Power transmitter, program, control method for power transmitter

Abstract

A power transmitter (20) is applied to a wireless power transfer system including a power transmitter (20) having a power transmitter coil (22) and a power receiver (100) having a power receiving coil (102). The power receiver (100) includes a power receiver circuit (500) having the power receiving coil (102). The received power of the power receiving coil (102) is supplied to a high-voltage storage battery (300) connected to the power receiver circuit (500). The power transmitter (20) is supplied with electric power from a direct-current voltage source (61) and includes a power transmitter circuit (400) having the power transmitter coil (22), and a power-transmitter control unit (70). The power-transmitter control unit (70) performs a switching process to switch a control or circuit topology in the power transmitter circuit (400).

Description

POWER TRANSMITTER, PROGRAM, CONTROL METHOD FOR POWER TRANSMITTERCross Reference

[0001] This application is based on Japanese Patent Application No. 2025-019569 filed on February 7, 2025, the contents of which are incorporated herein by reference.

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

[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 2024-122073 A

[0005] If the combination of the output characteristic of the power transmitter circuit and the output characteristic of the power receiver circuit is not appropriate, an issue may arise. For example, during wireless power transfer, there is a concern that a large current may flow from the power receiver circuit to an in-vehicle battery.

[0006] An object of the present disclosure is to provide a power transmitter, a program, and a control method for the power transmitter, which are capable of suppressing an occurrence of issues caused by an inappropriate combination of an output characteristic of a power transmitter circuit and an output characteristic of a power receiver circuit.

[0007] According to an aspect of the present disclosure, a power transmitter is 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 the power transmitter having a power transmitting antenna. Another of the vehicle-side device and the ground-side device is a power receiver having a power receiving antenna. The power transmitting antenna is configured to be energized to perform wireless power transfer to the power receiving antenna. The power receiver includes a power receiver circuit having the power receiving antenna. The power receiver circuit is connected to a power supply target device to be supplied with power received by the power receiving antenna. The power transmitter includes a power transmitter circuit having the power transmitting antenna to be supplied with power from a direct-current voltage source, and a power-transmitter control unit. The power-transmitter control unit is configured to perform a switching process to switch an output characteristic of the power transmitter circuit.

[0008] According to the present disclosure, even when a combination of the output characteristic of the power transmitter circuit and an output characteristic of the power receiver circuit is not appropriate, it is possible to switch the output characteristic of the power transmitter circuit, thereby suppressing the occurrence of the above-described issues.

[0009] 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 configuration diagram of the power transmitter including a DC-DC converter.FIG. 9 is a flowchart illustrating a process executed by the power transmitter.FIG. 10 is a configuration diagram of a power transmitter according to a second embodiment.FIG. 11 is a flowchart illustrating a process executed by the power transmitter.FIG. 12 is a configuration diagram of a power transmitter according to a third embodiment.FIG. 13 is a flowchart illustrating a process executed by the power transmitter.FIG. 14 is a diagram illustrating an example in which the combination of the power transmitter circuit and the power receiver circuit is switched to an appropriate combination.FIG. 15 is a configuration diagram of a power transmitter according to a modification of the third embodiment.FIG. 16 is a configuration diagram of a power transmitter according to a fourth embodiment.FIG. 17 is a configuration diagram of a power transmitter according to a fifth embodiment.FIG. 18 is a configuration diagram of a power transmitter according to a sixth embodiment.FIG. 19 is a configuration diagram of a power transmitter according to a seventh embodiment.FIG. 20 is a configuration diagram of a power transmitter according to an eighth embodiment.

[0010] Multiple embodiments will be described with reference to the drawings. In the embodiments, parts that functionally and / or structurally correspond to or are associated with each other may be assigned the same reference numeral, or reference numerals different in digit in the hundreds or higher place. The corresponding and / or associated parts may refer to the explanation in the other embodiments.

[0011] First Embodiment 　　　　　　 A first embodiment of a wireless power transfer system of the present disclosure will be described below with reference to the drawings.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] The power-transmitter power supply unit 51 includes a PFC (Power Factor Correction) circuit 61, a DC-DC converter 62 (corresponding to a power-transmitter power converter), 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.

[0016] The DC-DC converter 62 is connected to the PFC circuit 61. The DC-DC converter 62 transforms the DC voltage input from the PFC circuit 61 and outputs it to the inverter 60.

[0017] The inverter 60 is connected to the DC-DC converter 62. 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.

[0018] The filter circuit 52 removes noise contained in the AC current input from the inverter 60 and supplies the AC current from which noise has been removed to the power-transmitter coil unit 21. The filter circuit 52 is, for example, an LC filter that includes a coil and a capacitor. Circuits having various configurations can be used as the filter circuit 52, and, for example, a T-type filter circuit is used as the filter circuit 52.

[0019] The power-transmitter coil unit 21 includes a power transmitter coil 22 (corresponding to power transmitting antenna), a power-transmitter resonant circuit 30, and a power-transmitter communication coil 40. The power-transmitter resonant circuit 30 supplies the AC power supplied by the filter circuit 52 to the power transmitter coil 22. The power-transmitter resonant circuit 30 can employ various well-known resonant circuits such as a circuit including a resonant capacitor.

[0020] In the present embodiment, the DC-DC converter 62, the inverter 60, the filter circuit 52, and the power-transmitter resonant circuit 30 constitute the power transmitter circuit 400.

[0021] The power receiver 100 includes a power-receiver coil unit 101 and a power-receiver power supply unit 181. The power-receiver coil unit 101 includes a power receiver coil 102 (corresponding to a "power receiving antenna"). The power-receiver coil unit 101 is located at the bottom of the vehicle body of the vehicle 11. The power-receiver coil unit 101 is located at the bottom of the vehicle body to face the ground surface. When the vehicle 11 travels on the road RS where the power transmitter coil 22 is buried, the power transmitter coil 22 on the ground side and the power receiver coil 102 of the vehicle 11 face each other in the vertical direction.

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

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

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

[0025] 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.

[0026] 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.

[0027] 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.

[0028] In the present embodiment, the high-voltage storage battery 300 and the travelling inverter 310 correspond 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 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, switching control of the inverter 60, and switching control of the DC-DC converter 62. 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). A power-receiver control unit 230 includes a signal transmitter 240.

[0038] The power-transmitter coil unit 21, which constitutes the power transmitter 20, includes a power-transmitter communication coil 40 (corresponding to a power-transmitter communication antenna). The power-transmitter control unit 70 includes a signal receiver 80. The power-receiver communication coil 170 and the power-transmitter communication coil 40 are communication coils for narrow area wireless communication. Narrow area wireless 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 signal transmitter 240 is connected to the power-receiver controller 231. The signal transmitter 240 is connected to the power-receiver communication coil 170. The power-receiver controller 231 controls the signal transmitter 240 to supply a power supply request signal COMM to the power-receiver communication coil 170. The power supply request signal COMM is a signal requesting the power transmitter coil 22 near the vehicle 11 to transmit power to the power receiver coil 102.

[0041] The power-receiver control unit 230 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 signal transmitter 240 to the power-receiver communication coil 170. Consequently, a high-frequency current flows in the power-receiver communication coil 170, and a magnetic field for information communication is generated in the power-receiver communication coil 170. In 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 signal receiver 80. The signal receiver 80 recognizes the presence or absence of a power supply request and ID information based on the input signal from the power-transmitter communication coil 40. The signal receiver 80 also acquires the requested power Weq for the vehicle 11 with the recognized ID information, based on the signal from the power-transmitter communication coil 40. The information recognized by the signal receiver 80 and the requested power Weq are input to the power-transmitter controller 71.

[0043] In this embodiment, the power-receiver controller 231 controls the signal transmitter 240 so that the frequency of the high-frequency voltage applied to the power-receiver communication coil 170 becomes a second specified frequency between 10 kHz and 100 GHz. In this embodiment, the second specified frequency is a frequency that deviates from the first specified frequency above, specifically a frequency higher than the first specified frequency (e.g., 13.56 MHz).

[0044] The power-transmitter controller 71 determines whether to energize the power transmitter coil 22 based on the input signal from the signal receiver 80. In detail, on condition that the power-transmitter controller 71 determines that there is a power supply request based on the input signal from the signal receiver 80, the power-transmitter controller 71 applies high-frequency voltage to the power transmitter coil 22 by performing switching control of the inverter 60, the PFC circuit 61, and the DC-DC converter 62.

[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, the inverter 60 and the DC-DC converter 62. As a result, the switching elements of the PFC circuit 61, the inverter 60 and the DC-DC converter 62 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, the inverter 60 and the DC-DC converter 62 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] 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 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.

[0049] The vehicle 11 is equipped with a position sensor 330, a navigation device 331, and a communication unit 332. The position sensor 330 is a sensor that detects the current position of the vehicle, and is, for example, a GPS sensor. A storage unit (for example, storage) of the navigation device 331 stores map information including road information. The navigation device 331 receives information on the current position of the vehicle detected by the position sensor 330 and weather information. The power-transmitter control unit 70 of the power transmitter 20 includes a communication unit 90. The communication unit 332 of the vehicle 11 and the communication unit 90 of the power-transmitter control unit 70 perform wide area wireless communication via the communication network 16.

[0050] 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.

[0051] 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. 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, CD-ROM or DVD. In addition, program information transmitted over a communication network 16, such as OTA (Over The Air), is installed in the storage units.

[0052] An output characteristic of the power receiver circuit 500 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 (current source output 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 (voltage source output 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."

[0053] 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. In FIGS. 5 and 6, for the sake of convenience, the DC-DC converter 62 and other components are not shown.

[0054] FIG. 5 illustrates a wireless power transfer system employing the 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. In this embodiment, the output characteristic of the power transmitter circuit 400 refers to the combined output characteristics of the inverter 60, the filter circuit 52, the power-transmitter resonant circuit 30, and the power transmitter coil 22.

[0055] The power receiver circuit 500 of the wireless power transfer system 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. In the present embodiment, the output characteristic of the power receiver circuit 500 is the combined output characteristics of the power receiver coil 102, the power-receiver resonant circuit 140, the filter circuit 182, and the rectifier circuit 200.

[0056] In the wireless power transfer system adopting the SS topology, power is supplied to the inverter 60 from the PFC circuit 61 that functions as a voltage source. Since the filter circuit 52 does not function as an immittance converter that performs immittance conversion, the filter circuit 52 functions as a voltage source. Furthermore, since the power-transmitter resonant circuit 30 and the power-receiver resonant circuit 140 function as immittance converters, they function as current sources. Since the filter circuit 182 does not function as an immittance converter, the filter circuit 182 functions as a current source. As a result, the power supply to both the rectifier circuit 200 and the high-voltage storage battery 300 becomes the current source. The high-voltage storage battery 300 functions as a voltage source. 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.

[0057] 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.

[0058] FIG. 6 illustrates a wireless power transfer system 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.

[0059] The power receiver circuit 500 of the wireless power transfer system 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.

[0060] In the wireless power transfer system adopting the double-LCC topology, the filter circuit 52 functions as an immittance converter and therefore functions as a current source. Furthermore, since the power-transmitter resonant circuit 30 and the power-receiver resonant circuit 140 function as immittance converters, they function as voltage sources. Since the filter circuit 182 functions as an immittance converter, the filter circuit 182 functions as a current source. As a result, the power supply to both the rectifier circuit 200 and the high-voltage storage battery 300 becomes the current source. The high-voltage storage battery 300 functions as a voltage source.

[0061] 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.

[0062] As illustrated in FIGS. 5 and 6, the rectifier circuit 200 is configured to function as a current source. 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 output characteristic of the power transmitter circuit 400 and the output characteristic of the power receiver circuit 500 may not be appropriate. FIG. 7 illustrates, as an example where the combination is no longer appropriate, a case in which the power transmitter circuit 400 adopts the Double-LCC topology, and the filter circuit 182 of the power receiver circuit 500 is a band-pass filter instead of an immittance filter.

[0063] If the combination is not appropriate, an issue may arise due to the power supply to the rectifier circuit 200 and the high-voltage storage battery 300 functioning as a voltage source. 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.

[0064] To address such issues, the power-transmitter controller 71 acquires the output characteristic of the power receiver circuit 500 provided in the vehicle 11 before wireless power transfer is performed, and executes a switching process to switch control in the power transmitter circuit 400 based on the acquired output characteristic. More specifically, the power-transmitter controller 71 performs processing to control the output voltage (specifically, the output voltage effective value) of the DC-DC converter 62 in order to adjust the effective power Wact output from the inverter 60 to the filter circuit 52. The PFC circuit 61 and the DC-DC converter 62 may be used as an example of a power-transmitter power converter that receives power from the direct-current voltage source and varies an output power effective value. The PFC circuit 61 and the DC-DC converter 62 may be used as an example of a switching unit that switches the output characteristic of the power transmitter circuit to approximate the current source output characteristic or the voltage source output characteristic.

[0065] FIG. 9 is a flowchart of the switching process executed by the power-transmitter controller 71 of each power-transmitter power supply unit 51 disposed on the ground side.

[0066] In step S10, the power-transmitter controller 71 acquires information on the output characteristic of the power receiver circuit 500 provided in the power receiver 100 from the power receiver 100 of the vehicle 11.

[0067] For example, the power-transmitter controller 71 acquires information on the output characteristic of the power receiver circuit 500 via narrow area wireless communication using the power-receiver communication coil 170 and the power-transmitter communication coil 40. More specifically, the power-receiver controller 231 includes information on the output characteristic of the power receiver circuit 500 in the vehicle-side signal. The power-transmitter controller 71 acquires information on the output characteristic of the power receiver circuit 500 based on the signal received by the power-transmitter communication coil 40.

[0068] Further, for example, the power-transmitter controller 71 acquires information on the output characteristic of the power receiver circuit 500 via the above-mentioned wide area wireless communication or wired communication with the server 410. More specifically, the server 410 transmits information on the output characteristic of the power receiver circuit 500 to the power-transmitter controller 71 in association with the ID information of the vehicle 11. The power-transmitter controller 71 stores the received information on output characteristic in the storage unit in association with the ID information. The power-transmitter controller 71 acquires information on the output characteristic of the power receiver circuit 500, which is to be wirelessly supplied with power, based on the ID information identified from the received signal of the power-transmitter communication coil 40 and the information on output characteristic stored in the storage unit.

[0069] In the subsequent step S11, the power-transmitter controller 71 determines whether the combination of the output characteristic of the power transmitter circuit 400, which is a control target of the power-transmitter controller 71, and the output characteristic of the power receiver circuit 500 acquired in step S10 is appropriate. Specifically, for example, when the power-transmitter controller 71 determines that the total number of impedance converters included in the power receiver circuit 500 and the power transmitter circuit 400 is odd, it determines that the combination is appropriate. On the other hand, when the power-transmitter controller 71 determines that the total number of impedance converters included in the power receiver circuit 500 and the power transmitter circuit 400 is even, it determines that the combination is not appropriate.

[0070] When the power-transmitter controller 71 determines that the combination is appropriate, it proceeds to step S12 and controls the output voltage Vout of the DC-DC converter 62 so that, during the energizing process of the power transmitter coil 22, the output voltage of the PFC circuit 61 is output to the inverter 60 without being transformed. On the other hand, when the power-transmitter controller 71 determines that the combination is not appropriate, it proceeds to step S13 and performs processing to adjust the output voltage Vout of the DC-DC converter 62 during the energizing process of the power transmitter coil 22 in order to adjust the effective power Wact output from the inverter 60 to the filter circuit 52.

[0071] For example, when the power-transmitter controller 71 is capable of determining the output voltage of the rectifier circuit 200, which constitutes the power receiver circuit 500, and the terminal voltage of the high-voltage storage battery 300 via narrow area wireless communication, it performs processing to decrease (or increase) the output voltage Vout of the DC-DC converter 62 compared to the case where an appropriate combination is determined in step S11, while satisfying predetermined conditions, so as to lower (or raise) the effective power Wact compared to the case where the combination is determined to be appropriate in step S11. The predetermined condition is that the output voltage of the rectifier circuit 200 is higher than the terminal voltage of the high-voltage storage battery 300.

[0072] As a result, even in cases where the power supply to both the rectifier circuit 200 and the high-voltage storage battery 300 in the power receiver circuit 500 serves as a voltage source, the effective power Wact supplied to the power transmitter coil 22 can be adjusted. Therefore, the output voltage from the rectifier circuit 200 to the high-voltage storage battery 300 can be adjusted so as to suppress the occurrence of the aforementioned issues. As a result, power can be supplied from the rectifier circuit 200 to the high-voltage storage battery 300 without causing an overcurrent to flow from the rectifier circuit 200 to the high-voltage storage battery 300 and the travelling inverter 310.

[0073] Modification of First Embodiment 　　　　　　 The DC-DC converter 62 may not be provided in the power transmitter 20. In this case, the output power of the PFC circuit 61 is supplied to the inverter 60. The power-transmitter controller 71 may adjust the output voltage of the PFC circuit 61 in order to adjust the effective power Wact output from the PFC circuit 61 to the inverter 60.

[0074] Second Embodiment 　　　　　　 A second embodiment will be described below with reference to the drawings mainly in terms of differences from the first embodiment. In the present embodiment, as shown in FIG. 10, the DC-DC converter 62 is not provided. As a switching process, the power-transmitter controller 71 switches control of the inverter 60 from frequency control to duty control. In the duty control, the pair consisting of the first upper arm switch S1H and the second lower arm switch S2L, and the pair consisting of the first lower arm switch S1L and the second upper arm switch S2H are alternately turned on at a predetermined switching period Tsw.

[0075] In the duty control, the duty ratio (= Ton / Tsw) is adjusted. The duty ratio is the ratio of the ON period Ton of the pair of the first upper arm switch S1H and the second lower arm switch S2L (or the pair of the first lower arm switch S1L and the second upper arm switch S2H) to the switching period Tsw. The larger the duty ratio, the greater the effective power Wact becomes.

[0076] FIG. 11 is a flowchart of the switching process executed by the power-transmitter controller 71 of each power-transmitter power supply unit 51 disposed on the ground side.

[0077] When the power-transmitter controller 71 determines in step S11 that the combination is appropriate, it proceeds to step S14 and performs frequency control.

[0078] On the other hand, when the power-transmitter controller 71 determines that the combination is not appropriate, it proceeds to step S15 and performs duty control.

[0079] For example, when the power-transmitter controller 71 is capable of determining the output voltage of the rectifier circuit 200 constituting the power receiver circuit 500 and the terminal voltage of the high-voltage storage battery 300 via narrow area wireless communication, the power-transmitter controller 71 adjusts the duty ratio, while satisfying the above-mentioned predetermined condition, so as to decrease (or increase) the effective power Wact, compared to the case where it is determined in step S11 that the combination is appropriate.

[0080] As a result, it is possible to appropriately supply power from the rectifier circuit 200 to the high-voltage storage battery 300 without the DC-DC converter 62 shown in FIG. 8.

[0081] Third Embodiment 　　　　　　 A third embodiment will be described below with reference to the drawings mainly in terms of differences from the first and second embodiments. In the present embodiment, the power transmitter circuit 400 can be switched in circuit topology, when wireless power transfer is performed, so that the total number of impedance converters included in the power receiver circuit 500 and the power transmitter circuit 400 is an odd number. Specifically, the power transmitter circuit 400 is the circuit shown in FIG. 12. The power transmitter circuit 400 of the present embodiment employs the Double-LCC topology.

[0082] The power transmitter circuit 400 is provided with a characteristic switching switch SWA. The characteristic switching switch SWA connects an output portion of the inverter 60 to an input portion of the power-transmitter resonant circuit 30. Specifically, the output portion of the inverter 60 corresponds to a source terminal of the second upper arm switch S2H on its low potential side, and a drain terminal of the second lower arm switch S2L on its high potential side.

[0083] When the characteristic switching switch SWA is turned off, the inverter 60 and the power-transmitter resonant circuit 30 are connected via the filter circuit 52 (i.e., an immittance filter), which functions as an immittance converter. On the other hand, when the characteristic switching switch SWA is turned on, it connects the inverter 60 and the power-transmitter resonant circuit 30 without passing through the filter circuit 52.

[0084] FIG. 13 is a flowchart of the switching process executed by the power-transmitter controller 71 of each power-transmitter power supply unit 51 disposed on the ground side.

[0085] When the power-transmitter controller 71 determines in step S11 that the combination is appropriate, it proceeds to step S16 and turns off the characteristic switching switch SWA. As a result, when wireless power transfer is performed, the total number of immittance converters included in the power receiver circuit 500 and the power transmitter circuit 400 becomes an odd number. When the characteristic switching switch SWA is turned on, an immittance filter is interposed between the inverter 60 and the power-transmitter resonant circuit 30. As a result, harmonic components can be reduced.

[0086] On the other hand, when the power-transmitter controller 71 determines that the combination is not appropriate, it proceeds to step S17 and turns on the characteristic switching switch SWA. As a result, the filter circuit 52, which is an immittance filter, is bypassed, thereby reducing the number of immittance converters by one, as shown in FIG. 14. As a result, even in the case where the power receiver circuit 500 is the circuit shown in, for example, FIG. 7, the total number of immittance converters included in both the power receiver circuit 500 and the power transmitter circuit 400 can be made an odd number. Therefore, in the power receiver circuit 500, the power supply to the rectifier circuit 200 and the high-voltage storage battery 300 can be the current source.

[0087] According to the present embodiment described above, the circuit configuration of the power transmitter circuit 400 can be switched so that the combination of the output characteristic of the power transmitter circuit 400 and the output characteristic of the power receiver circuit 500 becomes appropriate.

[0088] Modification of Third Embodiment 　　　　　　 The power transmitter circuit 400, in which the number of immittance converters can be changed, is not limited to the circuit shown in FIG. 12, and may be, for example, the circuit shown in FIG. 15. The power transmitter circuit 400 is provided with a characteristic switching switch SWB that short-circuits the output portion of the filter circuit 52. The characteristic switching switch SWB connects ends of the first inductors 54A which are connected to the power-transmitter resonant circuit 30. When the characteristic switching switch SWB is turned on, the number of immittance converters in the power transmitter circuit 400 is reduced by one compared to when the characteristic switching switch SWB is turned off.

[0089] Fourth Embodiment 　　　　　　 Hereinafter, a fourth embodiment will be described with reference to the drawings, focusing on differences from the third embodiment. In the present embodiment, the power transmitter circuit 400 is the circuit shown in FIG. 16. The power transmitter circuit 400 of the present embodiment employs the SS topology.

[0090] The power transmitter circuit 400 is provided with characteristic switching switches SWC connected in parallel to respective series capacitors 53B.

[0091] When the characteristic switching switches SWC are turned off, as shown in FIG. 16(A), the filter circuit 52, which is a band-pass filter, does not function as an immittance converter. On the other hand, when the characteristic switching switches SWC are turned on, as shown in FIG. 16(B), the series capacitors 53B are bypassed by the respective characteristic switching switches SWC. As a result, the filter circuit 52 functions as an immittance converter. As a result, one additional immittance converter is provided in the power transmitter circuit 400.

[0092] The power-transmitter controller 71 performs a switching process similar to the process shown in FIG. 13. Specifically, the power-transmitter controller 71 turns the characteristic switching switches SWC on or off in accordance with the determination result as to whether the combination is appropriate in step S11.

[0093] For example, when the power-transmitter controller 71 determines that the power receiver circuit 500 uses the SS topology shown in FIG. 5, it determines that the combination is appropriate and turns off the characteristic switching switches SWC, as shown in FIG. 16(A). On the other hand, when the power-transmitter controller 71 determines that the power receiver circuit 500 uses the Double-LCC topology shown in FIG. 6, it determines that the combination is not appropriate and turns on the characteristic switching switches SWC, as shown in FIG. 16(B). As a result, the output characteristic of the filter circuit 52 is switched from the voltage source to the current source, and the total number of immittance converters included in the power receiver circuit 500 and the power transmitter circuit 400 can be made an odd number.

[0094] In addition, according to the present embodiment, since the circuit format can be switched by effectively using the band-pass filter, it is possible to reduce the number of elements or the like added to change the output characteristic.

[0095] Fifth Embodiment 　　　　　　 Hereinafter, a fifth embodiment will be described with reference to the drawings, focusing on differences from the third embodiment. In the present embodiment, the power transmitter circuit 400 is the circuit shown in FIG. 17. The power transmitter circuit 400 of the present embodiment employs the Double-LCC topology. In the present embodiment, the capacitor 54B is referred to as the first capacitor 54B.

[0096] The filter circuit 52 includes a second capacitor 54D connected in parallel with the power transmitter coil 22, and a characteristic switching switch SWD. The series connection of the second capacitor 54D (corresponding to a "target capacitor") and the characteristic switching switch SWD connects ends of the first inductors 54A which are connected to the power-transmitter resonant circuit 30.

[0097] The power-transmitter controller 71 performs a switching process similar to the process shown in FIG. 13. Specifically, the power-transmitter controller 71 turns the characteristic switching switch SWD on or off in accordance with the determination result as to whether the combination is appropriate in step S11. When the characteristic switching switch SWD is turned on, the filter circuit 52 functions as a fourth-order filter.

[0098] For example, when the power-transmitter controller 71 determines that the power receiver circuit 500 uses the Double-LCC topology shown in FIG. 6, it determines that the combination is appropriate and turns off the characteristic switching switch SWD, as shown in FIG. 17(A). On the other hand, when the power-transmitter controller 71 determines that the power receiver circuit 500 uses the SS topology shown in FIG. 5, it determines that the combination is not appropriate and turns on the characteristic switching switch SWD, as shown in FIG. 17(B). As a result, one immittance converter is reduced in the power transmitter circuit 400, and the output characteristic of the filter circuit 52 is switched from the current source to the voltage source. As a result, the total number of immittance converters included in the power receiver circuit 500 and the power transmitter circuit 400 can be made an odd number.

[0099] According to the above present embodiment, the same effect as that of the fourth embodiment can be obtained.

[0100] Modification of Fifth Embodiment 　　　　　　 The characteristic switching switch SWD may be connected in series to the first capacitor 54B instead of the second capacitor 54D.

[0101] Sixth Embodiment 　　　　　　 Hereinafter, a sixth embodiment will be described with reference to the drawings, focusing on differences from the fifth embodiment. In the present embodiment, the power transmitter circuit 400 is the circuit shown in FIG. 18. The power transmitter circuit 400 of the present embodiment employs the Double-LCC topology. The capacitance of the first capacitor 54B and the capacitance of the second capacitor 54D are the same.

[0102] The power transmitter circuit 400 is provided with a characteristic switching switch SWE. The series connection of the second capacitor 54D and the characteristic switching switch SWE connects ends of the first inductors 54A which are connected to the inverter 60.

[0103] The power-transmitter controller 71 performs a switching process similar to the process shown in FIG. 13. Specifically, the power-transmitter controller 71 turns the characteristic switching switch SWE on or off in accordance with the determination result as to whether the combination is appropriate in step S11.

[0104] For example, when the power-transmitter controller 71 determines that the power receiver circuit 500 uses the Double-LCC topology shown in FIG. 6, it determines that the combination is appropriate and turns off the characteristic switching switch SWE, as shown in FIG. 18(A). On the other hand, when the power-transmitter controller 71 determines that the power receiver circuit 500 uses the SS topology shown in FIG. 5, it determines that the combination is not appropriate and turns on the characteristic switching switch SWE, as shown in FIG. 18(B). As a result, one immittance converter is reduced in the power transmitter circuit 400, and the output characteristic of the filter circuit 52 is switched from the current source to the voltage source. As a result, the total number of immittance converters included in the power receiver circuit 500 and the power transmitter circuit 400 can be made an odd number.

[0105] According to the above present embodiment, the same effect as that of the fifth embodiment can be obtained.

[0106] Seventh Embodiment 　　　　　　 Hereinafter, a seventh embodiment will be described with reference to the drawings, focusing on the differences from the above-described embodiments. In the present embodiment, as shown in FIG. 19, the power-transmitter resonant circuit 30 is configured to allow switching of the presence or absence of the immittance conversion function.

[0107] The power-transmitter resonant circuit 30 is provided with a parallel capacitor 24, a first switch SW1, and second switches SW2. The series connection of the parallel capacitor 24 and the first switch SW1 is connected in parallel to the power transmitter coil 22. The second switches SW2 are connected in parallel to respective series capacitors 23.

[0108] The power-transmitter controller 71 performs a switching process similar to the process shown in FIG. 13. Specifically, the power-transmitter controller 71 turns the first switch SW1 and the second switch SW2 on or off in accordance with the determination result as to whether the combination is appropriate in step S11.

[0109] As shown in FIG. 19(A), when the first switch SW1 and the second switch SW2 are turned off, the power-transmitter resonant circuit 30 has an S (series) topology, in which each series capacitor 23 is connected in series to the power transmitter coil 22. On the other hand, as shown in FIG. 19(B), when the first switch SW1 and the second switch SW2 are turned on, the power-transmitter resonant circuit 30 has a P (parallel) topology, in which the parallel capacitor 24 is connected in parallel to the power transmitter coil 22. The P topology is capable of reducing the number of immittance converters by one in the power transmitter circuit 400 compared to the S topology.

[0110] Eighth Embodiment 　　　　　　 Hereinafter, an eighth embodiment will be described with reference to the drawings, focusing on differences from the seventh embodiment. Also in the present embodiment, as shown in FIG. 20, the power-transmitter resonant circuit 30 is configured to allow switching of the presence or absence of the immittance conversion function.

[0111] The power-transmitter resonant circuit 30 includes a resonant coil 25 magnetically coupled to the power transmitter coil 22, a sub capacitor 26, and a third switch SW3. The series connection of the sub capacitor 26 and the third switch SW3 is connected in parallel to the resonant coil 25.

[0112] The power-transmitter controller 71 performs a switching process similar to the process shown in FIG. 13. Specifically, the power-transmitter controller 71 turns the first switches SW1, the second switch SW2, and the third switch SW3 on or off according to the determination result of whether the combination is appropriate in step S11.

[0113] As shown in FIG. 20(A), when the first switches SW1, the second switch SW2, and the third switch SW3 are turned off, the power-transmitter resonant circuit 30 uses the S topology, and the closed circuit including the resonant coil 25 and the sub capacitor 26 is interrupted. On the other hand, as shown in FIG. 20(B), when the first switch SW1, the second switch SW2, and the third switch SW3 are turned on, the power-transmitter resonant circuit 30 uses the P topology, and the above-mentioned closed circuit is formed. As a result, compared to the case in FIG. 20(A), the number of immittance converters can be increased by one in the power transmitter circuit 400.

[0114] Other Embodiments 　　　　　　 The above embodiments may be changed and carried out as follows.

[0115] In each of the above embodiments, the power converter included in the power transmitter 20 may have the function of an immittance converter. For example, at least one of the inverter 60 and the PFC circuit 61 may be a circuit having the function of an immittance converter.

[0116] The wireless power transfer system may have the first function of executing wireless power transfer from the vehicle-side device to the ground-side device, in addition to the second function of executing 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] The wireless power transfer system may have the function of executing wireless power transfer from the vehicle-side device to the ground-side device, instead of the function of wireless power transfer from the ground-side device to the vehicle-side device.

[0121] 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.

[0122] 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 coils and use an electric field coupling method may be used.

[0123] 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.

[0124] 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.

[0125] 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 transmitter (20) 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 the power transmitter having a power transmitting antenna (22), another of the vehicle-side device and the ground-side device being a power receiver (100) having a power receiving antenna (102), the power transmitting antenna being configured to be energized to perform wireless power transfer to the power receiving antenna, the power receiver including a power receiver circuit (500) having the power receiving antenna, the power receiver circuit being connected to a power supply target device (300, 310) to be supplied with power received by the power receiving antenna, the power transmitter comprising: 　　　　　　 a power transmitter circuit (400) having the power transmitting antenna to be supplied with power from a direct-current voltage source (61); and 　　　　　　 a power-transmitter control unit (70), wherein 　　　　　　 the power-transmitter control unit is configured to perform a switching process to switch an output characteristic of the power transmitter circuit.

2. The power transmitter according to claim 1, further comprising 　　　　　　 a switching unit configured to switch the output characteristic of the power transmitter circuit, wherein 　　　　　　 the switching unit is configured to switch the output characteristic of the power transmitter circuit to approximate a current source output characteristic or a voltage source output characteristic.

3. The power transmitter according to claim 2, wherein 　　　　　　 the switching unit is a power-transmitter power converter (62, 61) configured to receive power from the direct-current voltage source and vary an output power effective value, and 　　　　　　 the power-transmitter control unit is configured to perform, as the switching process, a process of controlling an output voltage effective value of the power-transmitter power converter to adjust an effective power output from the power-transmitter power converter toward the power transmitting antenna.

4. The power transmitter according to claim 2, wherein 　　　　　　 the power transmitter circuit includes an inverter (60) supplied with power from the direct-current voltage source, and 　　　　　　 the power-transmitter control unit is configured to perform, as the switching process, a process of switching a control of the inverter from a frequency control to a control of an output power effective value.

5. The power transmitter according to claim 1, further comprising 　　　　　　 the power transmitter circuit is configured to be switched in circuit topology, when the wireless power transfer is performed, so that a total number of immittance converters (52, 30) included in the power receiver circuit and the power transmitter circuit combined becomes an odd number or an even number.

6. The power transmitter according to claim 5, wherein 　　　　　　 the power transmitter circuit includes 　　　　　　　　　　　　　 an immittance converter (52), and 　　　　　　　　　　　　　 a characteristic switching switch (SWA) configured to select whether the immittance converter is interposed between the power transmitting antenna and the direct-current voltage source, and 　　　　　　 the power-transmitter control unit is configured to perform, as the switching process, a process of controlling the characteristic switching switch to select whether the immittance converter is interposed between the power transmitting antenna and the direct-current voltage source.

7. The power transmitter according to claim 6, wherein 　　　　　　 the immittance converter is an immittance filter (52).

8. The power transmitter according to claim 5, wherein 　　　　　　 the power transmitter circuit includes 　　　　　　　　　　　　　 an immittance converter (52), and 　　　　　　　　　　　　　 a characteristic switching switch (SWC) configured to selectively insert or remove the immittance converter between the power transmitting antenna and the direct-current voltage source, 　　　　　　 the immittance converter is a band-pass filter provided between the direct-current voltage source and the power transmitting antenna, 　　　　　　 the band-pass filter includes 　　　　　　　　　　　　　 a parallel capacitor (53A) connected in parallel to the power transmitting antenna, 　　　　　　　　　　　　　 a series capacitor (53B) connected in series to the power transmitting antenna, and 　　　　　　　　　　　　　 an inductor (53C) connected in series to the series capacitor, 　　　　　　 the characteristic switching switch is connected in parallel to the series capacitor to bypass the series capacitor, and 　　　　　　 the power-transmitter control unit is configured to perform, as the switching process, a process controlling the characteristic switching switch to select whether the series capacitor is bypassed.

9. The power transmitter according to claim 5, wherein 　　　　　　 the power transmitter circuit includes 　　　　　　　　　　　　　 an immittance converter (52), and 　　　　　　　　　　　　　 a characteristic switching switch (SWD) configured to select whether the immittance converter is interposed between the power transmitting antenna and the direct-current voltage source, 　　　　　　 the immittance converter is a fourth-order filter provided between the direct-current voltage source and the power transmitting antenna, 　　　　　　 the fourth-order filter includes 　　　　　　　　　　　　　 a first inductor (54A) connected in series to the power transmitting antenna, 　　　　　　　　　　　　　 a second inductor (54C) connected in series to the first inductor, 　　　　　　　　　　　　　 a first capacitor (54B) connected between the first inductor and the second inductor, and connected in parallel to the power transmitting antenna, and 　　　　　　　　　　　　　 a second capacitor (54D) connected between the power transmitting antenna and the first inductor, and connected in parallel to the power transmitting antenna, 　　　　　　 the characteristic switching switch is connected in series to a target capacitor, which is either the first capacitor or the second capacitor, and 　　　　　　 the power-transmitter control unit is configured to perform, as the switching process, a process of controlling the characteristic switching switch to select whether the target capacitor is connected in parallel to the power transmitting antenna.

10. The power transmitter according to claim 5, wherein 　　　　　　 the power transmitter circuit includes 　　　　　　　　　　　　　 an immittance converter (52), and 　　　　　　　　　　　　　 a characteristic switching switch (SWE) configured to select whether the immittance converter is interposed between the power transmitting antenna and the direct-current voltage source, 　　　　　　 the immittance converter is an immittance filter provided between the direct-current voltage source and the power transmitting antenna, 　　　　　　 the immittance filter includes 　　　　　　　　　　　　　 a first inductor (54A) connected in series to the power transmitting antenna, 　　　　　　　　　　　　　 a second inductor (54C) connected in series to the first inductor, and 　　　　　　　　　　　　　 a first capacitor (54B) and a second capacitor (54D) connected between the first inductor and the second inductor, and connected in parallel to the power transmitting antenna, 　　　　　　 capacitances of the first capacitor and the second capacitor are identical, 　　　　　　 the characteristic switching switch is connected in series to a target capacitor, which is either the first capacitor or the second capacitor, and 　　　　　　 the power-transmitter control unit is configured to perform, as the switching process, a process of controlling the characteristic switching switch to select whether the target capacitor is connected in parallel to the power transmitting antenna.

11. The power transmitter according to claim 5, wherein 　　　　　　 the power transmitter circuit includes 　　　　　　　　　　　　　 an immittance converter (30), and 　　　　　　　　　　　　　 a characteristic switching switch (SW1, SW2) configured to select whether the immittance converter is interposed between the power transmitting antenna and the direct-current voltage source, 　　　　　　 the immittance converter is a resonance circuit connected to the power transmitting antenna, 　　　　　　 the resonance circuit includes 　　　　　　　　　　　　　 a parallel capacitor (24) provided between the direct-current voltage source and the power transmitting antenna, and connected in parallel to the power transmitting antenna, and 　　　　　　　　　　　　　 a series capacitor (23) connected in series to the power transmitting antenna, 　　　　　　 the characteristic switching switch includes 　　　　　　　　　　　　　 a first switch (SW1) connected in series to the parallel capacitor, and 　　　　　　　　　　　　　 a second switch (SW2) connected in parallel to the series capacitor to bypass the series capacitor, and 　　　　　　 the power-transmitter control unit is configured to perform, as the switching process, a process controlling the first switch and the second switch to select a P topology, in which the parallel capacitor is connected in parallel to the power transmitting antenna, or an S topology, in which the series capacitor is connected to the power transmitting antenna.

12. The power transmitter according to claim 5, wherein 　　　　　　 the power transmitting antenna is a communication coil, 　　　　　　 the power transmitter circuit includes 　　　　　　　　　　　　　 an immittance converter (30), and 　　　　　　　　　　　　　 a characteristic switching switch (SW1, SW2, SW3) configured to select whether the immittance converter is interposed between the power transmitting antenna and the direct-current voltage source, 　　　　　　 the immittance converter is a resonance circuit connected to the power transmitting antenna, 　　　　　　 the resonance circuit includes 　　　　　　　　　　　　　 a parallel capacitor (24) provided between the direct-current voltage source and the power transmitting antenna, and connected in parallel to the power transmitting antenna, and 　　　　　　　　　　　　　 a series capacitor (23) connected in series to the power transmitting antenna, 　　　　　　　　　　　　　 a resonant coil (25) magnetically coupled to the power transmitting antenna, and 　　　　　　　　　　　　　 a sub capacitor (26) connected to one end of the resonant coil, 　　　　　　 the characteristic switching switch includes 　　　　　　　　　　　　　 a first switch (SW1) connected in series to the parallel capacitor, and 　　　　　　　　　　　　　 a second switch (SW2) connected in parallel to the series capacitor to bypass the series capacitor, and 　　　　　　　　　　　　　 a third switch (SW3) configured to form a closed circuit including the resonant coil and the sub capacitor when the third switch is turned on, and interrupt the closed circuit when the third switch is turned off, and 　　　　　　 the power-transmitter control unit is configured to perform, as the switching process, a process controlling the first switch, the second switch and the third switch to 　　　　　　　　　　　　　 select a P topology, in which the parallel capacitor is connected in parallel to the power transmitting antenna, or an S topology, in which the series capacitor is connected to the power transmitting antenna, and 　　　　　　　　　　　　　 select whether the closed circuit is interrupt.

13. The power transmitter according to any one of claims 1 to 12, wherein 　　　　　　 the power-transmitter control unit is configured to 　　　　　　　　　　　　　 acquire an output characteristic of the power receiver circuit before the wireless power transfer is performed, and 　　　　　　　　　　　　　 perform the switching process to switch the output characteristic of the power transmitter circuit based on the acquired output characteristic.

14. A program for a power transmitter (20) 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 the power transmitter having a power transmitting antenna (22), another of the vehicle-side device and the ground-side device being a power receiver (100) having a power receiving antenna (102), the power transmitting antenna being configured to be energized to perform wireless power transfer to the power receiving antenna, the power receiver including a power receiver circuit (500) having the power receiving antenna, the power receiver circuit being connected to a power supply target device (300, 301) to be supplied with power received by the power receiving antenna, the power transmitter including a power transmitter circuit (400) supplied with power from a direct-current voltage source (61) and including the power transmitting antenna, the program configured to cause a processor to perform 　　　　　　 a switching process to switch an output characteristic of the power transmitter circuit.

15. A control method for a power transmitter (20) 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 the power transmitter having a power transmitting antenna (22), another of the vehicle-side device and the ground-side device being a power receiver (100) having a power receiving antenna (102), the power transmitting antenna being configured to be energized to perform wireless power transfer to the power receiving antenna, the power receiver including a power receiver circuit (500) having the power receiving antenna, the power receiver circuit being connected to a power supply target device (300, 301) to be supplied with power received by the power receiving antenna, the power transmitter including a power transmitter circuit (400) supplied with power from a direct-current voltage source (61) and including the power transmitting antenna, the method, executed by a processor, comprising 　　　　　　 performing a switching process to switch an output characteristic of the power transmitter circuit.

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