In-vehicle power receiver, program, and control method for in-vehicle power receiver

Abstract

A power receiver (100) includes a power-receiver communication coil (170) and a power-receiver control unit (230) that controls energization of the power-receiver communication coil (170) for supply of a power supply request signal, requesting the power transmitter coil (22) to supply power, to the power-receiver communication coil (170). The power-receiver control unit (230) executes an abnormality determination process determining whether an abnormality related to wireless power transfer has occurred, and a prevention process preventing supply of the power supply request signal to the power-receiver communication coil (170) when the abnormality related to wireless power transfer is determined to have occurred.

Description

IN-VEHICLE POWER RECEIVER, PROGRAM, AND CONTROL METHOD FOR IN-VEHICLE POWER RECEIVERCross Reference

[0001] This application is based on Japanese Patent Application No. 2024-168827 filed on September 27, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to an in-vehicle power receiver, a program, and a control method for an in-vehicle power receiver.

[0003] Patent Literature 1 discloses a system for executing wireless power transfer from a ground-based power transmitter to a power receiver installed in an electric vehicle. The power transmitter includes a power transmitter coil and a control unit that energizes the power transmitter coil. The power receiver includes a power receiver coil that is supplied with power wirelessly from the power transmitter coil.

[0004] The power transmitter and the power receiver include communication coils for narrow area wireless communication. The power receiver supplies a power supply request signal to the communication coil of the power receiver. The power transmitter determines whether there is a power supply request based on an output signal from the communication coil of the power transmitter. When the power transmitter determines that there is a power supply request, the power transmitter energizes the power transmitter coil.

[0005] Patent Literature 1: JP 2024-008088 A

[0006] An abnormality related to wireless power transfer may occur. It is undesirable for a power supply request signal to be transmitted from the in-vehicle power receiver when this abnormality has occurred.

[0007] A main purpose of the present disclosure is to provide an in-vehicle power receiver, a program, and a control method for the in-vehicle power receiver that can reduce the occurrence of a situation where a power supply request signal is sent from an in-vehicle power receiver while an abnormality related to wireless power transfer has occurred.

[0008] According to the present disclosure, an in-vehicle power receiver includes an in-vehicle power receiver, a power-receiver communication coil, and a power-receiver control unit. The in-vehicle power receiver includes a power receiver coil configured to wirelessly receive power supply from a power transmitter coil of a power transmitter. The power-receiver control unit is configured to control energization of the power-receiver communication coil for supply of a power supply request signal to the power-receiver communication coil. The power supply request signal is a signal requesting the power transmitter coil to supply power. The power-receiver control unit is configured to execute an abnormality determination process determining whether an abnormality related to wireless power transfer has occurred, and a prevention process preventing the supply of the power supply request signal to the power-receiver communication coil when the abnormality related to wireless power transfer is determined to have occurred.

[0009] This can reduce an occurrence of a situation where the power supply request signal is sent from the in-vehicle power receiver while an abnormality related to wireless power transfer has occurred.

[0010] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.FIG. 1 is an overall configuration diagram of a wireless power transfer system according to a first embodiment.FIG. 2 is an overall configuration diagram of the wireless power transfer system.FIG. 3 is a diagram illustrating a power transmitter and a power receiver.FIG. 4 is a diagram illustrating an electrical circuit of the power receiver.FIG. 5 is a flowchart illustrating a procedure a protection process.FIG. 6 is a diagram illustrating a short-circuit operation in which two lower arm switches are turned on.FIG. 7 is a diagram illustrating a power receiver according to a modification of the first embodiment.FIG. 8 is a diagram illustrating a communication unit of the power receiver according to a modification of the first embodiment.FIG. 9 is a diagram illustrating a communication unit of the power receiver according to the modification of the first embodiment.FIG. 10 is a diagram illustrating a communication unit of the power receiver according to the modification of the first embodiment.FIG. 11 is a diagram illustrating a communication unit of the power receiver according to the modification of the first embodiment.FIG. 12 is a diagram illustrating a communication unit of the power receiver according to a modification of the first embodiment.FIG. 13 is a diagram illustrating a communication unit of the power receiver according to the modification of the first embodiment.FIG. 14 is a flowchart illustrating a procedure of a protection process according to a second embodiment.

[0011] Multiple embodiments will be described with reference to the drawings. In the embodiments, parts that functionally and / or structurally correspond to or are associated with each other may be assigned the same reference numeral, or reference numerals different in digit in the hundreds or higher place. The corresponding and / or associated parts may refer to the explanation in the other embodiments.

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

[0013] First, an overall configuration of the wireless power transfer system will be described. As shown in FIGS. 1, 2, and 3, the wireless power transfer system 10 includes a power transmitter 20 and a power receiver 100. The power receiver 100 is mounted on a vehicle 11 as a moving object that travels on a road RS. The vehicle 11 is, for example, an electric automobile or a hybrid vehicle. The power is supplied from the power transmitter 20 to the power receiver 100 while the vehicle 11 is travelling or stopped. The wireless power transfer system 10 executes wireless power transfer from the power transmitter 20 to the power receiver 100 through magnetic field resonance coupling (magnetic field resonance). The wireless power transfer system 10 is also referred to as a dynamic wireless power transfer (D-WPT) system.

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

[0015] The configuration is not limited to one power-transmitter power supply unit 51 for each of the multiple power-transmitter coil units 21, but one power-transmitter power supply unit 51 may be provided for each power-transmitter coil unit 21.

[0016] The power-transmitter power supply unit 51 includes a PFC (Power Factor Correction) circuit 61, an inverter 60, and a filter circuit 52. The PFC circuit 61 includes an AC / DC converter and is connected to the AC power source 15. The PFC circuit 61 includes switching elements (e.g., IGBTs or MOSFETs) that are switched and controlled to convert the input AC power to DC (direct current) power and improve a power factor of the AC power input from the AC power source 15.

[0017] The inverter 60 is connected to the PFC circuit 61. The inverter 60 includes switching elements (e.g., IGBTs or MOSFETs) that are switched and controlled to convert the DC power input from the PFC circuit 61 to AC power.

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

[0019] The power-transmitter coil unit 21 includes a power transmitter coil 22, 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.

[0020] The power receiver 100 includes a power-receiver coil unit 101 and a power-receiver power supply unit 181. The power-receiver coil unit 101 includes a power receiver coil 102. In the present embodiment, the power receiver coil 102 includes a first power receiver coil 110 and a second power receiver coil 130. The power-receiver coil unit 101 is located at the bottom of the vehicle body of the vehicle 11. When the vehicle 11 travels on the road RS where the power transmitter coil 22 is buried, the power transmitter coil 22 on the ground side and the power receiver coil 102 of the vehicle 11 face each other in the vertical direction.

[0021] The power receiver 100 includes a first power-receiver resonant circuit 140A and a second power-receiver resonant circuit 140B. The first power receiver coil 110 is connected to the first power-receiver resonant circuit 140A, and the second power receiver coil 130 is connected to the second power-receiver resonant circuit 140B. The first power receiver coil 110 and the second power receiver coil 130 are supplied with power from the power transmitter coil 22. The first power receiver coil 110 supplies the received power to the first power-receiver resonant circuit 140A, and the second power receiver coil 130 supplies the received power to the second power-receiver resonant circuit 140B.

[0022] The power-receiver power supply unit 181 of the power receiver 100 includes a first filter circuit 182A, a first rectifier circuit 200A, a second filter circuit 182B, and a second rectifier circuit 200B. In this embodiment, each rectifier circuit 200A, 200B corresponds to a "DC-AC conversion circuit".

[0023] The configurations of the first power-receiver resonant circuit 140A, the first filter circuit 182A, and the first rectifier circuit 200A are basically the same as those of the second power-receiver resonant circuit 140B, the second filter circuit 182B, and the second rectifier circuit 200B. For this reason, the following descriptions focus on the configurations of the first power-receiver resonant circuit 140A, the first filter circuit 182A, and the first rectifier circuit 200A, and the subscript A in the reference numeral may be omitted in the subsequent descriptions.

[0024] As shown in FIG. 4, the power-receiver resonant circuit 140 includes a first resonant capacitor 141 and a second resonant capacitor 142. The power-receiver resonant circuit 140 is not limited to the circuit shown in FIG. 4, but various circuits can be employed.

[0025] 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 is an LC filter that includes a first reactor 183, a second reactor 184, and a capacitor 185. A first end of the first reactor 183 is connected to a first end of the power receiver coil 102 via the first resonant capacitor 141. A first end of the second reactor 184 is connected to a second end of the power receiver coil 102 via the second resonant capacitor 142. The first end of the first reactor 183 and the first end of the second reactor 184 are connected by a capacitor 185. The filter circuit 182 is not limited to the circuit shown in FIG. 4, but various circuits can be employed.

[0026] The rectifier circuit 200 is a full bridge circuit and includes a first upper arm switch QH1, a first lower arm switch QL1, a second upper arm switch QH2, and a second lower arm switch QL2. In this embodiment, each switch QH1, QL1, QH2, QL2 is a semiconductor switching device, and specifically, is an N-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). Each switch QH1, QL1, QH2, QL2 has a body diode DH1, DL1, DH2, DL2.

[0027] The rectifier circuit 200 may include an IGBT (Insulated Gate Bipolar Transistor) instead of the N-channel MOSFET. In this case, a freewheel diode may be connected in inverse parallel to the IGBT.

[0028] The source of the first upper arm switch QH1, which is the low potential terminal of the first upper arm switch QH1, and the drain of the first lower arm switch QL1, which is the high potential terminal of the first lower arm switch QL1, are connected to a second end of the first reactor 183 which constitutes the filter circuit 182. The source of the second upper arm switch QH2 and the drain of the second lower arm switch QL2 are connected to a second end of the second reactor 184 which constitutes the filter circuit 182.

[0029] The power receiver 100 includes a smoothing capacitor 210. The smoothing capacitor 210 connects the drains of the first and second upper arm switches QH1 and QH2 to the sources of the first and second lower arm switches QL1 and QL2. The smoothing capacitor 210 may be provided separately for each rectifier circuit 200A, 200B.

[0030] The power receiver coil, power-receiver resonant circuit, filter circuit, and rectifier circuit are not limited to the two systems as shown in FIG. 3. For example, a single system may be employed.

[0031] The vehicle 11 includes a high potential main switch 301H, a low potential main switch 301L, and a high-voltage storage battery 300 (corresponding to "power supply target device") 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 drain of the first upper arm switch QH1 and the drain of the second upper arm switch QH2 are connected to the positive terminal of the high-voltage storage battery 300 via the high potential main switch 301H. The source of the first lower arm switch QL1 and the source of the second lower arm switch QL2 are connected to the 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.

[0032] The vehicle 11 includes a travelling inverter 310 and a rotary electric machine 320. The travelling inverter 310 is a 3-phase inverter and is connected to the high-voltage storage battery 300 via the high potential main switch 301H and the low potential main switch 301L. The armature windings of the rotary electric machine 320 are connected to the upper and lower arm switches that constitute the travelling inverter 310. By switching control of the upper and lower arm switches of the travelling inverter 310 while the high potential main switch 301H and the low potential main switch 301L are turned on, the travelling inverter 310 converts the DC power supplied from the high-voltage storage battery 300 into AC power and supplies it to the armature winding. This causes the rotor of the rotary electric machine 320 to rotate, and the rotational power of the rotor rotates drive wheels of the vehicle 11. As a result, the vehicle 11 travels.

[0033] As shown in FIG. 3, the power-transmitter power supply unit 51, which constitutes the power transmitter 20, includes a power-transmitter control unit 70. The power-transmitter control unit 70 includes a power-transmitter controller 71. The power-transmitter controller 71 is an electronic control unit (ECU) that executes various controls of the power transmitters 20 and includes a processor as hardware, a storage unit, and a communication bus connecting the processor and storage unit.

[0034] 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.

[0035] For example, the program information stored on the non-transitory tangible storage medium is installed in the storage unit. The storage medium is, for example, a USB memory, CD-ROM or DVD. In addition, the program information transmitted over a communication network, such as OTA (Over The Air), for example, is installed in the storage unit.

[0036] 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 as shown in FIG. 4, includes a processor 232 as hardware, a storage unit 233, and a communication bus 234 that connects the processor 232 and storage unit 233.

[0037] The storage unit 233 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 232 with a work area for temporary use when the processor 232 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 232 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.

[0038] For example, the program information stored on the non-transitory tangible storage medium is installed in the storage unit 233. The storage medium is, for example, a USB memory, CD-ROM or DVD. In addition, the program information transmitted over a communication network, such as OTA (Over The Air), for example, is installed in the storage unit 233.

[0039] The power-transmitter controller 71 executes a switching control of the PFC circuit 61 and a switching control of the inverter 60. Through the switching control of the inverter 60, a high-frequency AC voltage is applied to the power transmitter coil 22. This causes a high-frequency current to flow in the power transmitter coils 22 and a magnetic field for power transmission is generated in the power transmitter coils 22.

[0040] 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.

[0041] When the magnetic field generated in the power transmitter coil 22 links with the power receiver coil 102 of the vehicle 11, a high-frequency current flows in the power receiver coil 102, varying with the frequency of the high-frequency current flowing in the power transmitter coil 22. The high-frequency current flowing in the power transmitter coil 22 is supplied to the rectifier circuit 200 through the power-receiver resonant circuit 140 and the filter circuit 182. The power-receiver controller 231 converts the supplied AC current into DC current by executing switching control (i.e., synchronous rectification control) of each of the switches QH1, QL1, QH2, and QL2 and outputs it. 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.

[0042] The high potential main switch 301H and the low potential main switch 301L can actually be controlled by a different controller than the power-receiver controller 231. For convenience, however, the high potential main switch 301H and the low potential main switch 301L are controlled by the power-receiver controller 231.

[0043] 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.

[0044] The vehicle 11 includes a voltage sensor 330, a current sensor 340, and a temperature sensor 350. The voltage sensor 330 detects voltages of various in-vehicle devices of the vehicle 11 (specifically, components of the power receiver 100), for example, a voltage of the smoothing capacitor 210. The current sensor 340 detects currents flowing in various in-vehicle devices of the vehicle 11 (specifically, the components of the power receiver 100), for example, currents flowing in the power receiver coil 102 and the rectifier circuit 200. The temperature sensor 350 detects temperatures of various in-vehicle components of the vehicle 11 (specifically, the components of the power receiver 100), for example, temperatures of the smoothing capacitor 210, the rectifier circuit 200 (e.g., the diodes of the rectifier circuit 200), the first power receiver coil 110 or the second power receiver coil 130. For example, the receiver coils 110, 130 each include a coil (e.g., copper wire) that conducts current and generates magnetic flux, a ferrite that facilitates generation of magnetic flux, an aluminum shield, and a synthetic resin casing that houses the coil, ferrite and aluminum shield. The aluminum shield is a component to prevent the magnetic flux generated by the energized coil from linking to the body of the vehicle 11 and causing heat generation. The temperature sensor 350 may detect the temperature of each of the coil, ferrite, aluminum shield, and casing individually, or it may detect the temperature of any combination (one, two, or three) of the coil, ferrite, aluminum shield, and casing. The detected values of each sensor 330, 340, 350 are input to the power-receiver controller 231.

[0045] 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. A power-receiver control unit 230 includes a signal transmitter 240.

[0046] The power-transmitter coil unit 21, which constitutes the power transmitter 20, includes the power-transmitter communication coil 40. The power-transmitter control unit 70 includes a signal receiver 80. The power-receiver communication coil 170 and the power-transmitter communication coil 40 are communication coils for narrow area wireless communication. Narrow area wireless communications are those with a communication distance of less than 10 meters (e.g., 2-3 meters). Narrow area wireless communication is a communication with a shorter communication distance than wide area wireless communication.

[0047] 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.

[0048] 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 power-receiver controller 231 controls the signal transmitter 240 to supply a power supply request signal to the power-receiver communication coil 170. The power supply request signal is a signal requesting the power transmitter coil 22 near the vehicle 11 to transmit power to the power receiver coil 102.

[0049] The power-receiver control unit 230 controls the signal transmitter 240 to supply a single frame to the power-receiver communication coil 170, and the single frame includes the power supply request signal, ID information of the vehicle 11, and a requested power Weq that is a requested value of the power supply to the vehicle 11. This control causes a high-frequency voltage to be applied from the signal transmitter 240 to the power-receiver communication coil 170. Consequently, a high-frequency current flows in the power-receiver communication coil 170, and a magnetic field for information communication is generated in the power-receiver communication coil 170.

[0050] When the power-receiver coil unit 101 of the vehicle 11 approaches the power-transmitter coil unit 21 on the ground side, the generated magnetic field 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 required 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.

[0051] 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).

[0052] The power-transmitter controller 71 determines whether to energize the power transmitter coil 22 based on the input signal from the signal receiver 80. In detail, when the power-transmitter controller 71 determines that there is a power supply request based on the input signal from the signal receiver 80, the power-transmitter controller 71 applies high-frequency voltage to the power transmitter coil 22 by controlling the inverter 60 and the PFC circuit 61. This results in a wireless power transmission from the power transmitter coil 22 to the power receiver coil 102.

[0053] An anomaly related to wireless power transfer may occur in the power receiver 100. As a countermeasure for this situation, the power-receiver controller 231 executes a protection process to protect the power receiver 100 from abnormalities.

[0054] FIG. 5 is a flowchart illustrating a procedure of the protection process.

[0055] In step S10, an abnormality determination process is executed to determine whether an overvoltage or overheat abnormality has occurred in the power receiver 100. The outline of the abnormality determination will be described. A range of normal values or an upper threshold value for the sensor detection value is set, and when the sensor detection value falls outside the range of normal values or exceeds the upper threshold value, an abnormality is determined to have occurred.

[0056] For example, when the voltage of the smoothing capacitor 210 or the voltage of the power receiver coil 102 detected by the voltage sensor 330 exceeds a voltage threshold Vth, an overvoltage abnormality may be determined to have occurred.

[0057] For example, when the temperature of the smoothing capacitor 210, the temperature of the high potential main switch 301H, the temperature of the low potential main switch 301L, the temperature of the power receiver coil 102, the temperature of the power-receiver resonant circuit 140, the temperature of the filter circuit 182, the temperature of the rectifier circuit 200 or the temperature of the high-voltage storage battery 300, detected by the temperature sensor 350, exceeds a first temperature threshold Tth1, an overheat abnormality may be determined to have occurred.

[0058] When it is determined in step S10 that an overvoltage or overheat abnormality has occurred, the process proceeds to step S11. In step S11, a prevention process is performed to prevent the supply of the power supply request signal to the power-receiver communication coil 170. Here, "preventing the supply of the power supply request signal" can be interpreted as "preventing the supply of the power supply request signal". This can reduce a situation where a power supply request signal is transmitted from the power receiver 100 while an abnormality related to wireless power transfer has occurred. Methods of preventing the supply of power supply request signals will be described in a modification of the first embodiment.

[0059] In step S12, a short-circuit operation is performed to turn on only the first and second lower arm switches QL1 and QL2 (corresponding to "short-circuit switch") among the first and second upper and lower arm switches QH1, QL1, QH2, and QL2 that constitute the rectifier circuit 200. As shown in FIG. 6, this forms a closed circuit including the power receiver coil 102, the power-receiver resonant circuit 140, the filter circuit 182, and the first and second lower arm switches QL1 and QL2, and current flows in this closed circuit. As a result, the power receiver 100 can be protected from overvoltage and components such as the smoothing capacitor 210 and each main switch 301H, 301L can protected from overheat. When the short-circuit operation is performed, Nscr, which represents the number of times the short-circuit operation has been performed and is stored in the storage unit 233, is incremented by 1.

[0060] In step S12, a short-circuit operation may be performed to turn on only the first and second upper arm switches QH1 and QH2 among the first and second upper and lower arm switches QH1, QL1, QH2, and QL2.

[0061] In step S13, it is determined whether a release condition is satisfied. When the release condition is determined to be satisfied, a release process is performed to release the short-circuit operation. This causes the first and second lower arm switches QL1 and QL2 to be switched off.

[0062] In this embodiment, when it is determined that a condition (A1) or a condition (A2) described below is satisfied, the release condition is determined to be satisfied.

[0063] The condition (A1) is a condition that current no longer flows in the closed circuit including the power receiver coil 102 and the first and second lower arm switches QL1 and QL2. For example, when it is determined that the current in the power receiver coil 102 or the current in the rectifier circuit 200 detected by the current sensor 340 has become 0 or is below a current threshold, the condition (A1) may be determined to be satisfied. The current threshold is, for example, a value close to zero.

[0064] The condition (A2) is a condition that the supply voltage to the high-voltage storage battery 300 (e.g., the voltage of the smoothing capacitor 210 detected by the voltage sensor 330) has fallen below a predetermined voltage.

[0065] When it is determined that the release condition is satisfied in step S13, the process proceeds to step S13. In step S13, it is determined whether a resumption condition is satisfied to permit the supply of the power supply request signal to the power-receiver communication coil 170. When it is determined that the resumption condition is satisfied, the process proceeds to step S15 to permit the supply of the power supply request signal to the power-receiver communication coil 170.

[0066] In this embodiment, when it is determined that all of the following conditions (B1), (B2), (B3) and (B4) below have been met, the resumption condition is determined to have been satisfied.

[0067] The condition (B1) is a condition that the above-described release process has been executed.

[0068] The condition (B2) is a condition that no overheat or overvoltage abnormality has occurred. For example, when the temperature of the smoothing capacitor 210 or the temperature of the power receiver coil 102 detected by the temperature sensor 350 is determined to be below a first threshold, an overheat abnormality may be determined to have not occurred. For example, when the voltage of the smoothing capacitor 210 or the voltage of the power receiver coil 102 detected by the voltage sensor 330 is determined to be below the voltage threshold Vth, an overvoltage abnormality may be determined to have not occurred.

[0069] The condition (B3) is a condition that the state of the high-voltage storage battery 300, the temperature of the high potential main switch 301H, and the temperature of the low potential main switch 301L are normal. For example, when it is determined that the upper power limit Win that can be input to the high-voltage storage battery 300 is within a normal power range, the state of the high-voltage storage battery 300 may be determined to be normal. When the temperature of the high potential main switch 301H or the temperature the low potential main switch 301L detected by the temperature sensor 350 is below a second threshold, the temperature of the high potential main switch 301H or the temperature the low potential main switch 301L may be determined to be normal.

[0070] The condition (B4) is a condition that the temperature of the first and second lower arm switches QL1 and QL2 to be turned on by the short-circuit operation, detected by the temperature sensor 350, is below a release threshold Trr. The release threshold Trr is less than or equal to the first temperature threshold Tth1.

[0071] The resumption condition may include a condition that a probability of occurrence of the short-circuit operation is below a probability threshold. The resumption condition is not limited to all of the conditions (B1), (B2), (B3) and (B4), but may be any combination (one, two or three) selected from these four.

[0072] When a negative determination is made in step S10, the process proceeds to step S16 to determine whether an overheat abnormality has occurred in the rectifier circuit 200. For example, when the highest one of temperatures of the switches QH1, QL1, QH2, QL2 detected by the temperature sensor 350 is determined to exceed a second temperature threshold Tth2, an overheating abnormality may be determined to have occurred in the rectifier circuit 200. The second temperature threshold Tth2 is higher than the first temperature threshold Tth1.

[0073] When it is determined in step S16 that an overheat abnormality has occurred, the process proceeds to step S17. In step S17, as in step S11, a prevention process is performed to prevent the supply of the power supply request signal to the power-receiver communication coil 170. In the subsequent step S18, each of the switches QH1, QL1, QH2, and QL2 constituting the rectifier circuit 200 are all maintained to be turned off. The prevention process prevents current from flowing to the rectifier circuit 200 and can protect the rectifier circuit 200 from overheating abnormalities.

[0074] In step S19, the temperature of each switch QH1, QL1, QH2, and QL2 detected by the temperature sensor 350 is used to determine whether the overheat abnormality in the rectifier circuit 200 has been resolved. When a positive determination is made in step S19, the process proceeds to step S15 and release the process of step S18.

[0075] According to this embodiment detailed above, it is possible to reduce occurrence of a situation in which a power supply request signal is transmitted from the power receiver 100 while an abnormality related to wireless power transfer has occurred.

[0076] Modifications of First Embodiment The resumption condition in step S14 of FIG. 5 may be a condition that a predetermined period of time has elapsed since the execution of the prevention process in step S11. In this case, the process of step S13 may be eliminated and the short-circuit operation may be released when the resumption condition is determined to be satisfied.

[0077] The short-circuit switch is not limited to the switch included in the rectifier circuit 200, but may be a switch provided separately from the rectifier circuit 200. FIG. 7 shows a short-circuit switch 400 connecting the first resonant capacitor 141 and the second resonant capacitor 142.

[0078] The methods of preventing the supply of a power supply request signal to the power-receiver communication coil 170 will explained using FIGS. 8 to 13.

[0079] As shown in FIG. 8, the power receiver 100 includes a first cutoff switch 401 that connects the power-receiver controller 231 and the low-voltage storage battery 302, and a second cutoff switch 402 that connects the signal transmitter 240 and the power-receiver controller 231. The power-receiver controller 231 switches off all or either one of the first and second cutoff switches 401 and 402 in the prevention process. Either one of the first cutoff switch 401 and the second cutoff switch 402 may not be provided.

[0080] As shown in FIG. 9, the signal transmitter 240 includes a carrier generator 241, comparator 242, and amplifier 243. The power-receiver controller 231, for example, outputs a signal such as a power supply request signal as a binary signal (specifically, H or L signal) to the comparator 242. The comparator 242 generates and outputs an AC signal by comparing the input signal from the power-receiver controller 231 with the carrier signal input from the carrier generator 241. The amplifier 243 amplifies the input signal from the comparator 242 at a predetermined amplification ratio and supplies the amplified signal to the power-receiver communication coil 170.

[0081] In this case, the power-receiver controller 231 prevents the supply of the power supply request signal by stopping the output of the amplifier 243. Alternatively, the power-receiver controller 231 prevents the supply of the power supply request signal by setting the frequency of the carrier signal output from the carrier generator 241 to 0 Hz.

[0082] As shown in FIG. 10, the power receiver 100 includes a filter circuit 250 to which the output signal of the signal transmitter 240 is input, and a resonant circuit 260 to which the output signal of the filter circuit 250 is input. The filter circuit 250 is an LC filter that includes first, second, and third reactors 251, 252, 253 and first and second capacitors 254, 255. The resonant circuit 260 includes first and second resonant capacitors 261 and 262. The power receiver 100 includes a first switch 403 and a second switch 404. The first switch 403, when turned on, shorts both ends of the second capacitor 254. The second switch 404, when turned on, connects one ends of the first and second resonant capacitors 261, 262.

[0083] In this case, the power-receiver controller 231 switches all or either one of the first and second switches 403 and 404 to be turned on in the prevention process. Either one of the first and second switches 403 and 404 may not be provided.

[0084] As shown in FIG. 11, an inductance of a reactor and a capacitance of a capacitor are variable in the filter circuit 250. In the example shown in FIG. 11, an inductance of a third reactor 253a and a capacitance of a second capacitor 255a are variable in the filter circuit 250.

[0085] In this case, the power-receiver controller 231 shifts the resonance frequency of the filter circuit 250 relative to the frequency of the high-frequency signal output from the signal transmitter 240 by varying at least one of the inductance and capacitance in the prevention process. This increases the impedance of the filter circuit 250 at the frequency of the high frequency signal output from the signal transmitter 240. As a result, the amplitude of the output signal of the filter circuit 250 is brought close to zero.

[0086] As shown in FIG. 12, the power receiver 100 includes an output short-circuit switch 405 that shorts the output side of the signal transmitter 240. In this case, the power-receiver controller 231 switches the output short-circuit switch 405 to be turned on in the prevention process.

[0087] As shown in FIG. 13, the power receiver 100 includes an open switch 406 that opens the output side of the signal transmitter 240. In this case, the power-receiver controller 231 switches the open switch 406 to be turned off in the prevention process.

[0088] Second Embodiment A second embodiment will be described below with reference to the drawings mainly in terms of differences from the first embodiment. In this embodiment, the protection process has been modified.

[0089] FIG. 14 is a flowchart illustrating a procedure of the protection process.

[0090] When it is determined in step S14 that the resumption condition has been satisfied, the process proceeds to step S20. In step S20, it is determined whether Nscr, which represents the number of times the short-circuit operations has been performed, exceeds a number threshold Nth. The number threshold Nth is a value for determining whether the short-circuit operation has been performed multiple times, for example, Nth is an integer greater than or equal to 1. Even if the resumption condition is satisfied, when the number of times the short-circuit operation has been performed is multiple times, an abnormality is considered to have occurred in the power receiver 100. It is undesirable to continue to use the power receiver 100 under such conditions. The number of times Nscr used in step S20 may be, for example, the number of short-circuit operations counted since the last time Nscr was initialized, which is stored in the storage unit 233.

[0091] When a negative determination is made in step S20, the process proceeds to step S15. On the other hand, when an affirmative determination is made in step S20, the process proceeds to step S21. In step S21, a notification process is executed, indicating that an abnormality has occurred in the power receiver 100. For example, the fact that an abnormality has occurred may be displayed on a display of a navigation device installed in the vehicle 11 or on a display in a cockpit of the vehicle 11. Alternatively, the fact that an abnormality has occurred may be notified by sound (e.g., voice) on the navigation device. This can prompt the user of the vehicle 11 to repair or replace the power receiver 100 or components of the power receiver 100. As a result, it is possible to reduce an occurrence of a situation where the power receiver 100 continues to be used while an abnormality occurs in the device 100.

[0092] Other Embodiments The above embodiments may be changed and carried out as follows.

[0093] The process of step S12 in FIG. 5 and FIG. 14 may not be provided.

[0094] The abnormality related to wireless power transfer may include, for example, an overcurrent abnormality in the power receiver 100 or a structural abnormality in the power receiver 100. The structural abnormality includes, for example, at least one of the following: an abnormality in a casing that houses the power receiver coil 102 and the power-receiver communication coil 170, an abnormality in a casing of the rectifier circuit 200, and an abnormality in cables constituting the power receiver 100.

[0095] The abnormality related to wireless power transfer include, for example, the inability of a vehicle user’s credit card to function. The power receiver 100 can identify this abnormality by receiving a notification from a credit card company's server via wide area wireless communication that the use of the credit card is prevented.

[0096] The abnormality related to wireless power transfer may include, for example, an abnormality in a SoC (State of Charge) of the high-voltage storage battery 300 obtained from the vehicle 11's CAN (Controller Area Network) or other information. For example, an abnormality related to wireless power transfer may include an abnormality in operating force of a brake operating member (e.g., brake pedal force) provided in the vehicle 11, an abnormality that emergency braking has occurred in the vehicle 11, an abnormality in steering angle of a steering wheel of the vehicle 11, an abnormality that emergency steering has occurred, or an abnormality determined based on a sensor detection value from a sensor such as sonar or radar (e.g., abnormality in the travelling control of the vehicle 11).

[0097] The power receiver 100 may determine whether to prevent the supply of a power supply request signal based on the output signal of an interface that is operated by the vehicle user and allows them to select the presence or absence of wireless power transfer. The interface is a device installed in the vehicle or carried by the user.

[0098] The rectifier circuit 200 is not limited to circuits with transistor-based switches, but may be, for example, a circuit with a diode bridge. When the configuration is such that a separate short-circuit path is provided, such as the short-circuit switch 400 in FIG. 7, the rectifier circuit 200 may be a diode bridge circuit.

[0099] 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.

[0100] The control units and methods thereof described in the present disclosure may be implemented using a dedicated computer with a processor and a memory, programmed to execute one or more functions defined by a computer program. 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. Furthermore, the computer program may be stored in a computer-readable non-transitory tangible storage medium as an instruction executed by a computer.

[0101] While the present disclosure has been described with reference to various exemplary embodiments thereof, it is to be understood that the disclosure is not limited to the disclosed embodiments and constructions. To the contrary, the disclosure is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the disclosure are shown in various combinations and configurations, which are exemplary, other various combinations and configurations, including more, less or only a single element, are also within the spirit of the disclosure.

Claims

1. An in-vehicle power receiver comprising: an in-vehicle power receiver (100) including a power receiver coil (102) configured to wirelessly receive power supply from a power transmitter coil (22) of a power transmitter (20); a power-receiver communication coil (170); and a power-receiver control unit (230) configured to control energization of the power-receiver communication coil for supply of a power supply request signal to the power-receiver communication coil, the power supply request signal being a signal requesting the power transmitter coil to supply power, wherein the power-receiver control unit is configured to execute an abnormality determination process determining whether an abnormality related to wireless power transfer has occurred, and a prevention process preventing the supply of the power supply request signal to the power-receiver communication coil when the abnormality related to wireless power transfer is determined to have occurred.

2. The in-vehicle power receiver according to claim 1, wherein the power-receiver control unit is configured to execute a process permitting the supply of the power supply request signal to the power-receiver communication coil when a resumption condition is determined to be satisfied after prevention of the supply of the power supply request signal.

3. The in-vehicle power receiver according to claim 2, comprising a short-circuit switch (QL1, QL2, 400), wherein the short-circuit switch forms a closed circuit including the power receiver coil and the short-circuit switch by tuning on of the short-circuit switch, and the power-receiver control unit is configured to determine, in the abnormality determination process, whether an overvoltage abnormality related to the wireless power transfer has occurred in the in-vehicle power receiver, and perform, in the prevention process, a short-circuit operation turning on the short-circuit switch and prevent the supply of the power supply request signal to the power-receiver communication coil when the overvoltage abnormality is determined to have occurred.

4. The in-vehicle power receiver according to claim 3, comprising a DC-AC conversion circuit (200) configured to convert AC current supplied from the power receiver coil to DC current and supply the DC current to a power supply target device (300), wherein the power-receiver control unit is configured to execute a release process releasing the short-circuit operation when a release condition is determined to be satisfied after turning on of the short-circuit switch, and the release condition is a condition that current no longer flows in the closed circuit including the power receiver coil and the short-circuit switch, or a condition that a supply voltage to the power supply target device has fallen below a predetermined voltage.

5. The in-vehicle power receiver according to claim 4, wherein the resumption condition includes a condition that the short-circuit operation has been released by the release process.

6. The in-vehicle power receiver according to any one of claims 3 to 5, wherein the resumption condition includes a condition that a state of a device constituting the closed circuit including the power receiver coil and the short-circuit switch is normal.

7. The in-vehicle power receiver according to any one of claims 2 to 6, comprising a DC-AC conversion circuit (200) configured to convert AC current supplied from the power receiver coil to DC current and supply the DC current to a storage battery (300), wherein a vehicle (11) equipped with the in-vehicle power receiver includes a main switch (301H, 301L) that connects the DC-AC conversion circuit and the storage battery, and the resumption condition includes a condition that a state of the storage battery and a state of the main switch are normal.

8. The in-vehicle power receiver according to claim 2, wherein the resumption condition is a condition that a predetermined period of time has elapsed since the supply of the power supply request signal was prevented.

9. The in-vehicle power receiver according to claim 1, wherein the power-receiver control unit is configured to determine, in the abnormality determination process, whether an overheat abnormality related to the wireless power transfer, in which a temperature of a component of a closed circuit including the power receiver coil exceeds a temperature threshold, has occurred, and prevent, in the prevention process, the supply of the power supply request signal to the power-receiver communication coil when the overheat abnormality is determined to have occurred.

10. The in-vehicle power receiver according to claim 9, comprising: a DC-AC conversion circuit (200) configured to convert AC current supplied from the power receiver coil to DC current and supply the DC current to a power supply target device (300); and a smoothing capacitor (210) provided between the DC-AC conversion circuit and the power supply target device, wherein the component is the smoothing capacitor, and the power-receiver control unit is configured to prevent, in the prevention process, the supply of the power supply request signal to the power-receiver communication coil and turn on a short-circuit switch (QH2, QL2) that constitutes one of upper and lower arms of the DC-AC conversion circuit, when the overheat abnormality is determined to have occurred.

11. The in-vehicle power receiver according to claim 10, wherein the power-receiver control unit is configured to execute a process permitting the supply of the power supply request signal to the power-receiver communication coil when a resumption condition is determined to be satisfied after prevention of the supply of the power supply request signal, and the resumption condition includes a condition that a temperature of the short-circuit switch is below a release threshold that is lower than or equal to the temperature threshold.

12. The in-vehicle power receiver according to claim 10, wherein the temperature threshold is a first temperature threshold, and the power-receiver control unit is configured to determine, in the abnormality determination process, whether an overheat abnormality related to the wireless power transfer, in which a temperature of the DC-AC conversion circuit exceeds a second temperature threshold that is higher than the first temperature threshold, has occurred, and maintain all upper and lower arm switches constituting the DC-AC conversion circuit turned off without turning on the short-circuit switch when the overheat abnormality in which the temperature of the DC-AC conversion circuit exceeds the second temperature threshold is determined to have occurred.

13. A program for an in-vehicle power receiver (100) including a power receiver coil (102) configured to wirelessly receive power supply from a power transmitter coil (22) of a power transmitter (20), the in-vehicle power receiver including a power-receiver communication coil (170) and a processor (232), the program causing the processor to execute: a process controlling energization of the power-receiver communication coil for supply of a power supply request signal to the power-receiver communication coil, the power supply request signal being a signal requesting the power transmitter coil to supply power; an abnormality determination process determining whether an abnormality related to wireless power transfer has occurred; and a prevention process preventing the supply of the power supply request signal to the power-receiver communication coil when the abnormality related to wireless power transfer is determined to have occurred.

14. A control method for an in-vehicle power receiver (100) including a power receiver coil (102) configured to wirelessly receive power supply from a power transmitter coil (22) of a power transmitter (20), the in-vehicle power receiver including a power-receiver communication coil (170) and a processor (232), the control method comprising causing the processor to execute: a process controlling energization of the power-receiver communication coil for supply of a power supply request signal to the power-receiver communication coil, the power supply request signal being a signal requesting the power transmitter coil to supply power; an abnormality determination process determining whether an abnormality related to wireless power transfer has occurred; and a prevention process preventing the supply of the power supply request signal to the power-receiver communication coil when the abnormality related to wireless power transfer is determined to have occurred.

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