Power receiver device

Abstract

A power receiver device includes a receiver coil including a first coil and a second coil different in power receiving period when performing wireless power transfer. The first coil is longer in power receiving period than the second coil. The resonant circuit unit (150) includes the first resonant capacitor (141) connected to the first coil, a second resonant capacitor (142) connected to the second coil, and a heat dissipation structure in which a heat dissipation performance of the first resonant capacitor (141) is higher than a heat dissipation performance of the second resonant capacitor (142).

Description

POWER RECEIVER DEVICECross Reference

[0001] This application is based on Japanese Application No. 2024-208023 filed on November 29, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a power receiver device.

[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 transmitter coil and a controller that energizes the 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 transmitter coil.

[0005] JP2024-008088A

[0006] When wireless power transfer is performed by transmitting power from a power transmitter coil, an electric current flows through a power receiver coil and an electric component connected to the power receiver coil. The electric component is, for example, a resonant capacitor that constitutes a resonant circuit. In this case, when the electric current flows through the power receiver coil and the electric component, the power receiver coil and the electric components generate heat. In order to prevent occurrence of overheating abnormality in the power receiver device, it is necessary to dissipate heat appropriately.

[0007] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a power receiver device that enables to properly dissipate heat from the power receiver device when wireless power transfer is performed.

[0008] According to the present disclosure, a power receiver device is to be applied to a non-contact power supply system, in which one of a device of a ground and a device of a vehicle is a power transmitter device including a power transmitter antenna, and the other is a power receiver device including a power receiver antenna and configured to receive electric power with the power receiver antenna. The power transmitter device is configured to wirelessly supply electric power to the power receiver antenna by energizing the power transmitter antenna. The power receiver antenna includes a first antenna portion and a second antenna portion having different power receiving periods when performing wireless power transfer. A power receiving period of the first antenna portion is longer than a power receiving period of the second antenna portion. The power receiver device comprises: a first power receiver portion including the first antenna portion and a first electric component, which is configured to be energized when the first antenna portion receives electric power; a second power receiver portion including the second antenna portion and a second electric component, which is configured to be energized when the second antenna portion receives electric power; and a heat dissipation structure, in which a heat dissipation performance of the first power receiver portion is higher than a heat dissipation performance of the second power receiver portion.

[0009] In the non-contact power supply system, the receiver antenna includes multiple antenna portions having different power receiving periods when performing the non-contact power supply. In this case, the antenna portions generate different degrees of heat caused by energization of the non-contact power supply. For example, the degree of heat generation differs in each antenna portion between a case, in which electric power is received using only the first antenna portion among the first antenna portion and the second antenna portion when the vehicle is stopped, and a case, in which electric power is received using both the first antenna unit and the second antenna unit when the vehicle is traveling. Further, in a case in which the length dimensions of the first antenna unit and the second antenna unit are different in the vehicle travel direction, the antenna portions are different in the power receiving period and the degree of heat generation when electric power is supplied while the vehicle is travelling.

[0010] In this respect, in the above configuration, the power receiving period of the first antenna portion is longer than the power receiving period of the second antenna portion among the plurality of antenna portions. The heat dissipation performance of the first power receiver portion including the first antenna portion and the first electric component is higher than the heat dissipation performance of the second power receiver portion including the second antenna portion and the second electric component. This enables the power receiver device to properly dissipate heat from the heat generating component.

[0011] The drawings described herein are intended to illustrate selected embodiments, do not depict all possible embodiments, and are not intended to limit the scope of the present disclosure.

[0012] Fig. 1 is an overall configuration diagram of a wireless power transfer system according to an 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 showing a power receiver coil.FIG. 5 is a diagram showing a configuration including two coils of the power receiver coil in the power receiver.FIG. 6 is a cross-sectional view showing a configuration of a resonant circuit unit.FIG. 7 is a cross-sectional view showing a configuration of the resonant circuit unit.FIG. 8 is a side view of a vehicle equipped with the power receiver.FIG. 9 is a front view of the vehicle equipped with the power receiver.FIG. 10 is a cross-sectional view showing a configuration of the resonant circuit unit.FIG. 11 is a cross-sectional view showing a configuration of the resonant circuit unit.FIG. 12 is a cross-sectional view showing a configuration of the resonant circuit unit.FIG. 13 is a plan view of a vehicle equipped with a power receiver according to a second embodiment.FIG. 14 is a side view of the vehicle equipped with the power receiver.FIG. 15 is a cross-sectional view showing a configuration of a resonant circuit unit.FIG. 16 is a plan view of a vehicle equipped with a power receiver.FIG. 17 is a side view of a vehicle equipped with the power receiver.FIG. 18 is a diagram showing a configuration of a power receiver coil and a coil heat dissipation structure.FIG. 19 is a diagram showing a power receiver coil.FIG. 20 is a diagram showing a power receiver coil.FIG. 21 is a diagram showing a power receiver coil.

[0013] Multiple embodiments will be described with reference to the drawings. In some embodiments, parts that are functionally and / or structurally corresponding to each other and / or associated with each other are given the same reference numerals, or reference numerals with different hundred digit or more digits. The corresponding and / or associated parts may refer to the explanation in the other embodiments.

[0014] <First Embodiment> An embodiment of a wireless power transfer system of the present disclosure will be described below with reference to the drawings.

[0015] First, an overall configuration of the wireless power transfer system will be described. As shown in FIGS. 1, 2, and 3, a 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.

[0016] 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 the four power-transmitter coil units 21. The power-transmitter coil units 21 are arranged at predetermined intervals in a vehicle traveling direction. The power-transmitter coil units 21 are installed such that the interval between the center positions of the power-transmitter coil units 21 in the vehicle travel direction is, for example, about 1.5 to 2 m, and the separation interval between the power-transmitter coil units 21 is, for example, about 0.5 to 0.8 m.

[0017] The configuration is not limited to one power-transmitter power supply unit 51 for 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] The power-transmitter coil unit 21 includes a power transmitter coil 22 (corresponding to power transmitter 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.

[0022] 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 receiver 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.

[0023] 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.

[0024] 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.

[0025] 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).

[0026] 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 supply target device or battery) 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 the AC power to the armature winding. This configuration 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.

[0028] 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, as hardware, a processor, a storage unit, and a communication bus connecting the processor with the storage unit.

[0029] The storage unit includes a memory and a storage as hardware. The memory is a storage device for storing data used in the processing of the power-transmitter controller 71. The memory, for example, provides the processor with a work area for temporary use when the processor performs processing. The memory 212 includes, for example, RAM and ROM. The storage is a storage device that stores various programs and data to be read and executed by the processor and is a non-transitory tangible storage medium. The storage includes, for example, HDD or flash memory. The storage contains program information and other information for the processes described below.

[0030] The power-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.

[0031] 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 212 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.

[0032] For example, the program information stored on the non-transitory tangible storage medium is installed in the storage units of the power-receiver controller 231 and the power-transmitter controller 71. The storage medium is, for example, a USB memory, CD-ROM or DVD. In addition, the program information transmitted over a communication network, such as OTA (Over The Air), for example, is installed in a storage unit 233.

[0033] The power-transmitter controller 71 executes switching control of the PFC circuit 61 and switching control of the inverter 60. Through the switching control of the inverter 60, a high-frequency AC voltage is applied to the power transmitter coil 22. This configuration causes a high-frequency current to flow in the power transmitter coil 22 and a magnetic field for power transmission is generated in the power transmitter coil 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 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 transmitter coil 22 is transmitted to the rectifier circuit 200 through the power-receiver resonant circuit 140 and the filter circuit 182. The rectifier circuit 200 converts the transmitted 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 has 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 transmitter 240. The power-receiver communication coil 170 is a planar coil formed by winding a conductive wire in a planar shape. The power-receiver communication coil 170 is provided on the bottom of the vehicle body with the surface direction of the planar coil facing the ground surface. In the power receiver 100, the power receiver coil 102 may also be configured as a planar coil. The same may be applicable for the power transmitter coil 22 and the power-transmitter communication coil 40 of the power transmitter 20.

[0038] 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 receiver 80. The power-receiver communication coil 170 and the power-transmitter communication coil 40 are communication coils for narrow area wireless communication. The narrow area wireless communication is those with a communication distance of less than 10 meters (e.g., a maximum of about 3 meters). The narrow area wireless communication is a communication with a shorter communication distance than wide area wireless communications.

[0039] Various short-range wireless communication 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 transmitter 240 is connected to the power-receiver controller 231. The transmitter 240 is connected to the power-receiver communication coil 170. The power-receiver controller 231 controls the 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 the power supply request signal COMM and a vehicle-side signal, which contains a traveling speed of the vehicle 11, into one frame and supplies the frame to the power-receiver communication coil 170. In this embodiment, the power supply request signal COMM includes ID information of the vehicle 11 and a requested power Weq that is a requested value of power to be supplied to the vehicle 11. This configuration causes a high-frequency voltage to be applied from the transmitter 240 to the power-receiver communication coil 170. Consequently, a high-frequency current flows in the power-receiver communication coil 170, and a magnetic field for information communication is generated in the power-receiver communication coil 170.

[0042] When the power-receiver coil unit 101 of the vehicle 11 approaches the power-transmitter coil unit 21 on the ground side, the magnetic field generated by the power-receiver communication coil 170 links to the power-transmitter communication coil 40, and a high-frequency current flows through the power-transmitter communication coil 40. This high-frequency current is input to the receiver 80. The 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 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 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 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 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 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 transfer from the power transmitter coil 22 to the power receiver coil 102.

[0045] The power receiver coil 102 is configured as a composite coil including two types of coils. In detail, as shown in FIG. 4, the power receiver coil 102 includes a first coil 111 made of a DD coil, a second coil 112 made of a ring-shaped Q coil, and a core 113. Each of the coils 111 and 112 is a planar coil having a flat shape, and is arranged in a state where the coils 111 and 112 overlap with each other.

[0046] The first coil 111 includes two adjacent coil portions 111a and 111b in which conductor wires are wound in opposite directions. The coil portions 111a and 111b are arranged side by side in the same plane. The coil portions 111a and 111b are configured to partially face each other closely. The second coil 112 faces and overlaps with a central portion of the first coil 111, i.e., portions of the two coil portions 111a and 111b of the first coil 111. The second coil 112 includes a single coil portion.

[0047] The power receiver coil 102 is mounted on the vehicle 11 such that the two coil portions 111a and 111b of the first coil 111 are aligned in a vehicle travel direction, i.e., a front-rear direction of the vehicle 11. That is, the power receiver coil 102 is mounted on the vehicle 11 such that a left-right direction of the power receiver coil 102 shown in FIG. 4 (i.e., coil longitudinal direction) corresponds to the vehicle travel direction.

[0048] The core 113 is, for example, a ferrite core, and functions as an iron core of the power receiver coil 102. The core 113 is configured by arranging rectangular parallelepiped core plates in an aligned state.

[0049] FIG. 5 is a diagram showing an electric configuration corresponding to the power receiver coil 102 including two coils 111 and 112 of the power receiver 100.

[0050] In the configuration of FIG. 5, the power-receiver resonant circuit 140 includes a first resonant circuit 140A connected to the first coil 111 and a second resonant circuit 140B connected to the second coil 112. The first resonant circuit 140A includes multiple first resonant capacitors 141 connected to the first coil 111. The second resonant circuit 140B includes multiple second resonant capacitors 142 connected to the second coil 112. The multiple first resonant capacitors 141 are connected in parallel to both ends or either one of the ends of the first coil 111. Further, the multiple second resonant capacitors 142 are connected in parallel to both ends or either one of the ends of the second coil 112.

[0051] The first resonant circuit 140A is connected in series with a first filter circuit 182A and a first rectifier circuit 200A. The second resonant circuit 140B is connected in series with a second filter circuit 182B and a second rectifier circuit 200B. In comparison with the configuration in FIG. 3, the first filter circuit 182A and the second filter circuit 182B correspond to the filter circuit 182. The first rectifier circuit 200A and the second rectifier circuit 200B correspond to the rectifier circuit 200.

[0052] The first coil 111 and the second coil 112 have different power receiving periods when wireless power transfer is performed, and the power receiving period of the first coil 111 is longer than that of the second coil 112.

[0053] In detail, the power receiver coil 102 is mounted on the vehicle 11 with its longitudinal direction oriented in the vehicle travel direction, and the length of the first coil 111 is longer than the length of the second coil 112 in the vehicle travel direction. Therefore, when the vehicle is travelling, the power receiving period of the first coil 111 is longer than the power receiving period of the second coil 112. In other words, the first coil 111 and the second coil 112 have different length dimensions in the vehicle travel direction, and the first coil 111 has a longer length dimension than the second coil 112.

[0054] In the wireless power transfer system 10, when wireless power transfer is performed while the vehicle is traveling, power is received using the first coil 111 (DD coil) and the second coil 112 (Q coil) of the power receiver coil 102. When wireless power transfer is performed while the vehicle 11 is parked or stopped, power is received using the first coil 111 among the first coil 111 and the second coil 112 of the power receiver coil 102. Power may be received using only the first coil 111 in a specified low-speed state, including a state in which the vehicle 11 is traveling at an extremely low speed (close to zero speed), not limited to when the vehicle 11 is parked or stopped (i.e., when the vehicle 11 is traveling at zero speed). For example, driving speed of 10 km / h or less is a low speed state. In the power receiver coil 102, the switching of power receiving by the coils 111 and 112 may be performed by the power-receiver controller 231.

[0055] In other words, in the present system 10, when the vehicle 11 is in the specified low-speed state where the speed is zero or close to zero, power is received using only the first coil 111 among the first coil 111 and the second coil 112. When the vehicle 11 is traveling, except when the vehicle 11 is traveling at a low speed, power is received using the first coil 111 and the second coil 112.

[0056] While the vehicle is traveling, the on-board power receiver coil 102 continuously passes above multiple power transmitter coils 22 that are aligned on the ground in the vehicle travel direction. In this case, taking into consideration that the relative positions of the power receiver coil 102 and the power transmitter coil 22 change sequentially, power is received by the first coil 111 (DD coil) and the second coil 112 (Q coil). On the other hand, while the vehicle 11 is parked or stopped, the relative positions of the on-board power receiver coil 102 and the ground-side power transmitter coil 22 do not change. Furthermore, when the vehicle 11 is traveling at a low speed, even when the relative positions of the power receiver coil 102 and the power transmitter coil 22 change, the change occurs slowly. Therefore, power is received using only the first coil 111 of the power receiver coil 102. As a result, in the vehicle 11, the power receiving period of the first coil 111 is longer than the power receiving period of the second coil 112.

[0057] In this embodiment, the first coil 111 corresponds to a "first antenna portion," and the second coil 112 corresponds to a "second antenna portion." It is noted that, it is also possible to configure the vehicle 11 to receive power through the second coil 112 rather than the first coil 111 when the vehicle 11 is in the specified low-speed state. In such a configuration, the first coil 111 can be referred to as the "second antenna portion" and the first coil 112 can be referred to as the "second antenna portion."

[0058] As described above, when the power receiving periods during which wireless power transfer is performed are different between the first coil 111 and the second coil 112, the amounts of heat generated in the coils 111 and 112 differ from each other. Therefore, the first power receiver portion including the first coil 111 and the second power receiver portion including the second coil 112 have different degrees of heat dissipation. In this case, it is desirable to determine the heat dissipation performance of each power receiver portion, taking into consideration the difference in the amounts of heat generated in the power receiver portions.

[0059] Therefore, in the present embodiment, in the power receiver 100, the heat dissipation performance of the first power receiver portion including the first coil 111 is set to be higher than the heat dissipation performance of the second power receiver portion including the second coil 112. The first power receiver portion includes first electric components that are energized when the first coil 111 receives power, such as the first resonant capacitor 141, a reactor and a capacitor of the first filter circuit 182A, and a semiconductor switching element and a diode of the first rectifier circuit 200A. The second power receiver portion also includes second electric components that are energized when the second coil 112 receives power, such as the second resonant capacitor 142, a reactor and a capacitor of the second filter circuit 182B, and a semiconductor switching element and a diode of the second rectifier circuit 200B. Herein, a heat dissipation target is the resonant capacitors 141 and 142, and a heat dissipation structure for dissipating heat from the resonant capacitors 141 and 142 will be described.

[0060] FIG. 6 is a cross-sectional view showing the configuration of a resonant circuit unit 150 including the resonant capacitors 141 and 142 of the power-receiver resonant circuit 140.

[0061] The resonant circuit unit 150 includes a circuit board 151, the first resonant capacitor 141, and the second resonant capacitor 142 mounted on both sides of the circuit board 151, and a case 152 that houses the circuit board 151 and the resonant capacitors 141 and 142. The circuit board 151 is a double-sided circuit board having both sides on which electric components can be mounted. Multiple first resonant capacitors 141 are mounted on a first surface side (bottom surface side in drawing) among both sides of the circuit board 151, and multiple second resonant capacitors 142 are mounted on a second surface side (top surface side in drawing), which is the reverse side of the first surface. The case 152 has, for example, a flat rectangular parallelepiped shape. The circuit board 151 is fixed at a center position in the vertical direction within the case 152 by a board fixing portion (not shown).

[0062] Inside the case 152, the first resonant capacitor 141 is in contact with the inner surface of the case. The first resonant capacitor 141 may be in contact with the inner surface of the case via a heat dissipation sheet 153. Inside the case 152, the second resonant capacitor 142 is in contact with the inner surface of the case. The second resonant capacitor 142 may be in contact with the inner surface of the case via a heat dissipation sheet 154. The case 152 includes an upper plate portion 152a and a lower plate portion 152b that face each other in the vertical direction. The first resonant capacitor 141 is provided on the side of the lower plate portion 152b of the case 152. The second resonant capacitor 142 is provided on the side of the upper plate portion 152a.

[0063] The heat dissipation sheets 153 and 154 are referred to as a first heat dissipation sheet 153 and a second heat dissipation sheet 154, respectively. In a case where the resonant capacitors 141 and 142 are in contact with the inner surfaces of the case via the heat dissipation sheets 153 and 154, the thickness dimension of the first heat dissipation sheet 153 is preferably greater than the thickness dimension of the second heat dissipation sheet 154. The thermal conductivities of the heat dissipation sheets 153 and 154 may be different from each other. The thermal conductivity of the first heat dissipation sheet 153 is preferably greater than the thermal conductivity of the second heat dissipation sheet 154.

[0064] The hardness of the first heat-dissipating sheet 153 may be less than the hardness of the second heat-dissipating sheet 154. This enables the first heat dissipation sheet 153 to be in closer contact with the first resonant capacitor 141, improving the heat dissipation performance of the first resonant capacitor 141.

[0065] In the case 152, the first resonant capacitor 141 may be in contact with the inner surface of the case (or heat dissipation sheet 153), and the second resonant capacitor 142 may not be in contact with the inner surface of the case (or heat dissipation sheet 154).

[0066] A heat sink 161, which is an air-cooling heat dissipation portion, is attached to the lower plate portion 152b of the case 152. The heat sink 161 includes multiple fins 162. The fin 162 has a long plate shape and is provided with its longitudinal direction oriented in the vehicle travel direction. The fin 162 may be divided into multiple pieces in the longitudinal direction.

[0067] The resonant circuit unit 150 is adapted to be attached to the bottom 11 a of the vehicle 11. In detail, it is preferable that the upper plate portion 152a of the case 152 is attached to a vehicle body bottom portion 11a. The case 152 and the heat sink 161 may be made of metal such as aluminum. The heat sink 161 may be provided integrally as part of the case 152.

[0068] In the resonant circuit unit 150 having the above-described configuration, the heat sink 161 is provided only to the first resonant capacitor 141 among the first resonant capacitor 141 and the second resonant capacitor 142. In this case, heat of the first resonant capacitor 141 is actively dissipated to the outside through the heat sink 161. In other words, the resonant circuit unit 150 has a heat dissipation structure in which the heat dissipation performance of the first resonant capacitor 141 is higher than the heat dissipation performance of the second resonant capacitor 142.

[0069] As the heat dissipation portion for the first resonant capacitor 141, instead of the air-cooling heat sink 161, a liquid-cooling heat dissipation portion may be provided.

[0070] As shown in FIG. 7, the case 152 may be filled with filler 165 and 166 such as synthetic resin. Since the resonant capacitors 141 and 142 are surrounded by the filler 165 and 166, the heat dissipation properties of the resonant capacitors 141 and 142 can be improved. In this case, it is preferable that the thermal conductivity of the filler 165 surrounding the first resonant capacitor 141 is higher than the thermal conductivity of the filler 166 surrounding the second resonant capacitor 142.

[0071] FIG. 8 is a sideview showing the vehicle 11 when viewed from the lateral side, and FIG. 9 is a front view showing the vehicle 11 when viewed from the front side. In FIG. 8, the right side of the drawing is a front end of the vehicle, and the left side of the drawing is a rear end of the vehicle. Although the resonant capacitors 141 and 142 are shown visible in the resonant circuit unit 150 in FIGS. 8 and 9, in practice the resonant capacitors 141 and 142 may be housed in a rectangular parallelepiped case 152. In FIGS. 8 and 9, the heat dissipation structure is omitted.

[0072] The vehicle 11 includes the power receiver 100 attached to the vehicle body bottom portion 11a. In the power receiver 100, the power receiver coil 102 and the resonant circuit unit 150 are arranged side by side in the front-rear direction of the vehicle in which the power receiver coil 102 is on the vehicle rear side and the resonant circuit unit 150 is on the vehicle front side. In the resonant circuit unit 150, the first resonant capacitor 141 is provided to the lower side, and the second resonant capacitor 142 is provided to the upper side, and these resonant capacitors 141 and 142 are arranged in two stages.

[0073] When the vehicle 11 is traveling, wind passes between the vehicle body and the ground surface, and the resonant circuit unit 150 is cooled by the wind. At this time, in the resonant circuit unit 150, the resonant capacitors 141 and 142 within the case 152 dissipate heat. As described with reference to FIG. 6, in the resonant circuit unit 150, the heat sink 161 is provided on the lower side of the case 152, and the heat dissipation of the heat sink 161 allows the first resonant capacitor 141 to dissipate heat with high efficiency.

[0074] In the configuration in which the heat sink 161 for dissipating heat from the first resonant capacitor 141 is provided on the lower side of the case, heat is dissipated from the first resonant capacitor 141 with a desired heat dissipation performance even when the vehicle 11 is parked or stopped, i.e., even when the vehicle traveling speed is zero and no wind is caused by traveling.

[0075] As described above, in the non-contact power supply system 10, when the vehicle 11 is in the specified low-speed state where the speed is zero or close to zero, power is received using only the first coil 111 among the first coil 111 and the second coil 112. When the vehicle 11 is traveling, except when the vehicle 11 is traveling at a low speed, power is received using the first coil 111 and the second coil 112. In this case, the first power receiver portion including the first coil 111 generates a relatively large amount of heat since electricity is supplied to the first power receiver portion, while the vehicle 11 is travelling and while the vehicle is stopped. Furthermore, the first power receiver portion receives (conducts) power, even in a state where the amount of heat of the resonant capacitor dissipated by wind is small when the vehicle 11 travels at or near zero speed.

[0076] In this aspect, in the resonant circuit unit 150 having the above-described configuration, the heat sink 161 for the first resonant capacitor 141 is provided on the lower side of the case. Therefore, even in the state where the amount of heat of the resonant capacitor dissipated by the wind is small when the vehicle 11 is traveling at zero or near zero speed, the above configuration allows the first resonant capacitor 141 to efficiently dissipate heat into the atmosphere.

[0077] In the resonant circuit unit 150, the heat dissipation portions may be provided to both the first resonant capacitor 141 and the second resonant capacitor 142. FIG. 10 is a cross-sectional view showing the resonant circuit unit 150 in which a part of the configuration described with FIG. 6 is modified.

[0078] In the resonant circuit unit 150 of FIG. 10, the heat sink 161, which is an air-cooling heat dissipation portion, is attached to each of the lower side of the case on the side of the first resonant capacitor 141 and the upper side of the case on the side of the second resonant capacitor 142. That is, a first heat sink 161A is provided on the side of the first resonant capacitor 141, and a second heat sink 161B is provided on the side of the second resonant capacitor 142. Each of the heat sinks 161A and 161B includes multiple fins 162.

[0079] The first heat sink 161A and the second heat sink 161B have different heat dissipation rates (thermal performance). The first heat sink 161A has a larger heat dissipation rate than the second heat sink 161B. As a result, even the amount of heat generated by the first resonant capacitor 141 and the second resonant capacitor 142 differs, heat can be dissipated according to the difference in the amount of heat generated.

[0080] As a specific configuration for differentiating the degree of heat dissipation between the first heat sink 161A and the second heat sink 161B, the following configurations may be adopted.

[0081] The first heat sink 161A and the second heat sink 161B have different thermal conductivities, and the thermal conductivity of the first heat sink 161A is higher than the thermal conductivity of the second heat sink 161B. For example, the heat sinks 161A and 161B may be made of different materials.

[0082] The first heat sink 161A and the second heat sink 161B have different heat dissipation areas, i.e., fin surface areas, and the heat dissipation area of the first heat sink 161A is larger than the heat dissipation area of the second heat sink 161B. For example, the height dimension of the fins 162 of the first heat sink 161A may be larger than the height dimension of the fins 162 of the second heat sink 161B. Alternatively, the number of fins 162 of the first heat sink 161A may be greater than the number of fins 162 of the second heat sink 161B.

[0083] A contact area of the first resonant capacitor 141 in contact with the heat dissipation portion and a contact area of the second resonant capacitor 142 in contact with the heat dissipation portion are different from each other, and the contact area of the first resonant capacitor 141 is larger than the contact area of the second resonant capacitor 142. In detail, the contact area of the first resonant capacitor 141 with lower plate portion 152b of the case 152 or the heat dissipation sheet 153 is preferably larger than the contact area of the second resonant capacitor 142 with the upper plate portion 152a of the case 152 or the heat dissipation sheet 154.

[0084] In the resonant circuit unit 150 shown in FIG. 10, the case 152 may be filled with the filler 165 and 166 such as synthetic resin as shown in FIG. 7. In this case, it is preferable that the thermal conductivity of the filler 165 surrounding the first resonant capacitor 141 is higher than the thermal conductivity of the filler 166 surrounding the second resonant capacitor 142.

[0085] As shown in FIG. 11, in the resonant circuit unit 150, liquid-cooling heat dissipation portions may be provided on the upper and lower sides of the case 152. A liquid-cooling first heat dissipation portion 401 is provided to the lower plate portion 152b of the case 152, and a liquid-cooling second heat dissipation portion 402 is provided to the upper plate portion 152a. Each of the heat dissipation portions 401 and 402 includes a passage through which cooling liquid such as cooling water flows, and heat from each of the resonant capacitors 141 and 142 is dissipated by the cooling liquid flowing through the passage. In detail, a circulation path 403 is connected to the first heat dissipation portion 401, and the cooling liquid is circulated through this circulation path 403 by a pump 404 or the like. A circulation path 405 is connected to the second heat dissipation portion 402, and the cooling liquid is circulated through the circulation path 405 by a pump 406 or the like. It is preferable that a heat dissipation device such as a radiator is provided midway along the circulation paths 403 and 405.

[0086] It is preferable that the degree of heat dissipation of the first heat dissipation portion 401 is greater than the degree of heat dissipation of the second heat dissipation portion 402. For example, the flow rate (flow rate per unit time) of the cooling liquid is set to be greater in the first heat dissipation portion 401 than in the second heat dissipation portion 402. In detail, it is preferable to differentiate the amount of cooling liquid pumped by the pumps 404 and 406 or the cross-sectional area of the passage of the heat dissipation portions 401 and 402.

[0087] It is also possible to use a single common pump for the pumps 404 and 406 and to differentiate the cross-sectional area of the passage of the heat radiating portions 401 and 402, thereby differentiating the degree of heat radiation of the heat radiating portions 401 and 402.

[0088] As shown in FIG. 12, in the resonant circuit unit 150, one of the upper and lower sides of the case 152 is provided with a liquid-cooling heat dissipation portion, and the other is provided with an air-cooling heat dissipation portion. In FIG. 12, unlike FIGS. 10 and 11, in the resonant circuit unit 150, the first resonant capacitor 141 is provided on the upper side of the case (i.e., vehicle body side) and the second resonant capacitor 142 is provided on the lower side of the case (i.e., opposite side of vehicle body). The first heat dissipation portion 401 which is a liquid-cooling heat dissipation portion is provided on the upper side of the case, and the second heat dissipation portion 402 which is an air-cooling heat dissipation portion is provided on the lower side of the case. The configuration of the first heat dissipation portion 401 (liquid-cooling heat dissipation portion) may be the same as that shown in FIG. 11. The second heat dissipation portion 402 (air-cooling heat dissipation portion) may have a configuration similar to that of the heat sink 161 in FIG. 6.

[0089] When the vehicle 11 is traveling, power is received using the first coil 111 and the second coil 112, and when the vehicle 11 is in the low-speed state, including when the vehicle is parked or stopped, power is received using the first coil 111 among the first coil 111 and the second coil 112. In this case, at least when the vehicle 11 is moving at a low speed, heat is dissipated from the first resonant capacitor 141 by circulation of the coolant in the first heat dissipation portion 401 shown in FIG. 12.

[0090] When the vehicle 11 is traveling at a low speed, the amount of heat dissipated from the first resonant capacitor 141 by the circulation of the coolant is anticipated to be reduced due to the wind generated by the vehicle 11 while traveling. Therefore, even when the vehicle is traveling at a low speed with little or no wind, the first resonant capacitor 141 properly dissipates heat.

[0091] According to the present embodiment described in detail above, the following excellent effects can be obtained.

[0092] In the wireless power transfer system 10, when the power receiver coil 102 includes multiple coils (first coil 111 and second coil 112) different in power receiving period when wireless power transfer is performed, the degree of heat generation differs in the coils when electric current is supplied during the wireless power transfer. In this regard, in the present embodiment, when the power receiving period of the first coil 111 is longer than the power receiving period of the second coil 112, the heat dissipation performance of the first resonant capacitor 141 connected to the first coil 111 is made higher than the heat dissipation performance of the second resonant capacitor 142 connected to the second coil 112. This allows the resonant capacitors 141 and 142 in the power receiver 100 to properly dissipate heat.

[0093] Among the first resonant capacitor 141 and the second resonant capacitor 142, only the first resonant capacitor 141 side is provided with the heat sink 161 (see FIGS. 6 and 7). This allows each of the resonant capacitors 141 and 142 to dissipate heat appropriately according to the amount of heat generated. Furthermore, since the heat sink 161 is provided to only one side of the resonant capacitors 141 and 142, an effect of suppressing an increase in size of the entire system can be expected.

[0094] When the vehicle 11 is moving at a specified low speed, power is received using only the first coil 111 of the power receiver coil 102. In addition, anticipating that the amount of heat dissipated by the capacitor due to the wind caused by traveling will be small during this low-speed state, the first resonant capacitor 141 is arranged on the lower side in the vertical direction, and the heat sink 161 is arranged below the first resonant capacitor 141 (see FIGS. 6 to 9). In this case, even when the vehicle is stopped and there is little or no wind, the first resonant capacitor 141 can properly dissipate heat.

[0095] The first heat sink 161A (first heat dissipation portion) for dissipating heat from the first resonant capacitor 141 and the second heat sink 161B (second heat dissipation portion) for dissipating heat from the second resonant capacitor 142 are provided on both sides of the circuit board 151, respectively. The heat sinks 161A and 161B are differentiated in degree of heat dissipation (see FIGS. 10 to 12). In this case, the resonant capacitors 141 and 142 and the heat sinks 161A and 161B are distributed in the thickness direction of the circuit board, and a desired degree of heat dissipation can be imparted to each of the resonant capacitors 141 and 142.

[0096] At the vehicle body bottom portion 11a, the heat dissipation portions 401 and 402 are provided such that the liquid-cooling first heat dissipation portion 401 that dissipates heat from the first resonant capacitor 141 is arranged on the upper side (vehicle body side), and the air-cooling second heat dissipation portion 402 that dissipates heat from the second resonant capacitor 142 is arranged on the lower side (away from vehicle body side) (see FIG. 12). In this case, the heat dissipation portion of the first resonant capacitor 141 has the liquid-cooling configuration, thereby to enable to allow the first resonant capacitor 141 to properly dissipate heat by circulating the cooling liquid while the vehicle is stopped. There is a concern that the vehicle body bottom portion 11a may come into contact with unevenness of the road surface or a foreign object on the road surface. However, by placing the liquid-cooling first heat dissipation portion 401 on the upper side, and by placing the air-cooling second heat dissipation portion on the lower side, leakage of the coolant can be suppressed even if the heat dissipation structure comes into contact with the road surface.

[0097] The first resonant capacitor 141 is provided with the liquid-cooling heat dissipation portion, and the second resonant capacitor 142 is provided with the air-cooling heat dissipation portion. Compared to a configuration in which both resonant capacitors 141 and 142 are provided with the liquid cooling heat dissipation portion, this configuration enables to simplify the heat dissipation structure while optimizing heat dissipation in each of resonant capacitors 141 and 142.

[0098] <Modification of First Embodiment> In the configuration in which electric components to which electric current flows when the coils 111 and 112 receive power are the heat dissipation target, an electric component other than the resonant capacitors 141 and 142 may also be a heat dissipation target. In this case, at least one of electric components such as the reactors and capacitors of the filter circuits 182A and 182B and the semiconductor switching elements or diodes of the rectifier circuits 200A and 200B may be the heat dissipation target. In this example as well, it is preferable that the heat dissipation performance of the electric component of the first power receiver portion is made higher than the heat dissipation performance of the electric component of the second power receiver portion. Specifically, in the heat dissipation structures shown in FIGS. 6, 7, and 10 to 12, instead of the first resonant capacitor 141, an electric component other than the resonant capacitor of the first power receiver portion may be the heat dissipation target, and instead of the second resonant capacitor 142, an electric component other than the resonant capacitor of the second power receiver portion may be the heat dissipation target.

[0099] A second embodiment in which the configuration of the first embodiment is partially modified will be described below.

[0100] <Second Embodiment> In this embodiment, the configuration of the resonant circuit unit 150 mounted on the vehicle 11 is differentiated from the configuration described above. As shown in FIGS. 13 and 14, the resonant circuit unit 150 is provided to the vehicle body bottom portion 11 a of the vehicle 11 on the vehicle front side of the power receiver coil 102. Further in this configuration, in the resonant circuit unit 150, the first resonant capacitor 141 is located on the vehicle front side, and the second resonant capacitor 142 is located on the vehicle rear side.

[0101] A specific configuration of the resonant circuit unit 150 is shown in FIG. 15. In the resonant circuit unit 150, the first resonant capacitor 141 and the second resonant capacitor 142 are mounted side by side on one surface of a circuit board 411. The resonant capacitors 141 and 142 mounted on the circuit board are housed in a case 412. The circuit board 411 may be different for the first resonant capacitor 141 and the second resonant capacitor 142. The resonant circuit unit 150 is attached to the vehicle body by fixing an upper plate portion 412a of the case 412 to the vehicle body bottom portion 11a.

[0102] Heat sinks 413A and 413B, which are air-cooling heat dissipation portions, are attached to the lower plate 412b of the case 412 respectively for the resonant capacitors 141 and 142. Each of the heat sinks 413A and 413B includes multiple heat dissipation fins 414. The case 412 and a heat sink 413 may be made of metal such as aluminum. The heat sink 413 may be provided integrally as part of the case 412.

[0103] The heat sink 413A on the side of the first resonant capacitor 141 and the heat sink 413B on the side of the second resonant capacitor 142 are different in heat dissipation performance, and it is preferable that the heat sink 413A on the side of the first resonant capacitor 141 has a higher heat dissipation performance. For example, the fin height may be different as shown in the drawing. Among the resonant capacitors 141 and 142, only the first resonant capacitor 141 may be provided with a heat dissipation portion (heat sink). By differentiating the heat dissipation configuration for the resonant capacitors 141 and 142, it is possible to construct a heat dissipation structure according to the required amount of heat dissipation. This enables to suppress inconveniences such as increased weight and costs due to provision of excessive heat dissipation fins.

[0104] As shown in FIGS. 13 and 14, in the resonant circuit unit 150, the first resonant capacitor 141 and the second resonant capacitor 142 may be aligned side by side such that the first resonant capacitor 141 is provided on the front side, and the second resonant capacitor 142 is provided on the rear side. Considering heat dissipation due to wind while the vehicle is traveling, the degree of heat dissipation is larger on the front side of the vehicle. As a result, in the resonant circuit unit 150, the heat dissipation performance of the first resonant capacitor 141 is higher than the heat dissipation performance of the second resonant capacitor 142, and the first resonant capacitor 141 can dissipate heat appropriately.

[0105] Furthermore, in the configuration in which the first resonant capacitor 141 and the second resonant capacitor 142 are aligned in the front side and the rear side of the vehicle, a larger number of the first resonant capacitors 141 can be arranged on the front side of the vehicle compared to a configuration in which the resonant capacitors 141 and 142 are aligned in the left and right direction of the vehicle 11. Therefore, it is possible to improve the heat dissipation performance of a large number of the first resonant capacitors 141.

[0106] As shown in FIG. 16 and FIG. 17, in the vehicle body bottom portion 11a of the vehicle 11, the first resonant capacitor 141 may be arranged on the front side of the power receiver coil 102 in the traveling direction of the vehicle 11, and the second resonant capacitor 142 may be arranged on the rear side of the power receiver coil 102. In this case, the first resonant circuit unit 150A including the first resonant capacitor 141 is arranged on the front side of the power receiver coil 102, and the second resonant circuit unit 150B including the second resonant capacitor 142 is arranged on the rear side of the power receiver coil 102. Each of the resonant circuit units 150A and 150B may include an air-cooling heat dissipation portion or a liquid-cooling heat dissipation portion.

[0107] In the resonant circuit units 150A and 150B, the heat dissipation portions that dissipate heat from the resonant capacitors 141 and 142 may have different heat dissipation performances. In this case, it is preferable that the heat dissipation portion on the side of the first resonant capacitor 141 has a higher heat dissipation performance. Among the resonant capacitors 141 and 142, only the first resonant capacitor 141 may be provided with a heat dissipation portion.

[0108] In the above configuration, while giving priority to installing of the power receiver coil 102 at, for example, the center position of the vehicle 11, it is possible to optimize the heat dissipation in each of the resonant capacitors 141 and 142.

[0109] <Modified Example of Second Embodiment> In the heat dissipation structure of the second embodiment as well, an electric component other than the resonant capacitors 141 and 142 may be the heat dissipation target. Specifically, in the heat dissipation structures shown in FIGS. 13 to 17, instead of the first resonant capacitor 141, an electric component other than the resonant capacitor of the first power receiver portion may be the heat dissipation target, and instead of the second resonant capacitor 142, an electric component other than the resonant capacitor of the second power receiver portion may be the heat dissipation target.

[0110] <Other Embodiments> The above embodiment may be modified as follows, for example.

[0111] The power receiver 100 may have a heat dissipation structure that dissipates heat from the power receiver coil 102 as a dissipation target. FIG. 18 is a diagram showing a configuration example for dissipating heat from the power receiver coil 102. FIG. 18 shows the same coil structure as FIG. 4. The power receiver coil 102 includes the first coil 111 as the first antenna portion and the second coil 112 as the second antenna portion. A heat dissipation portion 450 having a coolant passage for circulating a coolant is provided to the power receiver coil 102 as a heat dissipation structure for dissipating heat from the first coil 111. The heat dissipation portion 450 is in contact with the first coil 111 and surrounds the outer periphery of the first coil 111. The cooling liquid flows through the cooling liquid passage of the heat dissipation portion 450, whereby heat is dissipated from the first coil 111. The coolant passage may surround the entire circumference of the first coil 111. The heat dissipation portion 450 may have an air-cooling structure including multiple fins. In the configuration of FIG. 18, the second coil 112 is not provided with a heat dissipation portion.

[0112] The power receiver coil 102 may be provided with a heat dissipation structure including a first heat dissipation portion that dissipates heat from the first coil 111 and a second heat dissipation portion that dissipates heat from the second coil 112. In this case, it is preferable that the degree of heat dissipation of the first heat dissipation portion is greater than the degree of heat dissipation of the second heat dissipation portion. For example, a liquid-cooling heat dissipation portion (see FIG. 18) may be provided as a first heat dissipation portion for dissipating heat from the first coil 111, and an air-cooling heat dissipation portion may be provided as a second heat dissipation portion for dissipating heat from the second coil 112.

[0113] In the power receiver 100, the configuration of the power receiver coil 102 and the division of the power receiver coil 102 into coils with different power receiving periods (division into the first antenna portion and the second antenna portion) may be changed as appropriate. For example, the power receiver coil 102 shown in FIG. 19 includes two coils 501 and 502 arranged on the same plane, and a coil 503 overlapping with the two coils 501 and 502. With this power receiver coil 102, for example, it is considered that power is received by the coils 501 and 502 when the vehicle 11 is stopped (low speed state), and that power is received by the coils 501 to 503 when the vehicle 11 is traveling. In this case, the coils 501 and 502 correspond to a "first antenna portion," and the coil 503 corresponds to a "second antenna portion." Division of the antenna portions in the coils 501 to 503 may be be changed.

[0114] The power receiver coil 102 shown in FIG. 20 includes three coils 511, 512, and 513, and these coils 511 to 513 are arranged so as to overlap with each other at positions shifted from each other in the coil longitudinal direction of the power receiver coil 102. With this power receiver coil 102, for example, it is considered that power is received by the coil 513 when the vehicle 11 is stopped (low speed state), and that power is received by the coils 511 to 513 when the vehicle 11 is traveling. In this case, the coil 513 corresponds to a "first antenna portion," and the coils 511 and 512 correspond to a "second antenna portion."

[0115] The power receiver coil 102 shown in FIG. 21 includes three coils 521, 522, and 523 arranged in the coil longitudinal direction on the same plane. With this power receiver coil 102, for example, it is considered that power is received by the coil 522 when the vehicle 11 is stopped (low speed state), and that power is received by the coils 521 to 523 when the vehicle 11 is traveling. In this case, the coil 522 corresponds to a "first antenna portion," and the coils 521 and 523 correspond to a "second antenna portion."

[0116] In the resonant circuit unit 150, the resonant capacitors 141 and 142 may be arranged in the left-right direction of the vehicle, other than the up-down direction and the front-rear direction of the vehicle. In this configuration, the heat dissipation structure may be configured so that the heat dissipation performance of the first resonant capacitor 141 is higher than the heat dissipation performance of the second resonant capacitor 142.

[0117] The wireless power transfer system may have the first function of wirelessly supplying power from the vehicle-side device to the ground-side device, in addition to the second function of wirelessly supplying power from the ground-side device to the vehicle-side device. In this case, the in-vehicle power receiver 100 has a power transmitting function in addition to the power receiving function. Moreover, the power transmitter 20 on the ground side has a power receiving function in addition to the power transmitting function. The second function will be described below with reference to FIG. 3.

[0118] The power-receiver controller 231 applies a high frequency AC voltage to the power receiver coil 102 by controlling the switching of the rectifier circuit 200. This causes a high-frequency current to flow in the power receiver coil 102, and a magnetic field for power transmission is generated in the power receiver coil 102.

[0119] When the magnetic field generated in the power receiver coil 102 links with the power transmitter coil 22, a high-frequency current flows in the power transmitter coil 22, varying with the frequency of the high-frequency current flowing in the power receiver coil 102. The high-frequency current flowing through the power transmitter coil 22 is supplied to the AC power source 15 via the power-transmitter resonant circuit 30, the filter circuit 52, the inverter 60 and the PFC circuit 61. In this case, the power-transmitter controller 71 controls the switching of the inverter 60 and the PFC circuit 61.

[0120] In the wireless power transfer system having the second function, for example, the power transmitter 20 may include a transmitter that supplies a power supply request signal to the power-transmitter communication coil 40. Furthermore, the power receiver 100 may include a receiver that receives the power supply request signal received by the power-receiver communication coil 170 and inputs the information to the power-receiver controller 231.

[0121] The wireless power transfer system may have the function of wirelessly supplying power from the vehicle-side device to the ground-side device, instead of the function of wirelessly supplying power from the ground-side device to the vehicle-side device.

[0122] The method of wireless power transmission by the power transmitter antenna and the power receiver antenna is not limited to the magnetic field resonance method, and may be an electric field coupling method. In this case, a power transmitter antenna and a power receiver antenna that are different in form from coils and use an electric field coupling method may be used.

[0123] In a broad sense, the power-transmitter communication coil 40 and the power-receiver communication coil 170 may be a power transmitting communication antenna and a power-receiver communication antenna, and are not limited to communication coils, and various antennas may be used. For example, the communication antenna is a dipole antenna or a monopole antenna.

[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 may 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] Although the present disclosure has been described in accordance with the examples, it is understood that the present disclosure is not limited to such examples or structures. To the contrary, the present disclosure is intended to cover various modification and equivalent arrangements. Furthermore, although various combinations and modes are described in the present disclosure, the scope and idea of the present disclosure further include other combinations and modes including only one element, more elements, or less elements in these.

Claims

1. A power receiver device (100) to be applied to a non-contact power supply system, in which one of a device of a ground and a device of a vehicle (11) is a power transmitter device (20) including a power transmitter antenna (22), and the other is a power receiver device (100) including a power receiver antenna (102) and configured to receive electric power with the power receiver antenna, the power transmitter device configured to wirelessly supply electric power to the power receiver antenna by energizing the power transmitter antenna, wherein the power receiver antenna includes a first antenna portion and a second antenna portion having different power receiving periods when performing wireless power transfer, a power receiving period of the first antenna portion is longer than a power receiving period of the second antenna portion, the power receiver device comprising: a first power receiver portion including the first antenna portion and a first electric component, which is configured to be energized when the first antenna portion receives electric power; a second power receiver portion including the second antenna portion and a second electric component, which is configured to be energized when the second antenna portion receives electric power; and a heat dissipation structure, in which a heat dissipation performance of the first power receiver portion is higher than a heat dissipation performance of the second power receiver portion.

2. The power receiver device according to claim 1, wherein the heat dissipation structure includes a heat dissipation portion (161, 450) only in the first power receiver portion among the first power receiver portion and the second power receiver portion.

3. The power receiver device according to claim 1, wherein the power receiver device is mounted on a bottom of a vehicle body of the vehicle, the power receiver device is configured to receive electric power using only the first antenna portion among the first antenna portion and the second antenna portion in a specified low speed state, in which speed of the vehicle is zero or close to zero, and receive electric power using the first antenna portion and the second antenna portion in a state, in which the vehicle travels, other than the low speed state, the first electric component and the second electric component are arranged in two tiers, such that the first electric component is on a lower side, and the second electric component is on an upper side, and the heat dissipation structure includes a heat dissipation portion (161) provided to the first electric component and configured to dissipate heat from the first electric component.

4. The power receiver device according to claim 1, wherein the heat dissipation structure includes a first heat dissipation portion (161A, 401, 413A) configured to dissipate heat from the first power receiver portion, and a second heat dissipation portion (161B, 402, 413B) configured to dissipate heat from the second power receiver portion, and a degree of heat dissipation of the first heat dissipation portion is larger than a degree of heat dissipation of the second heat dissipation portion.

5. The power receiver device according to claim 1, further comprising: a double-sided circuit board (151) having a first surface and a second surface, which is a reverse surface of the first surface, wherein the first electric component is provided to the first surface, the second electric component is provided to the second surface, the heat dissipation structure includes a first heat dissipation portion (161A, 401) provided to the first surface of the double-sided circuit board and configured to dissipate heat from the first electric component, and a second heat dissipation portion (161B, 402) provided to the second surface of the double-sided circuit board and configured to dissipate heat from the second electric component, and a degree of heat dissipation of the first heat dissipation portion is larger than a degree of heat dissipation of the second heat dissipation portion.

6. The power receiver device according to claim 5, wherein the power receiver device is mounted on a bottom of a vehicle body in the vehicle, the first heat dissipation portion is a liquid-cooling heat dissipation portion configured to dissipate heat from the first electric component by circulating cooling liquid, the second heat dissipation portion is an air-cooling heat dissipation portion configured to dissipate heat from the second electric component with a heat dissipation fin, and the first heat dissipation portion and the second heat dissipation portion are arranged in the bottom of the vehicle body, such that the first heat dissipation portion is provided on an upper side, and the second heat dissipation portion is provided on a lower side.

7. The power receiver device according to claim 1, wherein the power receiver device is mounted on a bottom of a vehicle body in the vehicle, and the heat dissipation structure includes a liquid-cooling first heat dissipation portion (401) provided to the first electric component and configured to dissipate heat from the first electric component by circulating cooling liquid, and an air-cooling second heat dissipation portion (402) provided to the second electric component and configured to dissipate heat from the second electric component with a heat dissipation fin.

8. The power receiver device according to claim 6, wherein the power receiver device is configured to receive electric power using only the first antenna portion among the first antenna portion and the second antenna portion in a specified low speed state, in which speed of the vehicle is zero or close to zero, and receive electric power using the first antenna portion and the second antenna portion in a state, in which the vehicle travels, other than the low speed state, and the power receiver device is configured to cause the first heat dissipation portion to dissipate heat from the first electric component by circulating cooling liquid at least in the low speed state of the vehicle.

9. The power receiver device according to any one of claims 1 to 8, wherein the power receiver device is mounted on a bottom of a vehicle body in the vehicle, and the first electric component and the second electric component are arranged side by side, such that the first electric component is arranged on a vehicle front side, and the second electric component is arranged on a vehicle rear side in a traveling direction of the vehicle.

10. The power receiver device according to any one of claims 1 to 8, wherein the power receiver device is mounted on a bottom of a vehicle body in the vehicle, and the first electric component and the second electric component are arranged, such that the first electric component is arranged on a vehicle front side of the power receiver antenna, and the second electric component is arranged on a vehicle rear side of the power receiver antenna in a traveling direction of the vehicle.

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