Power transmission system and receiving device

Abstract

This invention provides a technology that enables stable power transmission from a power-transmitting device, which has multiple transmission coils arranged in a grid, to a power-receiving device that moves along these multiple transmission coils. [Solution] The power transmission system comprises a power transmission device having a plurality of power transmission coils arranged in a row, and a power receiving device that moves over the plurality of power transmission coils, wherein the power receiving device comprises a power receiving coil that generates an electromotive force in accordance with the magnetic field generated in each power transmission coil, an AC / DC converter connected to the power receiving coil, a battery connected to the AC / DC converter, and a smoothing circuit that smooths out pulsations in the output power of the AC / DC converter caused by changes in the strength of the magnetic field in the direction of arrangement of the plurality of power transmission coils.

Description

[Technical Field]

[0001] The present invention relates to a power transmission system and a power receiving device. [Background technology]

[0002] In recent years, dynamic wireless power transfer (DWPT), which wirelessly transmits power to electric vehicles moving along multiple power-transmitting coils arranged on roads and other surfaces, has attracted attention (see, for example, Non-Patent Document 1). This dynamic wireless power transfer allows the battery that supplies power to the traction motor to be charged while the electric vehicle is in motion, dramatically extending the driving range of the electric vehicle. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Z. Zhang, R. Ota, R. Okada and N. Hoshi, “Multi-port Inductive PowerTransfer System Considering Charging Auxiliary Battery in EVs,” in 2019 24thEuropean Conference on Power Electronics and Applications (EPC'22 ECCE Europe),2022, pp.1-9. [Overview of the project] [Problems that the invention aims to solve]

[0004] In a network of multiple power transmission coils arranged along a road or similar structure, the magnetic field strength tends to be weaker in the sections between adjacent coils compared to other sections. Therefore, changes in magnetic field strength occur in the direction of the arrangement of the multiple power transmission coils, potentially making it difficult to stably transmit power from the multiple coils to the receiving equipment of an electric vehicle.

[0005] Therefore, the present invention aims to provide a technology that enables stable power transmission from a power-transmitting device having multiple power-transmitting coils arranged in a row to a power-receiving device moving over the multiple power-transmitting coils. [Means for solving the problem]

[0006] To achieve the above objective, a power transmission system as one aspect of the present invention is a power transmission system comprising: a power transmission device having a plurality of power transmission coils arranged in a row; and a power receiving device moving over the plurality of power transmission coils, wherein the power receiving device comprises: a power receiving coil that generates an electromotive force in accordance with the magnetic field generated in each power transmission coil; an AC / DC converter connected to the power receiving coil; a battery connected to the AC / DC converter; and a smoothing circuit that smooths out pulsations in the output power of the AC / DC converter caused by changes in the strength of the magnetic field in the direction of the arrangement of the plurality of power transmission coils. [Effects of the Invention]

[0007] According to the present invention, for example, it is possible to provide a technology that enables stable power transmission from a power-transmitting device having a plurality of power-transmitting coils arranged in a row to a power-receiving device moving over the plurality of power-transmitting coils. [Brief explanation of the drawing]

[0008] [Figure 1] Schematic diagram showing the power transmission system of the first embodiment. [Figure 2] A diagram illustrating the concept of smoothing out pulsations in the output power of an AC / DC converter using a smoothing circuit. [Figure 3] A schematic diagram showing the configuration of the power transmission system of the first embodiment and the time progression of power at each location. [Figure 4] This figure shows an example of the circuit configuration of the power transmission system of the first embodiment. [Figure 5] Figure 4 shows the operating results of a power transmission system with the circuit configuration shown in Figure 4. [Figure 6] This figure shows a modified example of the circuit configuration of the power transmission system of the first embodiment. [Figure 7] Figure 6 shows the operating results of a power transmission system with the circuit configuration shown in Figure 6. [Figure 8] Schematic diagram showing the power transmission system of the second embodiment. [Figure 9] This figure shows an example of the circuit configuration of the power transmission system of the second embodiment. [Figure 10] This figure shows the configuration of the first power receiving coil and the second power receiving coil in Example 1 of the second embodiment. [Figure 11] This figure shows the state in which the first receiving coil is placed on top of the transmitting coil of the power transmitting device in Example 1 of the second embodiment. [Figure 12] This figure shows the state in which the second receiving coil is positioned between the transmitting coil and the transmitting coil of the power transmission device in Example 1 of the second embodiment. [Figure 13] This figure shows the experimental results of the power transmitted from the power transmitting device to the power receiving device in Example 1 of the second embodiment. [Figure 14] This figure shows the state in which the first receiving coil is placed on top of the transmitting coil of the power transmitting device in Example 2 of the second embodiment. [Figure 15] This figure shows the state in which the second receiving coil is positioned between the transmitting coil and the transmitting coil of the power transmission device in Example 2 of the second embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments, and includes changes and modifications to the configuration within the scope of the spirit of the invention. Furthermore, not all combinations of features described in these embodiments are essential to the present invention. The same reference numeral is used for identical components, and their descriptions are omitted.

[0010] <First Embodiment> A power transmission system 100A according to a first embodiment of the present invention will be described. Figure 1 is a schematic diagram showing the power transmission system 100A of this embodiment. The power transmission system 100A is a system that performs dynamic wireless power transfer (DWPT) in motion, wirelessly transmitting power to an electric vehicle EV that is moving (driving) on ​​a plurality of power transmission coils 11a to 11c embedded in the road surface (RD). The power transmission system 100 of this embodiment may include a power transmission device 10 equipped with a plurality of power transmission coils 11a to 11c embedded in the road surface (RD), and a power receiving device 20 mounted on an electric vehicle EV.

[0011] In this embodiment, an example of a power transmission device 10 in which three power transmission coils 11a to 11c are arranged is described, but the number of power transmission coils 11 provided in the power transmission device 10 is not limited to three, but can be two or four or more. In reality, the power transmission device 10 is equipped with a large number of power transmission coils 11, and these large number of power transmission coils 11 can be arranged (buried) in the road RD. Also, in this embodiment, an electric vehicle EV (four-wheeled vehicle) is used as an example to describe the vehicle on which the power receiving device 20 is mounted, but it is not limited to this, and may be a hybrid vehicle, for example. The vehicle on which the power receiving device 20 is mounted is not limited to a four-wheeled vehicle, but may be a mobile body that moves on a surface on which multiple power transmission coils 11 are arranged. For example, the vehicle on which the power receiving device 20 is mounted may be a saddle-type vehicle (two-wheeled or three-wheeled vehicle) that travels on a road where multiple power transmitting coils 11 are arranged, or an automated guided vehicle (AGV) that travels on a floor surface where multiple power transmitting coils 11 are arranged inside a factory or the like.

[0012] The power transmission device 10 may include a plurality of power transmission coils 11a to 11c arranged along the direction of travel of the electric vehicle EV on the road RD, a resonant circuit 12, an inverter 13, and a control unit 14. The resonant circuit 12 and the inverter 13 are individually provided for each of the plurality of power transmission coils 11a to 11c, and each power transmission coil 11a to 11c is supplied with power (AC power) from the inverter 13 via the resonant circuit 12. Each inverter 13 is supplied with power (DC power) from the power grid via an AC / DC converter 30. The AC / DC converter 30 may include, for example, a PFC (Power Factor Correction) circuit.

[0013] The control unit 14 of the power transmission device 10 can control the DC / AC conversion in the inverter 13 by controlling the on / off state of each switch element included in the inverter 13. The control unit 14 may be composed of a computer including a processor such as a CPU (Central Processing Unit), storage devices such as semiconductor memory, and interfaces with external devices.

[0014] In the example shown in Figure 1, not only the multiple transmission coils 11a to 11c, but also the resonant circuit 12 and inverter 13 are depicted as being buried in the road RD. However, the resonant circuit 12 and inverter 13 do not necessarily have to be buried in the road RD. Similarly, the AC / DC converter 30 does not necessarily have to be buried in the road RD.

[0015] The power receiving device 20 may include a power receiving coil 21, a resonant circuit 22, an AC / DC converter 23, a battery 24, a smoothing circuit 25, and a control unit 26. The power receiving coil 21 is located on the bottom surface of the electric vehicle (EV) and generates power (AC power) in accordance with the magnetic field Mv (e.g., a vertical magnetic field) generated by each of the power transmitting coils 11a to 11c of the power transmitting device 10. The power generated by the power receiving coil 21 is supplied to the AC / DC converter 23 via the resonant circuit 22. The power (DC power) converted from AC to DC by the AC / DC converter 23 is supplied to the battery 24. This charges the battery 24. For example, a lithium-ion battery (LIB) may be used as the battery 24. The power from the battery 24 is also supplied to the traction motor 32 via a three-phase inverter 31. The traction motor 32 is the drive source of the electric vehicle (EV), and the three-phase inverter 31 is a motor driver for driving the traction motor 32.

[0016] Incidentally, in section A between adjacent power transmission coils 11a to 11c arranged on the road RD, the magnetic field strength Mv tends to be weaker compared to other sections. As a result, changes in the magnetic field strength Mv occur in the direction of arrangement of the multiple power transmission coils 11a to 11c (i.e., the direction of travel of the electric vehicle EV), which can make it difficult to stably transmit power from the power transmission device 10 (multiple power transmission coils 11a to 11c) to the power receiving device 20 of the electric vehicle EV. For example, depending on the magnitude of the power generated in the power receiving coil 21 according to the magnetic field Mv of each power transmission coil 11, the power supplied from the AC / DC converter 23 to the battery 24 may exceed the rated power value (hereinafter sometimes simply referred to as the rated power value) that can charge the battery 24. On the other hand, in section A between adjacent power transmission coils 11, the magnetic field strength Mv is weaker compared to other sections, and the power supplied from the AC / DC converter 23 to the battery 24 is smaller. When the power supplied to the battery 24 pulsates (fluctuations) in this way, the battery 24 deteriorates due to its low-frequency components, and the amount of power transmitted per unit length of the power supply line [Wh / m] decreases, which increases equipment costs.

[0017] Therefore, in the power transmission system 100A of this embodiment, a smoothing circuit 25 is provided in the power receiving device 20. The smoothing circuit 25 is a circuit for smoothing the pulsations that occur in the output power of the AC / DC converter 23 due to changes in the strength of the magnetic field Mv in the direction of the arrangement of the multiple power transmitting coils 11a to 11c. In this embodiment, the smoothing circuit 25 is a capacitor C buff It may be composed of an active buffer including such a smoothing circuit 25. By providing such a smoothing circuit 25, the power supplied to the battery 24 can be stabilized, the degradation of the battery 24 can be reduced, and the amount of power transmitted per unit length of the power supply path can be improved.

[0018] Figure 2 illustrates the concept of smoothing the pulsations in the output power of the AC / DC converter 23 using a smoothing circuit 25. Figure 2(a) shows the power output from the AC / DC converter 23 (output power P1) according to the magnetic field Mv generated in each of the transmitting coils 11a to 11c. Figure 2(b) shows the power P2 supplied to the battery 24. Figures 2(a) and 2(b) also show the positions of the multiple transmitting coils 11a to 11c.

[0019] The smoothing circuit 25 (active buffer) removes a portion of the power exceeding the threshold TH during the first period 41 when the output power P1 of the AC / DC converter 23 exceeds the threshold TH, using capacitor C. buff It supplies power to the capacitor C. That is, in the first period 41, the smoothing circuit 25 supplies power to the capacitor C from the output power P1 of the AC / DC converter 23 that exceeds the threshold TH. buff It temporarily stores (stores) energy in the capacitor C. In addition, the smoothing circuit 25, in the second period 42 when the output power P1 of the AC / DC converter 23 is below the threshold TH, adds capacitor C to the output voltage P1 of the AC / DC converter 23. buff Power is supplied from to the battery 24. That is, the smoothing circuit 25, in the second period 42, the capacitor C buffreleases the power that has been temporarily stored therein. Through such operation of the smoothing circuit 25, pulsation occurring in the output power P1 of the AC / DC converter 23 due to a change in the intensity of the magnetic field Mv can be smoothed. That is, as shown in FIG. 2(b), the power P2 supplied to the battery 24 can be stabilized (smoothed).

[0020] Here, in the case of the present embodiment, the threshold TH can be set to the rated power value of the battery 24, but may also be set to a value equal to or less than the rated power value of the battery 24. Further, although the smoothing circuit 25 is connected in parallel to the battery 24 in the example of FIG. 1, the present invention is not limited thereto, and the smoothing circuit 25 may be connected in series to the battery 24. Furthermore, the smoothing circuit 25 of the present embodiment includes a capacitor C buff and is configured to temporarily store power in the capacitor C buff , but the configuration is not limited thereto. For example, the smoothing circuit 25 may include an inductor instead of the capacitor C buff or in addition to the capacitor C buff , and may be configured to temporarily store power in the capacitor C buff and / or the inductor.

[0021] FIG. 3 is a schematic diagram showing the configuration of the power transmission system 100A of the present embodiment and the time transition of power at each location. In FIG. 3, the respective power transmission-side coils 11a to 11c of the power transmission-side device 10 and the respective parts 21 to 25 of the power reception-side device 20 are shown. Each graph in FIG. 3 represents the time transition of power occurring at each location of the power transmission system 100A when the power reception-side device 20 (power reception-side coil 21) sequentially moves over the plurality of power transmission-side coils 11a to 11c, where the horizontal axis represents time and the vertical axis represents power.

[0022] In each transmission coil 11a to 11c, AC power is applied as shown in graphs G1 to G3 during the period when the receiving coil 21a is positioned above it. In the receiving device 20, AC power corresponding to the magnetic field Mv of each transmission coil 11a to 11c is generated in the receiving coil 21 as shown in graph G4. The AC power generated in the receiving coil 21 is converted to AC / DC by the AC / DC converter 23, and DC power is output from the AC / DC converter 23 as shown in graph G5.

[0023] During the period when the DC power output from the AC / DC converter 23 exceeds the threshold TH (first period 41), a portion of the DC power output from the AC / DC converter 23 that exceeds the threshold TH is absorbed by the capacitor C of the smoothing circuit 25. buff The remaining power is stored in the AC / DC converter and supplied to the battery 24. On the other hand, during the period when the DC power output from the AC / DC converter 23 is below the threshold TH (second period 42), the DC power output from the AC / DC converter 23 is supplied to the battery 24, and the capacitor C of the smoothing circuit 25 is also supplied. buff The DC power discharged from the AC / DC converter is also supplied to the battery 24. Therefore, the input power (output power) to the smoothing circuit 25 is as shown in graph G6. Through this operation, the pulsation of the DC power output from the AC / DC converter 23 is smoothed, and the temporal variation of the DC power supplied to the battery 24 is reduced, as shown in graph G7. In other words, the DC power supplied to the battery 24 can be stabilized.

[0024] The circuit configuration of the power transmission system 100A of this embodiment will be described below. Figure 4 shows an example of the circuit configuration of the power transmission system 100A of this embodiment. In the power transmission system 100A of this embodiment, a plurality of power transmission coils 11a to 11c are provided in the power transmission device 10, but here, in order to simplify the explanation and illustration, we will focus on one power transmission coil 11, and the resonant circuit 12 and inverter 13 connected to it.

[0025] First, the circuit configuration of the power transmission device 10 will be described. The power transmission device 10 may include a power transmission coil 11, a resonant circuit 12, an inverter 13, and a control unit 14. The power supply PS connected to the inverter 13 may be an AC / DC converter 30 (PFC circuit) connected to the power grid and supplying power (DC power) to the inverter 13.

[0026] The transmission coil 11 is embedded in the road RD and generates a magnetic field Mv in response to the power (AC power) supplied from the inverter 13 via the resonant circuit 12. The resonant circuit 12 is the inductor L of the transmission coil 11. pt , Capacitor C pt , inductor L pc and capacitor C pc It can be constructed by a resonant network consisting of the following.

[0027] Inverter 13 has the first transmission side leg LG connected in parallel to each other. p1 , 2nd power transmission side leg LG p2 and has a capacitor C1. First power transmission side leg LG p1 is contact point b p1 Two switch elements S connected in series via pu1 ,S pl1 Including the second transmission side leg LG p2 is contact point b p2 Two switch elements S connected in series via pu2 ,S pl2 Includes the first transmission side leg LG. p1 Contact point b p1 One end of the power transmission coil 11 is connected to an inductor L pc and capacitor C pt Connected via, the second power transmission side leg LG p2 Contact point b p2 The other end of the power transmission coil 11 is connected to this.

[0028] Each switch element S of the inverter 13 pu1 ,S pl1 ,S pu2 ,S pl2As such, transistors (power elements) that perform switching operations, such as IGBTs and MOSFETs, can be used. pu1 ,S pl1 ,S pu2 ,S pl2 The on / off state (conductive / non-conductive) can be controlled by the control unit 14 at a predetermined operating frequency (e.g., 85 kHz). Furthermore, the power supply PS is connected to the first power transmission side leg LG. p1 and the second transmission side leg LG p2 It is connected in parallel.

[0029] Next, the circuit configuration of the power receiving device 20 will be described. As mentioned above, the power receiving device 20 may include a power receiving coil 21, a resonant circuit 22, an AC / DC converter 23, a battery 24, a smoothing circuit 25 (active buffer), and a control unit 26.

[0030] The receiving coil 21 is located on the bottom of the electric vehicle (EV) and generates an electromotive force in response to the magnetic field Mv generated by the transmitting coil 11. The resonant circuit 22 is the inductor L of the receiving coil 21. st , Capacitor C st , inductor L sc and capacitor C sc It can be constructed by a resonant network consisting of the following.

[0031] The AC / DC converter 23 may include a diode rectifier (diode bridge circuit) composed of multiple diodes D1 to D4 and a capacitor C2. In the diode rectifier, diode D1 and diode D2 are connected by contact b s1 They are connected in series via the contact b s1 One end of the receiving coil 21 is connected to this. Diodes D3 and D4 are connected to contact b. s2 They are connected in series via the contact b s2 The other end of the receiving coil 21 is an inductor L sc and capacitor C stThe capacitor C2 is connected in parallel to the diode rectifier (specifically, the legs including diodes D1-D2 and the legs including diodes D3-D4). The battery 24 is also connected in parallel to the diode rectifier. Note that the AC / DC converter 23 may be composed of multiple switching elements instead of diode rectifiers.

[0032] The smoothing circuit 25 can be configured as a boost-type active buffer. For example, the smoothing circuit 25 has contact b s3 Two switch elements S1 and S2 connected in series via a crosshair, and an inductor L buff And, capacitor C buff It has the following: Inductor L buff This connects one end of capacitor C2 of AC / DC converter 23 to contact b s3 A connection is made between them. Also, capacitor C buff This is the terminal (contact b) of the switch element S1. s3 Two switching elements S1 and S2 are connected in parallel between the terminal on the opposite side and the other end of capacitor C2.

[0033] The switching elements S1 to S2 of the smoothing circuit 25 can be transistors (power elements) that perform switching operations, such as IGBTs or MOSFETs. The on / off (non-conductive) state of each switching element S1 to S2 can be controlled by the control unit 26. The control unit 26 can be composed of a computer including a processor such as a CPU (Central Processing Unit), a storage device such as semiconductor memory, and an interface with an external device. The control unit 26 may also be configured as part of an external control device such as an ECU (Electronic Control Unit) provided in an electric vehicle (EV). Furthermore, if the AC / DC converter 23 is composed of multiple switching elements, the control unit 26 may be configured to further control the on / off state of each switching element of the AC / DC converter 23.

[0034] Figure 5 shows the operation results of the power transmission system 100A having the circuit configuration of Figure 4, in which the smoothing circuit 25 is configured as a boost-type active buffer. In Figure 5, "i in " indicates the output current of the AC / DC converter 23. buff The value " indicates the input current to the smoothing circuit 25. A positive value indicates that current is input to the smoothing circuit 25, and a negative value indicates that current is output from the smoothing circuit 25. Cbuff " is the capacitor C of the smoothing circuit 25 buff This indicates the voltage applied to "i s " indicates the input current to the battery 24. Also, "GateSignal S1" indicates the signal (pulse signal) input to the gate electrode of the switch element S1 of the smoothing circuit 25.

[0035] As shown in Figure 5, according to the power transmission system 100A of this embodiment, by using the smoothing circuit 25, the output current i of the AC / DC converter 23 is reduced. in The pulsations that occur are smoothed out, and the input current i to the battery 24 is smoothed out. s This can stabilize the input current i to the battery 24. s This reduces fluctuations and thus reduces the degradation of the battery 24, while also improving the amount of power transmitted per unit length of the power supply line.

[0036] In the circuit configuration of Figure 4, the smoothing circuit 25 is configured as a boost-type active buffer, but the smoothing circuit 25 may also be configured as a buck-type active buffer. Figure 6 shows a modified example of the circuit configuration of the power transmission system 100A of this embodiment. In the circuit configuration of Figure 6, the only difference from the circuit configuration of Figure 4 is that the smoothing circuit 25 has been changed from a boost-type active buffer to a buck-type active buffer; the configurations other than the smoothing circuit 25 are the same. Therefore, the smoothing circuit 25 in the circuit configuration of Figure 6 will be described below, and the configurations other than the smoothing circuit 25 will not be described.

[0037] The smoothing circuit 25, configured as a step-down active buffer, has contact b as shown in Figure 6. s3 Two switch elements S1 and S2 connected in series via a crosshair, and an inductor L buff And, capacitor C buff It has the following. The leg, which consists of two switch elements S1 and S2 connected in series, is connected in parallel to the diode rectifier of the AC / DC converter 23. Contact b s3 The inductor L is included. buff It is connected. Also, capacitor C buff The inductor L is connected in parallel with the switching element S2. buff They are connected in series. In the smoothing circuit 25 of Figure 6, each switch element S1 to S2 can be a transistor (power element) that performs switching operation, such as an IGBT or MOSFET. The on (conducting) / off (non-conducting) state of each switch element S1 to S2 can be controlled by the control unit 26.

[0038] Figure 7 shows the operation results of the power transmission system 100A having the circuit configuration of Figure 6, in which the smoothing circuit 25 is configured as a step-down active buffer. Even when the smoothing circuit 25 is configured as a step-down active buffer, the output current i of the AC / DC converter 23 in The pulsations that occur are smoothed out, and the input current i to the battery 24 is smoothed out. s This can stabilize the input current i to the battery 24. s This reduces fluctuations and thus reduces the degradation of the battery 24, while also improving the amount of power transmitted per unit length of the power supply line.

[0039] As described above, in the power transmission system 100A of this embodiment, a smoothing circuit 25 is provided in the power receiving device 20. The smoothing circuit 25 smooths out the pulsations that occur in the output power of the AC / DC converter 23 due to changes in the strength of the magnetic field Mv in the direction of the arrangement of the multiple power transmitting coils 11a to 11c. This stabilizes the power supplied to the battery 24, reduces the degradation of the battery 24, and improves the amount of power transmitted per unit length of the power supply line.

[0040] <Second Embodiment> A second embodiment of the power transmission system 100B according to the present invention will be described. In this embodiment, a magnetic field Mh (e.g., a horizontal magnetic field) in a direction different from the magnetic field Mv (e.g., a vertical magnetic field) is generated in the section between adjacent power transmission coils 11a to 11c arranged on a road RD, and an example of power transmission using the magnetic field Mh will be described. Note that this embodiment may follow the first embodiment, and may conform to the first embodiment except for the matters mentioned below. In the following, the differences from the power transmission system 100A of the first embodiment will be described in detail.

[0041] Figure 8 is a schematic diagram showing the power transmission system 100B of this embodiment. In the power system 100B of this embodiment, compared to the power system 100A of the first embodiment, in the power transmission device 10, multiple power transmission coils 11a to 11c are energized such that the directions of the magnetic fields Mv generated in adjacent power transmission coils 11 are opposite to each other. This makes it possible to generate a magnetic field Mh in a direction different from the magnetic field Mv in the section between adjacent power transmission coils 11. For example, the magnetic field Mv is a vertical magnetic field (vertical magnetic field) generated individually in each power transmission coil 11a to 11c, and may be understood as the magnetic field component in a first direction among the magnetic fields generated in multiple power transmission coils 11a to 11b. The magnetic field Mh is a horizontal magnetic field (horizontal magnetic field) generated across two adjacent power transmission coils 11, and may be understood as the magnetic field component in a second direction different from the first direction among the magnetic fields generated in multiple power transmission coils 11a to 11b.

[0042] Furthermore, in the power system 100B of this embodiment, compared to the power system 100A of the first embodiment, instead of the smoothing circuit 25, multiple types of receiving coils 21 are provided in the receiving device 20. For example, in the power system 100B of this embodiment, as shown in Figure 8, a first receiving coil 21a and a second receiving coil 21b are provided. The first receiving coil 21a is mainly configured to generate an electromotive force in response to a vertical magnetic field Mv as a magnetic field component in the first direction. On the other hand, the second receiving coil 21b is mainly configured to generate an electromotive force in response to a horizontal magnetic field Mh as a magnetic field component in the second direction. As a result, not only is power generated in the first receiving coil 21a by the vertical magnetic field Mv on each transmitting coil 11a to 11c, but power can also be generated in the second receiving coil 21b by the horizontal magnetic field Mh in the section A between adjacent transmitting coils 11. In other words, power can be stably transmitted from the power transmission device 10 (multiple power transmission coils 11a to 11c) to the power receiving device 20.

[0043] The circuit configuration of the power transmission system 100B of this embodiment will be described below. Figure 9 shows an example of the circuit configuration of the power transmission system 100B of this embodiment.

[0044] First, the circuit configuration of the power transmission device 10 will be described. In the power transmission device 10, a resonant circuit 12 and an inverter 13 are individually provided for each of the multiple power transmission coils 11a to 11c. The multiple power transmission coils 11a to 11c are embedded in the road RD and generate a vertical magnetic field Mv and a horizontal magnetic field Mh in accordance with the power (AC power) supplied from the inverter 13 via the resonant circuit 12. The configuration of the resonant circuit 12 and inverter 13 provided for the power transmission coil 11a will be described below, but the resonant circuits 12 and inverters 13 provided for the other power transmission coils 11b to 11c have a similar configuration.

[0045] The resonant circuit 12 consists of the inductor L of the power transmission coil 11a. pt , Capacitor C pt , inductor L pf and capacitor C pfcan be configured by a resonant network consisting of the following. The inverter 13 includes a first power transmission-side leg LG p1 and a second power transmission-side leg L p2 and the first power transmission-side leg LG p1 includes a contact b p1 two switching elements S connected in series via pu1 , S pl1 , and the second power transmission-side leg LG p2 includes a contact b p2 two switching elements S connected in series via pu2 , S pl2 . The contact b of the first power transmission-side leg LG p1 contact b p1 is connected to one end of a power transmission-side coil 11a via an inductor L pf and a capacitor C pt , and the contact b of the second power transmission-side leg LG p2 contact b p2 is connected to the other end of the power transmission-side coil 11a. Each leg LG of the inverter 13 p1 to LG p2 supplied voltage E pdc may be DC power supplied from an AC / DC converter 30 (PFC circuit) connected to a power system.

[0046] Next, the circuit configuration of the power receiving-side device 20 will be described. The power receiving-side device 20 may include a first power receiving-side coil 21a, a second power receiving-side coil 21b, a resonant circuit 22, an AC / DC converter 23, and a battery 24. In the power receiving-side device 20 of the present embodiment, the resonant circuit 22 and the AC / DC converter 23 may be individually provided for each of the first power receiving-side coil 21a and the second power receiving-side coil 21b. For example, the first power receiving-side coil 21a is provided with a first resonant circuit 22a and a first AC / DC converter 23a, and the second power receiving-side coil 21b is provided with a second resonant circuit 22b and a second AC / DC converter 23b.

[0047] The first power receiving-side coil 21a is provided on the bottom surface of the electric vehicle EV, and generates an electromotive force according to a vertical magnetic field Mv generated by each power transmission-side coil 11a. The first resonant circuit 22a includes an inductor L of the first power receiving-side coil 21a st1, Capacitor C st1 , inductor L sf1 and capacitor C sf1 It may be composed of a resonant network consisting of the following. The first AC / DC converter 23a may include a diode rectifier (e.g., a diode bridge circuit) composed of multiple diodes. The output power of the first AC / DC converter 23a is supplied to the battery 24.

[0048] The second receiving coil 21b is located on the bottom of the electric vehicle (EV) and generates an electromotive force in response to the horizontal magnetic field Mh generated across the adjacent transmitting coil 11. The second resonant circuit 22b is connected to the inductor L of the second receiving coil 21b. st2 , Capacitor C st2 , inductor L sf2 and capacitor C sf2 It may be composed of a resonant network consisting of the following. The second AC / DC converter 23b may include a diode rectifier (e.g., a diode bridge circuit) composed of multiple diodes. The output power of the second AC / DC converter 23b is supplied to the battery 24.

[0049] The first receiving coil 21a and the second receiving coil 21b are configured as different types of coils. Specifically, the first receiving coil 21a is configured as a coil that easily generates electromotive force in response to a vertical magnetic field Mv, and the second receiving coil 21b may be configured as a coil that easily generates electromotive force in response to a horizontal magnetic field Mh. Embodiments of the first receiving coil 21a and the second receiving coil 21b will be described below.

[0050] [Example 1] Example 1 describes an example in which the first power-receiving coil 21a includes a coil wound around an axis parallel to the first direction (e.g., the vertical direction), and the second power-receiving coil 21b includes a coil wound around an axis parallel to the second direction (e.g., the horizontal direction).

[0051] Figure 10 shows the configuration of the first receiving coil 21a and the second receiving coil 21b in Embodiment 1. The first receiving coil 21a includes a coil wound around an axis parallel to the vertical direction. In Figure 10, the first receiving coil 21a is wound in a rectangular shape, but it may be wound in other shapes such as a circular shape. The second receiving coil 21a includes a solenoid coil wound around a ferrite core 27 around an axis parallel to the horizontal direction. In the example in Figure 10, the first receiving coil 21a and the second receiving coil 21b are stacked vertically to reduce compactness, but they are not limited to this and may be arranged horizontally.

[0052] Figure 11 shows the state in which the first receiving coil 21a is placed on the transmitting coil 11a of the transmitting device 10. In this state, the transmitting coil 11a receives current i through the resonant circuit 12 and inverter 13. pa A power supply is provided, which generates a vertical magnetic field Mv above the transmitting coil 11a. This vertical magnetic field Mv generates an electromotive force in the first receiving coil 21a, and the power received by the first receiving coil 21a is supplied to the battery 24 via the resonant circuit 22 and the AC / DC converter 23. In this state, almost no electromotive force is generated in the second receiving coil 21b.

[0053] Figure 12 shows the state in which the second receiving coil 21b is positioned between the transmitting coil 11a and the transmitting coil 11b of the transmitting device 10. In this state, the current i supplied to the transmitting coil 11a is supplied to the transmitting coil 11b. pa and a current i in the opposite direction pb Power is supplied, which generates a horizontal magnetic field Mh across the transmitting coil 11a and the transmitting coil 11b. This horizontal magnetic field Mh generates an electromotive force in the second receiving coil 21b, and the power received by the second receiving coil 21b is supplied to the battery 24 via the resonant circuit 22 and the AC / DC converter 23. In this state, almost no electromotive force is generated in the first receiving coil 21a.

[0054] Figure 13 shows the experimental results of power transmitted from the transmitting device 10 to the receiving device 20. In Figure 13, the horizontal axis represents the position [deg] of the receiving coil 21 (first receiving coil 21a, second receiving coil 21b), and the vertical axis represents the power transmitted from the transmitting device 10 to the receiving device 20 [kW]. In Figure 13, "Mode V1" represents the power transmitted due to the vertical magnetic field Mv generated by the transmitting coil 11a, "Mode V2" represents the power transmitted due to the vertical magnetic field Mv generated by the transmitting coil 11b, and "Mode V3" represents the power transmitted due to the vertical magnetic field Mv generated by the transmitting coil 11c. Furthermore, "Mode H1" represents the power transmitted due to the horizontal magnetic field Mh generated between the transmitting coil 11a and the transmitting coil 11b, and "Mode H2" represents the power transmitted due to the horizontal magnetic field Mh generated between the transmitting coil 11b and the transmitting coil 11c. As shown in Figure 13, the power transmission system 100B of Example 1 can be seen to reliably transmit power from the transmitting device 10 (multiple transmitting coils 11a to 11c) to the receiving device 20 even if the position of the receiving coil 21 changes.

[0055] [Example 2] In Example 2, an example is described in which the second power-receiving coil 21b includes a coil formed by connecting at least two coil elements that have different winding directions around an axis parallel to the first direction (e.g., the vertical direction) and are arranged along the second direction (e.g., the horizontal direction). The second power-receiving coil 21b in Example 2 includes, for example, a Double-D type coil. The first power-receiving coil 21a includes a coil wound around an axis parallel to the first direction, similar to Example 1.

[0056] Figure 14 shows the state in which the first receiving coil 21a is placed on the transmitting coil 11a of the transmitting device 10. In this state, the transmitting coil 11a receives current i through the resonant circuit 12 and inverter 13. paA power supply is provided, which generates a vertical magnetic field Mv above the transmitting coil 11a. This vertical magnetic field Mv generates an electromotive force in the first receiving coil 21a, and the power received by the first receiving coil 21a is supplied to the battery 24 via the resonant circuit 22 and the AC / DC converter 23. In this state, almost no electromotive force is generated in the second receiving coil 21b.

[0057] Figure 15 shows the state in which the second receiving coil 21b is positioned between the transmitting coil 11a and the transmitting coil 11b of the transmitting device 10. In this state, the current i supplied to the transmitting coil 11a is supplied to the transmitting coil 11b. pa and a current i in the opposite direction pb Power is supplied, which generates a horizontal magnetic field Mh across the transmitting coil 11a and the transmitting coil 11b. This horizontal magnetic field Mh generates an electromotive force in the second receiving coil 21b, and the power received by the second receiving coil 21b is supplied to the battery 24 via the resonant circuit 22 and the AC / DC converter 23. In this state, almost no electromotive force is generated in the first receiving coil 21a.

[0058] As described above, in the power transmission system 100B of this embodiment, the receiving device 20 is provided with a first receiving coil 21a that generates an electromotive force in response to a magnetic field component in a first direction (e.g., a vertical magnetic field Mv), and a second receiving coil 21a that generates an electromotive force in response to a magnetic field component in a second direction different from the first direction (e.g., a horizontal magnetic field Mh). As a result, even in section A between adjacent transmitting coils 11a to 11c among the multiple transmitting coils 11a to 11c, power can be generated in the second receiving coil 21b by the horizontal magnetic field Mh. In other words, power can be stably transmitted from the transmitting device 10 (multiple transmitting coils 11a to 11c) to the receiving device 20.

[0059] The present invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. [Explanation of symbols]

[0060] 10: Transmission equipment, 11a~11c: Transmission coil, 12: Resonant circuit, 13: Inverter, 20: Receiving equipment, 21: Receiving coil, 21a: First receiving coil, 21b: Second receiving coil, 22: Resonant circuit, 23: AC / DC converter, 24: Battery, 25: Smoothing circuit

Claims

1. A power transmission system, A power transmission device having multiple power transmission coils arranged in a row, The system includes a receiving device that moves on the plurality of transmitting coils, The power receiving device is, A receiving coil generates an electromotive force in response to the magnetic field generated in each transmitting coil, An AC / DC converter connected to the power receiving coil, The battery connected to the AC / DC converter, The system includes a smoothing circuit that smooths out pulsations in the output power of the AC / DC converter caused by changes in the magnetic field strength in the direction of arrangement of the plurality of power-transmitting coils. A power transmission system characterized by the following features.

2. The power transmission system according to claim 1, characterized in that the smoothing circuit is comprised of an active buffer including a capacitor and / or an inductor.

3. The aforementioned active buffer is During the first period in which the output power of the AC / DC converter exceeds a threshold, a portion of the power exceeding the threshold is supplied to the capacitor and / or the inductor. During the second period in which the output power of the AC / DC converter is below the threshold, power is supplied from the capacitor and / or the inductor to the battery. The power transmission system according to claim 2, characterized in that it is controlled in such a way.

4. The power transmission system according to claim 3, characterized in that the threshold is set to a rated power value that can charge the battery.

5. The power transmission system according to claim 2, characterized in that the active buffer is a boost-type active buffer.

6. The power transmission system according to claim 2, characterized in that the active buffer is a step-down active buffer.

7. A power transmission system, A power transmission device having multiple power transmission coils arranged in a row, The system includes a receiving device that moves on the plurality of transmitting coils, The power transmission system is characterized in that the power receiving device comprises a first power receiving coil that generates an electromotive force in accordance with a first magnetic field component of the magnetic field generated by the plurality of power transmitting coils, and a second power receiving coil that generates an electromotive force in accordance with a second magnetic field component of the magnetic field that is different from the first direction.

8. The first power receiving coil includes a coil wound around an axis parallel to the first direction, The power transmission system according to claim 7, characterized in that the second power receiving coil includes a coil wound around an axis parallel to the second direction.

9. The power transmission system according to claim 8, characterized in that the second power receiving coil is configured as a solenoid coil.

10. The first power receiving coil includes a coil wound around an axis parallel to the first direction, The power transmission system according to claim 7, characterized in that the second power receiving coil includes a coil comprising at least two coil elements connected to each other, the winding directions of which are different around an axis parallel to the first direction and which are arranged along the second direction.

11. The power transmission system according to claim 10, characterized in that the second power receiving coil is configured as a Double-D type coil.

12. The first direction is perpendicular to the arrangement direction of the plurality of power-transmitting coils, The power transmission system according to claim 7, characterized in that the second direction is parallel to the arrangement direction.

13. The magnetic field component in the first direction is the magnetic field component generated on each of the plurality of power-transmitting coils, The power transmission system according to claim 7, characterized in that the magnetic field component in the second direction is the magnetic field component generated between adjacent power transmission coils among the plurality of power transmission coils.

14. The power transmission system according to claim 7, characterized in that the receiving device controls the plurality of transmitting coils such that the directions of the magnetic fields generated in adjacent transmitting coils are opposite to each other.

15. The plurality of power transmission coils in the power transmission device are buried in the road. The power transmission system according to any one of claims 1 to 14, characterized in that the power receiving device is mounted on a vehicle traveling on the road.

16. A receiving device that receives power from a power transmitting device by moving over a plurality of power transmitting coils arranged on the power transmitting device, A receiving coil generates an electromotive force in response to the magnetic field generated in each transmitting coil, An AC / DC converter connected to the power receiving coil, The battery connected to the AC / DC converter, A smoothing circuit that smooths out the pulsations in the output power of the AC / DC converter caused by changes in the magnetic field strength in the direction of arrangement of the plurality of power-transmitting coils, A power receiving device characterized by comprising the following features.

17. A receiving device that receives power from a power transmitting device by moving over a plurality of power transmitting coils arranged on the power transmitting device, A first receiving coil that generates an electromotive force in accordance with the magnetic field component in the first direction among the magnetic fields generated by the plurality of transmitting coils, A second receiving coil that generates an electromotive force in accordance with a magnetic field component in a second direction different from the first direction of the aforementioned magnetic field, A power receiving device characterized by comprising the following features.

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