the combination is not appropriate, the power supply to the high-voltage storage battery 300 becomes the voltage source, which may lead to potential problems. Specifically, during wireless power transfer, if the output voltage of the rectifier circuit 200 is higher than that of the high-voltage storage battery 300, there is a concern that a large current may flow from the rectifier circuit 200 to the high-voltage storage battery 300. In addition, during wireless power transfer, if the output voltage of the rectifier circuit 200 is lower than that of the high-voltage storage battery 300, there is a concern that the rectifier circuit 200 will be unable to supply current to the high-voltage storage battery 300.

[0077] To address such disadvantages, the power-receiver control unit 230 is configured to acquire power-transmitter information related to the power transmitter 20 before wireless power transfer is performed, and changes the control performed in the power receiver circuit 500 based on the output characteristic of the power transmitter circuit 400 included in the acquired power-transmitter information. Hereinafter, a process flow in which the power-receiver control unit 230 checks the power-transmitter information and starts wireless power transfer will be described with reference to FIG. 8. FIG. 8 is a flowchart illustrating the process flow of a power-transfer start process executed by the power-receiver control unit 230. The power-transfer start process is executed at a predetermined timing.

[0078] The power-receiver control unit 230 performs wide area wireless communication via the communication unit 332 to acquire first power-transmitter information relating to the power transmitter 20 that the vehicle 11 is scheduled to pass over next (Step S1). As a result, the communication unit 332 functions as an information acquisition unit and as a second information acquisition unit. The communication counterpart of the power-receiver control unit 230 may be the power transmitter 20 that the vehicle 11 is scheduled to pass over next, or may be the server 410. The power transmitter 20 that the vehicle 11 is scheduled to pass over next can be specified, for example, based on the position information of the vehicle 11 or the road information of the road on which the vehicle 11 is traveling.

[0079] The power-transmitter information includes at least information related to the output characteristic of the power transmitter circuit 400. The information related to the output characteristic of the power transmitter circuit 400 may be information that directly indicates the output characteristic of the power transmitter circuit 400, such as the voltage source. Alternatively, if the output characteristic of the power transmitter circuit 400 is stored in association with the model number (identification number, serial number, etc.) of the power transmitter 20, the information may be indirectly indicates the output characteristic of the power transmitter circuit 400 by such model number or the like. Further, the power-transmitter information may include, in addition to the output characteristic, the antenna information related to the power transmitter coil 22, the communication standard information related to communication standards, the power information related to transmitted power, and the startup sequence information, for example.

[0080] The antenna information is information related to the power transmitter coil 22, such as the coil shape (including size and transmission range) of the power transmitter coils 22, the number of power transmitter coils 22, and the inductance of the power transmitter coil 22, for example. The antenna information may also include information relating to the power-transmitter communication coil 40.

[0081] The communication standard information is information about what kind of communication is performed. For example, it is information such as whether wide area wireless communication is executable, whether narrow-area wireless communication is executable, or whether other communication methods are executable. Furthermore, in a case where narrow-area wireless communication is executable, information about a specific communication standard of narrow-area wireless communication may be included. For example, the information may include which communication standard among the above-mentioned communication standards for narrow area wireless communication, such as Wi-Fi (registered trademark) or Bluetooth (registered trademark), is to be used. When other communication methods (such as wide area wireless communication) are executable, information about a specific communication standard of such communication methods may also be included.

[0082] The startup sequence information is information related to a procedure until wireless power transfer is started. In the present embodiment, the startup sequence information includes a procedure in which wide area wireless communication is performed first, followed by narrow area wireless communication, then transmission and reception of a power supply request signal COMM, tracking, and finally wireless power transfer (main power transfer).

[0083] In the present embodiment, tracking refers to a process of experimentally transmitting a predetermined amount of power (test electromagnetic wave) to the power supply target device prior to the start of power transfer to the power receiver (before the start of main power transfer), in order to confirm whether power is being appropriately transmitted from the power transmitter coil 22 to the power receiver coil 102.

[0084] The power information is information relating to the amount of power to be transmitted, or the amount of power that can be transmitted from the power transmitter 20. Further, the power-transmitter information may include other information, for example, information related to controllability in a cloud or matching of system efficiency.

[0085] Subsequently, the power-receiver control unit 230 performs narrow area wireless communication to acquire second power-transmitter information relating to the power transmitter 20 that the vehicle 11 is scheduled to pass over next (step S2). In the present embodiment, the second power-transmitter information is acquired by receiving the signal output from the power-transmitter communication coil 40 using the power-receiver communication device 240 and the power-receiver communication coil 170. In the present embodiment, the power-receiver communication device 240 corresponds to the information acquisition unit and a first information acquisition unit. The processes in steps S1 and S2 correspond to information acquisition step.

[0086] The second power-transmitter information includes at least information related to the output characteristic of the power transmitter circuit 400. Further, the second power-transmitter information may include, in addition to the information related to the output characteristic, the antenna information related to the power transmitter coil 22, the communication standard information related to communication standards, the power information related to transmitted power, and the startup sequence information, for example. Further, the second power-transmitter information may include information that is not included in the first power-transmitter information, and conversely, it may not include information that is included in the first power-transmitter information.

[0087] Next, the power-receiver control unit 230 checks the consistency between the first power-transmitter information acquired in step S1 and the second power-transmitter information acquired in step S2 (step S3). In step S3, it is determined whether the content of the information included in the first power-transmitter information matches the content of the information included in the second power-transmitter information. For example, it is determined whether the output characteristic of the power transmitter circuit 400 included in the first power-transmitter information matches the output characteristic of the power transmitter circuit 400 included in the second power-transmitter information. Specifically, when the output characteristic of the power transmitter circuit 400 included in the first power-transmitter information is the current source, and the output characteristic of the power transmitter circuit 400 included in the second power-transmitter information is also the current source, it is determined that they match. On the other hand, when of the power transmitter circuit 400 included in the second power-transmitter information is the voltage source, it is determined that they do not match.

[0088] As described above, the contents included in the first power-transmitter information and the contents included in the second power-transmitter information may differ. Therefore, it is not verified whether the information included in the first power-transmitter information is also included in the second power-transmitter information. It is determined whether the contents of the included information match.

[0089] When the first power-transmitter information and the second power-transmitter information are not consistent (Step S3: NO), the power-receiver control unit 230 terminates the process. On the other hand, when the first power-transmitter information and the second power-transmitter information are consistent (Step S3: YES), the power-receiver control unit 230 determines whether the output characteristic of the power transmitter circuit 400 included in the power-transmitter information is compatible with the power receiver circuit 500 (Step S4). In Step S4, it is determined whether the output characteristic of the power transmitter circuit 400 matches the output characteristic of the power transmitter circuit 400 required by the power receiver circuit 500, that is, whether the combination of the power transmitter circuit 400 and the power receiver circuit 500 is appropriate. In the initial state (normal state), the output characteristic of the power transmitter circuit 400 required by the power receiver circuit 500 is, for example, stored in the storage unit of the power-receiver controller 231.

[0090] For example, when the output characteristic of the power transmitter circuit 400 is the current source, and the output characteristic required by the power receiver circuit 500 (i.e., an output characteristic that allows the power receiver circuit 500 to properly receive power) is also the current source, affirmative determination is made in step S4. On the other hand, when the output characteristic required by the power receiver circuit 500 is the voltage source, negative determination is made in step S4. Similarly, when the output characteristic of the power transmitter circuit 400 is the voltage source, and the output characteristic required by the power receiver circuit 500 is the voltage source, affirmative determination is made in step S4. On the other hand, when the output characteristic required by the power receiver circuit 500 is the current source, negative determination is made in step S4.

[0091] When the determination result in step S4 is affirmative, the power-receiver control unit 230 transmits a power supply request signal COMM (Step S5). Upon receiving the power supply request signal COMM, the power-transmitter controller 71 controls the power transmitter circuit 400 to transmit a predetermined test power (test signal) on a trial basis, and initiates tracking. The power-receiver control unit 230 receives the power transmitted by the tracking through its power receiver circuit 500 (Step S6).

[0092] The power-receiver control unit 230 determines whether the tracking has been performed normally (Step S7). In step S7, it is determined whether the test signal transmitted by the tracking is a predetermined test signal. Specifically, it is determined whether the waveform (such as amplitude and frequency) of the test signal is as predetermined.

[0093] When the determination result is negative, the power-receiver control unit 230 does not start wireless power transfer (main power transfer), and terminates the process. At that time, the power-receiver control unit 230 may transmit a stop signal, which notifies the suspension (stoppage) of wireless power transfer, via narrow area wireless communication (or wide area wireless communication).

[0094] On the other hand, when the determination result in step S7 is affirmative, the power-receiver control unit 230 starts wireless power transfer (main power transfer) (Step S8). Specifically, the power-transmitter controller 71 starts the main power transfer after a predetermined period has elapsed following the execution of the tracking. On the other hand, after the start of the main power transfer, the power-receiver control unit 230 supplies power to the high-voltage storage battery 300, which is the power supply target device, thereby charging it.

[0095] Until the main power transfer is started, the power-receiver control unit 230 implements short-circuit control of the power receiver coil 102 by means of a protection circuit (in the present embodiment, the rectifier circuit 200) to restrict power supply to the high-voltage storage battery 300. After the start of the main power transfer, the short-circuit control is released, rectification by the rectifier circuit 200 is performed, and power supply to the high-voltage storage battery 300 is started.

[0096] On the other hand, when the determination result in Step S4 is negative, the power-receiver control unit 230 performs a switching process to change the output characteristic (Step S9). In step S9, the power-receiver controller 231 determines (sets) to change the control of the rectifier circuit 200. Specifically, the power-receiver controller 231 determines (sets) to switch the control of the rectifier circuit 200 from frequency control to duty control. In the duty control, the pair consisting of the first upper arm switch S11H and the second lower arm switch S12L, and the pair consisting of the first lower arm switch S11L and the second upper arm switch S12H are alternately turned on at a predetermined switching period Tsw.

[0097] In the duty control, the duty cycle (= Ton / Tsw) is adjusted. The duty cycle is the ratio of the ON period Ton of the pair of the first upper arm switch S11H and the second lower arm switch S12L (or the pair of the first lower arm switch S11L and the second upper arm switch S12H) to the switching period Tsw. The larger the duty cycle, the greater the effective power Wact becomes.

[0098] Then, the power-receiver control unit 230 proceeds to the processing of step S5. After the processing of step S9, when the main power transfer (wireless power transfer) is started in step S8, the power-receiver control unit 230 changes the switching control of the rectifier circuit 200 as determined in step S9, in order to change the output characteristic. Specifically, the power-receiver controller 231 adjusts the duty cycle so that a constant current flows to the high-voltage storage battery 300. As a result, the output characteristic of the rectifier circuit 200 can be changed from the voltage source to the current source.

[0099] When the power receiver circuit 500 has the SS topology (e.g., the power receiver circuit 500 in FIG. 5) and the power transmitter circuit 400 has the Double-LCC topology (e.g., the power transmitter circuit 400 in FIG. 6), an overcurrent may flow depending on the duty cycle setting. Therefore, in the present embodiment, after the start of the main power transfer, the power-receiver control unit 230 performs an adjustment process shown in FIG. 9. This will be described below in detail.

[0100] After the start of the main power transfer (step S101), the power-receiver control unit 230 determines whether the output characteristic of the filter circuit 182 for the rectifier circuit 200 is the current source (step S102). In step S102, the output characteristic of the filter circuit 182 for the rectifier circuit 200 (i.e., an output characteristic immediately before an input of the rectifier circuit 200) is specified based on the information related to the output characteristic of the power transmitter circuit 400 included in the power-transmitter information, as well as the circuit configuration of the power receiver coil 102 and the power receiver circuit 500, and it is determined whether the output characteristic is the current source.

[0101] In step S102, for example, when the power receiver circuit 500 has the SS topology (e.g., the power receiver circuit 500 in FIG. 5), the power-receiver control unit 230 may determine whether the output characteristic of the power transmitter circuit 400 included in the received power-transmitter information is the voltage source. Further, for example, when the power receiver circuit 500 has the Double-LCC topology (e.g., the power receiver circuit 500 in FIG. 6), the power-receiver control unit 230 may determine whether the output characteristic of the power transmitter circuit 400 included in the received power-transmitter information is the current source.

[0102] Further, for example, when the power receiver circuit 500 has the SS topology (e.g., the power receiver circuit 500 in FIG. 5), it may be determined whether the power transmitter circuit 400 has the SS topology (e.g., the power transmitter circuit 400 in FIG. 5). Further, for example, when the power receiver circuit 500 has the Double-LCC topology (e.g., the power receiver circuit 500 in FIG. 6), it may be determined whether the power transmitter circuit 400 has the Double-LCC topology (e.g., the power transmitter circuit 400 in FIG. 6).

[0103] That is, in step S102, it may be determined based on whether the information related to the output characteristic of the power transmitter circuit 400 included in the received power-transmitter information is predetermined such that no change in control is required (i.e., the processing in step S9 is not performed).

[0104] When the determination result is affirmative, the power-receiver control unit 230 controls the duty control of the rectifier circuit 200 so as to continuously or stepwise increase the duty cycle (step S103). For example, control is performed so as to increase the duty cycle stepwise over multiple cycles of the transmitted AC power.

[0105] Further, in step S103, an initial value (first initial value) of the duty cycle is 0%. However, the initial value may be changed based on the power-transmitter information. For example, when the power-transmitter information includes information related to the inductance of the power transmitter coil 22 or the power supply voltage, the initial value of the duty cycle may be changed to a value greater than 0% (for example, 20%) based on those values.

[0106] On the other hand, when the determination result in step S102 is negative, the power-receiver control unit 230 proceeds to the processing of step S104. In step S102, when the power receiver circuit 500 has the SS topology (e.g., the power receiver circuit 500 shown in FIG. 5) and the output characteristic of the power transmitter circuit 400 is the current source, the determination result becomes negative. For example, when the power receiver circuit 500 has the SS topology (e.g., the power receiver circuit 500 shown in FIG. 5) and the power transmitter circuit 400 has the Double-LCC topology (e.g., the power transmitter circuit 400 shown in FIG. 6), the determination result becomes negative.

[0107] When the power-receiver control unit 230 proceeds to step S104, it controls the duty cycle in the duty control of the rectifier circuit 200 so as to continuously or stepwise decrease the duty cycle such that the output voltage from the rectifier circuit 200 approaches the required voltage of the high-voltage storage battery 300. For example, control is performed so as to decrease the duty cycle stepwise over multiple cycles of the transmitted AC power.

[0108] The required voltage of the high-voltage storage battery 300 is determined based on the terminal voltage of the high-voltage storage battery 300. Further, when the processing of step S104 is executed for the first time, an initial value (second initial value) of the duty cycle is 100%. However, the initial value may be changed based on the power-transmitter information. For example, when the power-transmitter information includes information related to the inductance of the power transmitter coil 22 or the power supply voltage, the initial value of the duty cycle may be changed to a value smaller than 100% (for example, 80%) based on those values.

[0109] Then, the power-receiver control unit 230 determines whether the difference between the required voltage of the high-voltage storage battery 300 and the output voltage from the rectifier circuit 200 falls within a predetermined range (step S105). When the determination result is affirmative, the power-receiver control unit 230 terminates the process. On the other hand, when the determination result in step S105 is negative, the power-receiver control unit 230 executes the process of step S104 again and continues to decrease the duty cycle until the difference between the required voltage of the high-voltage storage battery 300 and the output voltage from the rectifier circuit 200 falls within the predetermined range. In the present embodiment, the processes of steps S103 to S105 correspond to power-receiver control step.

[0110] According to the first embodiment, the following effects are achieved.

[0111] The power-receiver control unit 230 changes the amplitude of the output voltage of the power-receiver resonant circuit 140, which has been input to the rectifier circuit 200, in accordance with the output characteristic of the power transmitter circuit 400 included in the acquired power-transmitter information. Specifically, when the power-receiver control unit 230 determines that the output characteristic of the filter circuit 182 for the rectifier circuit 200 is the voltage source, it continuously or stepwise decreases the duty cycle in the duty control of the rectifier circuit 200 (switching rectifier) so that the output voltage from the rectifier circuit 200 approaches the required voltage of the high-voltage storage battery 300. As a result, it is possible to gradually decreases the apparent load voltage, thereby preventing overcurrent and achieving stable control.

[0112] The case where the output characteristic of the filter circuit 182 for the rectifier circuit 200 is determined to be the voltage source is, for example, a case where the power receiver circuit 500 has the SS topology and the output characteristic of the power transmitter circuit 400 is determined to be the current source, or a case where the power receiver circuit 500 has the SS topology and, during wireless power transfer, the output characteristic of the power receiver coil 102 between the power receiver coil 102 and the power receiver circuit 500 is determined to be the voltage source.

[0113] Further, when decreasing the duty cycle, the power-receiver control unit 230 normally sets the initial value of the duty cycle to 100%. However, when the power-transmitter information includes information such as the power supply voltage, the initial value of the duty cycle is decreased based on the power-transmitter information. As a result, the time required for the output voltage from the rectifier circuit 200 to approach the required voltage of the high-voltage storage battery 300 can be shortened. That is, since the required power can be reached immediately, the charging time can be shortened.

[0114] Further, in the duty control of the rectifier circuit 200, where the output characteristic of the filter circuit 182 for the rectifier circuit 200 is determined to be the current source, the power-receiver control unit 230 is configured to increase the duty cycle either continuously or stepwise. As a result, the power supplied to the high-voltage storage battery 300 can be gradually increased.

[0115] The case where the output characteristic of the filter circuit 182 for the rectifier circuit 200 is determined to be the current source is, for example, a case where the power receiver circuit 500 has the SS topology and the output characteristic of the power transmitter circuit 400 is determined to be the voltage source, or a case where the power receiver circuit 500 has the SS topology and, during wireless power transfer, the output characteristic of the power receiver coil 102 between the power receiver coil 102 and the power receiver circuit 500 is determined to be the current source.

[0116] Further, when increasing the duty cycle, the power-receiver control unit 230 normally sets the initial value of the duty cycle to 0%. However, when the power-transmitter information includes information such as the power supply voltage, the initial value of the duty cycle is increased based on the power-transmitter information. As a result, the time required for the output voltage from the rectifier circuit 200 to approach the required voltage of the high-voltage storage battery 300 can be shortened. That is, since the required power can be reached immediately, the charging time can be shortened.

[0117] The power-receiver control unit 230 changes the control related to wireless power transfer based on the output characteristic of the power transmitter circuit 400 included in the power-transmitter information acquired by the power-receiver communication device 240 or the communication unit 332 before wireless power transfer is performed. That is, when the output characteristic of the power transmitter circuit 400 match the output characteristic required by the power receiver circuit 500, and the combination of the power transmitter circuit 400 and the power receiver circuit 500 is appropriate, wireless power transfer is initiated. On the other hand, when the output characteristic of the power transmitter circuit 400 do not match the output characteristic required by the power receiver circuit 500, and the combination of the power transmitter circuit 400 and the power receiver circuit 500 is not appropriate, the control related to wireless power transfer is changed so as to switch the output characteristic of the power receiver circuit 500.

[0118] Specifically, the power-receiver control unit 230 changes the output characteristic of the power receiver circuit 500 so that, compared to before the change, the output characteristic approach the voltage source characteristic or the current source characteristic. In the present embodiment, the power-receiver control unit 230 switches the output characteristic of the power receiver circuit 500 by controlling the rectifier circuit 200 so that the output characteristic from the power receiver circuit 500 to the high-voltage storage battery 300 becomes closer to the current source characteristic. As a result, power supply can be appropriately performed. Further, it is sufficient to change the control of the rectifier circuit 200, and thus, it is not necessary to provide a special circuit configuration.

[0119] The power-receiver control unit 230 determines whether compatibility of the power transmitter circuit 400 with the power receiver circuit 500 is present or not, based on the output characteristic of the power transmitter circuit 400 included in the power-transmitter information. Then, the power-receiver control unit 230 changes the control related to the wireless power transfer according to the presence or absence of compatibility. As a result, it is possible to prevent failures in a case where the power receiver circuit 500 is not compatible.

[0120] The power-receiver control unit 230 changes the control related to wireless power transfer based on the power-transmitter information before transmitting the power supply request signal COMM. Specifically, the control related to the wireless power transfer can be changed before the tracking. As a result, it is possible to reliably prevent the erroneous start of power transfer from the power transmitter 20 before the change, and to appropriately perform power transfer.

[0121] The power-receiver communication device 240 corresponds to the first information acquisition unit and is capable of performing narrow area wireless communication. The communication unit 332 corresponds to the second information acquisition unit and is capable of performing wide area wireless communication. The power-receiver control unit 230 acquires at least the first power-transmitter information via the communication unit 332 before wireless power transfer is performed. As a result, since the power-transmitter information can be acquired from a farther distance, it is possible to make preparations such as changing the control in advance.

[0122] The power-receiver communication device 240 and the communication unit 332 respectively acquire the first power-transmitter information and the second power-transmitter information before wireless power transfer is performed, and the power-receiver control unit 230 checks whether the content of the second power-transmitter information matches the content of the first power-transmitter information. Therefore, the output characteristic can be known more accurately. As a result, power supply can be performed more appropriately. Therefore, abnormality can be reliably prevented.

[0123] When the content of the second power-transmitter information does not match the content of the first power-transmitter information, the power-receiver control unit 230 cancels the wireless power transfer. As a result, abnormality can be reliably prevented.

[0124] Second Embodiment 　　　　　　 A second embodiment will be described below with reference to the drawings mainly in terms of differences from the first embodiment.

[0125] In a power receiver circuit 500 of the second embodiment, as shown in FIG. 10, a DC-DC converter 201 serving as a power converter is provided between a rectifier circuit 200 and a high-voltage storage battery 300. The DC-DC converter 201 is configured to transform the DC voltage input from the rectifier circuit 200 and output it to the high-voltage storage battery 300. This DC-DC converter 201 is configured to be controlled by a power-receiver control unit 230 (power-receiver controller 231).

[0126] Next, the power-transfer start process of the second embodiment will be described with reference to FIG. 11. Steps S1 to S8 are the same as in the first embodiment, and therefore, description thereof will be omitted. In the second embodiment, when the determination result in Step S4 is negative, the power-receiver control unit 230 performs a switching process to change the output characteristic (Step S10). In step S10, in order to change the output characteristic of the power receiver circuit 500, the control of the DC-DC converter 201 is determined (set) to be changed. Then, the power-receiver control unit 230 proceeds to the processing of step S5.

[0127] After the process of step S10 is executed, when the main power transfer (wireless power transfer) is started in step S8, the power-receiver control unit 230 performs a process of adjusting the output voltage Vout of the DC-DC converter 201. For example, the power-receiver controller 231 adjusts the output voltage Vout so that a constant current flows to the high-voltage storage battery 300.

[0128] By adjusting the output voltage Vout in this manner, the output voltage from the rectifier circuit 200 to the high-voltage storage battery 300 can be regulated so as to suppress the occurrence of the aforementioned disadvantages. That is, in effect, the DC-DC converter 201 can change the output characteristic of the power receiver circuit 500 from the voltage source to the current source. As a result, power can be supplied from the rectifier circuit 200 to the high-voltage storage battery 300 without causing an overcurrent from the power receiver circuit 500 to the high-voltage storage battery 300.

[0129] In the second embodiment, when performing the adjustment process, the power-receiver control unit 230 adjusts the duty cycle in the duty control of the DC-DC converter 201 instead of the rectifier circuit 200. Other explanations are the same as in the first embodiment, and therefore will be omitted.

[0130] Modifications 　　　　　　 Modifications in which part of the configuration of the above embodiments is changed will be described below.

[0131] In the above embodiments, when the determination result of step S105 is affirmative, that is, when the difference between the required voltage and the output voltage falls within the predetermined range, the power-receiver control unit 230 may thereafter control the duty cycle so that the output voltage follows the required voltage of the high-voltage storage battery 300. As a result, even if the required voltage of the high-voltage storage battery 300 changes, it is possible to prevent overcurrent and stably supply electric power.

[0132] In the above embodiments, when decreasing the duty cycle (in the case where the output characteristic immediately before the input of the rectifier circuit 200 is the voltage source), the power-receiver control unit 230 may change the variation width of the duty cycle in accordance with the difference between the required voltage of the high-voltage storage battery 300 and the output voltage from the rectifier circuit 200. For example, if the difference is large, the variation width may be increased.

[0133] In the above embodiments, both the first power-transmitter information and the second power-transmitter information are acquired, however, only one of them may be acquired.

[0134] In the above embodiments, consistency between the first power-transmitter information and the second power-transmitter information is determined, however, availability of wireless power transfer may be determined based on either of the power-transmitter information.

[0135] In the above embodiments, when the first power-transmitter information and the second power-transmitter information are not consistent, the second power-transmitter information acquired via narrow area wireless communication may be regarded as correct (highly reliable), and subsequent processing (such as changing output characteristic) may be performed based thereon.

[0136] In step S4 of the power-transfer start process in the above embodiments, it is determined whether the output characteristic of the power transmitter circuit 400 matches the output characteristic of the power transmitter circuit 400 required by the power receiver circuit 500. As another example, the output characteristic of the power receiver coil 102 during wireless power transfer may be determined based on the information related to the output characteristic of the power transmitter circuit 400, and it may be determined whether the output characteristic of the power receiver coil 102 matches an output characteristic of the power receiver coil 102 required by the power receiver circuit 500. The output characteristic of the power receiver coil 102 can be determined based on the output characteristic of the power transmitter circuit 400 and the configuration of the power receiver coil 102 in the power receiver 100. For example, in the case of the circuit configurations shown in FIG. 5 or FIG. 6, the output characteristic of the power receiver coil 102 corresponds to an output characteristic obtained by inverting the output characteristic of the power transmitter circuit 400 (from the current source to the voltage source, or from the voltage source to the current source). Therefore, the power-receiver control unit 230 may invert the output characteristic of the power transmitter circuit 400 included in the transmitted power-transmitter information.

[0137] Further, the output characteristic of the power receiver coil 102 may be measured and stored in advance for each model of the power transmitter 20, and the power-receiver control unit 230 may read out and specify the output characteristic of the power receiver coil 102 based on the model information included in the acquired power-transmitter information. In this case, the model information corresponds to the information related to the output characteristic of the power transmitter circuit 400.

[0138] Alternatively, the power-receiver control unit 230 may directly determine whether the power transmitter 20 and the power receiver 100 itself are an appropriate combination. For example, the power-receiver control unit 230 may store in advance a list such as model information indicating models of power transmitters 20 that can appropriately transfer power without modification (initial state), and may determine the appropriate combination based on whether the model information indicated in the acquired power-transmitter information is included in the list.

[0139] In the above embodiments, the procedure until the start of the wireless power transfer may be changed based on the power-transmitter information. For example, when it is specified in the startup sequence information that the first power-transmitter information is not acquired via wide area wireless communication, subsequent processing may be executed based only on the second power-transmitter information. In this case, the consistency of the power-transmitter information is not determined. Similarly, when it is specified in the startup sequence information that the second power-transmitter information is not acquired via narrow area wireless communication, subsequent processing may be executed based only on the first power-transmitter information. In this case, the consistency of the power-transmitter information is not determined. Similarly, when it is specified in the startup sequence information that the tracking is not performed, wireless power transfer may be started without checking tracking.

[0140] In the above embodiments, the communication method or the like may be changed based on the antenna information or the communication standard information included in the power-transmitter information. As a result, the control related to wireless power transfer can be more appropriately changed according to the configuration of the power transmitter, the control content, and the like, before the wireless power transfer is performed. In addition, the amount of power to be transmitted or the like may be changed based on the power information included in the power-transmitter information. As a result, power can be transmitted with an appropriate amount of power.

[0141] In the above first embodiment, the travelling inverter 310 may serve as a "power supply target device." In this case, the power supply source for the travelling inverter 310 may be the voltage source. Accordingly, in the first embodiment, the output characteristic required by the power receiver circuit 500 is changed.

[0142] In the above embodiments, it is also possible to configure the system to enable inter-vehicle communication, in which wireless communication is performed between the vehicle 11 (own vehicle) and other vehicles in the vicinity of the vehicle 11. Then, as shown in FIG. 12, the vehicle 11 may include an inter-vehicle communication unit 91 that acquires power-transmitter information of a power transmitter 20 via inter-vehicle communication from another vehicle that has acquired the power-transmitter information of the power transmitter 20 which the vehicle 11 is scheduled to pass over next. The inter-vehicle communication unit 91 may also serve as a part of the information acquisition unit. That is, the inter-vehicle communication unit 91 may be used in place of other information acquisition units (such as narrow area wireless communication or wide area wireless communication), or may be used together with other information acquisition units (such as narrow area wireless communication or wide area wireless communication).

[0143] In the above embodiments, the vehicle 11 may include a position information acquisition unit 92 that acquires position information of the vehicle 11 from a GPS sensor or the like, and acquires, based on the acquired position information, power-transmitter information of the power transmitter 20 that the vehicle 11 is scheduled to pass over next. For example, power-transmitter information may be stored in advance in association with each piece of position information, and the power-transmitter information may be read out based on the acquired position information of the vehicle 11. Further, power-transmitter information corresponding to the acquired position information of the vehicle 11 may be acquired from an external server using wide area wireless communication or the like.

[0144] As shown in FIG. 12, the position information acquisition unit 92 may be provided as a part of the information acquisition unit. That is, the position information acquisition unit 92 may be used in place of other information acquisition units (such as narrow area wireless communication or wide area wireless communication), or may be used together with other information acquisition units (such as narrow area wireless communication or wide area wireless communication).

[0145] In the above embodiments, the vehicle 11 may include an image recognition unit 93 that captures an image of a sign installed along the road RS through which the vehicle 11 passes, and acquires power-transmitter information of the power transmitter 20 that the vehicle 11 is scheduled to pass next, by performing image recognition on the captured sign. That is, the power-transmitter information displayed on the recognized sign may be acquired. Alternatively, the power-transmitter information stored in advance in the storage unit or the like in association with the sign may be read.

[0146] As shown in FIG. 12, the image recognition unit 93 may be provided as a part of the information acquisition unit. That is, the image recognition unit 93 may be used in place of other information acquisition units (such as narrow area wireless communication or wide area wireless communication), or may be used together with other information acquisition units (such as narrow area wireless communication or wide area wireless communication).

[0147] In the above embodiments, the vehicle 11 may include a marker recognition unit 94 that recognizes a marker installed on the road RS through which the vehicle 11 passes, and acquires power-transmitter information of the power transmitter 20 that the vehicle 11 is scheduled to pass next, based on the recognized marker. The marker recognition unit 94 may acquire the power-transmitter information, for example, by recognizing a signal such as an electrical signal, optical signal, or magnetic signal emitted by the maker. At this time, the power-transmitter information may be directly included in the signal. Alternatively, information about the marker such as the type and position information about the marker may be acquired from the signal from the marker, and then, the power-transmitter information stored in the storage unit or the external device may be identified from the information about the marker.

[0148] As shown in FIG. 12, the marker recognition unit 94 may be provided as a part of the information acquisition unit. That is, the marker recognition unit 94 may be used in place of other information acquisition units (such as narrow area wireless communication or wide area wireless communication), or may be used together with other information acquisition units (such as narrow area wireless communication or wide area wireless communication).

[0149] In the above embodiments, the information acquisition unit consist of only two units: a second information acquisition unit that acquires power-transmitter information using wide area wireless communication, and a first information acquisition unit that acquires power-transmitter information using narrow area wireless communication; however, three or more information acquisition units may be provided. The information acquisition unit may include any one or more of the aforementioned inter-vehicle communication unit 91, position information acquisition unit 92, image recognition unit 93, or marker recognition unit 94.

[0150] In step S3 of the above embodiments, when the first power-transmitter information and the second power-transmitter information do not match, the second power-transmitter information, that is, the power-transmitter information acquired via narrow area wireless communication, may be regarded as correct, and the processing from step S4 onward may be performed accordingly. That is, the power-receiver control unit 230 may regard the second power-transmitter information, which is acquired at a shorter distance and immediately prior, as correct, and may modify any one or more of the control related to wireless power transfer, the power receiver circuit 500, or the determination whether the wireless power transfer can be performed. As a result, it is possible to more appropriately perform power supply or appropriately restrict power supply.

[0151] In the second embodiment described above, the DC-DC converter 201 may be a synchronous rectifier (such as the rectifier 200 shown in FIG. 5). Here, the rectification method using a synchronous rectifier will be described with reference to FIGS. 13 to 16. In FIG. 13, rectification of the AC power is performed by turning on the combination of the first upper arm switch S11H and the second lower arm switch S12L, and in FIG. 14, commutation (circulation) is performed by turning on the first lower arm switch S11L and the second lower arm switch S12L. In FIG. 15, rectification of the AC power is performed by turning on the combination of the first lower arm switch S11L and the second upper arm switch S12H, and in FIG. 16, commutation (circulation) is performed by turning on the first lower arm switch S11L and the second lower arm switch S12L. Then, by controlling the ratio (i.e., duty cycle) at which the first lower arm switch S11L and the second lower arm switch S12L are turned on (i.e., duty control), the output power can be controlled.

[0152] The wireless power transfer system may have a first function of performing wireless power transfer from the vehicle-side device to the ground-side device, in addition to a second function of performing wireless power transfer 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] The wireless power transfer system may have the function of performing wireless power transfer from the vehicle-side device to the ground-side device, instead of the function of performing wireless power transfer from the ground-side device to the vehicle-side device.

[0157] 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.

[0158] The method of wireless power transfer 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 the coils and use an electric field coupling method may be used.

[0159] 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.

[0160] 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.

[0161] 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.

Claims

1. A power receiver (100) for a wireless power transfer system (10) including a vehicle-side device and a ground-side device, one of the vehicle-side device and the ground-side device being a power transmitter (20) having a power transmitting antenna (22) and a power transmitter circuit (400), another of the vehicle-side device and the ground-side device being the power receiver having a power receiving antenna (102) and a power receiver circuit (500), the power transmitting antenna being configured to be energized to perform wireless power transfer to the power receiving antenna, 　　　　　　 the power receiver circuit including a power-receiver resonator configured to resonate with the power receiving antenna, and a power converter configured to convert power received by the power receiving antenna to correspond to power required by a power supply target device. the power receiver comprising: 　　　　　　 an information acquisition unit configured to acquire power-transmitter information including at least information related to an output characteristic of the power transmitter circuit; and 　　　　　　 a power-receiver control unit configured to control the power converter, wherein 　　　　　　 the power-receiver control unit is configured to change an amplitude of an output voltage of the power-receiver resonator input to the power converter, based on the information related to the output characteristic of the power transmitter circuit acquired by the information acquisition unit.

2. The power receiver according to claim 1, wherein 　　　　　　 the power-receiver control unit is configured to control a duty cycle in duty control of the power converter to continuously or stepwise decrease the duty cycle such that an output voltage from the power converter approaches a required voltage of the power supply target device when the power-receiver control unit determines, based on the power-transmitter information, that an output characteristic immediately before an input of the power converter is a voltage source characteristic.

3. The power receiver according to claim 2, wherein 　　　　　　 the power-receiver control unit is configured to set an initial value of the duty cycle to 100% when the power-receiver control unit determines, based on the power-transmitter information, that the output characteristic immediately before the input of the power converter is the voltage source characteristic.

4. The power receiver according to claim 2, wherein 　　　　　　 the power-receiver control unit is configured to set an initial value of the duty cycle to a value smaller than 100% based on the power-transmitter information.

5. The power receiver according to any one of claims 1 to 4, wherein 　　　　　　 the power-receiver control unit is configured to control a duty cycle in duty control of the power converter to continuously or stepwise increase the duty cycle when the power-receiver control unit determines, based on the power-transmitter information, that an output characteristic immediately before an input of the power converter is a current source characteristic.

6. The power receiver according to claim 5, wherein 　　　　　　 the power-receiver control unit is configured to set an initial value of the duty cycle to 0% when the power-receiver control unit determines, based on the power-transmitter information, that the output characteristic immediately before the input of the power converter is the current source characteristic.

7. The power receiver according to claim 5, wherein 　　　　　　 the power-receiver control unit is configured to set an initial value of the duty cycle to a value larger than 0% based on the power-transmitter information.

8. The power receiver according to claim 1, wherein 　　　　　　 the power-receiver control unit is configured to control a duty cycle in duty control of the power converter, 　　　　　　 the power-receiver control unit is configured to use a first initial value of the duty cycle when the power-receiver control unit determines, based on the power-transmitter information, that an output characteristic immediately before an input of the power converter is a current source characteristic, 　　　　　　 the power-receiver control unit is configured to use a second initial value of the duty cycle when the power-receiver control unit determines, based on the power-transmitter information, that the output characteristic immediately before the input of the power converter is a voltage source characteristic, 　　　　　　 the first initial value is smaller than the second initial value, and 　　　　　　 the power-receiver control unit is configured to 　　　　　　　　　　　　　 control the duty cycle to decrease continuously or stepwise from the second initial value such that an output voltage from the power converter approaches a required voltage of the power supply target device when the power-receiver control unit determines, based on the power-transmitter information, that the output characteristic immediately before the input of the power converter is the voltage source characteristic, and 　　　　　　　　　　　　　 control the duty cycle to increase continuously or stepwise from the first initial value when the power-receiver control unit determines, based on the power-transmitter information, that the output characteristic immediately before the input of the power converter is the current source characteristic.

9. The power receiver according to any one of claims 2 to 8, wherein 　　　　　　 the power-receiver control unit is configured to control the duty cycle such that the output voltage from the power converter follows the required voltage of the power supply target device, when the power-receiver control unit determines, based on the power-transmitter information, that the output characteristic immediately before the input of the power converter is the voltage source characteristic, a difference between the required voltage of the power supply target device and the output voltage from the power converter falls within a predetermined range, and thereafter.

10. The power receiver according to any one of claims 2 to 9, wherein 　　　　　　 the power-receiver control unit is configured to change a variation width of the duty cycle in accordance with a difference between the required voltage of the power supply target device and the output voltage from the power converter when the power-receiver control unit determines, based on the power-transmitter information, that the output characteristic immediately before the input of the power converter is the voltage source characteristic.

11. A program for a power receiver (100) to be applied to a wireless power transfer system (10) including a vehicle-side device and a ground-side device, one of the vehicle-side device and the ground-side device being a power transmitter (20) having a power transmitting antenna (22) and a power transmitter circuit (400), another of the vehicle-side device and the ground-side device being the power receiver having a power receiving antenna (102) and a power receiver circuit (500), the power transmitting antenna being configured to be energized to perform wireless power transfer to the power receiving antenna, 　　　　　　 the power receiver circuit including a power-receiver resonator configured to resonate with the power receiving antenna, and a power converter configured to convert power received by the power receiving antenna to correspond to power required by a power supply target device, 　　　　　　 the program being configured to perform: 　　　　　　 an information acquisition step of acquiring power-transmitter information including at least information related to an output characteristic of the power transmitter circuit; and 　　　　　　 a power-receiver control step of controlling the power converter, wherein 　　　　　　 the power-receiver control step includes changing an amplitude of an output voltage of the power-receiver resonator input to the power converter, based on the information related to the output characteristic of the power transmitter circuit acquired by the information acquisition step.

12. A control method for a power receiver (100) to be applied to a wireless power transfer system (10) including a vehicle-side device and a ground-side device, one of the vehicle-side device and the ground-side device being a power transmitter (20) having a power transmitting antenna (22) and a power transmitter circuit (400), another of the vehicle-side device and the ground-side device being the power receiver having a power receiving antenna (102) and a power receiver circuit (500), the power transmitting antenna being configured to be energized to perform wireless power transfer to the power receiving antenna, 　　　　　　 the power receiver circuit including a power-receiver resonator configured to resonate with the power receiving antenna, and a power converter configured to convert power received by the power receiving antenna to correspond to power required by a power supply target device, 　　　　　　 the control method comprising: 　　　　　　 an information acquisition step of acquiring power-transmitter information including at least information related to an output characteristic of the power transmitter circuit; and 　　　　　　 a power-receiver control step of controlling the power converter, wherein 　　　　　　 the power-receiver control step includes changing an amplitude of an output voltage of the power-receiver resonator input to the power converter, based on the information related to the output characteristic of the power transmitter circuit acquired by the information acquisition step.

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