Non-contact power receiving device and non-contact power supply system

Abstract

In this non-contact power receiving device 20, a power acquiring circuit 22 has: a coil 30 that is coupled by a magnetic field to a power feeding line 10 having one end connected to an AC power supply; and a first electrode 32 that is coupled by an electronic field to the power feeding line 10. The power acquiring circuit 22 acquires, through the coil 30 and the first electrode 32, a first AC power transmitted by traveling waves propagating on the power feeding line 10 from one end toward the other end and a second AC power transmitted by reflected waves propagating on the power feeding line 10 from the other end toward the one end. A power synthesis circuit 24 synthesizes the first AC power and the second AC power which are acquired by the power acquiring circuit 22 and outputs the synthesized power.

Description

Cross - reference to related applications

[0001] This application is based on Japanese Patent Application No. 2021 - 19679 filed on February 10, 2021, claims the benefit of its priority, and all the contents of that patent application are incorporated herein by reference.

Technical Field

[0002] The present disclosure relates to a non - contact power receiving device and a non - contact power supply system.

Background Art

[0003] Conventionally, a non - contact power supply system has been proposed that transmits power to a vehicle without contact and runs the vehicle with the transmitted power. For example, Patent Document 1 discloses a non - contact power supply system during travel that arranges a plurality of coils along the travel route of a vehicle and switches the coil for power transmission according to the position of the vehicle.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The inventors recognized that by supplying power to a vehicle from a transmission line installed along a road, it becomes easier to install the transmission line over a wider area than the technology of arranging a plurality of coils, and the non-contact power supply system can be made less expensive. However, when there are reflected waves in the transmission line, a position where the current of the traveling wave and the current of the reflected wave weaken each other occurs, and when power is supplied using the magnetic field, the received power by the magnetic field decreases at that position. Also, a position where the voltage of the traveling wave and the voltage of the reflected wave weaken each other occurs in the transmission line, so when power is supplied using the electric field, the received power decreases at that position. If a terminating resistor is provided in the transmission line to suppress the reflected wave, power loss occurs due to the terminating resistor. Therefore, the inventors recognized that it is desirable to suppress the decrease in received power while eliminating the need to suppress the reflected wave.

[0006] One of the exemplary objects of the present disclosure is to provide a non-contact power receiving device and a non-contact power supply system that can eliminate the need to suppress reflected waves in a power supply line while suppressing a decrease in received power.

Means for Solving the Problem

[0007] To solve the above problems, a non-contact power receiving device according to an aspect of the present disclosure includes a coil that magnetically couples to a power supply line to which an AC power supply is connected at one end, and a first electrode that electrically couples to the power supply line. Through the coil and the first electrode, a power acquisition circuit that acquires first AC power due to a traveling wave propagating from one end to the other end of the power supply line and second AC power due to a reflected wave propagating from the other end to one end of the power supply line, and a power synthesis circuit that synthesizes the first AC power and the second AC power acquired by the power acquisition circuit and outputs the synthesized power.

[0008] Another aspect of the present disclosure is a contactless power supply system. This contactless power supply system includes a power supply line with an AC power source connected to one end, and a contactless power receiving device that receives power from the power supply line. The contactless power receiving device has a coil that magnetically couples to the power supply line and a first electrode that capacitively couples to the power supply line. Through the coil and the first electrode, a first AC power due to a traveling wave propagating from one end to the other end of the power supply line and a second AC power due to a reflected wave propagating from the other end to one end of the power supply line are obtained by a power acquisition circuit, and a power combining circuit that combines the first AC power and the second AC power obtained by the power acquisition circuit and outputs the combined power.

[0009] In addition, any combination of the above components, or those obtained by mutually replacing the components and expressions of the present disclosure between methods, systems, etc., are also effective as aspects of the present disclosure.

Advantages of the Invention

[0010] According to the present disclosure, it is possible to provide a contactless power receiving device and a contactless power supply system that can suppress a decrease in received power while eliminating the need to suppress reflected waves in the power supply line.

Brief Description of the Drawings

[0011]

Figure 1

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Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0012] (First Embodiment) FIG. 1 is a diagram for explaining a schematic configuration of a contactless power supply system 1 according to the first embodiment. FIG. 2 is a perspective view of the power supply line 10 in FIG. 1. FIG. 3 is an equivalent circuit diagram of the contactless power supply system 1 in FIG. 1.

[0013] The contactless power supply system 1 performs wireless power supply to a moving body 100 on a moving path such as a road. The contactless power supply system 1 can supply power whether the moving body 100 is stopped or moving. The moving body 100 is a vehicle such as an automobile. The contactless power supply system 1 includes a power supply line 10 and a contactless power receiving device 20.

[0014] An AC power supply 18 is connected to one end of the power supply line 10, and the other end of the power supply line 10 is open. The other end of the power supply line 10 may be short-circuited. The power supply line 10 includes a first conductor 12a and a second conductor 12b arranged in parallel along the road at a predetermined interval. AC power is supplied from the AC power supply 18 between one end of the first conductor 12a and one end of the second conductor 12b. The first conductor 12a and the second conductor 12b are each plate-shaped and elongated electrodes, and can also be called power transmission electrode plates. The first conductor 12a and the second conductor 12b may be mesh-shaped electrodes. Although not shown, the power supply line 10 is covered with asphalt or the like and embedded in the road. The road can also be called an electrified road.

[0015] The power supply line 10 functions as a transmission line for high-frequency power supplied from the AC power supply 18. Based on the characteristic impedance of the power supply line 10, a voltage V and a current I are generated in the power supply line 10, and an electric field E and a magnetic field H are generated. The power supply line 10 supplies power to the contactless power receiving device 20 by both the electric field E and the magnetic field H.

[0016] The frequency of the AC power supply 18 can be appropriately determined by experiments or simulations based on the characteristics of the power supply line 10 as a transmission line and the relationship between the wavelength and the size of the moving body 100. For example, it is 1 MHz to 100 MHz. The shorter the length of the power supply line 10, the higher the frequency is preferred.

[0017] The contactless power receiving device 20 is mounted on the moving body 100. The moving body 100 moves on the power supply line 10, and during the stop and movement of the moving body 100, the contactless power receiving device 20 receives power from the power supply line 10. The received power is used for driving the wheels of the moving body 100 and the like.

[0018] As described above, since the other end of the power supply line 10 is open, there is a reflected wave in addition to the traveling wave in the power supply line 10. The contactless power receiving device 20 receives power from both the traveling wave and the reflected wave by utilizing the principle of a directional coupler.

[0019] As shown in FIGS. 1 and 3, the contactless power receiving device 20 includes a power acquisition circuit 22, a power combining circuit 24, a smoothing circuit 26, and a load 28.

[0020] The power acquisition circuit 22 has a coil 30 that magnetically couples to the first conductor 12a and the second conductor 12b, a first electrode 32 that electrically couples to the first conductor 12a, and a second electrode 34 that electrically couples to the second conductor 12b.

[0021] The power acquisition circuit 22 acquires first AC power due to a traveling wave propagating from one end to the other end of the power supply line 10 via the coil 30, the first electrode 32, and the second electrode 34, and acquires second AC power due to a reflected wave propagating from the other end to one end of the power supply line. One end of the coil 30 outputs the first AC power to the power combining circuit 24, and the other end of the coil 30 outputs the second AC power to the power combining circuit 24.

[0022] The coil 30 is disposed on the bottom surface of the vehicle body 102 of the moving body 100 such that the coil surface is substantially parallel to the road. That is, the coil 30 is disposed such that the magnetic flux generated from the first conductor 12a and the second conductor 12b penetrates the coil 30. When the moving body 100 is stopped and during movement, the magnetic flux is maintained in a state of penetrating the coil 30. The coil 30 may include a magnetic core.

[0023] The first electrode 32 and the second electrode 34 are, for example, rectangular metal plates, and are disposed on the bottom surface of the vehicle body 102 of the moving body 100 so as to be substantially parallel to each other and such that each plate surface is substantially parallel to the road. When the moving body 100 is stopped and during movement, the first electrode 32 faces the first conductor 12a, and the second electrode 34 faces the second conductor 12b. The areas of the first electrode 32 and the second electrode 34 are, for example, equal. The first electrode 32 and the second electrode 34 may also be referred to as power receiving electrode plates.

[0024] The first electrode 32 is connected to the midpoint N1 of the coil 30. The midpoint N1 is a point where the inductance between the midpoint N1 and one end of the coil 30 is equal to the inductance between the midpoint N1 and the other end of the coil 30. In FIG. 3, the portion between the midpoint N1 and one end of the coil 30 is represented as the first inductor L1, and the portion between the midpoint N1 and the other end of the coil 30 is represented as the second inductor L2.

[0025] The second electrode 34 is electrically connected to the vehicle body 102 of the moving body 100. The vehicle body 102 is made of a conductor such as metal and functions as a common ground in the moving body 100. The common ground has a floating potential from the road, the first conductor 12a, and the second conductor 12b.

[0026] As shown in FIG. 3, the first inductor L1 of the coil 30 forms a transformer T1 together with the inductance component L10 of the first conductor 12a magnetically coupled. The second inductor L2 of the coil 30 forms a transformer T2 together with the inductance component L11 of the second conductor 12b magnetically coupled.

[0027] A first capacitor C1 is formed between the first electrode 32 capacitively coupled and the first conductor 12a. A second capacitor C2 is formed between the second electrode 34 capacitively coupled and the second conductor 12b. The capacitances of the first capacitor C1 and the second capacitor C2 are equal. By providing a second electrode 34 separate from the vehicle body 102, the capacitance of the second capacitor C2 can be easily designed. Note that the second electrode 34 may not be provided separately from the vehicle body 102. In this case, the vehicle body 102 functions as the second electrode 34, the vehicle body 102 is capacitively coupled to the second conductor 12b, and a second capacitor C2 is formed between the vehicle body 102 and the second conductor 12b.

[0028] The first capacitor C1, the transformer T1, and the transformer T2 constitute a CM type, more specifically a CCM type, directional coupler. Assuming a situation where the voltages of the traveling wave and the reflected wave are in phase and their currents are out of phase, due to the configuration of the directional coupler, the received power current I1 due to the traveling wave flows through the path of the first conductor 12a, the first capacitor C1, and the first inductor L1. The received power current I2 due to the reflected wave flows through the path of the first conductor 12a, the first capacitor C1, and the second inductor L2. Thereby, the first AC power due to the traveling wave can be output from one end of the coil 30, and the second AC power due to the reflected wave can be output from the other end of the coil 30.

[0029] The power combining circuit 24 is connected to both ends of the coil 30, combines the first AC power and the second AC power acquired by the power acquisition circuit 22, and outputs the combined power to the smoothing circuit 26.

[0030] The power combining circuit 24 is a double-current rectifying circuit and includes a first rectifying element D1, a second rectifying element D2, a third inductor L3, and a fourth inductor L4. The first rectifying element D1 and the second rectifying element D2 are diodes. The anode of the first rectifying element D1 is connected to the common ground, and the cathode is connected to one end of the coil 30. The anode of the second rectifying element D2 is connected to the common ground, and the cathode is connected to the other end of the coil 30. One end of the third inductor L3 is connected to one end of the coil 30. One end of the fourth inductor L4 is connected to the other end of the coil 30. The other ends of the third inductor L3 and the fourth inductor L4 are connected, and the combined power is output from these connection nodes.

[0031] Note that a DC-cut capacitor may be inserted between one end of the coil 30 and the connection node between the cathode of the first rectifying element D1 and one end of the third inductor L3, and a DC-cut capacitor may be inserted between the other end of the coil 30 and the connection node between the cathode of the second rectifying element D2 and one end of the fourth inductor L4.

[0032] The smoothing circuit 26 smooths the power output from the power combining circuit 24 and supplies the smoothed DC power to the load 28. The smoothing circuit 26 has a smoothing capacitor C6 including one end to which the power output from the power combining circuit 24 is supplied and the other end connected to the common ground.

[0033] The power combining circuit 24 and the smoothing circuit 26 output a voltage with reference to the voltage of the second electrode 34, which is the voltage of the common ground.

[0034] DC power is supplied to one end of the load 28, and the other end of the load 28 is connected to the common ground. The load 28 includes, for example, a motor that generates driving force for traveling, in-vehicle devices, a storage battery, and the like.

[0035] The received current I1 flowing through the first inductor L1 flows through the paths of the third inductor L3, the smoothing capacitor C6, the common ground, the second capacitor C2, and the second conductor 12b. The first capacitor C1, the first inductor L1, and the second capacitor C2 constitute a series resonance circuit for traveling-wave power reception.

[0036] The received power current I2 flowing through the second inductor L2 flows through the path of the fourth inductor L4, the smoothing capacitor C6, the common ground, the second capacitor C2, and the second conductor 12b. The first capacitor C1, the second inductor L2, and the second capacitor C2 constitute a series resonance circuit for receiving reflected waves.

[0037] The resonance frequencies of the series resonance circuit for traveling wave power reception and the series resonance circuit for reflected wave power reception are equal to the frequency of the AC power supply 18 and are included in a predetermined frequency band including the frequency of the AC power supply 18. By series resonance, the reactance can be reduced in each current path of the received power current I1 and the received power current I2, and the voltage drop due to the reactance can be suppressed. Therefore, wireless power supply can be performed with high transmission efficiency using both an electric field and a magnetic field.

[0038] Here, a non-contact power supply system of a comparative example for power transmission using both an electric field and a magnetic field recognized by the present inventors will be described. FIG. 4(a) is a circuit diagram of the non-contact power supply system of the comparative example, and FIG. 4(b) is an equivalent circuit diagram between the power transmission side circuit 110 and the power reception side circuit 112 of FIG. 4(a).

[0039] In the comparative example, a parallel circuit of a mutual capacitance C40 and a leakage inductance L40 shown in FIG. 4(b) equivalently exists between the power transmission side circuit 110 and the power reception side circuit 112. The mutual capacitance C40 is the sum of the capacitances of the capacitor C30 and the capacitor C32 due to electric field coupling and the parasitic capacitance between the inductor L30 and the inductor L32 that are magnetically coupled. The leakage inductance L40 is the leakage inductance between the inductor L30 and the inductor L32 that are magnetically coupled. When the parallel circuit of the mutual capacitance C40 and the leakage inductance L40 is in parallel resonance, the output voltage of the power transmission side circuit 110 decreases and is transmitted to the power reception side circuit 112. Therefore, the transmission efficiency and the transmission capacity decrease.

[0040] On the other hand, in the embodiment, as described above, since series resonance occurs in the path from the first conductor 12a on the power transmission side to the second conductor 12b on the power transmission side via the non-contact power receiving device 20, even if there is leakage inductance, a decrease in transmission efficiency can be suppressed.

[0041] According to the embodiment, since both the electric field and the magnetic field are used to receive the power of both the traveling wave and the reflected wave, while suppressing a decrease in the received power according to the position of the non-contact power receiving device 20 on the power supply line 10, it is possible to eliminate the need to suppress the reflected wave in the power supply line 10.

[0042] Since it is not necessary to suppress the reflected wave from the other end of the power supply line 10, the other end of the power supply line 10 does not need to be terminated with a termination resistor. Therefore, the power loss due to the termination resistor can be eliminated. For example, when the termination resistor is 50 Ω and the termination voltage is 300 V, the power loss of the termination resistor is 1.8 kW. Such a relatively large power loss can be eliminated.

[0043] Also, when impedance mismatch occurs due to other vehicles on the road or the like, a reflected wave is generated from there, but it is not necessary to suppress this reflected wave. Therefore, power supply can be performed with high transmission efficiency regardless of the position even in a situation where a plurality of vehicles exist on the road. When it is necessary to suppress the generation of the reflected wave from the vehicle, a technique of performing automatic impedance control such as a termination load according to the position of the vehicle can be considered, but since such control is not necessary, complication of the circuit and control, cost increase, and increase in power loss can be suppressed.

[0044] (Modification of the First Embodiment) Various modifications of the non-contact power supply system 1 are possible. Hereinafter, the description will focus on the differences from the first embodiment.

[0045] FIG. 5 is an equivalent circuit diagram of the non-contact power supply system 1 according to the first modification of the first embodiment. The non-contact power receiving device 20 further includes a resonance capacitor C4 connected between one end and the other end of the coil 30. The resonance capacitor C4 and the coil 30 form a parallel resonance circuit. The resonance frequency of the parallel resonance circuit is equal to the frequency of the AC power supply 18 and is included in a predetermined frequency band including the frequency of the AC power supply 18. By parallel resonance, the reactance that could not be eliminated by series resonance can be further reduced. Therefore, the transmission efficiency can be made higher.

[0046] FIG. 6 is an equivalent circuit diagram of the non-contact power supply system 1 according to the second modification of the first embodiment. The configuration of the power combining circuit 24 is different. The power combining circuit 24 has a first rectifying element D1, a second rectifying element D2, a third rectifying element D3, and a fourth rectifying element D4. The anode of the third rectifying element D3 is connected to one end of the coil 30. The anode of the fourth rectifying element D4 is connected to the other end of the coil 30. The cathodes of the third rectifying element D3 and the fourth rectifying element D4 are connected, and the combined power is output from these connection nodes. The first rectifying element D1 and the third rectifying element D3 form a voltage doubler rectifying circuit, and the second rectifying element D2 and the fourth rectifying element D4 also form a voltage doubler rectifying circuit. Depending on the circuit design, the power acquisition circuit 22 may function as a current source. In that case, by using the voltage doubler rectifying circuit, rectification and power combination can be performed more appropriately.

[0047] FIG. 7 is an equivalent circuit diagram of the non-contact power supply system 1 according to the third modification of the first embodiment. The power acquisition circuit 22 has an adjustment circuit 40 connected between the midpoint N1 of the coil 30 and the second electrode 34 which is a common ground. The adjustment circuit 40 adjusts at least one of the voltage and current at the midpoint N1. Thereby, the characteristics of the power acquisition circuit 22 can be adjusted. The adjustment circuit 40 has, for example, a resistor or an adjustment capacitor connected between the midpoint N1 and the common ground. A resistor and an adjustment capacitor may be connected in parallel between the midpoint N1 and the common ground.

[0048] When the adjustment circuit 40 has a resistor, the resistance value is set large so as to reduce the decrease in the AC voltage at the midpoint N1. Basically, it is difficult for a DC bias voltage to be generated at the midpoint N1, but if it is generated for some reason, the resistor can eliminate the DC bias voltage at the midpoint N1. Thereby, it is possible to prevent the DC bias voltage from adversely affecting the operation of the power combining circuit 24.

[0049] When the adjustment circuit 40 has an adjustment capacitor, the AC voltage at the midpoint N1 can be adjusted by dividing the voltage of the first conductor 12a by the first capacitor C1 and the adjustment capacitor of the adjustment circuit 40. Thereby, the accuracy of separation between the traveling wave and the reflected wave can be improved. The resonance frequency can also be adjusted.

[0050] FIG. 8 is an equivalent circuit diagram of the non-contact power feeding system 1 according to the fourth modification of the first embodiment. The non-contact power receiving device 20 further includes a detection unit 42 and an adjustment unit 44. The detection unit 42 detects the current flowing through the coil 30. The adjustment unit 44 adjusts the inductance of the coil 30 and the capacitance of the first capacitor C1 based on the current detected by the detection unit 42. The adjustment unit 44 may also adjust the capacitance of the second capacitor C2.

[0051] The coil 30 is configured to be able to change the number of turns, that is, the inductance, in accordance with the control of the adjustment unit 44. Well-known techniques can be used to change the number of turns. For example, it may be changed stepwise by switching the conduction and non-conduction of a switch element (not shown).

[0052] The first capacitor C1 is configured to be able to change the capacitance in accordance with the control of the adjustment unit 44. Well-known techniques can be used to change the capacitance. For example, by switching the conduction and non-conduction of a switch element (not shown), the area of the first electrode 32 can be changed, and the capacitance can be changed stepwise.

[0053] The non-contact power receiving device 20 can receive power using both an electric field and a magnetic field from a power supply line designed according to a well-known power receiving device that receives power using only an electric field, or from a power supply line designed according to a well-known power receiving device that receives power using only a magnetic field. For example, when receiving power from a power supply line for a power receiving device that uses only an electric field, in the non-contact power receiving device 20 designed according to the characteristic impedance of the power supply line 10 of the first embodiment, the current flowing through the coil 30 may be smaller than that in the first embodiment. Therefore, when the current detected by the detection unit 42 is equal to or less than the threshold value, the adjustment unit 44 increases the inductance of the coil 30 by a first predetermined amount. Thereby, the current flowing through the coil 30 can be increased. Further, when the current detected by the detection unit 42 is equal to or less than the threshold value, the adjustment unit 44 decreases the capacitance of the first capacitor C1 by a second predetermined amount. Thereby, the resonance frequency of the series resonance circuit that changes due to the adjustment of the inductance of the coil 30 can be made closer to the frequency of the AC power supply 18. Therefore, the received power can be increased according to the characteristics of the existing power supply line.

[0054] FIG. 9 is a diagram for explaining the schematic configuration of the non-contact power supply system 1 according to the fifth modification of the first embodiment. The two first electrodes 32 and the two second electrodes 34 are each a metal part inside the wheel 104. Even with this configuration, the first electrode 32 can be capacitively coupled to the first conductor 12a, and the second electrode 34 can be capacitively coupled to the second conductor 12b. In this case, the degree of freedom in the configuration of the non-contact power receiving device 20 can be improved.

[0055] FIG. 10 is a perspective view of the power supply line 10 according to the sixth modification of the first embodiment. The power supply line 10 is a transmission line including one first conductor 12a. One end of the AC power supply 18 is connected to one end of the first conductor 12a, and the other end of the AC power supply 18 is connected to an earth bar (not shown) to the ground. A ground path plate may be provided below the first conductor 12a, and the other end of the AC power supply 18 may be connected to the ground path plate. The ground or the ground path plate functions as a second conductor. The other end of the first conductor 12a is open. The other end of the first conductor 12a may be short-circuited to the ground or the ground path plate.

[0056] FIG. 10 also shows the positional relationship between the coil 30 and the first electrode 32 with respect to the power supply line 10. The coil 30 is arranged such that the coil plane is substantially perpendicular to the road and substantially parallel to the extending direction of the first conductor 12a. That is, the coil 30 is arranged such that the magnetic flux generated from the first conductor 12a penetrates the coil 30.

[0057] The first electrode 32 is arranged to face the first conductor 12a. The second electrode 34 may not be provided, or may be arranged to face the ground or the ground path plate (not shown). When the second electrode 34 is not provided, the vehicle body 102 that functions as the second electrode is capacitively coupled to the ground or the ground path plate that functions as the second conductor, and a second capacitor C2 is formed between the vehicle body 102 and the ground or the ground path plate. The operation of this non-contact power supply system 1 is the same as that of the first embodiment. In this modification, the degree of freedom in the configuration of the power supply line 10 can be improved. The installation of the power supply line 10 can also be performed more easily.

[0058] Note that the power supply line 10 may include three or more conductors. For example, in the case of three conductors, a central conductor may be arranged at the lane boundary of a two-lane road, and one conductor may be arranged in each lane. A vehicle traveling in one lane receives power from the conductor in that lane and the central conductor. The central conductor is shared by vehicles traveling in each lane.

[0059] (Second Embodiment) In the second embodiment, the configuration of the power acquisition circuit 22 is different from that of the first embodiment. Hereinafter, the description will focus on the differences from the first embodiment.

[0060] FIG. 11 is an equivalent circuit diagram of the non-contact power supply system 1 according to the second embodiment. The first electrode 32 has a third electrode 36 and a fourth electrode 38. The third electrode 36 is capacitively coupled to the first conductor 12a and connected to one end of the coil 30. The fourth electrode 38 is capacitively coupled to the first conductor 12a and connected to the other end of the coil 30.

[0061] The third electrode 36 and the fourth electrode 38 are, for example, rectangular metal plates, and are arranged on the bottom surface of the vehicle body 102 of the moving body 100 such that each plate surface is substantially parallel to the road. When the moving body 100 is stopped and during movement, the third electrode 36 and the fourth electrode 38 are maintained in a state facing the first conductor 12a. The areas of the third electrode 36 and the fourth electrode 38 are, for example, equal.

[0062] A first capacitor C1 is formed between the third electrode 36 and the first conductor 12a which are electrostatically coupled. A third capacitor C3 is formed between the fourth electrode 38 and the first conductor 12a which are electrostatically coupled. The capacitances of the first capacitor C1 and the third capacitor C3 are equal.

[0063] The first capacitor C1, the third capacitor C3, the transformer T1 and the transformer T2 constitute a CMC type directional coupler. Assuming a situation where the voltages of the traveling wave and the reflected wave are in phase and their currents are out of phase, according to the configuration of the directional coupler, the received current I1 due to the traveling wave is the sum of the current flowing through the path of the first conductor 12a, the third capacitor C3, the second inductor L2, and the first inductor L1, and the current flowing through the path of the first conductor 12a and the first capacitor C1. The received current I2 due to the reflected wave is the sum of the current flowing through the path of the first conductor 12a and the third capacitor C3, and the current flowing through the path of the first conductor 12a, the first capacitor C1, the first inductor L1, and the second inductor L2. Thereby, the first AC power due to the traveling wave can be output from one end of the coil 30, and the second AC power due to the reflected wave can be output from the other end of the coil 30. With the CMC type directional coupler, the traveling wave and the reflected wave can be more clearly separated.

[0064] The received current I1 flows through the paths of the power combining circuit 24, the smoothing capacitor C6, the common ground, the second capacitor C2, and the second conductor 12b.

[0065] The received current I2 flows through the paths of the power combining circuit 24, the smoothing capacitor C6, the common ground, the second capacitor C2, and the second conductor 12b.

[0066] The inductance of the coil 30 and the capacitances of the first capacitor C1, the third capacitor C3, and the second capacitor C2 may be set so that reactance is reduced by resonance in the current path from the first conductor 12a to the second conductor 12b. Thereby, voltage drop due to reactance can be suppressed. Therefore, wireless power feeding can be performed with high transmission efficiency using both an electric field and a magnetic field.

[0067] As described above, the present disclosure has been described based on the embodiments. It is understood by those skilled in the art that the present disclosure is not limited to the above-described embodiments, various design changes are possible, various modifications are possible, and such modifications are also within the scope of the present disclosure.

[0068] For example, any two or more of the first to sixth modifications of the first embodiment may be combined. The new embodiment produced by the combination has the effects of the respective embodiments to be combined. When combining the first modification and the fourth modification, when the adjustment unit 44 changes the inductance of the coil 30, the capacitance of the resonance capacitor C4 may also be adjusted so that the parallel resonance frequency approaches the frequency of the AC power supply 18.

[0069] Each of the first, second, fourth to sixth modifications of the first embodiment may be combined with the second embodiment. Any two or more of the first, second, fourth to sixth modifications may be combined with the second embodiment. The new embodiment produced by the combination has the effects of the respective embodiments to be combined. When combining the fourth modification with the second embodiment, the adjustment unit 44 may adjust the inductance of the coil 30, the capacitance of the first capacitor C1, and the capacitance of the third capacitor C3 based on the current detected by the detection unit 42.

[0070] The non-contact power supply system 1 can be applied not only to automobiles but also to, for example, railways, electric aircraft, amusement facilities such as jet coasters in amusement parks, cleaning robots, delivery robots, guiding robots, self-propelled conveyance equipment within a factory site, and toys such as model cars. When applied to an electric aircraft, power can be supplied during ground travel.

[0071] In the embodiment, an example in which the power supply line 10 is arranged on a road and the non-contact power receiving device 20 is mounted on the moving body 100 has been described, but it is not limited thereto. The power supply line 10 may be arranged on a charging stand, and the non-contact power receiving device 20 may be mounted on a portable device such as a smartphone. In this case, the portable device can be charged by placing it at an arbitrary position on the power supply line 10 of the charging stand.

[0072] The outline of one aspect of the present disclosure is as follows. A non-contact power receiving device according to an aspect of the present disclosure includes a coil that magnetically couples to a power supply line to which an AC power supply is connected at one end, and a first electrode that capacitively couples to the power supply line. Through the coil and the first electrode, a power acquisition circuit that acquires first AC power by a traveling wave propagating from one end to the other end of the power supply line and second AC power by a reflected wave propagating from the other end to one end of the power supply line, and a power combining circuit that combines the first AC power and the second AC power acquired by the power acquisition circuit and outputs the combined power. According to this aspect, it is possible to suppress a decrease in received power and eliminate the need to suppress reflected waves in the power supply line.

[0073] The power supply line includes a first conductor and a second conductor arranged in parallel. The first electrode capacitively couples to the first conductor and is connected to the midpoint of the coil. One end of the coil outputs the first AC power, and the other end of the coil outputs the second AC power. The power acquisition circuit may further include a second electrode that capacitively couples to the second conductor. The power combining circuit may output a voltage based on the voltage of the second electrode. In this case, a CM-type directional coupler can be configured.

[0074] A first capacitor formed between the first electrode and the first conductor, a portion between the midpoint of the coil and one end or the other end, and a second capacitor formed between the second electrode and the second conductor may form a series resonance circuit. In this case, due to series resonance, the reactance of the current path from the first conductor to the second conductor via the coil can be reduced.

[0075] The non-contact power receiving device may further include a detection unit that detects the current flowing through the coil, and an adjustment unit that adjusts the inductance of the coil and the capacitance of the first capacitor based on the current detected by the detection unit. In this case, the received power can be increased according to the characteristics of the power supply line.

[0076] The power acquisition circuit may further include an adjustment circuit that adjusts at least one of the voltage and current at the midpoint of the coil. In this case, the characteristics of the power acquisition circuit can be adjusted.

[0077] The power supply line includes a first conductor and a second conductor arranged in parallel. One end of the coil outputs the first AC power, and the other end of the coil outputs the second AC power. The power acquisition circuit further includes a second electrode that is capacitively coupled to the second conductor, and the power combining circuit may output a voltage based on the voltage of the second electrode. The first electrode may include a third electrode that is capacitively coupled to the first conductor and connected to one end of the coil, and a fourth electrode that is capacitively coupled to the first conductor and connected to the other end of the coil. In this case, a CMC type directional coupler can be formed, and the traveling wave and the reflected wave can be more clearly separated.

[0078] The non-contact power receiving device may further include a detection unit that detects the current flowing through the coil, and an adjustment unit that adjusts the inductance of the coil, the capacitance of the first capacitor formed between the third electrode and the first conductor, and the capacitance of the third capacitor formed between the fourth electrode and the first conductor based on the current detected by the detection unit. In this case, the received power can be increased according to the characteristics of the power supply line.

[0079] The non-contact power receiving device may further include a resonance capacitor connected between one end and the other end of the coil. In this case, the reactance can be further reduced by parallel resonance of the coil and the resonance capacitor.

[0080] A non-contact power supply system according to an aspect of the present disclosure includes a power supply line having an AC power source connected to one end, and a non-contact power receiving device that receives power from the power supply line. The non-contact power receiving device has a coil that magnetically couples to the power supply line and a first electrode that capacitively couples to the power supply line, and obtains first AC power by a traveling wave propagating from one end to the other end of the power supply line via the first coil and the first electrode, and a power acquisition circuit that obtains second AC power by a reflected wave propagating from the other end to one end of the power supply line, and a power combining circuit that combines the first AC power and the second AC power obtained by the power acquisition circuit and outputs the combined power. According to this aspect, it is possible to suppress a decrease in received power and eliminate the need to suppress reflected waves in the power supply line.

[0081] The other end of the power supply line may be open or short-circuited. In this case, power loss can be reduced compared to the case where a termination resistor for impedance matching is connected to the power supply line.

Industrial Applicability

[0082] The present disclosure can be used in non-contact power receiving devices and non-contact power supply systems.

Explanation of Reference Numerals

[0083] 1... Non-contact power supply system, 10... Power supply line, 12a... First conductor, 12b... Second conductor, 18... AC power source, 20... Non-contact power receiving device, 22... Power acquisition circuit, 24... Power combining circuit, 30... Coil, 32... First electrode, 34... Second electrode, 36... Third electrode, 38... Fourth electrode, 42... Detection unit, 44... Adjustment unit, C1... First capacitor, C2... Second capacitor, C3... Third capacitor, C4... Resonance capacitor, N1... Midpoint.

Claims

1. A non-contact power receiving device comprising: a coil that magnetically couples to a power supply line to which an AC power supply is connected at one end; and a first electrode that capacitively couples to the power supply line, wherein a power acquisition circuit acquires first AC power due to a traveling wave propagating from one end to the other end of the power supply line and second AC power due to a reflected wave propagating from the other end to one end of the power supply line via the coil and the first electrode; a power combining circuit that combines the first AC power and the second AC power acquired by the power acquisition circuit and outputs the combined power. The non-contact power receiving device is characterized by comprising the above components.

2. The power supply line includes a first conductor and a second conductor arranged in parallel. The first electrode capacitively couples to the first conductor and is connected to the midpoint of the coil. One end of the coil outputs the first AC power. The other end of the coil outputs the second AC power. The power acquisition circuit further includes a second electrode that capacitively couples to the second conductor. The power combining circuit outputs a voltage based on the voltage of the second electrode. The non-contact power receiving device according to claim 1, characterized by the above features.

3. A first capacitor formed between the first electrode and the first conductor, a portion between the midpoint of the coil and one end or the other end, and a second capacitor formed between the second electrode and the second conductor constitute a series resonance circuit. The non-contact power receiving device according to claim 2, characterized by the above features.

4. a detection unit that detects the current flowing through the coil; an adjustment unit that adjusts the inductance of the coil and the capacitance of the first capacitor based on the current detected by the detection unit. The non-contact power receiving device according to claim 3, further comprising the above components.

5. The power acquisition circuit further includes an adjustment circuit that adjusts at least one of the voltage and current at the midpoint of the coil. The non-contact power receiving device according to any one of claims 2 to 4, characterized by the above features.

6. The power supply line includes a first conductor and a second conductor arranged in parallel. One end of the coil outputs the first AC power. The other end of the coil outputs the second AC power. The power acquisition circuit further includes a second electrode that capacitively couples to the second conductor. The power combining circuit outputs a voltage based on the voltage of the second electrode. The first electrode includes a third electrode that capacitively couples to the first conductor and is connected to one end of the coil; and a fourth electrode that capacitively couples to the first conductor and is connected to the other end of the coil. The non-contact power receiving device according to claim 1, characterized by having

7. a detection unit that detects the current flowing through the coil; an adjustment unit that adjusts the inductance of the coil, the capacitance of a first capacitor formed between the third electrode and the first conductor, and the capacitance of a third capacitor formed between the fourth electrode and the first conductor based on the current detected by the detection unit; The non-contact power receiving device according to claim 6, further comprising

8. further comprising a resonance capacitor connected between one end and the other end of the coil; The non-contact power receiving device according to any one of claims 2 to 7, characterized by

9. a power supply line with an AC power supply connected to one end; a non-contact power receiving device that receives power from the power supply line; comprising the non-contact power receiving device has a coil that magnetically couples to the power supply line and a first electrode that capacitively couples to the power supply line, and through the coil and the first electrode, a first AC power due to a traveling wave propagating from one end to the other end of the power supply line and a second AC power due to a reflected wave propagating from the other end to one end of the power supply line are obtained by a power acquisition circuit; a power synthesis circuit that synthesizes the first AC power and the second AC power obtained by the power acquisition circuit and outputs the synthesized power; A non-contact power supply system, characterized by comprising

10. the other end of the power supply line is open or short-circuited; The non-contact power supply system according to claim 9, characterized by

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