Wireless power supply device for motors, motor drive system, vehicle wireless power supply system, and vehicle-to-vehicle power supply system

Abstract

To provide a wireless power feeding device that transmits power to a motor in which the state of the motor or peripheral circuits thereof is stabilized.SOLUTION: A wireless power feeding device 10 includes a power feeding resonant circuit 1 that couples wirelessly, that is, in a contactless manner, to a power receiving resonant circuit 2 that supplies power to a motor MT. The wireless power feeding device 10 further includes a switching power supply 20 that supplies power to the power feeding resonant circuit 1 by switching. The wireless power feeding device 10 further includes a control unit 3 coupled to the power feeding resonant circuit 1. The control unit 3 includes a feedback unit 16 and a phase adjustment unit 18 and switches a switching power source 20 at a timing corresponding to a time change in voltage or current in the power feeding resonant circuit 1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wireless power supply device for a motor, a motor drive system, a vehicle wireless power supply system, and a vehicle-to-vehicle power supply system, and particularly relates to wireless power supply to a motor.

Background Art

[0002] Extensive research and development have been conducted on a wireless power supply system that supplies power to a load device from a power supply device without contact. In a wireless power supply system, there is one that non-contact couples a resonance circuit provided in the power supply device and a resonance circuit provided in the load device, and supplies power from the power supply device to the load device by resonating these resonance circuits. The following Patent Documents 1 and 2 describe technologies related to such wireless power supply.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a wireless power supply system, when the state of a load circuit connected to the resonance circuit of the load device changes, the resonance states of the resonance circuit of the power supply device and the resonance circuit of the load device change, and the voltage applied to the load device and the current flowing through the load device may fluctuate. For example, when the load device includes a motor, the voltage or current in the electric circuit connected to the motor fluctuates due to fluctuations in the rotational speed or load of the motor, and the state of the motor or its peripheral circuit may become unstable.

[0005] The objective of the present invention is to stabilize the state of the motor or its peripheral circuitry in a wireless power supply device that transmits power to a motor. [Means for solving the problem]

[0006] This invention Wireless power supply device for motors related to this device The system comprises a power supply resonant circuit that is non-contactually coupled to a power receiving resonant circuit that supplies power to a motor, a switching power supply that supplies power to the power supply resonant circuit by switching, and a control unit that is coupled to the power supply resonant circuit and switches the switching power supply at timings corresponding to the time change of voltage or current in the power supply resonant circuit. A feedback inductor coupled to the power supply resonant circuit, Equipped with The control unit comprises a feedback unit that generates a feedback signal corresponding to the voltage or current in the feedback inductor, and a phase adjustment unit that adjusts the phase of the feedback signal. The switching power supply comprises a switching circuit that turns the current or voltage in the power supply resonant circuit on or off depending on whether the phase-adjusted feedback signal exceeds a reference value. It is characterized by the following.

[0007] Preferably, the control unit is A comparator that outputs a high or low value depending on whether the value of the feedback signal exceeds a reference value, thereby outputting a phase control signal; and a switching driver that turns on or off the switching elements of the switching circuit depending on whether the value of the phase control signal is high or low. It is equipped with.

[0008] Preferably, the control unit includes a feedback unit that generates a feedback signal corresponding to the voltage or current in the feedback inductor, and a phase adjustment unit that adjusts the phase of the feedback signal, and the switching circuit turns the current or voltage in the power supply resonant circuit on or off based on the phase-adjusted feedback signal.

[0009] Preferably, the system comprises the power receiving resonant circuit, the motor, and a power conversion circuit that supplies power output from the power receiving resonant circuit to the motor.

[0010] Furthermore, the present invention relates to a vehicle wireless power supply system comprising a plurality of the aforementioned wireless power supply devices for motors, wherein the plurality of the aforementioned wireless power supply devices for motors are arranged along the road.

[0011] Furthermore, the present invention is mounted on an electric vehicle. The aforementionedThe system comprises a wireless power supply device for a motor and a wireless power receiving device provided on the wheel of the electric vehicle together with the in-wheel motor, which acquires power supplied from the wireless power supply device for the motor, wherein the wireless power receiving device supplies power to the in-wheel motor.

[0012] Furthermore, the present invention relates to an inter-vehicle power supply system in which the motor wireless power supply device is mounted on each of a plurality of electric vehicles, and each of the electric vehicles is equipped with a wireless power receiving device that acquires power supplied from the motor wireless power supply device mounted on the other electric vehicles, and power is exchanged between the plurality of electric vehicles. [Effects of the Invention]

[0013] According to the present invention, the state of the motor or its peripheral circuit can be stabilized. [Brief explanation of the drawing]

[0014] [Figure 1] This diagram shows the basic configuration of a wireless power supply system for motors. [Figure 2] This figure shows a specific example configuration of a wireless power supply system for motors. [Figure 3] This figure shows the results of simulations that determined the characteristics of load power and transmission efficiency in relation to load resistance. [Figure 4] This figure shows the results of simulations that determined the characteristics of load voltage and load current with respect to load resistance. [Modes for carrying out the invention]

[0015] FIG. 1 shows the basic configuration of a wireless power supply system 100 for a motor according to an embodiment of the present invention. The wireless power supply system 100 for a motor includes a wireless power supply device 10 and a wireless power receiving device 12. A motor MT is connected to the wireless power receiving device 12 as a load RL, power is transmitted from the wireless power supply device 10 to the wireless power receiving device 12, and power is supplied to the motor MT. That is, a motor drive system in which power is supplied from the wireless power supply device 10 to the motor MT via the wireless power receiving device 12 is constituted by the wireless power supply system 100 for a motor.

[0016] The wireless power supply device 10 includes a switching power supply 20, a first capacitor C1, a first resistor R1, a power supply inductor L1, a feedback unit 16, and a phase adjustment unit 18. The first capacitor C1, the first resistor R1, and the power supply inductor L1 are connected in series to constitute a power supply resonance circuit 1. A switching power supply 20 is connected between one end of the first capacitor C1 on the side opposite to the side to which the first resistor R1 is connected and one end of the power supply inductor L1 on the side opposite to the side to which the first resistor R1 is connected.

[0017] Note that the first resistor R1 may be a resistance component included in the power supply inductor L1. However, in FIG. 1, the first resistor R1 is depicted as a separate element from the power supply inductor L1, including the case where the first resistor R1 is a resistance component included in the power supply inductor L1.

[0018] The wireless power receiving device 12 includes a power receiving inductor L2, a second resistor R2, a second capacitor C2, a rectifier circuit 14, and a smoothing capacitor Cs. The power receiving inductor L2, the second resistor R2, and the second capacitor C2 are connected in series to form a power receiving resonance circuit 2. The resonance frequencies of the power feeding resonance circuit 1 and the power receiving resonance circuit 2 are the same or approximate. A rectifier circuit 14 is connected as a power conversion circuit between one end of the second capacitor C2 on the side opposite to the side to which the second resistor R2 is connected and one end of the power receiving inductor L2 on the side opposite to the side to which the second resistor R2 is connected. A motor MT and a smoothing capacitor Cs connected in parallel to the motor MT are connected to the rectifier circuit 14.

[0019] The motor MT may be, in addition to a DC motor, a DC brushless motor, an AC motor, a switched reluctance, a stepping motor, or an ultrasonic motor. Depending on whether the power supplied to the motor MT is AC power or DC power, the rectifier circuit may be replaced with another power conversion circuit.

[0020] Similar to the first resistor R1, the second resistor R2 may be a resistance component included in the power receiving inductor L2. However, in FIG. 1, the second resistor R2 is depicted as a separate element from the power receiving inductor L2, including the case where the second resistor R2 is a resistance component included in the power receiving inductor L2.

[0021] The switching power supply 20 may be constituted by an oscillation circuit that generates an AC voltage by switching. The switching power supply 20 outputs, for example, a rectangular wave voltage whose value repeats high and low as an AC voltage at a frequency the same as or approximate to the resonance frequency of the power feeding resonance circuit 1. As a result, a resonance current as a power feeding current flows through the power feeding resonance circuit 1. The feedback unit 16 is coupled to the power feeding resonance circuit 1, detects the power feeding current flowing through the power feeding inductor L1, and outputs a feedback signal corresponding to the detected value to the phase adjustment unit 18. The phase adjustment unit 18 adjusts the phase of the AC voltage output by the switching power supply 20 so that the phase difference between the phase of the power feeding current (resonance current) and the current flowing through the switching power supply 20 is reduced or becomes zero.

[0022] The phase adjustment unit 18 adjusts the phase of the feedback signal, thereby positively feeding back the value of the power supply current flowing through the power supply resonant circuit 1 to the AC voltage output by the switching power supply 20. This configures a self-excited oscillator in the wireless power supply device 10, and stably maintains the resonant state of the power supply resonant circuit 1.

[0023] The power supply resonant circuit 1 and the power receiving resonant circuit 2 are magnetically coupled or electromagnetically coupled. That is, the power supply resonant circuit 1 and the power receiving resonant circuit 2 may be magnetically coupled by electromagnetic induction from the power supply inductor L1 and the power receiving inductor L2. Alternatively, the power supply resonant circuit 1 may generate an electromagnetic field, and the power receiving resonant circuit 2 may receive that electromagnetic field, causing the power supply resonant circuit 1 and the power receiving resonant circuit 2 to be electromagnetically coupled.

[0024] Since the resonant frequencies of the power supply resonant circuit 1 and the power receiving resonant circuit 2 are the same or approximate, the power supply resonant circuit 1 and the power receiving resonant circuit 2 resonate together. The power supply current flowing through the power supply resonant circuit 1 causes a power receiving current to flow through the power receiving resonant circuit 2. The power receiving current is rectified by the rectifier circuit 14, and a current containing a DC component flows through the smoothing capacitor Cs and the motor MT. In other words, the rectifier circuit 14 converts the AC power output from the power receiving resonant circuit 2 into DC power and supplies it to the motor MT.

[0025] The above description concerns a feedback unit 16 that detects the power supply current flowing through the power supply inductor L1 and outputs a feedback signal to the phase adjustment unit 18 according to the detected value. The feedback unit 16 may also be a circuit that detects the voltage appearing in the power supply inductor L1 or the first capacitor C1 and outputs a feedback signal to the phase adjustment unit 18 according to the detected value. In this case, the voltage value appearing in the power supply resonant circuit 1 is positively fed back to the AC voltage output by the switching power supply 20.

[0026] As described above, the wireless power supply device 10 (wireless power supply device for motors) according to this embodiment includes a power supply resonant circuit 1 that is wirelessly, i.e., non-contactually coupled to a power receiving resonant circuit 2 that supplies power to a motor MT. The wireless power supply device 10 also includes a switching power supply 20 that supplies power to the power supply resonant circuit 1 by switching. The wireless power supply device 10 further includes a control unit 3 that is coupled to the power supply resonant circuit 1. The control unit 3 consists of a feedback unit 16 and a phase adjustment unit 18, and switches the switching power supply 20 at a timing corresponding to the time change of voltage or current in the power supply resonant circuit 1.

[0027] In conventional wireless power transfer systems, fluctuations in motor speed or load can cause changes in the resonant frequencies of the power supply and receiving devices' resonant circuits, resulting in fluctuations in the voltage or current appearing in the motor and surrounding circuits. This can make motor control difficult or necessitate increasing the voltage resistance or current tolerance of components used in the surrounding circuits.

[0028] In the wireless power supply system 100 for motors according to this embodiment, the detected value of the power supply current flowing through the power supply resonant circuit 1 is positively fed back to the AC voltage output by the switching power supply 20. As a result, the resonant state of the power supply resonant circuit 1 and the power receiving resonant circuit 2 is stably maintained. This suppresses fluctuations in voltage or current appearing in the motor MT and its surrounding circuits, making it easier to control the motor MT. Furthermore, even if the state of the motor MT changes, such as when the rotational speed or torque of the motor MT fluctuates, the resonant state of the power supply resonant circuit 1 and the power receiving resonant circuit 2 is stably maintained, and power is stably supplied to the motor MT.

[0029] Furthermore, in the wireless power supply system 100 for motors according to this embodiment, even if a power conversion circuit using a switching element is used instead of the rectifier circuit 14, it is not necessary to synchronize the switching of the switching power supply 20 with the switching of the power conversion circuit. This simplifies the configuration of the wireless power supply system 100 for motors.

[0030] Figure 2 shows a wireless power supply system 102 for a motor as a specific example of the configuration of a wireless power supply system 100 for a motor according to an embodiment of the present invention. The wireless power supply system 102 for a motor comprises a wireless power supply device 10, a wireless power receiving device 12, a rectifier circuit 14, and a motor MT.

[0031] The wireless power supply device 10 includes a switching circuit 22, a power supply resonant circuit 1a, a feedback unit 16, and a phase adjustment unit 18.

[0032] The switching circuit 22 corresponds to the switching power supply 20 shown in Figure 1. The switching circuit 22 includes a switching driver 54 and a half-bridge 56. The half-bridge 56 includes a first switching element S1 and a second switching element S2, one end of which is connected in common. The end of the first switching element S1 opposite to the second switching element S2 is connected to a DC voltage source 58, and the end of the second switching element S2 opposite to the first switching element S1 is connected to a ground conductor.

[0033] The switching driver 54 alternately turns the first switching element S1 and the second switching element S2 on and off in phase according to the phase control signal output from the phase adjustment unit 18. When the first switching element S1 is switched from off to on, the second switching element S2 is switched from on to off, and when the first switching element S1 is switched from on to off, the second switching element S2 is switched from off to on.

[0034] The power supply resonant circuit 1a comprises a first capacitor C1, a first power supply inductor La, and a second power supply inductor Lb. The first power supply inductor La and the second power supply inductor Lb correspond to the power supply inductor L1 shown in Figure 1. One end of the first capacitor C1 is connected to the connection point of the first switching element S1 and the second switching element S2 in the half bridge 56. The other end of the first capacitor C1 is connected to one end of the first power supply inductor La. The other end of the first power supply inductor La is connected to one end of the second power supply inductor Lb, and the other end of the second power supply inductor Lb is connected to the ground conductor.

[0035] The feedback section 16 includes a feedback transformer T and an amplification circuit 50. The feedback transformer T includes a magnetically coupled second power supply inductor Lb and a feedback inductor Lf. That is, the feedback transformer T and the power supply resonant circuit 1a share the second power supply inductor Lb. Both ends of the feedback inductor Lf are connected between the positive-sequence terminal 50p and the negative-sequence terminal 50n of the amplification circuit 50.

[0036] The amplification circuit 50 comprises a differential amplifier 51, a positive-sequence input resistor Ra3, a negative-sequence input resistor Ra1, a feedback resistor Ra2, and shunt resistors Ra4 to Ra6. The positive-sequence input resistor Ra3 is connected between the positive-sequence terminal 50p and the positive-sequence input terminal of the differential amplifier 51, and the negative-sequence input resistor Ra1 is connected between the negative-sequence terminal 50n and the negative-sequence input terminal of the differential amplifier 51. The feedback resistor Ra2 is connected between the output terminal and the negative-sequence input terminal of the differential amplifier 51. The shunt resistor Ra4 is connected between the negative-sequence terminal 50n and the ground conductor. The shunt resistor Ra5 is connected between the positive-sequence terminal 50p and the ground conductor, and the shunt resistor Ra6 is connected between the positive-sequence input terminal of the differential amplifier 51 and the ground conductor. The gain of the amplification circuit 50 is determined by the resistance values ​​of the positive-sequence input resistor Ra3, the negative-sequence input resistor Ra1, the feedback resistor Ra2, and the shunt resistors Ra4 to Ra6.

[0037] The amplification circuit 50 amplifies the voltage across the feedback inductor Lf and outputs a feedback signal to the phase adjustment unit 18. The feedback signal is a signal corresponding to the current flowing through the power supply resonant circuit 1a. The amplification circuit 50 may be replaced with an amplification circuit that outputs a feedback signal corresponding to the current flowing through the feedback inductor Lf. In this case, the amplification circuit may have a resistor or the like connected in series with the feedback inductor Lf, amplify the voltage appearing across the resistor, and output a feedback signal to the phase adjustment unit 18.

[0038] The phase adjustment unit 18 includes a phase shift capacitor Cb, a first variable resistor Rb1, a second variable resistor Rb2, and a comparator 52. The phase shift capacitor Cb and the first variable resistor Rb1 are connected in parallel. One connection point of the phase shift capacitor Cb and the first variable resistor Rb1 is connected to the output terminal of the amplifier circuit 50. The other connection point of the phase shift capacitor Cb and the first variable resistor Rb1 is connected to the input terminal of the comparator 52 and one end of the second variable resistor Rb2. The other end of the second variable resistor Rb2 is connected to a ground conductor.

[0039] The phase-shift capacitor Cb, the first variable resistor Rb1, and the second variable resistor Rb2 change the phase of the feedback signal and output it to the comparator 52. The amount of phase change is adjusted by changing the resistance value of either the first variable resistor Rb1 or the second variable resistor Rb2.

[0040] The comparator 52 outputs a phase control signal to the switching driver 54, which becomes high when the feedback signal exceeds a reference value and low when it is below the reference value. The switching driver 54 alternately turns the first switching element S1 and the second switching element S2 on and off in synchronization with the timing of the high and low switching of the phase control signal.

[0041] When the first switching element S1 is turned on and the second switching element S2 is turned off, current flows through the path from the ground conductor through the second power supply inductor Lb and the first power supply inductor La to the DC voltage source 58.

[0042] When the second switching element S2 is turned on and the first switching element S1 is turned off, one end of the first capacitor C1 is short-circuited to the ground conductor. A current loop is formed by the second switching element S2, the first capacitor C1, the first power supply inductor La, and the second power supply inductor Lb.

[0043] As the first switching element S1 and the second switching element S2 alternately turn on and off, a resonant current flows as a power supply current through the first capacitor C1, the first power supply inductor La, and the second power supply inductor Lb of the power supply resonant circuit 1a. A feedback signal corresponding to the power supply current is output from the feedback unit 16 to the phase adjustment unit 18, and a phase control signal corresponding to the phase of the feedback signal is output to the switching driver 54. The switching driver 54 alternately turns the first switching element S1 and the second switching element S2 on and off in synchronization with the timing of the high and low switching of the phase control signal.

[0044] With this configuration, the switching circuit 22 switches the half-bridge 56 (by switching the switching power supply 20) at a timing corresponding to the time change of the voltage or current in the feedback inductor Lf, thereby turning the voltage or current in the power supply resonant circuit 1a on or off.

[0045] In the wireless power supply system 102 for motors according to this embodiment, the amount of phase change in the phase adjustment unit 18 is set so that the feedback signal and phase control signal based on the power supply current are positive feedback to the power supply current. That is, the amount of phase change in the phase adjustment unit 18 is set so that the phase of the power supply current and the switching timing of the first switching element S1 and the second switching element S2 are synchronized. As a result, a self-excited oscillator is configured in the wireless power supply device 10, and the resonance state of the power supply resonant circuit 1 is stably maintained.

[0046] The wireless power receiving device 12 includes a power receiving resonant circuit 2a and a rectifier circuit 14. The power receiving resonant circuit 2a includes a power receiving inductor L2 and a second capacitor C2. The rectifier circuit 14 includes diodes D1 to D4. The anode of diode D1 is connected to the cathode of diode D2, and the anode of diode D3 is connected to the cathode of diode D4. The cathode of diode D1 is connected to the cathode of diode D3, and the anode of diode D2 is connected to the anode of diode D4.

[0047] One end of the second capacitor C2 is connected to the connection point of diodes D1 and D2. The other end of the second capacitor C2 is connected to one end of the receiving inductor L2, and the other end of the receiving inductor L2 is connected to the connection point of diodes D3 and D4. A smoothing capacitor Cs and a motor MT are connected between the connection point of diodes D1 and D3 and the connection point of diodes D2 and D4.

[0048] The first power supply inductor La and the power receiving inductor L2 are coupled, thereby coupling the power supply resonant circuit 1a and the power receiving resonant circuit 2a. Alternatively, the power supply resonant circuit 1a generates an electromagnetic field, and the power receiving resonant circuit 2a receives this electromagnetic field, causing the power supply resonant circuit 1a and the power receiving resonant circuit 2a to be electromagnetically coupled. Based on the power supply current flowing through the first capacitor C1, the first power supply inductor La, and the second power supply inductor Lb of the power supply resonant circuit 1a, a power receiving current flows through the power receiving inductor L2 and the second capacitor C2 of the power receiving resonant circuit 2a. The power receiving current is rectified by the rectifier circuit 14. That is, the power receiving current is rectified into a DC current that flows out from the connection point of diodes D1 and D3 to the motor MT and smoothing capacitor Cs side, and flows from the motor MT and smoothing capacitor Cs side to the connection point of diodes D2 and D4.

[0049] The DC voltage applied to the motor MT is smoothed by the smoothing capacitor Cs. The current flowing from the rectifier circuit 14 to the motor MT and the voltage applied from the rectifier circuit 14 to the motor MT generate torque and cause the motor MT to rotate.

[0050] Generally, changes in the rotational state of a motor, such as rotational speed and torque, cause changes in the magnitude and phase of the voltage appearing at the power supply end, as well as the magnitude and phase of the current flowing through the motor. Therefore, if a wireless power supply device is not equipped with a circuit to stabilize the resonant frequency, changes in the motor's rotational state may cause changes in the resonant frequencies of the power supply resonant circuit and the power receiving resonant circuit, as well as the Q values ​​of the power supply resonant circuit and the power receiving resonant circuit.

[0051] In the wireless power supply system 102 for motors according to this embodiment, a self-excited oscillator is configured in the wireless power supply device 10. Therefore, the resonant state of the power supply resonant circuit 1a is stably maintained, and furthermore, the resonant state of the power supply resonant circuit 1a and the power receiving resonant circuit 2a is stably maintained. As a result, power is stably supplied to the motor MT.

[0052] Figure 3 shows the results of simulations determining the characteristics of load power and transmission efficiency with respect to the resistance value of the load RL (load resistance value). Load power is the power supplied from the wireless power receiving device 12 to the load RL, such as the motor MT. Transmission efficiency is the ratio of load power to the power output by the DC voltage source (switching power supply 20 or DC voltage source 58) in the wireless power supply device 10. The horizontal axis represents the load resistance value. The left vertical axis represents load power, and the right vertical axis represents transmission efficiency.

[0053] Characteristic 70-1 is the load power characteristic of the wireless power supply system 102 for motors according to this embodiment. Characteristic 70-2 is the load power characteristic of a conventional wireless power supply system for motors.

[0054] Characteristic 72-1 is a transmission efficiency characteristic of the wireless power supply system 102 for motors according to this embodiment. Characteristic 72-2 is a transmission efficiency characteristic of a conventional wireless power supply system for motors.

[0055] Here, the conventional wireless power supply system for motors is the same as the wireless power supply system 100 for motors shown in Figure 1, but with the feedback unit 16 and the phase adjustment unit 18 removed. In the conventional wireless power supply system for motors, the value of the power supply current flowing through the power supply resonant circuit 1 is not positively fed back into the voltage output by the switching power supply 20. Also, when an AC / DC converter is used, it performs switching synchronized with the AC voltage output by the switching power supply 20.

[0056] The critical value P for the load resistance is the value at which the natural frequencies of the power supply resonant circuit 1 and the power receiving resonant circuit 2 change from two to one when the load resistance is changed from a small value to a large value. The natural angular frequencies ωe of the power supply resonant circuit 1 and the power receiving resonant circuit 2 are expressed by the following equation (Equation 1).

[0057] (Math 1) ωe = ω0 ± (κ) 2 -γ 2 ) 1 / 2

[0058] κ is the coupling coefficient between the first power supply inductor La and the power receiving inductor L2. Given that their respective self-inductances are La and L2, and their mutual inductance is M, the coupling coefficient κ is expressed by the following equation (Equation 2).

[0059] (Math 2) κ = M / (La·L²) 1 / 2

[0060] γ is a value that represents the magnitude of the losses in the power supply resonant circuit 1a and the power receiving resonant circuit 2a. If the element constants of the power supply resonant circuit 1a and the power receiving resonant circuit 2a are different, γ can be expressed by a complex mathematical formula. However, if the inductances of the first power supply inductor La and the power receiving inductor L2 are equal to L, the capacitances of the first capacitor C1 and the second capacitor C2 are equal to C, and the resistances of the first resistor R1 and the second resistor R2 are 0, then, with the load resistance value R, γ can be approximated by the following (Equation 3).

[0061] (Math 3)γ=R·(C / L) 1 / 2

[0062] The critical value P is the load resistance value that satisfies κ=γ in (Equation 1).

[0063] When the load resistance is less than or equal to the critical value P, the coupling between the power supply resonant circuit 1 and the power receiving resonant circuit 2 is tight, and there are two natural angular frequencies ωe. When the load resistance exceeds the critical value P, the coupling between the power supply resonant circuit 1 and the power receiving resonant circuit 2 is loose, and there is one natural angular frequency ωe.

[0064] When the load resistance value exceeds the critical value P, no significant difference in load power and transmission efficiency is observed between the conventional technology and this embodiment. When the load resistance value is below the critical value P, this embodiment exhibits lower transmission efficiency compared to the conventional technology, but higher load power.

[0065] Figure 4 shows the results of simulations determining the characteristics of load voltage and load current with respect to load resistance. Load voltage is the voltage applied across load RL, and load current is the current flowing through load RL. The horizontal axis represents the load resistance. The left vertical axis represents the load voltage, and the right vertical axis represents the load current.

[0066] Characteristic 74-1 is the load voltage characteristic for the wireless power supply system 102 for motors according to this embodiment. Characteristic 74-2 is the load voltage characteristic for a conventional wireless power supply system for motors.

[0067] Characteristic 76-1 is the load current characteristic for the wireless power supply system 102 for motors according to this embodiment. Characteristic 76-2 is the load current characteristic for a simulation of a conventional wireless power supply system for motors.

[0068] When the load resistance value exceeds the critical value P, no significant difference in load voltage and load current is observed between the conventional technology and this embodiment. When the load resistance value is less than or equal to the critical value P, the load voltage and load current are greater in this embodiment compared to the conventional technology.

[0069] The motor wireless power supply system 100 or 102 according to this embodiment may be used in a vehicle wireless power supply system that supplies power to the motor of an electric vehicle such as a hybrid vehicle or an electric vehicle. In a vehicle power supply system, wireless power supply devices 10 are arranged at predetermined intervals along the road. Each wireless power supply device 10 may be placed on a guardrail, shoulder, under or on the road surface, on the ceiling or wall of a tunnel, etc. A wireless power receiving device 12 is mounted on the electric vehicle. Power may be supplied from the wireless power supply device 10 closest to the electric vehicle to the wireless power receiving device 12 mounted on the electric vehicle. As the electric vehicle moves, the wireless power supply devices 10 that supply power to the electric vehicle are sequentially replaced along the road. The wireless power receiving device 12 supplies power to the motor mounted on the electric vehicle, and the motor drives the electric vehicle with the supplied power.

[0070] Generally, electric vehicles traveling on roads experience fluctuations in motor speed and torque due to their varying speeds and acceleration. By using the wireless power supply system 100 or 102 for motors, the resonance state of the power supply resonant circuit 1 and the power receiving resonant circuit 2 is stably maintained, ensuring a stable power supply to the motor of the electric vehicle while it is in motion.

[0071] The motor wireless power supply system 100 or 102 according to this embodiment may also be used in a vehicle-to-vehicle power supply system. In a vehicle-to-vehicle power supply system, each of a plurality of electric vehicles is equipped with a wireless power supply device 10 and a wireless power receiving device 12, and power is exchanged between the electric vehicles. Each electric vehicle is equipped with a wireless control device, and the wireless control device of each electric vehicle shares the State of Charge (SOC) of the battery installed in each electric vehicle. For example, the wireless control device of each electric vehicle controls the wireless power supply device 10 and the wireless power receiving device 12 so that power is supplied from the electric vehicle with a larger SOC to the electric vehicle with a smaller SOC between electric vehicles that are in a positional relationship where wireless power supply is possible.

[0072] The vehicle-to-vehicle power supply system may be comprised of multiple electric vehicles operating in a platoon. Alternatively, the system may be comprised of multiple electric vehicles that have registered an ID (Identification) as members. In this case, the wireless control device of each electric vehicle communicates with other wireless control devices whose IDs have been authenticated, and performs control to exchange power between the electric vehicles. Furthermore, the vehicle-to-vehicle power supply system may be comprised of multiple automated guided vehicles (AGVs) used in factories, etc.

[0073] The wireless power supply system 100 or 102 for motors according to this embodiment may be used for in-wheel motors of electric vehicles. In-wheel motors are fixed to the wheels and drive the wheels. A wireless power supply device 10 is located on the body side of the electric vehicle, and a wireless power receiving device 12 is located on the wheel to supply power to the in-wheel motor.

[0074] Generally, in-wheel motors rotate with the wheels. Therefore, the electrical wiring between the power supply device installed in the electric vehicle and the in-wheel motor becomes complex. By using the motor wireless power supply system 100 or 102 for the in-wheel motor, the electrical wiring between the in-wheel motor and wireless power receiving device 12 located on the wheel side and the wireless power supply device 10 located on the body side becomes unnecessary. This simplifies the mechanical structure of the in-wheel motor. [Explanation of symbols]

[0075] 1a Power supply resonant circuit, 2,2a Power receiving resonant circuit, 3 Control unit, 10 Wireless power supply device, 12 Wireless power receiving device, 14 Rectifier circuit, 16 Feedback section, 18 Phase adjustment section, 20 Switching power supply, 22 Switching circuit, 50 Amplifier circuit, 50p Positive-phase input terminal, 50n Negative-phase input terminal, 51 Differential amplifier, 52 Comparator, 54 Switching driver, 56 Half-bridge, 58 DC voltage source, 100,102 Wireless power supply system for motor, L1 Power supply inductor, C1 First capacitor, R1 First resistor, L2 Power supply inductor, C2 Second capacitor, R2 Second resistor, Cs Smoothing capacitor, RL Load, La First power supply inductor, Lb Second power supply inductor, Lf Feedback inductor, Ra1 Negative-phase input resistor, Ra2 Feedback resistor, Ra3 Positive-phase input resistor, Ra4~Ra6 Shunt resistor, Cb phase shift capacitor, Rb1, Rb2 variable resistors, D1~D4 diodes, MT motor.

Claims

1. A power supply resonant circuit that is non-contactually coupled to a power receiving resonant circuit that supplies power to the motor, A switching power supply that supplies power to the aforementioned power supply resonant circuit by switching, A control unit coupled to the power supply resonant circuit switches the switching power supply at a timing corresponding to the time change of voltage or current in the power supply resonant circuit, The system comprises a feedback inductor coupled to the power supply resonant circuit, The control unit, A feedback unit that generates a feedback signal corresponding to the voltage or current in the feedback inductor, The system includes a phase adjustment unit that adjusts the phase of the feedback signal, The aforementioned switching power supply is A wireless power supply device for a motor, characterized by comprising a switching circuit that turns on or off the current or voltage in the power supply resonant circuit depending on whether the phase-adjusted feedback signal exceeds a reference value.

2. A wireless power supply device for a motor according to claim 1, The control unit, A comparator that outputs a phase control signal by outputting a high or low value depending on whether the value of the feedback signal exceeds a reference value, A wireless power supply device for a motor, comprising a switching driver that turns on and off a switching element in the switching circuit depending on whether the value of the phase control signal is high or low.

3. A wireless power supply device for a motor according to claim 1 or claim 2, A motor drive system characterized by comprising the power receiving resonant circuit, the motor, and a power conversion circuit that supplies power output from the power receiving resonant circuit to the motor.

4. A vehicle wireless power supply system comprising a plurality of wireless power supply devices for motors according to claim 1 or claim 2, A vehicle wireless power supply system characterized in that multiple wireless power supply devices for motors are arranged along the road.

5. A wireless power supply device for a motor according to claim 1 or claim 2, mounted on an electric vehicle, The vehicle includes an in-wheel motor and a wireless power receiving device provided on the wheel of the electric vehicle, which receives power supplied from the wireless power supply device for the motor, The aforementioned wireless power receiving device is A vehicle wireless power supply system characterized by supplying power to the in-wheel motor.

6. It is a vehicle-to-vehicle power supply system, A wireless power supply device for a motor according to claim 1 or claim 2 is mounted on each of a plurality of electric vehicles, Each of the electric vehicles is equipped with a wireless power receiving device that acquires power supplied from the wireless power supply device for the motor mounted on another electric vehicle. A vehicle-to-vehicle power supply system characterized by the exchange of power between multiple electric vehicles.

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