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

Abstract

To provide a technology that suppresses the reduction in received power while eliminating the need to suppress reflected waves in the power supply line.SOLUTION: In a non-contact power receiving device 20, a power acquisition circuit 22 acquires a first AC power from a traveling wave propagating along a power supply line 10 connected with an AC power supply at one end from one end toward the other end, and a second AC power from a reflected wave propagating along the power supply line 10 from the other end toward the one end.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application is based on and claims the benefit of priority from Japanese Patent Application No. 2021-19679, filed on February 10, 2021, the entire contents of which are incorporated herein by reference.

[0002] (Technical field) The present disclosure relates to a contactless power receiving device, a contactless power supply system, and a power supply line. [Background technology]

[0003] Conventionally, contactless power transfer systems have been proposed that transfer power to a vehicle in a contactless manner and run the vehicle using the transferred power. For example, Patent Document 1 discloses a contactless power transfer system for when the vehicle is moving, in which multiple coils are arranged along the vehicle's travel path and the coil that transfers power is switched depending on the vehicle's position. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-48369 Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors recognized that supplying power to vehicles from transmission lines installed along roads makes it easier to install transmission lines over a wider area than with technologies that use multiple coils, thereby reducing the cost of contactless power transfer systems. However, when reflected waves are present on the transmission line, positions are created where the current of the traveling wave and the current of the reflected wave weaken each other, and when power is supplied using a magnetic field, the received power due to the magnetic field decreases at those positions. Furthermore, positions are also created on the transmission line where the voltage of the traveling wave and the voltage of the reflected wave weaken each other, and when power is supplied using an electric field, the received power decreases at those positions. Installing a termination resistor on the transmission line to suppress reflected waves results in power loss due to the termination resistor. Therefore, the inventors recognized that it is desirable to suppress the decrease in received power while eliminating the need to suppress reflected waves.

[0006] An exemplary object of the present disclosure is to provide a technology that can eliminate the need to suppress reflected waves on a power supply line while suppressing a decrease in received power. [Means for solving the problem]

[0007] In order to solve the above problem, a contactless power receiving device according to one embodiment of the present disclosure includes a power acquisition circuit that acquires a first AC power generated by a traveling wave propagating from one end to the other end of a power supply line connected to one end of the power supply line, and a second AC power generated by a reflected wave propagating from the other end to the one end of the power supply line.

[0008] Another aspect of the present disclosure is a contactless power supply system. The contactless power supply system includes a power supply line having an AC power source connected to one end thereof, and a contactless power receiving device that receives power from the power supply line. The contactless power receiving device includes a power acquisition circuit that acquires first AC power generated by a traveling wave propagating from one end of the power supply line to the other end thereof, and second AC power generated by a reflected wave propagating from the other end of the power supply line to the one end thereof. Yet another aspect of the present disclosure is a power supply line in a contactless power supply system including a power supply line connected to one end thereof with an AC power source, and a contactless power receiving device including a power acquisition circuit that acquires first AC power generated by a traveling wave propagating along the power supply line from one end to the other end thereof and second AC power generated by a reflected wave propagating along the power supply line from the other end to the one end thereof, the power supply line including a conductor connected to the AC power source at one end thereof and open or short-circuited at the other end thereof.

[0009] Any combination of the above components, or mutual substitution of the components or expressions of the present disclosure between methods, systems, etc., are also valid aspects of the present disclosure. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a technology that can suppress a decrease in received power while eliminating the need to suppress reflected waves on a power feed line. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating a schematic configuration of a contactless power supply system according to a first embodiment. [Figure 2] FIG. 2 is a perspective view of the power supply line of FIG. 1. [Figure 3] FIG. 2 is an equivalent circuit diagram of the contactless power supply system of FIG. [Figure 4] FIG. 4(a) is a circuit diagram of a contactless power supply system of a comparative example, and FIG. 4(b) is an equivalent circuit diagram between the power transmitting side circuit and the power receiving side circuit of FIG. 4(a). [Figure 5] FIG. 10 is an equivalent circuit diagram of a contactless power supply system according to a first modified example of the first embodiment. [Figure 6] FIG. 10 is an equivalent circuit diagram of a contactless power supply system according to a second modified example of the first embodiment. [Figure 7] FIG. 10 is an equivalent circuit diagram of a contactless power supply system according to a third modified example of the first embodiment. [Figure 8] FIG. 10 is an equivalent circuit diagram of a contactless power supply system according to a fourth modified example of the first embodiment. [Figure 9]FIG. 10 is a diagram illustrating a schematic configuration of a contactless power supply system according to a fifth modified example of the first embodiment. [Figure 10] FIG. 13 is a perspective view of a feeder line according to a sixth modified example of the first embodiment. [Figure 11] FIG. 10 is an equivalent circuit diagram of a contactless power supply system according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] (First embodiment) Fig. 1 is a diagram illustrating a schematic configuration of a contactless power supply system 1 according to a first embodiment. Fig. 2 is a perspective view of a 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 wirelessly supplies power to a moving object 100 on a path such as a road. The contactless power supply system 1 can supply power whether the moving object 100 is stationary or moving. The moving object 100 is, for example, 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 source 18 is connected to one end of the power feeder line 10, and the other end of the power feeder line 10 is open. The other end of the power feeder line 10 may be short-circuited. The power feeder line 10 includes a first conductor 12a and a second conductor 12b arranged in parallel along a road at a predetermined interval. AC power is supplied from the AC power source 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 elongated, plate-shaped electrodes and may also be called transmission electrode plates. The first conductor 12a and the second conductor 12b may also be mesh-shaped electrodes. Although not shown, the power feeder line 10 is covered with asphalt or the like and embedded in the road. The road may also be called an electrified road.

[0015] The power supply line 10 functions as a transmission line for high-frequency power supplied from an AC power source 18. A voltage V and a current I are generated in the power supply line 10 based on the characteristic impedance of 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 AC power supply 18 can be appropriately determined by experiments or simulations based on the characteristics of power supply line 10 as a transmission line and the relationship between wavelength and the size of mobile object 100, and is, for example, 1 MHz to 100 MHz. The shorter the length of power supply line 10, the higher the frequency is preferable.

[0017] The contactless power receiving device 20 is mounted on a moving object 100. The moving object 100 moves on a power supply line 10, and the contactless power receiving device 20 receives power from the power supply line 10 while the moving object 100 is stopped and while the moving object 100 is moving. The received power is used to drive the wheels of the moving object 100, for example.

[0018] As described above, the other end of the power supply line 10 is open, and therefore a reflected wave exists in addition to a traveling wave on 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 .

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

[0021] The power acquisition circuit 22 acquires first AC power from a traveling wave propagating from one end of the power supply line 10 to the other end, and acquires second AC power from a reflected wave propagating from the other end of the power supply line to the one end, via the coil 30, the first electrode 32, and the second electrode 34. 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 body 102 of the moving body 100 so that the coil surface is approximately parallel to the road. In other words, the coil 30 is disposed so that the magnetic flux generated from the first conductor 12a and the second conductor 12b passes through the coil 30. When the moving body 100 is stopped and moving, the state in which the magnetic flux passes through the coil 30 is maintained. 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 arranged on the bottom surface of the body 102 of the mobile object 100 so that they are approximately parallel to each other and so that each plate surface is approximately parallel to the road. When the mobile object 100 is stopped or moving, the first electrode 32 is maintained facing the first conductor 12a, and the second electrode 34 is maintained facing 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 can also be called receiving electrode plates.

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

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

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

[0027] A first capacitor C1 is formed between the first electrode 32 and the first conductor 12a, which are electric field coupled. A second capacitor C2 is formed between the second electrode 34 and the second conductor 12b, which are electric field coupled. The capacitances of the first capacitor C1 and the second capacitor C2 are equal. By providing the 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 does not need to 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 electric field coupled to the second conductor 12b, and the second capacitor C2 is formed between the vehicle body 102 and the second conductor 12b.

[0028] The first capacitor C1, transformer T1, and transformer T2 constitute a CM-type, or more specifically, CCM-type, directional coupler. Assuming that the voltages of the traveling wave and the reflected wave are in phase and their currents are in opposite phases, the directional coupler configuration causes a receiving current I1 due to the traveling wave to flow through the first conductor 12a, first capacitor C1, and first inductor L1. A receiving current I2 due to the reflected wave to flow through the first conductor 12a, first capacitor C1, and second inductor L2. This allows a first AC power due to the traveling wave to be output from one end of the coil 30, and a second AC power due to the reflected wave to 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 .

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

[0031] In addition, a DC blocking capacitor may be inserted between one end of the coil 30 and the connection node between the cathode of the first rectifier element D1 and one end of the third inductor L3, and a DC blocking capacitor may be inserted between the other end of the coil 30 and the connection node between the cathode of the second rectifier element D2 and one end of the fourth inductor L4.

[0032] The smoothing circuit 26 smoothes 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 that has one end to which the power output from the power combining circuit 24 is supplied and the other end connected to a common ground.

[0033] The power combining circuit 24 and the smoothing circuit 26 output a voltage based on 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 a common ground. The load 28 includes, for example, a motor that generates driving force for traveling, in-vehicle equipment, a storage battery, and the like.

[0035] The receiving current I1 flowing through the first inductor L1 flows through 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 form a series resonant circuit for traveling wave power reception.

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

[0037] The resonant frequencies of the series resonant circuit for traveling wave power reception and the series resonant 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 that includes the frequency of the AC power supply 18. Series resonance reduces the reactance in each current path of the receiving current I1 and the receiving current I2, thereby suppressing voltage drops due to the reactance. Therefore, wireless power transmission can be achieved with high transmission efficiency using both an electric field and a magnetic field.

[0038] Here, we will explain a contactless power transfer system of a comparative example that transmits power using both an electric field and a magnetic field, as recognized by the present inventors. Figure 4(a) is a circuit diagram of the contactless power transfer system of the comparative example, and Figure 4(b) is an equivalent circuit diagram between the power transmitting side circuit 110 and the power receiving side circuit 112 of Figure 4(a).

[0039] In the comparative example, a parallel circuit of mutual capacitance C40 and leakage inductance L40 shown in FIG. 4(b) exists equivalently between the power transmitting side circuit 110 and the power receiving side circuit 112. The mutual capacitance C40 is the sum of the capacitance of capacitor C30 and capacitor C32 due to electric field coupling and the parasitic capacitance between inductor L30 and inductor L32, which are magnetically coupled. The leakage inductance L40 is the leakage inductance between inductor L30 and inductor L32, which are magnetically coupled. Parallel resonance of the parallel circuit of mutual capacitance C40 and leakage inductance L40 reduces the output voltage of the power transmitting side circuit 110 and transmits it to the power receiving side circuit 112. This reduces the transmission efficiency and transmission capacity.

[0040] In contrast to this, in the embodiment, as already described, series resonance occurs in the path from the first conductor 12a on the power transmitting side to the second conductor 12b on the power transmitting side via the non-contact power receiving device 20, so that even if leakage inductance exists, a decrease in transmission efficiency can be suppressed.

[0041] According to the embodiment, both the electric field and the magnetic field are used to receive power from both the traveling wave and the reflected wave, so that it is possible to suppress the reduction in the received power depending on the position of the non-contact power receiving device 20 on the power supply line 10, while eliminating the need to suppress the reflected wave on the power supply line 10.

[0042] Since there is no need to suppress reflected waves from the other end of the power feed line 10, there is no need to terminate the other end of the power feed line 10 with a termination resistor. This eliminates power loss due to the termination resistor. For example, if the termination resistor is 50 Ω and the termination voltage is 300 V, the power loss of the termination resistor is 1.8 kW. This relatively large power loss can be eliminated.

[0043] Furthermore, if an impedance mismatch occurs due to other vehicles on the road, a reflected wave will be generated, but there is no need to suppress this reflected wave. Therefore, even when there are multiple vehicles on the road, power can be supplied with high transmission efficiency regardless of their position. If it is necessary to suppress the generation of reflected waves from vehicles, technology that performs automatic impedance control such as terminating loads according to the vehicle's position can be considered, but because such control is not necessary, it is possible to suppress the complexity of the circuit and control, increase costs, and increase power loss.

[0044] (Modification of the first embodiment) There are many possible modifications of the contactless power supply system 1. The following description will focus on the differences from the first embodiment.

[0045] 5 is an equivalent circuit diagram of the contactless power supply system 1 according to a first modification of the first embodiment. The contactless power receiving device 20 further includes a resonant capacitor C4 connected between one end and the other end of the coil 30. The resonant capacitor C4 and the coil 30 form a parallel resonant circuit. The resonant frequency of the parallel resonant circuit is equal to the frequency of the AC power supply 18 and is included in a predetermined frequency band that includes the frequency of the AC power supply 18. The parallel resonance can further reduce the reactance that could not be eliminated by the series resonance. This can further increase the transmission efficiency.

[0046] FIG. 6 is an equivalent circuit diagram of a wireless power transfer system 1 according to a second modification of the first embodiment. The power combining circuit 24 has a different configuration. The power combining circuit 24 includes 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 cathode of the third rectifying element D3 and the cathode of the fourth rectifying element D4 are connected, and combined power is output from the connection node. The first rectifying element D1 and the third rectifying element D3 form a voltage doubler rectifier circuit, and the second rectifying element D2 and the fourth rectifying element D4 also form a voltage doubler rectifier circuit. Depending on the circuit design, the power acquisition circuit 22 may function as a current source. In this case, using a voltage doubler rectifier circuit allows for more appropriate rectification and power combining.

[0047] FIG. 7 is an equivalent circuit diagram of a contactless power supply system 1 according to a third modification of the first embodiment. The power acquisition circuit 22 includes an adjustment circuit 40 connected between a midpoint N1 of the coil 30 and the second electrode 34, which is the common ground. The adjustment circuit 40 adjusts at least one of the voltage and current at the midpoint N1, thereby adjusting the characteristics of the power acquisition circuit 22. The adjustment circuit 40 includes, 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] If the adjustment circuit 40 has a resistor, the resistance value is set large to reduce the drop in AC voltage at the midpoint N1. While a DC bias voltage is generally unlikely to occur at the midpoint N1, if one does occur for some reason, the resistor can eliminate the DC bias voltage at the midpoint N1. This prevents 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 using the first capacitor C1 and the adjustment capacitor of the adjustment circuit 40. This improves the accuracy of separating the forward wave and the reflected wave. The resonant frequency can also be adjusted.

[0050] 8 is an equivalent circuit diagram of a contactless power supply system 1 according to a fourth modification of the first embodiment. The contactless 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 so that the number of turns, i.e., the inductance, can be changed under the control of the adjustment unit 44. Well-known techniques can be used to change the number of turns, and for example, the number of turns may be changed in stages by switching a switching element (not shown) between conductive and non-conductive states.

[0052] The first capacitor C1 is configured so that its capacitance can be changed under the control of the adjustment unit 44. Well-known techniques can be used to change the capacitance; for example, the capacitance may be changed in stages by switching a switching element (not shown) between conductive and non-conductive states to change the area of ​​the first electrode 32.

[0053] The contactless power receiving device 20 can also receive power using both an electric field and a magnetic field from a power supply line designed for a known power receiving device that receives power using only an electric field, or from a power supply line designed for a 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, the current flowing through the coil 30 in the contactless power receiving device 20 designed to match the characteristic impedance of the power supply line 10 of the first embodiment may be smaller than that of the first embodiment. Therefore, when the current detected by the detection unit 42 is equal to or less than a threshold value, the adjustment unit 44 increases the inductance of the coil 30 by a first predetermined amount. This increases the current flowing through the coil 30. Furthermore, when the current detected by the detection unit 42 is equal to or less than a threshold value, the adjustment unit 44 decreases the capacitance of the first capacitor C1 by a second predetermined amount. This allows the resonant frequency of the series resonant circuit, which changes depending on the inductance of the coil 30, to approach the frequency of the AC power source 18. Therefore, the received power can be increased in accordance with the characteristics of the existing power supply line.

[0054] 9 is a diagram illustrating a schematic configuration of a contactless power supply system 1 according to a fifth modified example of the first embodiment. The two first electrodes 32 and the two second electrodes 34 are metal parts inside the wheel 104. Even in this configuration, the first electrodes 32 can be electric field coupled to the first conductor 12a, and the second electrodes 34 can be electric field coupled to the second conductor 12b. In this case, the degree of freedom in the configuration of the contactless power receiving device 20 can be improved.

[0055] FIG. 10 is a perspective view of a feeder line 10 according to a sixth modified example of the first embodiment. The feeder line 10 is a transmission line including one first conductor 12a. One end of an 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 a ground rod (not shown) connected 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 the second conductor. The other end of the first conductor 12a is open. The other end of the first conductor 12a may be shorted to the ground or the ground path plate.

[0056] 10 also shows the positional relationship of the coil 30 and the first electrode 32 with respect to the power supply line 10. The coil 30 is positioned so that the coil plane is approximately perpendicular to the road and approximately parallel to the direction in which the first conductor 12a extends. In other words, the coil 30 is positioned so that the magnetic flux generated from the first conductor 12a passes through the coil 30.

[0057] The first electrode 32 is arranged to face the first conductor 12a. The second electrode 34 does not have to be provided, or may be arranged to face the ground or a ground path plate (not shown). When the second electrode 34 is not provided, the car body 102 functioning as the second electrode is electrically coupled to the ground or ground path plate functioning as the second conductor, and a second capacitor C2 is formed between the car body 102 and the ground or ground path plate. The operation of this contactless power transfer system 1 is similar to that of the first embodiment. This modification can improve the degree of freedom in the configuration of the power feed line 10. It can also make installation of the power feed line 10 easier.

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

[0059] (Second embodiment) The second embodiment differs from the first embodiment in the configuration of the power acquisition circuit 22. The following description will focus on the differences from the first embodiment.

[0060] 11 is an equivalent circuit diagram of the contactless 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 electric field coupled to the first conductor 12a and connected to one end of the coil 30. The fourth electrode 38 is electric field 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 body 102 of the mobile object 100 so that each plate surface is approximately parallel to the road. When the mobile object 100 is stopped or moving, 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 electric field coupled third electrode 36 and the first conductor 12a. A third capacitor C3 is formed between the electric field coupled fourth electrode 38 and the first conductor 12a. 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 directional coupler. Assuming that the voltages of the traveling wave and the reflected wave are in phase and their currents are out of phase, the directional coupler configuration allows the received current I1 due to the traveling wave to be the sum of the current flowing through the path from the first conductor 12a, the third capacitor C3, the second inductor L2, and the first inductor L1 and the current flowing through the path from 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 from the first conductor 12a and the third capacitor C3 and the current flowing through the path from the first conductor 12a, the first capacitor C1, the first inductor L1, and the second inductor L2. This allows a first AC power due to the traveling wave to be output from one end of the coil 30, and a second AC power due to the reflected wave to be output from the other end of the coil 30. The CMC directional coupler allows for clearer separation of the traveling wave and the reflected wave.

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

[0065] The receiving current I2 flows through 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 the reactance in the current path from the first conductor 12a to the second conductor 12b is reduced by resonance. This makes it possible to suppress voltage drops due to reactance. Therefore, wireless power supply can be achieved with high transmission efficiency using both the electric field and the magnetic field.

[0067] The present disclosure has been described above based on the embodiments. It will be understood by those skilled in the art that the present disclosure is not limited to the above embodiments, that various design changes are possible, and that various modifications are possible, and that 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. A new embodiment resulting from the combination will have the combined effects of the respective combined embodiments. When the first and fourth modifications are combined, the adjustment unit 44 may also adjust the capacitance of the resonance capacitor C4 when changing the inductance of the coil 30 so that the parallel resonance frequency approaches the frequency of the AC power supply 18.

[0069] Each of the first, second, and fourth to sixth modifications of the first embodiment may be combined with the second embodiment. Any two or more of the first, second, and fourth to sixth modifications may be combined with the second embodiment. A new embodiment resulting from the combination combines the effects of the combined embodiments. When the fourth modification is combined 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 contactless power supply system 1 can be applied to not only automobiles but also trains, electric aircraft, amusement park rides such as roller coasters, cleaning robots, delivery robots, guide robots, self-propelled transport equipment in factory sites, and toys such as model cars. When applied to an electric aircraft, power can be supplied while the aircraft is moving on the ground.

[0071] In the embodiment, an example has been described in which the power supply line 10 is placed on a road and the contactless power receiving device 20 is mounted on the mobile object 100, but the present invention is not limited to this. The power supply line 10 may be placed on a charging stand, and the contactless power receiving device 20 may be mounted on a mobile device such as a smartphone. In this case, the mobile device can be charged by placing it at any position on the power supply line 10 on the charging stand.

[0072] An overview of one aspect of the present disclosure is as follows: A contactless power receiving device according to an aspect of the present disclosure includes a power acquisition circuit that has a coil that is magnetically coupled to a power supply line having one end connected to an AC power source and a first electrode that is electric field coupled to the power supply line, and that acquires, via the coil and the first electrode, first AC power generated by a traveling wave propagating from one end of the power supply line to the other end and second AC power generated by a reflected wave propagating along the power supply line from the other end to the one end, 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 embodiment, it is possible to suppress a decrease in the received power and eliminate the need to suppress reflected waves on the power supply line.

[0073] The power supply line may include a first conductor and a second conductor arranged in parallel, the first electrode is electric field coupled to the first conductor and connected to a 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 further includes a second electrode that is electric field coupled to the second conductor, and the power combining circuit outputs 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 of the coil between the midpoint and one end or the other end, and a second capacitor formed between the second electrode and the second conductor may form a series resonant circuit. In this case, the series resonance can reduce the reactance of the current path from the first conductor to the second conductor via the coil.

[0075] The contactless power receiving device may further include a detection unit that detects a 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 in accordance with 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, thereby enabling adjustment of the characteristics of the power acquisition circuit.

[0077] The power supply line may include 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 may further include a second electrode that is electric field 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 electric field coupled to the first conductor and connected to one end of the coil, and a fourth electrode that is electric field coupled to the first conductor and connected to the other end of the coil. In this case, a CMC-type directional coupler can be configured, and forward waves and reflected waves can be more clearly separated.

[0078] The contactless power receiving device may further include a detection unit that detects a current flowing through the coil, and 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. In this case, the received power can be increased in accordance with the characteristics of the power supply line.

[0079] The contactless power receiving device may further include a resonant capacitor connected between one end and the other end of the coil, in which case reactance can be further reduced by parallel resonance between the coil and the resonant capacitor.

[0080] A contactless power supply system according to one aspect of the present disclosure includes a power supply line having an AC power source connected to one end thereof, and a contactless power receiving device that receives power from the power supply line. The contactless power receiving device includes: a power acquisition circuit having a coil that is magnetically coupled to the power supply line and a first electrode that is electric-field coupled to the power supply line, the power acquisition circuit acquiring, via the first coil and the first electrode, first AC power generated by a traveling wave propagating from one end of the power supply line to the other end thereof, and second AC power generated by a reflected wave propagating from the other end of the power supply line to the one end thereof; 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. This aspect makes it possible to suppress a decrease in received power while eliminating the need to suppress reflected waves on the power supply line.

[0081] The other end of the power supply line may be open or short-circuited, which can reduce power loss compared to when a termination resistor for impedance matching is connected to the power supply line. [Industrial Applicability]

[0082] The present disclosure can be used in a contactless power receiving device and a contactless power supply system. [Explanation of symbols]

[0083] 1...contactless power supply system, 10...power supply line, 12a...first conductor, 12b...second conductor, 18...AC power source, 20...contactless 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 power acquisition circuit that acquires a first AC power generated by a traveling wave propagating from one end to the other end of a power supply line connected to one end of the power supply, and a second AC power generated by a reflected wave propagating from the other end to the one end of the power supply line; A non-contact power receiving device characterized by:

2. the power supply line includes a first conductor and a second conductor arranged in parallel; the power acquisition circuit has a coil that is magnetically coupled to the first conductor and the second conductor, a first electrode that is electric-field coupled to the first conductor, and a second electrode that is electric-field coupled to the second conductor, and acquires the first AC power and the second AC power via the coil, the first electrode, and the second electrode; the first electrode is connected to a 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 non-contact power receiving device according to claim 1 .

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

4. a detection unit that detects a 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 contactless power receiving device according to claim 3 , further comprising:

5. the power acquisition circuit further includes an adjustment circuit that adjusts at least one of a voltage and a current at a midpoint of the coil; 5. The contactless power receiving device according to claim 2, wherein the power receiving device is a power receiving device.

6. the power supply line includes a first conductor and a second conductor arranged in parallel; the power acquisition circuit has a coil that is magnetically coupled to the first conductor and the second conductor, a first electrode that is electric-field coupled to the first conductor, and a second electrode that is electric-field coupled to the second conductor, and acquires the first AC power and the second AC power via the coil, the first electrode, and the second conductor; One end of the coil outputs the first AC power, The other end of the coil outputs the second AC power, The first electrode is a third electrode that is electric field coupled to the first conductor and connected to one end of the coil; a fourth electrode that is electric field coupled to the first conductor and connected to the other end of the coil; 2. The contactless power receiving device according to claim 1, further comprising:

7. a detection unit that detects a 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 contactless power receiving device according to claim 6, further comprising:

8. Further, a resonant capacitor is connected between one end and the other end of the coil.

8. The contactless power receiving device according to claim 2, wherein the power receiving device is a power receiving device.

9. a power supply line having an AC power source connected to one end thereof; a contactless power receiving device that receives power from the power supply line; Equipped with the contactless power receiving device includes a power acquisition circuit that acquires first AC power generated by a traveling wave propagating from one end to the other end of the power supply line and second AC power generated by a reflected wave propagating from the other end to the one end of the power supply line; A contactless power supply system characterized by:

10. The other end of the power supply line is open or short-circuited. The contactless power supply system according to claim 9 .

11. a power supply line in a contactless power supply system, the power supply line having one end connected to an AC power source; and a contactless power receiving device having a power acquisition circuit that acquires first AC power generated by a traveling wave propagating through the power supply line from one end to the other end, and second AC power generated by a reflected wave propagating through the power supply line from the other end to the one end, The AC power source has a conductor connected at one end and open or shorted at the other end. A power supply line characterized by:

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