Power supply device and power supply system

Abstract

To improve power supply efficiency from a power transmission coil to a power reception coil.SOLUTION: A power supply device 250 includes a plurality of repeater coils 70a to 70f sequentially relaying power supply between a power transmission coil 40 and a power reception coil 240 disposed along a surface on which a mobile moves along with the movement of the mobile 200, and a power reception circuit 230 which is connected with the power reception coil and receives power used by the mobile, and supplies the power to the mobile. Each of the plurality of repeater coils relaying the power has a first coil 71 which has magnetic field coupling with the power transmission coil, a second coil 72 which has magnetic field coupling with the power reception coil when the first coil has magnetic field coupling with the power transmission coil, and a connection circuit 90 connecting the first coil with the second coil in accordance with the movement position of the mobile. In the connection circuit, resonance capacitors Ct1, Cw1 participating in the setting of a resonance frequency of at least one of the first coil and the second coil have parallel characteristics.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a technology for supplying power to a moving object from a road surface or a floor surface. [Background technology]

[0002] In recent years, various technologies have been proposed for supplying power to vehicles that move using wheels in a non-contact manner from the road surface or floor surface. For example, Patent Document 1 discloses a configuration in which a relay coil is provided on the wheel and power is supplied to a moving vehicle via the relay coil. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-23003 Summary of the Invention [Problem to be solved by the invention]

[0004] The configuration in Patent Document 1 supplies power from a power transmitting coil to a power receiving coil on the vehicle side via a relay coil provided in the tire, and is an excellent system that can increase transmission efficiency by narrowing the gap between the power transmitting coil and the relay coil. However, because the position of the relay coil relative to the power transmitting coil and the power receiving coil changes as the wheel rotates, there is a demand for a configuration that further increases the transmission efficiency of the entire system. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, there is provided a power supply device including a power receiving coil (240) mounted on a moving body (200), a plurality of relay coils (70) that sequentially relay the supply of power between a power transmitting coil (40) and the power receiving coil as the moving body moves, and a power receiving circuit (230) connected to the power receiving coil and receiving power used by the moving body. 、Each of the plurality of relay coils includes a first coil (71) that magnetically couples with the power transmission coil depending on the moving position of the moving body, a second coil (72) that magnetically couples with the power receiving coil when the first coil is magnetically coupled with the power transmission coil, and a connection circuit (90) that connects the first coil and the second coil. the plurality of relay coils are provided along the circumferential direction of the wheels (60) of the moving body, and relay the power from the power transmitting coil to the power receiving coil in sequence according to the rotational position of the wheels as the moving body moves; the connection circuit teeth a resonant capacitor ( Ct1,Cw1 ) wherein the resonant capacitor is By providing either a parallel resonant capacitor connected in parallel to at least one of the first coil and the second coil, or a parallel resonant capacitor connected in parallel to the first coil and the second coil via a coil for series resonance, The relay coil has parallel characteristics. According to this configuration, the distance between the power transmitting coil and the first coil and the distance between the second coil and the power receiving coil can be narrowed, thereby improving the power transmission efficiency. Furthermore, the current flowing through the other relay coils that do not directly face the power transmitting coil can be suppressed, thereby improving the power supply efficiency of the power supply device.

[0006] The present disclosure can be realized in various forms, for example, in addition to a power supply device, it can be implemented in various aspects such as a power supply system and a design method thereof. [Brief explanation of the drawings]

[0007] [Figure 1A] 1 is an explanatory diagram illustrating a power transmission system including a power supply device according to an embodiment; [Figure 1B] FIG. 2 is an explanatory diagram showing a power transmission circuit to a power receiving circuit. [Figure 2] FIG. 2 is an explanatory diagram showing the configuration of a wheel when viewed from a direction along the center axis of the wheel. [Figure 3] 3 is an explanatory diagram showing the internal structure of the wheel along a cross section taken along line III-III in FIG. 2. [Figure 4] 4 is an explanatory diagram schematically showing a state in which the first coil is viewed from the center axis of the wheel. FIG. [Figure 5] 4 is an explanatory diagram schematically showing a state in which the second coil is viewed from the center axis of the wheel. FIG. [Figure 6] FIG. 2 is a circuit diagram showing an outline of the electrical configuration of the power supply device. [Figure 7]FIG. 4 is an explanatory diagram showing the relationship between the phase of a wheel and self-inductance. [Figure 8A] 3A and 3B are explanatory diagrams illustrating the configuration of a relay coil of a PS resonance type and resonance conditions according to the first embodiment. [Figure 8B] FIG. 10 is an explanatory diagram showing the configuration of a relay coil of an SS resonance type and resonance conditions as a reference example. [Figure 9] 10 is a graph showing the current reduction rate of the first coil and the second coil. [Figure 10] FIG. 10 is an explanatory diagram showing the power supplied in the reference example and the first embodiment with respect to different battery voltages. [Figure 11] 10 is an explanatory diagram showing the average power supplied in comparison between the SS resonance method of the reference example and the PS resonance method of the first embodiment. FIG. [Figure 12] 2 is an explanatory diagram showing an equivalent circuit of the power supply device using the PS resonance method according to the first embodiment. FIG. [Figure 13] FIG. 10 is an explanatory diagram showing a voltage equation of the PS resonance method. [Figure 14] 10A to 10C are explanatory diagrams showing the configurations and resonance conditions of the relay coils of the second to fourth embodiments. [Figure 15] 10 is a graph showing the current reduction rate of the first coil and the second coil in the configurations of the first to fourth embodiments. [Figure 16] FIG. 4 is an explanatory diagram showing the power supplied in the first to fourth embodiments according to different battery voltages. [Figure 17] FIG. 10 is an explanatory diagram showing a comparison of average power supplied in the second to fourth embodiments. [Figure 18] FIG. 10 is an explanatory diagram showing an equivalent circuit of a power supply device using an SP resonance method according to a third embodiment. [Figure 19] FIG. 11 is an explanatory diagram showing a voltage equation of the SP resonance method according to the third embodiment. [Figure 20] FIG. 10 is an explanatory diagram showing an equivalent circuit of a power supply device using an SPS resonance method according to a fourth embodiment. [Figure 21] FIG. 10 is an explanatory diagram showing a voltage equation of the SPS resonance method according to the fourth embodiment. [Figure 22]10A to 10C are explanatory diagrams showing the configurations and resonance conditions of the relay coils of the fifth to seventh embodiments. [Figure 23] FIG. 13 is an explanatory diagram showing an example of an arrangement of relay coils in a power supply device according to an eighth embodiment. [Figure 24] FIG. 13 is an explanatory diagram showing a modified example of the eighth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] A. First embodiment: (A1) Overall configuration of power transmission system: FIG. 1A shows a schematic configuration of a power transmission system 500 including a power supply device 250 according to the first embodiment. The power transmission system 500 supplies power to a vehicle 200, which is a type of moving object, from a road 105 corresponding to the surface on which the vehicle 200 moves. As shown in the figure, the power transmission system 500 includes a power transmission system 100 provided on the road 105 and a power supply device 250 mounted on the vehicle 200. While the vehicle 200 is stopped or traveling, the power transmission system 500 transmits power from the power transmission system 100 to the power supply device 250 of the vehicle 200 using a relay coil 70 provided on the wheel 60. The wheel 60 is in contact with the road 105 but is not electrically in contact with the power transmission system 100. Power from the power transmission system 100 is relayed by one of the relay coils 70 provided on the wheel 60 and transmitted to the power supply device 250. The mechanism of power transmission will be described in detail later.

[0009] Vehicle 200 receiving contactless power transmission may be configured as, for example, an electric vehicle that uses electricity as an energy source to drive a motor to obtain power, or a hybrid vehicle that is equipped with a power source such as an internal combustion engine in addition to a motor. Note that vehicle 200 is not limited to a four-wheeled vehicle, but may also be a three-wheeled vehicle, a two-wheeled vehicle such as a motorcycle, a vehicle with multiple wheels such as a truck, or a transport vehicle or self-propelled robot used in a factory, etc. The surface on which such a moving object such as a vehicle moves may be an outdoor road 105, or an indoor floor surface, etc.

[0010] The power transmission system 100 on the road 105 side includes a plurality of power transmission coils 40 buried in the road 105, a plurality of power transmission circuits 30 that supply power by applying an AC voltage to each of the plurality of power transmission coils 40, an external power source 10 (hereinafter abbreviated as "power source 10") that supplies power to the plurality of power transmission circuits 30, a coil position detection unit 20, and a control device 50.

[0011] In this embodiment, the multiple power transmitting coils 40 are installed along the traveling direction of the road 105. The power transmitting coils 40 may be arranged not only in one direction but also two-dimensionally. The power transmitting circuit 30 is a circuit that converts a DC voltage supplied from the power source 10 into a high-frequency AC voltage and applies it to the power transmitting coil 40. The power transmitting circuit 30 will be described later. The power source 10 is a circuit that supplies a DC voltage to the power transmitting circuit 30. For example, the power source 10 is supplied with a DC voltage from a system power supply via a power factor correction circuit (PFC). The PFC is not shown. The DC voltage output by the power source 10 does not need to be a perfect DC voltage and may include a certain degree of fluctuation (ripple). Note that a filter is usually provided between the power transmitting circuit 30 and the power transmitting coil 40, but is not shown in FIG. 1A. The filter will be described together with the electrical circuits related to power transmission.

[0012] The coil position detection unit 20 detects the relative position of the repeater coil 70 mounted on the wheel 60 of the vehicle 200 with respect to the power transmitting coil 40. The coil position detection unit 20 may detect the position of the repeater coil 70 from the magnitude of the power transmission power or power transmission current in the multiple power transmitting circuits 30, for example. Alternatively, the coil position detection unit 20 may detect the position of the repeater coil 70 by wireless communication with the vehicle 200 or by using a position sensor that detects the position of the vehicle 200. Since the repeater coil 70 is mounted on the wheel 60, the position of the wheel 60 may be detected by using the load received from the wheel 60, for example. The control device 50 controls one or more power transmitting circuits 30 and power transmitting coils 40 that are close to the repeater coil 70 to transmit power, depending on the position of the repeater coil 70 detected by the coil position detection unit 20.

[0013] (A2) Configuration of power supply device: In addition to the relay coil 70, power receiving circuit 230, and power receiving coil 240 that constitute the power feeding device 250, the vehicle 200 also includes a main battery 210, an auxiliary battery 215, a control device 220, a DC / DC converter circuit 260, an inverter circuit 270, a motor generator 280, and auxiliary equipment 290. The wheel 60 has a tire 62 and a wheel 64, and the power receiving coil 240 is provided on the inside of the wheel 64 of the wheel 60 (on the central axis 61 side). The power receiving coil 240 is connected to the power receiving circuit 230. The output of the power receiving circuit 230 is connected to the main battery 210, a high-voltage side of the DC / DC converter circuit 260, and the inverter circuit 270. The low-voltage side of the DC / DC converter circuit 260 is connected to the auxiliary battery 215 and the auxiliary equipment 290. The inverter circuit 270 is connected to the motor generator 280.

[0014] 1A includes a rectifier circuit that converts the AC current output from power receiving coil 240 into a DC current. Note that power receiving circuit 230 may also include a DC / DC converter circuit that converts the DC voltage generated by the rectifier circuit into a voltage suitable for charging main battery 210. The DC power output from power receiving circuit 230 can be used to charge main battery 210 or drive motor generator 280 via inverter circuit 270, and can also be used to charge auxiliary battery 215 or drive auxiliary equipment 290 by stepping down the DC voltage using DC / DC converter circuit 260.

[0015] Main battery 210 is a secondary battery that outputs a relatively high DC voltage for driving motor generator 280. Motor generator 280 operates as a three-phase AC motor and generates driving force for running vehicle 200. Motor generator 280 operates as a generator and generates a three-phase AC voltage when vehicle 200 is decelerating. When motor generator 280 operates as a motor, inverter circuit 270 converts the DC voltage of main battery 210 into a three-phase AC voltage and supplies it to motor generator 280. When motor generator 280 operates as a generator, inverter circuit 270 converts the three-phase AC voltage output by motor generator 280 into a DC voltage and supplies it to main battery 210.

[0016] DC / DC converter circuit 260 converts the DC voltage of main battery 210 into a DC voltage suitable for driving auxiliary device 290 and supplies it to auxiliary device battery 215 and auxiliary device 290. Auxiliary device battery 215 is a secondary battery that outputs a DC voltage for driving auxiliary device 290. Auxiliary device 290 includes peripheral devices such as an air conditioning system, an electric power steering system, headlights, blinkers, and wipers of vehicle 200, as well as various accessories of vehicle 200. DC / DC converter circuit 260 may be omitted if voltage conversion is not necessary.

[0017] The control device 220 controls the above-mentioned components in the vehicle 200. When receiving contactless power supply while traveling, the control device 220 controls the power receiving circuit 230 to execute processing required for receiving power.

[0018] (A3) Relay coil configuration: The relay coil 70 is provided on the wheel 60. As shown in FIG. 1B, the relay coil 70 includes a first coil 71, a second coil 72, and a resonant connection circuit 90 connecting the first coil 71 and the second coil 72. Six relay coils 70 are provided equiangularly around the rotation axis of the wheel 60, i.e., spaced apart by 60 degrees. When distinguishing between the six relay coils 70, they are referred to as relay coils 70a, 70b, 70c, 70d, 70e, and 70f. However, when no distinction is required, they are simply referred to as relay coils 70. FIG. 1B shows relay coil 70a and adjacent relay coils 70b and 70f. In each set of relay coils 70, the first coil 71, the second coil 72, and the resonant connection circuit 90 are connected by wire.

[0019] The first coil 71 of the relay coil 70 is provided on the outer side of the wheel 64, i.e., on the tire 62 side, and the second coil 72 is provided on the inner side of the wheel 64. Therefore, the distance from the central axis 61 of the wheel 60 to the first coil 71 is different from the distance from the central axis 61 to the second coil 72, with the distance from the central axis 61 to the first coil 71 being larger. This allows the first coil 71 to be closer to the power transmitting coil 40 buried in the road 105 than the second coil 72. When the wheel 60 rotates and the first coil 71 faces the power transmitting coil 40 buried in the road 105, the first coil 71 and the power transmitting coil 40 are magnetically coupled, and electromagnetic induction between the first coil 71 and the power transmitting coil 40 to which an AC voltage is applied generates an AC induced current in the first coil 71. The first coil 71 and the second coil 72 are connected via a resonant connection circuit 90, and this induced current flows from the first coil 71 to the second coil 72 through a conductor. At this time, the power receiving coil 240 is positioned opposite the second coil 72, and the second coil 72 and the power receiving coil 240 are magnetically coupled. As a result, an AC induced current is generated in the power receiving coil 240 due to electromagnetic induction between the power receiving coil 240 and the second coil 72, through which an AC induced current flows. In this manner, the relay coil 70 relays the transmission of power from the power transmitting coil 40 to the power receiving coil 240 using the first coil 71 and the second coil 72. That is, as shown in FIG. 1B , power is transmitted from the power transmitting circuit 30 to the power receiving circuit 230 via the power transmitting coil 40, the relay coil 70 (the first coil 71 and the second coil 72), and the power receiving coil 240.

[0020] FIG. 2 is an explanatory diagram showing the configuration of the wheel 60 as viewed from a direction along the central axis 61 of the wheel 60. For ease of understanding, FIG. 2 shows the right half as a perspective view. The first coil 71 is provided outside the outer periphery 64o of the wheel 64 and inside the tire 62. The second coil 72 is provided inside the outer periphery 64o of the wheel 64. The power receiving coil 240 is installed on the vehicle 200 inside the outer periphery 64o of the wheel 64. The power receiving coil 240 is attached to the vehicle 200 in a manner similar to that of a brake caliper of a disc brake, for example. Therefore, the relative positions of the power receiving coil 240 and the wheel 60 do not change regardless of the traveling state of the vehicle 200.

[0021] 2 shows only some of the relay coils 70a, 70b, 70c, and 70d. In adjacent relay coils 70, the first coils 71 do not overlap each other, and the second coils 72 do not overlap each other. Therefore, the size of each of the first coils 71 and second coils 72 in the direction along the circumference of the wheel 60 is slightly less than 1 / 6 of the circumference at the position where they are arranged. Note that two adjacent first coils 71 may overlap, and two adjacent second coils 72 may overlap. Note that three phases may be configured by using three coils each of the six relay coils 70.

[0022] FIG. 3 is an explanatory diagram showing the configuration of the wheel 60 as viewed from a direction perpendicular to the central axis 61. FIG. 3 is a partially see-through view. The first coil 71 is held by a heat conductive plate 80 and arranged inside the tire 62, outside the wheel 64. The heat conductive plate 80 is made of aluminum, which has high thermal conductivity, and is provided separately or integrally on the outer circumferential surface of the wheel 64, which is also made of aluminum die-cast. In the first embodiment, the surface of this heat conductive plate 80 is insulated, and a parallel resonant capacitor (Ct1), which will be described later, is attached to it. Note that the entire resonant connection circuit 90 may also be attached to the heat conductive plate 80. Since the first coil 71 and the second coil 72 are arranged in the tire 62 and the wheel 64, respectively, a wire connecting them passes through the wheel 64. The passage is sealed to maintain the airtightness of the tire 62.

[0023] In the first embodiment, the first coil 71 and the second coil are arranged in an overlapping position when viewed from the central axis 61. A distance G2 between the second coil 72 and the power receiving coil 240 from an axis passing through the first coil and the second coil is narrower than a distance G1 between the first coil 71 and the power transmitting coil 40. As shown in FIG. 3 , the tire 62 is in contact with the road 105 and is deformed by the unevenness of the road 105. If the first coil 71 is present in this deforming area, it will be affected by deformation and other factors. Therefore, a certain distance G1 is required between the first coil 71 and the outer edge of the tire 62. In contrast, the relative position of the power receiving coil 240 and the wheel 60 is not affected by the unevenness of the road 105 and remains unchanged. Therefore, the distance G2 between the second coil 72 and the power receiving coil 240 can be narrowed. In fact, the distance G2 between the second coil 72 and the power receiving coil 240 is narrower than the distance G1 between the first coil 71 and the power transmitting coil 40. By narrowing the gap G2 between the second coil 72 and the power receiving coil 240, the efficiency of transmission from the second coil 72 to the power receiving coil 240 can be increased.

[0024] FIG. 4 is a view of the first coil 71 as viewed from the central axis 61 of the wheel 60, and FIG. 5 is a view of the second coil 72 as viewed from the central axis 61 of the wheel 60. In FIGS. 4 and 5, portions of the coils 71 and 72 are omitted from illustration. The first coil 71 and the second coil 72 are each spirally wound. The number of turns of the first coil 71 and the second coil 72 is determined based on the desired inductance values ​​of the first coil 71 and the second coil 72, and is approximately 5 to 10 turns in the first embodiment. As shown in FIG. 4, when a clockwise induced current flows in the first coil 71 as viewed from the central axis 61, as shown in FIG. 5, a counterclockwise induced current flows in the second coil 72 as viewed from the central axis 61. Conversely, when a counterclockwise induced current flows in the first coil 71 as viewed from the central axis 61, a clockwise induced current flows in the second coil 72 as viewed from the central axis 61. The first coil 71 and the second coil are arranged in an overlapping position when viewed from the central axis 61, so that the magnetic fields generated by the currents flowing through the first coil 71 and the second coil 72 cancel each other out, thereby suppressing leakage electromagnetic fields.

[0025] FIG. 6 is a circuit diagram showing a schematic electrical configuration of a power transmission system 500. The power transmission circuits 30 operate by receiving power supplied from a power source 10. Each power transmission circuit 30 includes an inverter 35 and a filter 36. In this embodiment, the filter 36 is an immittance converter that functions as a band-pass filter. Each power transmission circuit 30 includes a smoothing capacitor 37 on the power input side, and a resonant capacitor 38 and a power transmission coil 40 on the output side. The first embodiment employs an SS system in which the power transmission coil 40 and the resonant capacitor 38 are connected in series. Instead of the SS system, a PP system in which the power transmission coil 40 and the resonant capacitor are connected in parallel, or an SPS system in which resonant capacitors are connected in series and in parallel may be employed.

[0026] The power receiving circuit 230 receives power via a relay coil 70 provided on the wheel 60 and includes a resonant capacitor 232 connected in series to the power receiving coil 240, a filter 241, a rectifier 243 that performs full-wave rectification, and a smoothing capacitor 245. In this embodiment, the filter 241 is also configured as an immittance converter. The power received by the power receiving circuit 230 is converted to direct current by the rectifier 243 and used to charge the main battery 210. The voltage of the main battery 210 is arbitrary, but can be, for example, 100 volts or 400 volts. Therefore, if necessary, a DC / DC converter compatible with both voltages can be provided between the rectifier 243 and the main battery 210.

[0027] As shown in FIG. 6 , in this embodiment, six relay coils 70 are arranged around the wheel 60, spaced at 60-degree central angle intervals. Each of the relay coils 70a to 70f includes a first coil 71, a second coil 72, and a resonant connection circuit 90 that connects the first coil 71 and the second coil 72. The number of relay coils 70 may be one or more, and is arbitrary. As the wheel 60 rotates, the relay coils 70 also rotate, and the first coils 71 facing the road 105 are sequentially switched, and the power transmitting coils 40 facing the first coils 71 are also sequentially switched. The second coils 72 facing the power receiving coil 240 are also sequentially switched. The resonant connection circuit 90 ensures that the resonant frequency of the circuit including the first coil 71 of the relay coil 70, which has reached a position facing the power transmitting coil 40, is close to the frequency of the AC power applied to the power transmitting coil 40, and that the resonant frequency of the circuit including the second coil 72 of the relay coil 70, which has reached a position facing the power receiving coil 240, is close to the resonant frequency of the circuit formed by the resonant capacitor 232 and the power receiving circuit 230. The resonant frequency is determined by the self-inductance of the coils 71 and 72 at that time due to the magnetic flux passing through each of the coils 71 and 72, the capacitance of the resonant capacitor included in the resonant connection circuit 90, and other factors. In this embodiment, the resonant frequency is approximately 85 kHz. The configuration of the resonant connection circuit 90 will be described in detail later.

[0028] 7 is an explanatory diagram showing the relationship between the phase of the wheel 60 and the self-inductance of the first coil 71 and the second coil 72 of the relay coil 70. As shown in the lower part of the diagram, the self-inductance of each relay coil 70 is greatest when the first coil 71 of each relay coil 70 faces the power transmitting coil 40. At phase 0°, the first coil 71a of the relay coil 70a faces the power transmitting coil 40, and the combined inductance Lt1 of the first coil 71a is maximized. Similarly, at phase 60°, the first coil 71b of the relay coil 70b faces the power transmitting coil 40, and the self-inductance Lt2 of the relay coil 70b is maximized. At phase 120°, the first coil 71c of the relay coil 70c faces the power transmitting coil 40, and at phase 180°, the first coil 71d of the relay coil 70d faces the power transmitting coil 40, with the self-inductance Lt3 of the relay coil 70c and the self-inductance Lt4 of the relay coil 70d each reaching a maximum. That is, the self-inductance Lt of the relay coils 70a, 70b, 70c, and 70d reaches a maximum at phases of 0°, 60°, 120°, and 180°, providing the strongest coupling between the first coil 71 and the power transmitting coil 40. The same is true for the relay coils 70e and 70f.

[0029] On the other hand, as shown in the upper part of FIG. 7, when the second coils 72a to 72f of the relay coils 70a to 70f reach a position facing the power receiving coil 240, the inductances Lw1 to Lw6 of the relay coils 70a to 70f facing the power receiving coil 240 reach their respective maximums. Note that the power transmitting coil 40 and the power receiving coil 240 are equipped with a magnetic material, and when the first coil 71 or the second coil 72 of each relay coil 70 approaches, the magnetic material causes a significant change in the inductance of each coil. The capacitance of the resonant capacitor, which will be described later, is preferably determined using the maximum value of the changing inductance. Note that a magnetic material may be provided on only one of the power transmitting coil 40 and the power receiving coil 240, or may not be provided on either one.

[0030] Focusing on one relay coil 70, the self-inductance is maximized when the first coil 71 faces the power transmitting coil 40. The capacitance of a resonant capacitor (described below) provided in the resonant connection circuit 90 is set using the maximum value of this self-inductance so that the resonant frequency of the first coil 71 matches or is close to the frequency of the AC voltage applied to the power transmitting coil 40. Note that the resonant frequency may be calculated assuming that the impedance of the circuit including the first coil is sufficiently small, or the capacitance of the resonant capacitor may be set based on the resonant frequency determined by actual measurement. Similarly, if the impedance of the circuit including the second coil is sufficiently small, the resonant frequency of the second coil is determined by the inductance value of the second coil when the second coil faces the power receiving coil and the capacitance of the resonant capacitor. Therefore, the capacitance of the resonant capacitor is set so that the resonant frequency of the second coil matches or is close to the designed frequency when the power receiving coil 240 receives power. In this embodiment, when the first coil 71 faces the transmitting coil 40, the receiving coil 240 reaches a position facing the second coil 72, so that the coupling coefficient ka between the transmitting coil 40 and the first coil 71 and the coupling coefficient kb between the second coil 72 and the receiving coil 240 can both be maximized, thereby improving the efficiency of power transmission from the transmitting coil 40 to the receiving coil 240 via the relay coil 70.

[0031] (A3) Configuration and function of relay resonant circuit 90: The configuration and operation of the relay resonant circuit 90 in the first embodiment will be described below. FIG. 8A shows the configuration of the relay resonant circuit 90 in the first embodiment. The relay resonant circuit 90 in the first embodiment includes a series resonant capacitor Cw1 connected in series and a parallel resonant capacitor Ct1 connected in parallel in a circuit connecting the first coil 71 and the second coil 72. This circuit configuration is called a PS resonant type. In contrast, the circuit configuration of a relay resonant circuit 90S shown as a reference example in FIG. 8B is called an SS resonant type (series type) because the resonant capacitors Ct1 and Cw1 are connected in series to the first coil 71 and the second coil 72.

[0032] For capacitors, the symbol and its capacitance are both written as Ct1, Cw1, etc. The inductance of the first coil 71 is written as Lt1, and the current as It1. Similarly, the inductance of the second coil 72 is written as Lw1, and the current as Iw1. The subscript t attached to the capacitance C of the capacitor, the inductance L of the coil, and the current I flowing through the coil indicates the tire side, i.e., the first coil 71 side, and the subscript w indicates the wheel side, i.e., the second coil 72 side. The symbol Iarc indicates the resonant current.

[0033] As shown in the figure, the first coil 71 and the parallel resonant capacitor Ct1 are provided outside the outer periphery 64o of the wheel 64, i.e., inside the tire 62, while the second coil 72 and the series resonant capacitor Cw1 connected thereto are provided inside the wheel 64. As already explained, in the first embodiment, the parallel resonant capacitor Ct1 is mounted on the heat conduction plate 80.

[0034] The lower part of FIG. 8A shows an equation showing the resonance condition in the relay resonance circuit 90 of the PS resonance type. As shown in the figure, ω·Lt1-1 / (ω·Ct1)=0 ω·Lw1-1 / (ω·Cw1)+1 / (ω·Ct1)=0 The frequency F(ω=2πF) that satisfies this is the resonant frequency. On the other hand, as a reference example, the equation showing the resonance condition in the relay resonance circuit of the SS resonance system is shown in the lower part of Figure 8B. In the SS resonance system, the resonance condition is ω·Lt1-1 / (ω·Ct1)=0 ω·Lw1-1 / (ω·Cw1)=0 is.

[0035] In the first embodiment, the relay resonant circuit 90 employs a PS resonant system. , averageThe relay coil 70 has a series characteristic. Various characteristics related to power supply using this type of relay coil 70 are shown in Figures 9, 10, and 11, in comparison with those of the SS resonance system, which is a reference example. The upper part of Figure 9 shows the normalized currents flowing through the first coils 71b to 71f of the other relay coils 70b to 70f when one relay coil 70a, of the six relay coils 70a to 70f provided every 60 degrees in phase, faces the power transmitting coil 40. In the figures, the vertical axis represents the current reduction rate. The current flowing through the tire-side first coil 71a is normalized to the same magnitude of 1.0 in both the SS resonance system and the PS resonance system, and the currents It2 to It6 flowing through the first coils 71b to 71f, respectively, are shown as ratios It2 / It1 to It6 / It1 to the current It1 flowing through the first coil 71a. The vertical axis represents the current decrease rate because it shows the current flowing through each first coil as a ratio to the current flowing through first coil 71 directly facing power transmission coil 40. Therefore, the smaller the current decrease rate, the less unnecessary current is flowing.

[0036] Similarly, the lower part of Fig. 9 shows the currents flowing through the second coils 72b to 72f of the other relay coils 70b to 70f when one relay coil 70a, out of six relay coils 70a to 70f arranged every 60 degrees, faces the power transmission coil 40. In the figure, the vertical axis represents the current reduction rate. The current flowing through the tire-side second coil 72a is normalized to the same magnitude of 1.0 in both the SS resonance method and the PS resonance method. The currents Iw2 to Iw6 flowing through the second coils 72b to 72f are then plotted as ratios Iw2 / Iw1 to Iw6 / Iw1 to the current Iw1 flowing through the second coil 71a. Again, a smaller current reduction rate indicates less unnecessary current.

[0037] Since power is supplied from the transmitting coil 40 to the receiving coil 240, ideally, current would flow only through the relay coil 70a facing the transmitting coil 40 as shown in Fig. 6, and no current would flow through the other relay coils 70b to 70f. However, in reality, current also flows through the other relay coils 70b to 70f. This current is wasted power that does not contribute to power supply and is actually converted into heat.

[0038] In this embodiment, the PS resonance type is adopted for the relay resonance circuit 90, and because it has parallel characteristics, as shown in Figure 9, the current reduction rate in the other relay coils 70b to 70f is smaller in both the first coil and the second coil compared to the SS resonance type, and it can be seen that wasteful power consumption is reduced. This reduces heat generation in the tire 62 and the wheel 64, and can reduce temperature rises in these areas. Since the tire 62 and the wheel 64 are generally closed spaces and do not have cooling means, the effect of reducing heat generation is significant.

[0039] 10 is a graph showing the phase change of power during power supply using the SS resonance method as a reference example and the PS resonance method of this embodiment. In the figure, the solid line indicates the case where the power supply voltage, i.e., the charging voltage of the main battery 210, is 100 volts, and the dashed line indicates the case where the power supply voltage is 400 volts. The figure shows the change in phase of ±60 degrees, or one-third of a rotation (±60 degrees) of the wheel 60, with angle θ=0, which is the state where one relay coil 70 directly faces the power transmitting coil 40. As shown in the figure, when the voltage used for power supply changes, the peak power supply level drops off in the SS resonance method, whereas the PS resonance method supplies power corresponding to the theoretical current amount shown in FIG. 7.

[0040] Furthermore, Figure 11 is a graph comparing the average power supplied in the SS resonance method and the PS resonance method. In the figure, the primary-side filter is filter 36 shown in Figure 6, and the secondary-side filter is filter 241 in the same figure. In this example, immittance converters are used as filters for both filters 36 and 241. An immittance converter is a two-terminal pair circuit in which the impedance seen from one terminal pair is proportional to the admittance of the circuit or element connected to the other terminal pair. When such an immittance converter is used, although some loss occurs, it functions as a noise filter and improves the conversion characteristics between coils.

[0041] As shown in FIG. 11 , the average power supplied from the road to the vehicle 200 using the PS resonance system of this embodiment is smaller than that supplied using the SS resonance system of the reference example, regardless of whether the main battery 210 is 100 volts or 400 volts. On the other hand, as shown in FIG. 9 , the current flowing through the first coil 71 of the relay coil 70 (hereinafter referred to as the non-opposing coil) that is not directly opposite the power transmitting coil 40 is smaller than that supplied using the SS resonance system of the reference example. Therefore, even if the average amount of power supplied via the relay coil 70 is equal to or smaller than that supplied using the SS system, as shown in FIG. 11 , the loss due to the current flowing through the non-opposing coil that is not directly involved in the exchange of power from the power transmitting coil 40 to the power receiving coil 240 can be minimized, thereby optimizing the overall efficiency of the power transfer system 500. In particular, reducing the amount of current flowing through the non-opposing coil reduces heat generated by loss in the non-opposing coil, which is a significant advantage in reducing the temperature rise in the wheel 60, which is an enclosed space and difficult to cool.

[0042] The circuit configuration and equivalent circuit for this PS resonance method are shown in Figure 12. In the equivalent circuit, the coupling between the transmitting coil 40 and the first coil 71 is divided into the mutual inductance Mp2t1 between the two coils and the self-inductance of each of the two coils. Similarly, the coupling between the second coil 72 of the relay coil 70 and the receiving coil 240 is divided into the mutual inductance Mw1s between the two coils and the self-inductance of each of the two coils. Furthermore, voltage equations (1) to (4) were formulated from the equivalent circuit and solved to determine the currents Ip, It, Iw, and Is, and the resonance conditions were calculated from these, as shown in Figure 13. Note that the equivalent circuit does not take into account the effects of coils other than the relay coil 70 that face the transmitting coil 40 and the receiving coil 240 (referred to as non-facing coils).

[0043] (A4) Advantages of the first embodiment: According to the first embodiment described above, in power supply using the relay coil 70, the relay resonant circuit 90 is configured as a PS resonant type in which the resonant capacitor has parallel characteristics. Therefore, of the multiple relay coils 70 arranged on the wheel 60, it is possible to suppress the current flowing to relay coils 70b to 70f other than the relay coil 70 (for example, relay coil 70a) that faces the power transmitting coil 40 and the power receiving coil 240 and is involved in power supply. This makes it possible to increase the average amount of power supplied via the relay coil 70 and improve the efficiency of the power transmission system 500.

[0044] Furthermore, in the first embodiment, the relay coil 70 is disposed between the power transmitting coil 40 and the power receiving coil 240, and the first coil 71 is disposed outside the wheel 64 and inside the tire 62. This allows for a narrow gap G1 between the first coil 71 and the power transmitting coil 40, which is embedded in the road 105. Furthermore, the second coil 72 and the power receiving coil 240 are both disposed inside the wheel 64, allowing for a narrow gap G2 between the second coil 72 and the power receiving coil 240. Therefore, according to the first embodiment, by separating the relay coil 70 into the first coil 71 and the second coil 72, it is possible to narrow the gap between the power transmitting coil 40 and the first coil 71 and the gap between the second coil 72 and the power receiving coil 240. Furthermore, since the first coil 71 and the second coil 72 are directly connected via the relay resonant circuit 90, loss between them is extremely small. As a result, the total efficiency of power transmission from the power transmitting coil 40 to the power receiving coil 240 can be improved.

[0045] Furthermore, according to the first embodiment, when viewed from the central axis 61 of the wheel 60, the direction of the induced current flowing through the first coil 71 and the direction of the induced current flowing through the second coil 72 are opposite, thereby suppressing leakage electromagnetic fields. Note that when viewed from the central axis 61 of the wheel 60, the direction of the induced current flowing through the first coil 71 and the direction of the induced current flowing through the second coil 72 do not have to be opposite. Note that, depending on the arrangement of the first coil 71 and the second coil 72, the directions of the magnetic fields generated by both coils may be the same or opposite.

[0046] B. Second to Fourth Embodiments: Next, second to fourth embodiments will be described. The power transfer system 500 and the power supply device 250 used therein in the second to fourth embodiments are the same as those in the first embodiment, except for the configuration of the relay resonant circuit 90. The configurations of the relay resonant circuits 90A to 90C of the relay coil 70 in the second to fourth embodiments are shown in FIG. 14. As shown in the figure, the relay resonant circuit 90A in the second embodiment includes a resonant capacitor Ctw1 connected in parallel to the first coil 71 and the second coil 72. The second embodiment does not include a series resonant capacitor. This relay resonant circuit 90A has parallel characteristics. This is called a P-resonant system. The resonance conditions are shown in the lower part of the column for the second embodiment in FIG. 14.

[0047] Similarly, as shown in the figure, the relay resonant circuit 90B of the third embodiment has a configuration in which a series resonant capacitor Ct1 is connected in series to the first coil 71 and a parallel resonant capacitor Cw1 is connected in parallel to the second coil 72. Therefore, this relay resonant circuit 90B has parallel characteristics. This is called an SP resonance type. The resonance conditions are shown in the lower part of the column for the third embodiment in FIG. 14.

[0048] As shown in the figure, the relay resonant circuit 90C of the fourth embodiment has a first series resonant capacitor Ct1 connected in series to the first coil 71, a second series resonant capacitor Cw1 connected in series to the second coil 72, and a parallel resonant capacitor Ctw1 connected in parallel to these. Therefore, this relay resonant circuit 90C has parallel characteristics. This is called an S+P+S (hereinafter, abbreviated as SPS) resonance method. The resonance conditions are shown in the lower part of the column for the fourth embodiment in FIG. 14.

[0049] FIG. 15 shows the current reduction rate of the first coil 71 and the second coil 72 in the second to fourth embodiments, FIG. 16 shows the phase change of the power supply in each embodiment, and FIG. 17 shows the average power supplied in each embodiment. As shown in FIG. 15 , in each of the second to fourth embodiments, the current flowing through the non-opposing coil is smaller than the current flowing in the SS resonance system of the reference example. Therefore, as shown in FIG. 17 , even if the average amount of power supplied via the relay coil 70 in the second to fourth embodiments is equal to or smaller than that in the SS system, the loss due to the current flowing through the non-opposing coil, which is not directly involved in the transmission and reception of power from the transmitting coil 40 to the receiving coil 240, can be minimized, thereby optimizing the overall efficiency of the power transfer system 500. Furthermore, by reducing the amount of current flowing through the non-opposing coil, heat generation due to loss in the non-opposing coil can be reduced. Therefore, similar to the first embodiment, the effect of reducing the temperature rise in the space inside the wheel 60, which is an enclosed space and difficult to cool, is significant.

[0050] The circuit configuration and its equivalent circuit for the SP resonance method of the third embodiment are shown in Fig. 18, and the circuit configuration and its equivalent circuit for the SPS resonance method of the fourth embodiment are shown in Fig. 20. The concept of the equivalent circuit is the same as that of the first embodiment (Fig. 12). Furthermore, a voltage equation is established from the equivalent circuit and solved to determine the currents Ip, It, Iw, and Is, and equations for determining the resonance conditions from these are shown in Figs. 19 and 21. Note that these equivalent circuits do not take into account the influence of non-opposing coils either.

[0051] C. Fifth to Seventh Embodiments: Next, fifth to seventh embodiments will be described. The power transfer system 500 and the power supply device 250 used therein in the fifth to seventh embodiments are identical to those in the first, third, and fourth embodiments, except for the configurations of the relay resonant circuits 90, 90B, and 90C. The configurations of the relay resonant circuits 90D to 90F of the relay coil 70 in the fifth to seventh embodiments are shown in FIG. 22. As shown in the figure, the relay resonant circuits 90D to 90F in the fifth to seventh embodiments are similar to those in the first, third, and fourth embodiments, except that the series resonant capacitors Cw1 and Ct1 in the first, third, and fourth embodiments are divided into two and placed on both sides of the first coil 71 and the second coil 72. Therefore, these relay resonant circuits 90D to 90F have parallel characteristics, similar to the first, third, and fourth embodiments. The resonance conditions for each embodiment are shown in the lower part of FIG. 22. The capacitance of the series resonant capacitor may be divided equally or approximately equally to satisfy the resonance conditions. For example, Ct1 = 2·Ct1′.

[0052] The relay resonant circuits 90D to 90F of the fifth to seventh embodiments each have the same advantageous effects as those of the first, third, and fourth embodiments, and also have the advantageous effect of improving noise resistance. The advantageous effects of the power transfer system 500 using these relay resonant circuits 90D to 90F are also similar to those of the first, third, and fourth embodiments.

[0053] D. Eighth embodiment: In each of the above embodiments, a plurality of relay coils 70 are provided on the wheels 60 of the vehicle 200 concentrically around the central axis 61 and are configured to receive power from the power transmission circuit 30 on the ground. However, even if a plurality of relay coils 70 are arranged in a line, the current flowing through the non-opposing coils can be suppressed, and the same effects as those of the other embodiments can be achieved. Fig. 23 shows an example in which relay coils 70X to 70Z are arranged between the power receiving coil 240 of the power receiving circuit 230 provided on the mobile object and the power transmission coil 40 on the ground. As with the first embodiment, the number of relay coils 70 is not limited to three.

[0054] In the eighth embodiment, a ground-side power transmission circuit 30 and a power transmission coil 40 are provided in accordance with each of the relay coils 70X to 70Z, but a configuration in which one power transmission circuit 30 and one power transmission coil 40 are provided for multiple relay coils 70X, etc. may also be used, as shown in the modified example of Fig. 24. Such a configuration in which power is supplied to a linear relay coil 70X, etc., may be used, for example, in a linear section of a crawler vehicle in which steel plates are connected in a strip shape and surround the front and rear wheels, or in a linear motor for a robot.

[0055] E. Other configuration examples: Other embodiments are described below. (1) Another embodiment is a power supply device. The power supply device includes a power receiving coil mounted on a mobile object, multiple relay coils arranged along a plane on which the mobile object moves and sequentially relaying the supply of power between the power transmitting coil and the power receiving coil as the mobile object moves, and a power receiving circuit connected to the power receiving coil and receiving power used by the mobile object. Each of the multiple relay coils includes a first coil that magnetically couples with the power transmitting coil depending on the mobile object's position, a second coil that magnetically couples with the power receiving coil when the first coil is magnetically coupled with the power transmitting coil, and a connection circuit that connects the first coil and the second coil. The connection circuit includes resonant capacitors (Ct1, Cw1) that are involved in setting the resonant frequency of at least one of the first coil and the second coil, and the resonant capacitors have parallel characteristics. This allows the distance between the power transmitting coil and the first coil and the distance between the second coil and the power receiving coil to be narrowed, thereby improving power transmission efficiency. Furthermore, since the resonant capacitor involved in setting the resonant frequency has parallel characteristics, it is possible to suppress the current flowing through other relay coils that do not directly face the power transmission coil among the multiple relay coils, thereby improving the power supply efficiency of the power supply device.

[0056] If the impedance of the circuit including the first coil is sufficiently small, the resonant frequency of the first coil is determined by the inductance value of the first coil when the first coil faces the power transmitting coil and the capacitance of the resonant capacitor. Therefore, the capacitance of the resonant capacitor may be set so that the resonant frequency of the first coil matches or is close to the frequency of power transmitted from the power transmitting coil. Similarly, if the impedance of the circuit including the second coil is sufficiently small, the resonant frequency of the second coil is determined by the inductance value of the second coil when the second coil faces the power receiving coil and the capacitance of the resonant capacitor. Therefore, the capacitance of the resonant capacitor may be set so that the resonant frequency of the second coil matches or is close to the designed frequency when the power receiving coil receives power.

[0057] This power supply device can be applied to a variety of moving objects, such as wheeled vehicles and robots that move parallel to the ground. The number of wheels may be any number, from single to multiple. It can also be applied to crawler vehicles. The moving object can move on any surface, whether indoors or outdoors, including roads, floors, and other surfaces. A flat surface is preferable, but curved surfaces or surfaces with slight steps are also acceptable. The surface on which the moving object travels does not have to be horizontal; it can be a wall or ceiling, as long as the moving object can be attracted to the surface and maintained in contact with it using magnetic or electrostatic forces. Furthermore, the relay coils can be arranged in the circumferential direction of wheels or other structures, or multiple relay coils can be arranged linearly. For example, a configuration in which the moving object is levitated, like a hovercraft, with multiple relay coils arranged on the bottom of the moving object and power is supplied via a relay coil facing a power transmission coil provided on the surface on which the moving object travels. The number of relay coils can be any number, including two to five, or even seven or more, in addition to the six shown in the above embodiment.

[0058] Each of the multiple relay coils may include a first coil that is magnetically coupled with the power transmitting coil and a second coil that is magnetically coupled with the power receiving coil, and may further include other coils. A magnetic body may or may not be interposed between the first coil and the second coil for magnetic coupling.

[0059] (2) In this configuration, the resonant capacitor may be connected in parallel to both the first coil and the second coil. That is, the first coil and the second coil may form a closed circuit, and a resonant capacitor may be connected in parallel to both of them. This simple configuration allows the resonant capacitor to have parallel characteristics, and balances the suppression of current flowing through other relay coils that do not directly face the power transmitting coil and the setting of resonance conditions. One resonant capacitor may be used, but from the perspective of noise countermeasures, one may be provided on the first coil side and one on the second coil side.

[0060] (3) In this configuration, the resonant capacitor may be composed of a parallel resonant capacitor connected in parallel to the first coil and a series resonant capacitor connected in series to the second coil. This allows the resonance between the first coil and the power transmitting coil to have parallel characteristics, and the resonance between the second coil and the power receiving coil to have series characteristics, making it possible to achieve a balance between suppressing current flowing through other relay coils that do not directly face the power transmitting coil and setting resonance conditions. One series resonant capacitor may be used, but from the perspective of noise countermeasures, two series resonant capacitors may be provided on both ends of the second coil.

[0061] (4) In the configuration of (3), the capacitance of the resonant capacitor is determined by a first voltage equation taking into consideration a power transmission voltage applied to a circuit passing through the power transmission coil and a first capacitor for resonance, the inductance of the power transmission coil, the capacitance of the first capacitor, the mutual inductance between the power transmission coil and the first coil, and the circuit impedance; a second voltage equation taking into consideration the inductance of the first coil in a circuit including the first coil and the parallel resonant capacitor, the capacitance of the parallel resonant capacitor, the mutual inductance between the power transmission coil and the first coil, and the circuit impedance; The capacitance of the resonant capacitor may be determined by solving a set of simultaneous equations consisting of a third voltage equation taking into consideration the inductance of the second coil, the capacitance of the parallel resonant capacitor, the capacitance of the series resonant capacitor, the mutual inductance between the second coil and the power receiving coil, and circuit impedance in a circuit including the power receiving coil, the parallel resonant capacitor, and the series resonant capacitor, and a fourth voltage equation taking into consideration the inductance of the power receiving coil, the capacitance of the second capacitor, the mutual inductance between the power receiving coil and the second coil, and circuit impedance in a circuit passing through the power receiving coil and the second capacitor for resonance. In this way, the capacitance of the resonant capacitor can be set to an appropriate value through theoretical analysis.

[0062] (5) In this configuration, the resonant capacitor may be composed of a series resonant capacitor connected in series to the first coil and a parallel resonant capacitor connected in parallel to the second coil. This allows the resonance between the first coil and the power transmitting coil to have a series characteristic, and the resonance between the second coil and the power receiving coil to have a parallel characteristic, making it possible to achieve a balance between suppressing current flowing through other relay coils that do not directly face the power transmitting coil and setting resonance conditions. One series resonant capacitor may be used, but from the perspective of noise countermeasures, two series resonant capacitors may be provided on both ends of the first coil.

[0063] (6) In the configuration of (5), the capacitance of the resonant capacitor is determined by a first voltage equation taking into consideration the power transmission voltage applied to a circuit passing through the power transmission coil and a first capacitor for resonance, the inductance of the power transmission coil, the capacitance of the first capacitor, the mutual inductance between the power transmission coil and the first coil, and circuit impedance, and the inductance of the first coil in a circuit including the first coil, the series resonant capacitor, and the parallel resonant capacitor, the capacitance of the series resonant capacitor, the capacitance of the parallel resonant capacitor, the mutual inductance between the power transmission coil and the first coil, and circuit impedance. The capacitance of the resonant capacitor may be determined by solving a system of simultaneous equations consisting of a second voltage equation taking into account the circuit impedance, a third voltage equation taking into account the inductance of the second coil in a circuit including the second coil and the parallel resonant capacitor, the capacitance of the parallel resonant capacitor, the mutual inductance between the second coil and the power receiving coil, and the circuit impedance, and a fourth voltage equation taking into account the inductance of the power receiving coil in a circuit passing through the power receiving coil and the second capacitor for resonance, the capacitance of the second capacitor, the mutual inductance between the power receiving coil and the second coil, and the circuit impedance. In this way, the capacitance of the resonant capacitor can be set to an appropriate value through theoretical analysis.

[0064] (7) In this configuration, the resonant capacitor may include first and second series resonant capacitors connected in series to the first coil and the second coil, respectively, and a parallel resonant capacitor connected in parallel to the first coil and the first series resonant capacitor and the second coil and the second series resonant capacitor. This allows the resonance between the first coil and the power transmitting coil and the resonance between the second coil and the power receiving coil to have both series and parallel characteristics, thereby achieving a balance between suppressing current flowing through other relay coils that do not directly face the power transmitting coil and setting resonance conditions. There may be one first and one second series resonant capacitor each, but from the perspective of noise countermeasures, one first and one second series resonant capacitor may be provided at both ends of at least one of the first coil and the second coil.

[0065] (8) In the configuration (7), the capacitance of the resonant capacitor is determined by a first voltage equation taking into consideration a power transmission voltage applied to a circuit passing through the power transmission coil and a first capacitor for resonance, the inductance of the power transmission coil, the capacitance of the first capacitor, the mutual inductance between the power transmission coil and the first coil, and circuit impedance; a second voltage equation taking into consideration the inductance of the first coil in a circuit including the first coil, the first series resonant capacitor, and the parallel resonant capacitor, the capacitance of the first series resonant capacitor, the capacitance of the parallel resonant capacitor, the mutual inductance between the power transmission coil and the first coil, and circuit impedance; The capacitance of the resonant capacitor may be determined by solving a system of simultaneous equations consisting of a second voltage equation, a third voltage equation taking into consideration the inductance of the second coil, the capacitance of the second series resonant capacitor, the capacitance of the parallel resonant capacitor, the mutual inductance between the second coil and the power receiving coil, and circuit impedance in a circuit including the second coil, the second series resonant capacitor, and the parallel resonant capacitor, and a fourth voltage equation taking into consideration the inductance of the power receiving coil, the capacitance of the second capacitor, the mutual inductance between the power receiving coil and the second coil, and circuit impedance in a circuit passing through the power receiving coil and the second capacitor for resonance. In this way, the capacitance of the resonant capacitor can be set to an appropriate value through theoretical analysis.

[0066] (9) In any of the configurations (1) to (8), the mobile object may include wheels, and the multiple relay coils may be arranged along the circumferential direction of the wheels and sequentially relay the power from the power transmitting coil to the power receiving coil according to the rotational position of the wheels as the mobile object moves. This allows for efficient and continuous power supply from the power transmitting coil to the power receiving coil of the mobile object via the wheels. The mobile object may have one or more wheels, and multiple relay coils may be provided on all of the wheels, or on some of the wheels. When multiple relay coils are provided on any of the wheels, the relay coils may be arranged along the circumferential direction of the wheel, spaced apart by a predetermined distance or a predetermined central angle, or may be arranged so as to overlap or contact each other. Furthermore, the first coil and the second coil may be arranged in an overlapping position, and the first coil and the second coil may be arranged in an overlapping position as viewed from the axis of rotation of the wheel, so that the direction of current flowing through the first coil and the direction of current flowing through the second coil are opposite to each other. The first coil may be configured as a coil pattern formed on a metal belt used in a tire.

[0067] (10) In the configuration of (9), each of the first coils of the multiple relay coils may be provided inside the tire of the wheel, and each of the second coils of the multiple relay coils may be provided inside the wheel of the wheel. This narrows the gap between the first coil and the power transmitting coil, making it easier to improve power supply efficiency. Furthermore, since the second coil is closer to the axle, the position where it is magnetically coupled with the power receiving coil can be away from the surface on which the mobile object travels. In other words, since the second coil can be closer to the mobile object, it is easier to arrange the power receiving coil. Here, the conductor connecting the first coil and the second coil may be routed through a through-hole or the like provided in the wheel. The through-hole and the conductor may be hermetically sealed while being insulated. Such sealing can be easily achieved by filling the gap between the through-hole and the conductor with an insulating adhesive or sealant. The second coil may be provided outside the wheel and magnetically coupled with the power receiving coil. In this case, the conductor connecting the first coil may be arranged to pass through the tire. The conductors that pass through the tire, as in the case of the wheel, should be designed to keep the tire airtight, and may be made of Litz wire or bus bars.

[0068] (11) In the configuration of (10), the resonant capacitor that sets the resonant frequency of the second coil may be provided inside the wheel. This reduces heat generation in the connection circuit, thereby suppressing temperature increases inside the wheel, which is difficult to dissipate heat. The heat-generating parts, including the second coil, may be mounted on a heat-conducting plate made of a material with high thermal conductivity, such as copper or aluminum, or connected to a heat pipe or the like, so that heat is transferred to the wheel and dissipated.

[0069] (12) In the configuration of (10), the resonant capacitor that sets the resonant frequency of the first coil may be provided inside the tire. This reduces heat generation in the connection circuit, thereby suppressing temperature rise inside the tire, which is difficult to dissipate heat.

[0070] (13) In the configuration of (9), the plurality of repeater coils may be disposed at positions that divide the circumference of the wheel into equal angles with respect to the rotation axis of the wheel. In this way, when the mobile object is traveling at a constant speed, the intervals between peaks of the electromotive force generated in the receiving coil become constant, and the frequency of the supplied power becomes stable, allowing the receiving circuit to operate efficiently. Note that the plurality of repeater coils may be disposed so that the central angles are not equiangular.

[0071] (14) In the configurations (1) to (8), at least one of the power transmitting coil and the power receiving coil may include a magnetic material that changes the mutual inductance with the repeater coil, and the resonant capacitor may have a capacitance that is set using the maximum value of the inductance of the repeater coil. This allows the power supply device to operate properly even if at least one of the power transmitting coil and the power receiving coil includes a magnetic material that changes the mutual inductance with the repeater coil.

[0072] (15) Another aspect of the present disclosure provides a power supply system. The power supply system includes any one of the power supply devices described above, a plurality of power transmission coils provided on a travel surface on which the moving object travels, and a power transmission device that applies an AC current of a frequency corresponding to the resonant frequency to at least one of the plurality of power transmission coils, the power transmission coil being the one on which the moving object is located. This improves the power supply efficiency of the entire power supply system, enabling the power required by the moving object to be supplied with less power. If the moving object is an electric vehicle or other electrically powered object, the transmitted power required to travel a given distance can be reduced.

[0073] (16) Another aspect of the present disclosure provides a power supply system design method. The power supply system design method includes a power supply device, and determines which of the power supply devices described in (2), (3), (5), or (7) is to be used as the power supply device according to the power efficiency of the entire power supply system, which is determined by the currents flowing through the multiple repeater coils in the power supply device during power supply to the mobile object. This allows the power supply system to be designed by selecting a connection circuit configuration suitable for the power supply system.

[0074] The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features of the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0075] 10... power supply (external power supply), 30... power transmission circuit, 40... power transmission coil, 50... control device, 60 wheel, 61... central axis, 62... tire, 64... wheel, 70, 70a to 70f... relay coil, 71, 71a to 71f... first coil, 72, 72a to 72f... second coil, 100... power transmission system, 105... road, 200... vehicle, 220... control device, 230... power receiving circuit, 240... power receiving coil, 250... power supply device, 280... motor generator, 500... power transmission system

Claims

1. a receiving coil (240) mounted on the moving body (200); a plurality of relay coils (70) that sequentially relay the supply of power between the power transmitting coil (40) and the power receiving coil, the power transmitting coil (40) being arranged along the plane on which the moving body moves as the moving body moves; a receiving circuit (230) connected to the receiving coil to receive power used in the moving body; Equipped with Each of the plurality of relay coils includes a first coil (71) that magnetically couples with the power transmission coil depending on the moving position of the moving body, a second coil (72) that magnetically couples with the power receiving coil when the first coil is magnetically coupled with the power transmission coil, and a connection circuit (90) that connects the first coil and the second coil, the plurality of relay coils are provided along the circumferential direction of the wheels (60) of the moving body, and relay the power from the power transmitting coil to the power receiving coil sequentially in accordance with the rotational position of the wheels accompanying the movement of the moving body; The connection circuit includes a resonant capacitor that is involved in setting a resonant frequency of at least one of the first coil and the second coil, and the resonant capacitor is a parallel resonant capacitor connected in parallel to at least one of the first coil and the second coil; or a parallel resonant capacitor connected in parallel to the first coil and the second coil via a series resonant coil; By having any one of the above, it has parallel characteristics, A power supply device (250).

2. The resonant capacitor is the parallel resonant capacitor connected in parallel to the first coil; a series resonant capacitor connected in series to the second coil; The power supply device according to claim 1 ,

3. The capacitance of the resonant capacitor is a first voltage equation taking into consideration a power transmission voltage applied to a circuit passing through the power transmission coil and a first capacitor for resonance, an inductance of the power transmission coil, a capacitance of the first capacitor, a mutual inductance between the power transmission coil and the first coil, and a circuit impedance; a second voltage equation taking into consideration the inductance of the first coil, the capacitance of the parallel resonant capacitor, the mutual inductance between the power transmitting coil and the first coil, and circuit impedance in a circuit including the first coil and the parallel resonant capacitor; a third voltage equation taking into consideration the inductance of the second coil, the capacitance of the parallel resonant capacitor, the capacitance of the series resonant capacitor, the mutual inductance between the second coil and the power receiving coil, and circuit impedance in a circuit including the second coil, the parallel resonant capacitor, and the series resonant capacitor; a fourth voltage equation taking into consideration the inductance of the power receiving coil, the capacitance of the second capacitor, the mutual inductance between the power receiving coil and the second coil, and circuit impedance in a circuit passing through the power receiving coil and a second capacitor for resonance; The power supply device according to claim 2, wherein the power supply device is determined by solving a simultaneous equation consisting of:

4. The power supply device according to claim 1 , wherein the resonant capacitor is a parallel resonant capacitor commonly connected in parallel to the first coil and the second coil.

5. The resonant capacitor is a series resonant capacitor connected in series to the first coil; the parallel resonant capacitor connected in parallel to the second coil; The power supply device according to claim 1 ,

6. The capacitance of the resonant capacitor is a first voltage equation taking into consideration a power transmission voltage applied to a circuit passing through the power transmission coil and a first capacitor for resonance, an inductance of the power transmission coil, a capacitance of the first capacitor, a mutual inductance between the power transmission coil and the first coil, and a circuit impedance; a second voltage equation taking into consideration the inductance of the first coil, the capacitance of the series resonant capacitor, the capacitance of the parallel resonant capacitor, the mutual inductance between the power transmitting coil and the first coil, and circuit impedance in a circuit including the first coil, the series resonant capacitor, and the parallel resonant capacitor; a third voltage equation taking into consideration the inductance of the second coil, the capacitance of the parallel resonant capacitor, the mutual inductance between the second coil and the power receiving coil, and circuit impedance in a circuit including the second coil and the parallel resonant capacitor; a fourth voltage equation taking into consideration the inductance of the power receiving coil, the capacitance of the second capacitor, the mutual inductance between the power receiving coil and the second coil, and circuit impedance in a circuit passing through the power receiving coil and a second capacitor for resonance; The power supply device according to claim 5, wherein the power supply device is determined by solving a simultaneous equation consisting of:

7. The resonant capacitor is a first series resonant capacitor and a second series resonant capacitor connected in series to the first coil and the second coil, respectively; the parallel resonant capacitor connected in parallel with the first coil and the first series resonant capacitor and the second coil and the second series resonant capacitor; The power supply device according to claim 1 ,

8. The capacitance of the resonant capacitor is a first voltage equation taking into consideration a power transmission voltage applied to a circuit passing through the power transmission coil and a first capacitor for resonance, an inductance of the power transmission coil, a capacitance of the first capacitor, a mutual inductance between the power transmission coil and the first coil, and a circuit impedance; a second voltage equation taking into consideration the inductance of the first coil, the capacitance of the first series resonant capacitor, the capacitance of the parallel resonant capacitor, the mutual inductance between the power transmitting coil and the first coil, and circuit impedance in a circuit including the first coil, the first series resonant capacitor, and the parallel resonant capacitor; a third voltage equation taking into consideration the inductance of the second coil, the capacitance of the second series resonant capacitor, the capacitance of the parallel resonant capacitor, the mutual inductance between the second coil and the power receiving coil, and circuit impedance in a circuit including the second coil, the second series resonant capacitor, and the parallel resonant capacitor; a fourth voltage equation taking into consideration the inductance of the power receiving coil, the capacitance of the second capacitor, the mutual inductance between the power receiving coil and the second coil, and circuit impedance in a circuit passing through the power receiving coil and a second capacitor for resonance; The power supply device according to claim 7, wherein the power supply device is determined by solving a simultaneous equation consisting of:

9. Each of the first coils of the plurality of relay coils is provided within a tire (62) of the wheel, Each of the second coils of the plurality of relay coils is provided within a wheel (64) of the wheel. The power supply device according to claim 1 .

10. The power supply device according to claim 9 , wherein the resonant capacitor that sets the resonant frequency of the second coil is provided within the wheel.

11. The power supply device according to claim 9 , wherein the resonant capacitor that sets the resonant frequency of the first coil is provided inside the tire.

12. The power supply device according to claim 1 , wherein the plurality of relay coils are provided at positions that divide the circumference of the wheel into equal angles with respect to the rotation axis of the wheel.

13. at least one of the power transmitting coil and the power receiving coil includes a magnetic body that changes the inductance of the relay coil; the resonant capacitor has a capacitance set using the maximum value of the inductance of the relay coil. The power supply device according to any one of claims 1 to 8.

14. The power supply device according to any one of claims 1 to 8; a plurality of power transmission coils provided on a travel surface on which the moving body travels; a power transmission device (100) that applies an AC current having a frequency corresponding to the resonance frequency to at least one of the plurality of power transmission coils, the power transmission coil being located in the power transmission coil where the moving body is located; A power transmission system (500) comprising:

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