Power transmission and receiving systems, power transmission equipment, and power receiving equipment

Abstract

This system provides a power transmission and reception system that can control power even when switching on the vehicle's coils. [Solution] A power transmission and reception system 100 comprises a power transmission coil 20 (20a, 20b), a resonant capacitor 24 (24a, 24b), and a first rectifier circuit 26a and a second rectifier circuit 26b, which are combinations of multiple legs each equipped with switching elements 26a-1 to 26a-4, 26b-1 to 26b-4 connected to the power transmission coil 20 (20a, 20b) and the resonant capacitor 24 (24a, 24b), wherein the timing for starting the switching of the switching elements 26a-1 to 26a-4, 26b-1 to 26b-4 is controlled in accordance with the AC voltage or AC current detected in the first rectifier circuit 26a and the second rectifier circuit 26b, and the duty cycles of the switching elements 26a-1 to 26a-4, 26b-1 to 26b-4 constituting the multiple legs are controlled in a coordinated manner.

Description

[Technical Field]

[0001] This invention relates to a power transmission and reception system, a power transmission device, and a power receiving device. [Background technology]

[0002] A power transmission and reception system comprising a roadside coil and roadside inverter, and a vehicle-side coil, rectifier circuit, and resonant circuit is disclosed (Patent Document 1). The rectifier circuit has an active semiconductor element and a voltage sensor, and transmits and receives power from the roadside coil and roadside inverter in a contactless manner. In this transmission and reception system, the coil is connected to two-phase legs, and the timing for turning on each switch is detected by a voltage detection circuit in each leg, and synchronous rectification operation is achieved by generating a gate signal based on this. In addition, depending on the detected value of the output power, if the output current is sufficiently low, the switch operation in each leg is prohibited to prevent unnecessary switching. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2024-22249 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In such power transmission and reception systems, the position of the magnetic field generated by the roadside coil relative to the vehicle-side coil changes as the vehicle moves. In on-road power supply, multiple coils are arranged so that if one cannot receive power, the other can. This enables continuous power supply while the vehicle is in motion, as shown in Figure 13. For example, the standard DDQ coil uses two types of coils stacked on top of each other, and is designed so that if one cannot receive power, the other can, thus achieving continuous power transmission and reception.

[0005] As shown in Figure 13, large fluctuations in the received power can cause the battery to deteriorate due to heat generation and other factors. Therefore, it is important to keep the battery's charging power constant to suppress battery deterioration.

[0006] Furthermore, if the timing of power control is not appropriate when the vehicle-side coil switches, overshoot will occur. Figure 14 shows the results of a circuit simulation when the vehicle-side coil switches from an eight-shaped DD coil to a Q coil with multiple coils. For example, if (1) DC current is allowed to flow until the DC current of the Q coil exceeds 10A, and (2) the low-side switching of the Q coil is started, (3) a rapid increase in the current of the Q coil occurs, and (4) an overshoot current is generated due to the increase in the DC current of the Q coil. Thus, if control is started from a small duty cycle when the DC current of the Q coil has started to flow and is around 10A, the coil current increases rapidly and an overshoot of the DC current occurs. There is a need for a technology that can smoothly switch the vehicle-side coil while keeping the power constant without causing such overshoot.

[0007] Furthermore, if the coil coupling between the vehicle-side coil and the roadside coil is low, insufficient current will flow through the coil, causing the diode to fail to conduct. In this state, if the switch on the upper arm is turned on, current will flow in the reverse direction because there is no reverse current protection for the diode, leading to unstable control. In addition, it may be necessary to control the received power depending on the charging status and acceleration state. Power control is possible with the inverter control on the power transmission side, but from a safety standpoint, it is desirable to be able to control it on the vehicle side as well. [Means for solving the problem]

[0008] One aspect of the present invention is a power transmission and reception system comprising a plurality of coil windings, a plurality of resonant circuits, and a plurality of rectifier circuits formed by combining a plurality of legs, each of which is connected to the coil windings and the resonant circuits and has a switching element capable of controlling switching, characterized in that the timing for initiating the switching of the switching element is controlled in accordance with the AC voltage or AC current detected in the rectifier circuit, and the switching duty cycles of the switching elements constituting the plurality of legs are controlled in a coordinated manner.

[0009] Here, the leg is configured by combining two of the switching elements, and it is preferable to control the timing at which one of the switching elements constituting the leg starts switching according to the AC voltage or the AC current.

[0010] Furthermore, it is preferable to control the timing at which the switching of one of the switching elements constituting the leg starts to switch to the timing at which the other switching element constituting the leg starts to switch.

[0011] Furthermore, it is preferable to maintain a constant total power output even when the coil windings are switched.

[0012] Furthermore, it is preferable that the plurality of coil windings include coil windings connected between the legs included in each of the rectifier circuits.

[0013] Furthermore, it is preferable that the plurality of coil windings include coil windings connected between the legs included in different rectifier circuits.

[0014] Another aspect of the present invention is a power transmission device comprising a plurality of coil windings, a plurality of resonant circuits, and a plurality of rectifier circuits formed by combining a plurality of legs, each having a switching element connected to the coil windings and the resonant circuits and capable of controlling switching, characterized in that the timing for initiating the switching of the switching elements is controlled in accordance with the AC voltage or AC current detected in the rectifier circuit, and the switching duty cycles of the switching elements constituting the plurality of legs are controlled in a coordinated manner.

[0015] Another aspect of the present invention is a power receiving device comprising a plurality of coil windings, a plurality of resonant circuits, and a plurality of rectifier circuits formed by combining a plurality of legs, each having a switching element connected to the coil windings and the resonant circuits and capable of controlling switching, characterized in that the timing for initiating the switching of the switching elements is controlled in accordance with the AC voltage or AC current detected in the rectifier circuit, and the switching duty cycles of the switching elements constituting the plurality of legs are controlled in a coordinated manner. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a power transmission and reception system that can control power even when switching vehicle-side coils. This prevents overcharging of the battery from the roadside coil when charging is not needed or during regenerative braking. [Brief explanation of the drawing]

[0017] [Figure 1] This is a diagram showing the configuration of the power transmission and reception system according to the first embodiment. [Figure 2] This diagram shows the control logic of the power transmission and reception system according to the first embodiment. [Figure 3] This figure shows the results of an operation simulation of the power transmission and reception system according to the first embodiment. [Figure 4] This figure shows the results of an operation simulation of the power transmission and reception system according to the first embodiment. [Figure 5] This figure shows another example of the configuration of the power transmission and reception system according to the first embodiment. [Figure 6] This diagram shows the configuration of the power transmission and reception system according to the second embodiment. [Figure 7] This figure shows an example of the configuration of a power transmission coil in a power transmission and receiving system according to the second embodiment. [Figure 8] This figure shows the control logic of the power transmission and reception system according to the second embodiment. [Figure 9] This figure shows the results of an operation simulation of the power transmission and reception system according to the second embodiment. [Figure 10] This figure shows another example of the configuration of a power transmission and reception system according to the second embodiment. [Figure 11] This figure shows another example of the configuration of a power transmission and reception system according to the second embodiment. [Figure 12] This figure shows another example of the configuration of a power transmission and reception system according to the second embodiment. [Figure 13] This figure shows the results of a simulation of the operation of a conventional power transmission and reception system. [Figure 14] This figure shows the results of a simulation of the operation of a conventional power transmission and reception system. [Modes for carrying out the invention]

[0018] Embodiments of the present invention will be described below. The same reference numerals are used for identical components shown in multiple drawings to simplify their description. Unless otherwise specified, terms indicating directions such as up, down, left, and right in this specification refer to directions in the drawings. These terms are for explanatory convenience and do not limit the orientation of each component when it is positioned.

[0019] As shown in Figure 1, the power transmission and reception system 100 in the first embodiment is configured to include a power transmission device 102, a power conversion device 104, and a control unit 106.

[0020] The power transmission device 102 is used, for example, as a roadside device placed on the road surface where a vehicle travels. The power converter 104 is used, for example, as a vehicle-side device mounted on a vehicle. The power transmission and reception system 100 is used for power transmission, supplying power from the power transmission device 102 to the power converter 104 wirelessly. The power transmission and reception system 100 is also used for power transmission while the vehicle is in motion. The power converter 104 is mounted on a vehicle such as an electric vehicle and can send and receive current to and from the power transmission device 102. In addition, the power transmission and reception system 100 can be used with the power transmission device 102 as the receiving side and the power converter 104 as the transmitting side. That is, the power converter 104 can function as either a power transmission device or a power receiving device.

[0021] The power transmission device 102 includes a DC voltage source 10, an input capacitor 12, a switching bridge 14, a resonant capacitor 16, and a transmission coil 18.

[0022] The DC voltage source 10 may include an AC / DC converter that converts AC power supplied from a commercial power system (power grid) into DC power. Alternatively, the DC voltage source 10 may be a battery. The switching bridge 14 is configured by connecting in parallel a series-connected switching element 14-1 and switching element 14-2, and a series-connected switching element 14-3 and switching element 14-4. The switching elements 14-1 to 14-4 may be semiconductor elements such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors). Two MOSFETs connected in series means that the source of one MOSFET is connected to the drain of the other MOSFET. Two IGBTs connected in series means that the collector of one IGBT is connected to the emitter of the other IGBT. Note that each of the switching elements 14-1 to 14-4 also has the function of a recirculating diode indicated.

[0023] The input capacitor 12 and the switching bridge 14 are connected in parallel to the DC voltage source 10. One end of the resonant capacitor 16 is connected to the connection point of switching elements 14-1 and 14-2. One end of the transmission coil 18 is connected to the other end of the resonant capacitor 16. The other end of the transmission coil 18 is connected to the connection point of switching elements 14-3 and 14-4.

[0024] In Figure 1, only one set of resonant capacitor 16 and transmission coil 18 is shown, but multiple sets of resonant capacitor 16 and transmission coil 18 may be connected in parallel. Alternatively, multiple sets of resonant capacitor 16 and transmission coil 18 may be connected in series. Furthermore, multiple sets of resonant capacitor 16 and transmission coil 18 may be provided, with some connected in parallel and others connected in series to the parallel-connected portion. By arranging multiple sets of resonant capacitor 16 and transmission coil 18 along the road, the battery can be charged and discharged even when a vehicle equipped with the power converter 104 is traveling on the road.

[0025] The power conversion device 104 comprises a power transmission coil 20 (20a, 20b), resonant capacitors 24 (24a, 24b), a first rectifier circuit 26a and a second rectifier circuit 26b, smoothing capacitors 28 (28a, 28b), and a battery 30.

[0026] Of the two ends of the power transmission coil 20 (20a, 20b), the end marked with a black dot is the reference end. The reference end is defined as the terminal at which an induced electromotive force of the same polarity appears when the magnetic flux linking two adjacent power transmission coils in the same direction increases or decreases. In the following explanation, the terminal of the power transmission coil 20 (20a, 20b) opposite to the reference end is referred to as the dependent end. However, the terms reference end and dependent end are for convenience in distinguishing the polarity of the windings and do not limit the structure of the windings, such as the winding method.

[0027] The power transmission coil 20a is connected in series with the resonant capacitor 24a. The power transmission coil 20b is connected in series with the resonant capacitor 24b. The power transmission coil 20a and the resonant capacitor 24a are connected to the first rectifier circuit 26a. The power transmission coil 20b and the resonant capacitor 24b are connected to the second rectifier circuit 26b.

[0028] In this embodiment, it is preferable that the power transmission coils 20a and 20b be of different types, forms, shapes, and sizes. For example, the power transmission coil 20a may be a DD coil composed of eight-shaped coils. The power transmission coil 20b may be a Q coil, which is a combination of multiple coils. By using coils of different types, forms, shapes, and sizes for the power transmission coils 20a and 20b, the possibility of power transmission and reception being possible with the other coil even when power transmission and reception is not possible with one coil can be increased.

[0029] The first rectifier circuit 26a has a configuration in which a leg A, consisting of switching elements 26a-1 and 26a-2 connected in series, and a leg B, consisting of switching elements 26a-3 and 26a-4 connected in series, are connected in parallel. The switching elements 26a-1 to 26a-4 may be semiconductor elements such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors). Two MOSFETs connected in series means that the source of one MOSFET is connected to the drain of one MOSFET. Two IGBTs connected in series means that the collector of one IGBT is connected to the emitter of one IGBT. In addition, the function of a recirculating diode is also indicated for each of the switching elements 26a-1 to 26a-4.

[0030] The reference end of the power transmission coil 20a is connected to one end of the resonant capacitor 24a. The other end of the resonant capacitor 24a is connected to the connection point of switching elements 26a-1 and 26a-2 of the first rectifier circuit 26a. The dependent end of the power transmission coil 20a is connected to the connection point of switching elements 26a-3 and 26a-4 of the first rectifier circuit 26a.

[0031] Furthermore, the first rectifier circuit 26a is connected in parallel to the smoothing capacitor 28a and the battery 30. That is, one end of the smoothing capacitor 28a and the positive terminal of the battery 30 are connected to the connection point of switching elements 26a-1 and 26a-3 of the first rectifier circuit 26a. The other end of the smoothing capacitor 28a and the negative terminal of the battery 30 are connected to the connection point of switching elements 26a-2 and 26a-4 of the first rectifier circuit 26a.

[0032] The second rectifier circuit 26b has a configuration in which a leg C, formed by connecting switching elements 26b-1 and 26b-2 in series, and a leg D, formed by connecting switching elements 26b-3 and 26b-4 in series, are connected in parallel. Switching elements 26b-1 to 26b-4 may be semiconductor elements such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors). Two MOSFETs being connected in series means that the source of one MOSFET is connected to the drain of one MOSFET. Two IGBTs being connected in series means that the collector of one IGBT is connected to the emitter of one IGBT. In addition, the function of a recirculating diode is also indicated for each of the switching elements 26b-1 to 26b-4.

[0033] The reference end of the power transmission coil 20b is connected to one end of the resonant capacitor 24b. The other end of the resonant capacitor 24b is connected to the connection point of switching elements 26b-1 and 26b-2 of the second rectifier circuit 26b. The dependent end of the power transmission coil 20b is connected to the connection point of switching elements 26b-3 and 26b-4 of the second rectifier circuit 26b.

[0034] Furthermore, the second rectifier circuit 26b is connected in parallel to the smoothing capacitor 28b and the battery 30. That is, one end of the smoothing capacitor 28b and the positive terminal of the battery 30 are connected to the connection point of switching elements 26b-1 and 26b-3 of the second rectifier circuit 26b. The other end of the smoothing capacitor 28b and the negative terminal of the battery 30 are connected to the connection point of switching elements 26b-2 and 26b-4 of the second rectifier circuit 26b.

[0035] A load device may be connected in parallel to the battery 30. The load device may include, for example, a circuit that drives a motor for propelling a vehicle such as an electric car. Alternatively, a load device may be connected instead of the battery 30.

[0036] The control unit 106 controls the switching of the power converter 104. The control unit 106 controls the switching of the first rectifier circuit 26a and the second rectifier circuit 26b of the power converter 104. Specifically, the control unit 106 controls the timing of the switching control of the switching elements 26a-1 to 26a-4 in the first rectifier circuit 26a and the switching elements 26b-1 to 26b-4 in the second rectifier circuit 26b using a timing signal S. a-1 ~S a-4 ,S b-1 ~S b-4 The control unit 106 generates and outputs to the power converter 104. The control unit 106 also generates duty signals DutyA, DutyB, DutyC, and DutyD to control the switching duty cycles in legs A and B of the first rectifier circuit 26a and legs C and D of the second rectifier circuit 26b, and outputs them to the power converter 104.

[0037] The switching elements 14-1 to 14-4 of the power transmission device 102 are switched to control the conversion of the DC voltage source 10 into AC power of a desired frequency. Switching elements 14-1 and 14-2 are switched to switch on and off alternately. That is, when switching element 14-1 switches from off to on, switching element 14-2 switches from on to off. Similarly, switching elements 14-3 and 14-4 are switched to switch on and off alternately. That is, when switching element 14-3 switches from off to on, switching element 14-4 switches from on to off. The switching phase of switching elements 14-3 and 14-4 lags the switching phase of switching elements 14-1 and 14-2 by 180°-δ, where δ is a phase angle smaller than 180°.

[0038] While the phase angle is between 0° and 180° - δ, the switching element 14-1 and the switching element 14-4 are on, and the switching element 14-2 and the switching element 14-3 are off. During this first period, the voltage Vdc is applied to the resonant capacitor 16 and the transmission coil 18. While the phase angle is between 180° - δ and 180°, the switching element 14-1 and the switching element 14-3 are on, and the switching element 14-2 and the switching element 14-4 are off. During this second period, the voltage applied to the resonant capacitor 16 and the transmission coil 18 is 0. While the phase angle is between 180° and 360° - δ, the switching element 14-1 and 14-4 are off, and the switching element 14-2 and 14-3 are on. During this third period, the voltage -Vdc is applied to the resonant capacitor 16 and the transmission coil 18. While the phase angle is between 360° - δ and 360°, the switching element 14-1 and 14-3 are off, and the switching element 14-2 and 14-4 are on. During this fourth period, the voltage applied to the resonant capacitor 16 and the transmission coil 18 is 0. Thus, by switching the switching elements 14-1 to 14-4, the voltage Vin applied to the resonant capacitor 16 and the transmission coil 18 is repeated as Vdc, 0, -Vdc, 0, Vdc, 0, -Vdc, ······ over time.

[0039] FIG. 2 shows the control logic of the switching control of the power conversion device 104 by the control unit 106.

[0040] The control unit 106 is configured to generate timing signals S DSA [[ID=DNA10]]、V DSB 、V DSC 、V DSD such that on / off switching control is possible during the period when the detected voltages V TH1 exceed the threshold voltage V a-2 、S a-4 、S b-2 、S b-4It generates the detected voltage V. DSA , V DSB , V DSC , V DSD is an AC voltage v DSA , v DSB , v DSC , v DSD This shows the absolute value of the amplitude. However, the detected voltage V DSA , V DSB , V DSC , V DSD is an AC voltage v DSA , v DSB , v DSC , v DSD It may also be the average of the absolute values.

[0041] In other words, the detected voltage V between the connection point of switching elements 26a-1 and 26a-2 of leg A and ground. DSA The threshold voltage V TH1 During the period exceeding this time, a timing signal S enables switching of the switching element 26a-2. a-2 It generates the detection voltage V between the connection point of switching elements 26a-3 and 26a-4 of leg B and ground. DSB The threshold voltage V TH1 During the period exceeding this time, a timing signal S enables switching of the switching element 26a-4. a-4 It generates the detection voltage V between the connection point of switching elements 26b-1 and 26b-2 of leg C and ground. DSC The threshold voltage V TH1 During the period exceeding this time, the timing signal S enables switching of the switching element 26b-2. b-2 It generates the detection voltage V between the connection point of switching elements 26b-3 and 26b-4 of leg D and ground. DSD The threshold voltage V TH1 During the period exceeding this time, a timing signal S enables switching of the switching element 26b-4. b-4 This generates the threshold voltage V. TH1 This can be set to a different value for each leg.

[0042] The control unit 106 detects a voltage V for the high-side switching elements 26a-1 and 26a-3 of the first rectifier circuit 26a and the high-side switching elements 26b-1 and 26b-3 of the second rectifier circuit 26b. DSA , V DSB , V DSC , V DSD The threshold voltage V TH2 A timing signal S is used to enable on / off switching control during the period exceeding a certain threshold. a-1 S a-3 S b-1 S b-3 This generates the threshold voltage V. TH2 The threshold voltage V TH1 It is preferable to set it to a larger value.

[0043] In other words, the detected voltage V between the connection point of switching elements 26a-1 and 26a-2 of leg A and ground. DSA The threshold voltage V TH2 During the period exceeding this time, a timing signal S enables switching of the switching element 26a-1. a-1 It generates the detection voltage V between the connection point of switching elements 26a-3 and 26a-4 of leg B and ground. DSB The threshold voltage V TH2 During the period exceeding this time, a timing signal S enables switching of the switching element 26a-3. a-3 It generates the detection voltage V between the connection point of switching elements 26b-1 and 26b-2 of leg C and ground. DSC The threshold voltage V TH2 During the period exceeding this time, a timing signal S enables switching of the switching element 26b-1. b-1 It generates the detection voltage V between the connection point of switching elements 26b-3 and 26b-4 of leg D and ground. DSD The threshold voltage V TH2 During the period exceeding this time, a timing signal S enables switching of the switching element 26b-3. b-3 This generates the threshold voltage V. TH2This can be set to a different value for each leg. Also, during periods when switching control is not possible, each switching element rectifies using a recirculating diode without switching control.

[0044] Furthermore, the control unit 106 controls the DC current I flowing through the battery 30. DC The switching duty cycle in each leg is controlled accordingly. The control unit 106 controls the detected DC current I DC And the DC current I obtained from the vehicle's accelerator opening, etc. DC The target value is the target current I DC * Depending on the difference, duty cycle signals DutyA, DutyB, DutyC, and DutyD are generated to control the duty cycle in legs A to D. Specifically, the detected DC current I DC and target current I DC * By applying PI control to the difference value, duty signals DutyA, DutyB, DutyC, and DutyD are generated to control the duty cycle of switching elements 26a-1 and 26a-2 constituting leg A of the first rectifier circuit 26a; duty signal DutyB controls the duty cycle of switching elements 26a-3 and 26a-4 constituting leg B of the first rectifier circuit 26a; duty signal DutyC controls the duty cycle of switching elements 26b-1 and 26b-2 constituting leg C of the second rectifier circuit 26b; and duty signal DutyD controls the duty cycle of switching elements 26b-3 and 26b-24 constituting leg D of the second rectifier circuit 26b.

[0045] It is not mandatory to control the duty cycles in Legs A to D to be the same; they may be controlled to have different duty cycles depending on the amount of power transmitted and received by power transmission coils 20a and 20b.

[0046] Figure 3 shows the result of an operation simulation when switching from the power transmission coil 20a to the power transmission coil 20b in the circuit configuration of the power transmission and reception system 100. Before the coil is switched, rectification is performed in the first rectifier circuit 26a to which the power transmission coil 20a is connected, and switching control of leg A is performed. In this state, a current i ACa flows through the power transmission coil 20a, and the main component of the current I DC flowing through the battery 30 is the current I ACa based on the current i DCa in the power transmission coil 20a. When the electromagnetic coupling with the transmission coil 18 starts to switch from the power transmission coil 20a to the power transmission coil 20b and the detected voltage V DSC becomes equal to or higher than the threshold voltage V TH1 , the switching of the switching element 26b-2 on the low side of leg C of the second rectifier circuit 26b is started ((1) in the figure). At this time, the current i ACb flowing through the power transmission coil 20b does not increase rapidly and becomes a constant current ((2) in the figure). As the electromagnetic coupling between the transmission coil 18 and the power transmission coil 20b becomes stronger, the current i ACb in the power transmission coil 20b increases ((3) in the figure). Along with this, the main component of the current I DC flowing through the battery 30 changes from the current I ACa based on the current i DCa in the power transmission coil 20a to the current I ACb based on the current i DCb in the power transmission coil 20b. Thus, it becomes possible to smoothly perform the transition from the power transmission coil 20a to the power transmission coil 20b so as to maintain the total current of the current I DC flowing through the battery 30 substantially constant ((4) in the figure).

[0047] Figure 4 shows the result of an operation simulation of the power transmission and reception system 100 when the switching between the power transmission coil 20a and the power transmission coil 20b is repeated. Each time the coil is switched, the current i ACa flowing through the power transmission coil 20a and the current i ACbis smoothly transitioning. As a result, the current I flowing through the battery 30 DC The main component of is the current i of the power transmission coil 20a ACa Based on the current I DCa And the current i of the power transmission coil 20b ACb Based on the current I DCb Is smoothly switched between, and the current I DC Is maintained substantially constant.

[0048] FIG. 5 shows the current I flowing through the power transmission coil 20a and the power transmission coil 20b ACa (Current i L1 ) And the current I ACb (Current i L2 ) Shows a configuration example of the power transmission and reception system 100 that performs switching control of the power conversion device 104.

[0049] The control unit 106 detects the current I with respect to the switching elements 26a-2 and 26a-4 on the low side of the first rectifier circuit 26a and the switching elements 26b-2 and 26b-4 on the low side of the second rectifier circuit 26b ACa , I ACb Is in a state where on / off switching control is possible during the period when exceeds the threshold current I TH1 To generate the timing signals S a-2 , S a-4 , S b-2 , S b-4 To generate. Note that the detected currents I ACa , I ACb Is the absolute value of the amplitude of the alternating currents i ACa , i ACb . However, the detected currents I ACa , I ACb May be the average value of the absolute values of the alternating currents i ACa , i ACb .

[0050] That is, during the period when the detected current I of the power transmission coil 20a ACa Exceeds the threshold current I TH1 The timing signal S that enables switching of the switching elements 26a-2 and 26a-4 is enabled during the period whena-2 and timing signal S a-4 It generates the detection current I of the power transmission coil 20b. ACb The threshold current I TH1 During the period exceeding this time, a timing signal S enables switching of switching elements 26b-2 and 26b-4. b-2 and timing signal S b-4 This generates the threshold current I. TH1 This can be set to a different value for each leg.

[0051] The control unit 106 detects a current I for the high-side switching elements 26a-1 and 26a-3 of the first rectifier circuit 26a and the high-side switching elements 26b-1 and 26b-3 of the second rectifier circuit 26b. ACa , I ACb The threshold current I TH2 A timing signal S is used to enable on / off switching control during the period exceeding a certain threshold. a-1 S a-3 S b-1 S b-3 This generates the threshold current I. TH2 The threshold current I TH1 It is preferable to set it to a larger value.

[0052] In other words, the detection current I of the power transmission coil 20a ACa The threshold current I TH2 During the period exceeding this time, a timing signal S enables switching of switching elements 26a-1 and 26a-3. a-1 and timing signal S a-3 This generates the detection current I of the power transmission coil 20b. ACb The threshold current I TH2 During the period exceeding this time, a timing signal S enables switching of switching elements 26b-1 and 26b-3. b-1 and timing signal S b-3 This generates the threshold current I. TH2This can be set to a different value for each leg. Also, during periods when switching control is not possible, each switching element rectifies using a recirculating diode without switching control.

[0053] Furthermore, the control unit 106 supplies a DC current I to the high-side switching elements 26a-1 and 26a-3 of the first rectifier circuit 26a and the high-side switching elements 26b-1 and 26b-3 of the second rectifier circuit 26b. DC The threshold current I TH2 A timing signal S is used to enable on / off switching control during the period exceeding a certain threshold. a-1 S a-3 S b-1 S b-3 It may also be possible to generate a DC current I flowing through the battery 30. DC The threshold current I TH2 During the period exceeding this time, a timing signal S enables switching of switching elements 26a-1, 26a-3, 26b-1, and 26b-3. a-1 S a-3 S b-1 S b-3 This generates [the specified value]. Furthermore, during periods when switching control is not possible, each switching element performs rectification using a recirculating diode without switching control.

[0054] Even in this configuration, the current I flowing through the battery 30 DC This makes it possible to smoothly transition from power transmission coil 20a to power transmission coil 20b while maintaining the total current at approximately a constant level.

[0055] As shown in Figure 6, the power transmission and receiving system 110 in the second embodiment includes a power transmission device 112, a power converter 114, and a control unit 116.

[0056] The power transmission device 112 is used, for example, as a roadside device placed on the road surface where a vehicle travels. The power converter 114 is used, for example, as a vehicle-side device mounted on a vehicle. The power transmission and reception system 110 is used for power transmission, supplying power from the power transmission device 112 to the power converter 114 wirelessly. The power transmission and reception system 110 is also used for power transmission while the vehicle is in motion. The power converter 114 is mounted on a vehicle such as an electric vehicle and can send and receive current to and from the power transmission device 112.

[0057] The power transmission device 112 has the same configuration as the power transmission device 102 in the power transmission and reception system 100 of the first embodiment. Therefore, a description of the power transmission device 112 will be omitted.

[0058] The power converter 114 comprises power transmission coils 20 (20a, 20b, 20c, 20d), resonant capacitors 24 (24a, 24b, 24c, 24d), a first rectifier circuit 26a and a second rectifier circuit 26b, smoothing capacitors 28 (28a, 28b), and a battery 30.

[0059] The first rectifier circuit 26a has a configuration in which a leg A, in which switching elements 26a-1 and 26a-2 are connected in series, and a leg B, in which switching elements 26a-3 and 26a-4 are connected in series, are connected in parallel. The switching elements 26a-1 to 26a-4 may be semiconductor elements such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors). Two MOSFETs being connected in series means that the source of one MOSFET is connected to the drain of one MOSFET. Two IGBTs being connected in series means that the collector of one IGBT is connected to the emitter of one IGBT. In addition, the function of a recirculating diode is also indicated for each of the switching elements 14-1 to 14-4.

[0060] Furthermore, the first rectifier circuit 26a is connected in parallel to the smoothing capacitor 28a and the battery 30. That is, one end of the smoothing capacitor 28a and the positive terminal of the battery 30 are connected to the connection point of switching elements 26a-1 and 26a-3 of the first rectifier circuit 26a. The other end of the smoothing capacitor 28a and the negative terminal of the battery 30 are connected to the connection point of switching elements 26a-2 and 26a-4 of the first rectifier circuit 26a.

[0061] The second rectifier circuit 26b has a configuration in which a leg C, formed by connecting switching elements 26b-1 and 26b-2 in series, and a leg D, formed by connecting switching elements 26b-3 and 26b-4 in series, are connected in parallel. Switching elements 26b-1 to 26b-4 may be semiconductor elements such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors). Two MOSFETs being connected in series means that the source of one MOSFET is connected to the drain of one MOSFET. Two IGBTs being connected in series means that the collector of one IGBT is connected to the emitter of one IGBT. In addition, the function of a recirculating diode is also indicated for each of the switching elements 26b-1 to 26b-4.

[0062] Furthermore, the second rectifier circuit 26b is connected in parallel to the smoothing capacitor 28b and the battery 30. That is, one end of the smoothing capacitor 28b and the positive terminal of the battery 30 are connected to the connection point of switching elements 26b-1 and 26b-3 of the second rectifier circuit 26b. The other end of the smoothing capacitor 28b and the negative terminal of the battery 30 are connected to the connection point of switching elements 26b-2 and 26b-4 of the second rectifier circuit 26b.

[0063] A load device may be connected in parallel to the battery 30. The load device may include, for example, a circuit that drives a motor for propelling a vehicle such as an electric car. Alternatively, a load device may be connected instead of the battery 30.

[0064] Of the two ends of the power transmission coil 20 (20a, 20b, 20c, 20d), the end marked with a black dot is the reference end. The reference end is defined as the terminal at which an induced electromotive force of the same polarity appears when the magnetic flux linking two adjacent power transmission coils in the same direction increases or decreases. In the following explanation, the terminal on the opposite side of the power transmission coil 20 (20a, 20b, 20c, 20d) from the reference end is referred to as the dependent end. However, the terms reference end and dependent end are for convenience in distinguishing the polarity of the windings and do not limit the structure of the windings, such as the winding method.

[0065] In this embodiment, the power transmission coils 20 (20a, 20b, 20c, 20d) are preferably stackless coils formed in a flat rectangular loop shape. Figure 7 shows the circuit diagram of the power transmission coils 20 (20a, 20b, 20c, 20d). Each power transmission coil 20a to 20d is formed in a flat rectangular loop shape by a conductor. The power transmission coils 20a to 20d are arranged in a row in a specific direction, such that the areas around which the conductors revolve do not overlap. The number of turns of the power transmission coils 20a to 20d is the same. That is, each power transmission coil 20a to 20d is composed of a conductor that revolves in a rectangular shape counterclockwise the same number of times from the reference end to the dependent end. In two adjacent power transmission windings, the conductors corresponding to the sides extending in the vertical direction are arranged in close proximity. When the magnetic flux linking two adjacent power transmission windings in the same direction increases or decreases, induced electromotive forces of the same polarity appear at the reference ends of the two adjacent power transmission windings, with respect to their respective dependent ends.

[0066] However, the power transmission coils 20 (20a, 20b, 20c, 20d) are not limited to these. For example, it is preferable that the power transmission coils 20 (20a, 20b, 20c, 20d) be coils of different types, forms, shapes, and sizes. By applying coils of different types, forms, shapes, and sizes as the power transmission coils 20 (20a, 20b, 20c, 20d), the possibility of power transmission and reception being possible with other coils even when power transmission and reception is not possible with one coil can be increased.

[0067] The reference end of the power transmission coil 20a is connected to one end of the resonant capacitor 24a. The other end of the resonant capacitor 24a is connected to the connection point Ta of switching elements 26a-1 and 26a-2 of the first rectifier circuit 26a. The dependent end of the power transmission coil 20b is connected to one end of the resonant capacitor 24b. The other end of the resonant capacitor 24b is connected to the connection point Tb of switching elements 26a-3 and 26a-4 of the first rectifier circuit 26a.

[0068] The reference terminal of the power transmission coil 20c is connected to one terminal of the resonant capacitor 24c. The other terminal of the resonant capacitor 24c is connected to the connection point Tc of switching elements 26b-1 and 26b-2 of the second rectifier circuit 26b. The dependent terminal of the power transmission coil 20d is connected to one terminal of the resonant capacitor 24d. The other terminal of the resonant capacitor 24d is connected to the connection point Td of switching elements 26b-3 and 26b-4 of the second rectifier circuit 26b.

[0069] The dependent end of power transmission coil 20a, the reference end of power transmission coil 20b, the dependent end of power transmission coil 20c, and the reference end of power transmission coil 20d are connected in common.

[0070] Specifically, power transmission coils 20a and 20b are connected between leg A and leg B in the first rectifier circuit 26a. Power transmission coils 20c and 20d are connected between leg C and leg D in the second rectifier circuit 26b. Power transmission coils 20b and 20c are connected between leg B and leg C in different first rectifier circuits 26a and second rectifier circuits 26b.

[0071] The control unit 116 controls the switching of the power converter 114. The control unit 116 controls the switching of the first rectifier circuit 26a and the second rectifier circuit 26b of the power converter 114. Specifically, the control unit 116 controls the timing of the switching control of the switching elements 26a-1 to 26a-4 in the first rectifier circuit 26a and the switching elements 26b-1 to 26b-4 in the second rectifier circuit 26b using a timing signal S. a-1 ~S a-4 ,S b-1 ~S b-4 The control unit 116 generates and outputs to the power converter 114. The control unit 116 also generates duty signals DutyA, DutyB, DutyC, and DutyD to control the switching duty cycles in legs A and B of the first rectifier circuit 26a and legs C and D of the second rectifier circuit 26b, and outputs them to the power converter 114.

[0072] Figure 8 shows the control logic for the switching control of the power converter 114 by the control unit 116.

[0073] The control unit 116 detects a voltage V for the switching elements 26a-2 and 26a-4 on the low side of the first rectifier circuit 26a and the switching elements 26b-2 and 26b-4 on the low side of the second rectifier circuit 26b. DSA , V DSB , V DSC , V DSD The threshold voltage V TH1 A timing signal S is used to enable on / off switching control during the period exceeding a certain threshold. a-2 S a-4 Sb-2 S b-4 It generates the detected voltage V. DSA , V DSB , V DSC , V DSD is an AC voltage v DSA , v DSB , v DSC , v DSD This shows the absolute value of the amplitude. However, the detected voltage V DSA , V DSB , V DSC , V DSD is an AC voltage v DSA , v DSB , v DSC , v DSD It may also be the average of the absolute values.

[0074] In other words, the detected voltage V between the connection point of switching elements 26a-1 and 26a-2 of leg A and ground. DSA The threshold voltage V TH1 During the period exceeding this time, a timing signal S enables switching of the switching element 26a-2. a-2 It generates the detection voltage V between the connection point of switching elements 26a-3 and 26a-4 of leg B and ground. DSB The threshold voltage V TH1 During the period exceeding this time, a timing signal S enables switching of the switching element 26a-4. a-4 It generates the detection voltage V between the connection point of switching elements 26b-1 and 26b-2 of leg C and ground. DSC The threshold voltage V TH1 During the period exceeding this time, the timing signal S enables switching of the switching element 26b-2. b-2 It generates the detection voltage V between the connection point of switching elements 26b-3 and 26b-4 of leg D and ground. DSD The threshold voltage V TH1 During the period exceeding this time, a timing signal S enables switching of the switching element 26b-4. b-4 This generates the threshold voltage V. TH1 This can be set to a different value for each leg.

[0075] The control unit 116 detects a voltage V for the high-side switching elements 26a-1 and 26a-3 of the first rectifier circuit 26a and the high-side switching elements 26b-1 and 26b-3 of the second rectifier circuit 26b. DSA , V DSB , V DSC , V DSD The threshold voltage V TH2 A timing signal S is used to enable on / off switching control during the period exceeding a certain threshold. a-1 S a-3 S b-1 S b-3 This generates the threshold voltage V. TH2 The threshold voltage V TH1 It is preferable to set it to a larger value.

[0076] In other words, the detected voltage V between the connection point of switching elements 26a-1 and 26a-2 of leg A and ground. DSA The threshold voltage V TH2 During the period exceeding this time, a timing signal S enables switching of the switching element 26a-1. a-1 It generates the detection voltage V between the connection point of switching elements 26a-3 and 26a-4 of leg B and ground. DSB The threshold voltage V TH2 During the period exceeding this time, a timing signal S enables switching of the switching element 26a-3. a-3 It generates the detection voltage V between the connection point of switching elements 26b-1 and 26b-2 of leg C and ground. DSC The threshold voltage V TH2 During the period exceeding this time, a timing signal S enables switching of the switching element 26b-1. b-1 It generates the detection voltage V between the connection point of switching elements 26b-3 and 26b-4 of leg D and ground. DSD The threshold voltage V TH2 During the period exceeding this time, a timing signal S enables switching of the switching element 26b-3. b-3This generates the threshold voltage V. TH2 This can be set to a different value for each leg. Also, during periods when switching control is not possible, each switching element rectifies using a recirculating diode without switching control.

[0077] Furthermore, the control unit 116 controls the DC current I flowing through the battery 30. DC The switching duty cycle in each leg is controlled accordingly. The control unit 116 controls the detected DC current I DC And the DC current I obtained from the vehicle's accelerator opening, etc. DC The target value is the target current I DC * Depending on the difference, duty cycle signals DutyA, DutyB, DutyC, and DutyD are generated to control the duty cycle in legs A to D. Specifically, the detected DC current I DC and target current I DC * By applying PI control to the difference value, duty signals DutyA, DutyB, DutyC, and DutyD are generated to control the duty cycle of switching elements 26a-1 and 26a-2 constituting leg A of the first rectifier circuit 26a; duty signal DutyB controls the duty cycle of switching elements 26a-3 and 26a-4 constituting leg B of the first rectifier circuit 26a; duty signal DutyC controls the duty cycle of switching elements 26b-1 and 26b-2 constituting leg C of the second rectifier circuit 26b; and duty signal DutyD controls the duty cycle of switching elements 26b-3 and 26b-24 constituting leg D of the second rectifier circuit 26b.

[0078] It is not mandatory to control the duty cycles in Legs A to D to be the same; they may be controlled to have different duty cycles depending on the amount of power transmitted and received by power transmission coils 20a and 20b.

[0079] Figure 9 shows the results of a simulation of the operation of the power transmission and reception system 110 when the power transmission coil 20a and power transmission coil 20b are repeatedly switched. The current i flows through the power transmission coils 20a to 20d each time the coils are switched. ACa ~i ACd The switching is smooth. This allows the current I DC It is maintained at approximately a constant level.

[0080] Figure 10 shows the current I flowing through power transmission coils 20a to 20d. ACa From I ACd This shows an example configuration of a power transmission and reception system 110 that performs switching control of the power converter 114.

[0081] The control unit 116 detects a current I for the switching elements 26a-2 and 26a-4 on the low side of the first rectifier circuit 26a and the switching elements 26b-2 and 26b-4 on the low side of the second rectifier circuit 26b. ACa , I ACb , I ACc , I ACd The threshold current I TH1 A timing signal S is used to enable on / off switching control during the period exceeding a certain threshold. a-2 S a-4 S b-2 S b-4 It generates the detected current I. ACa , I ACb , I ACc , I ACd is an alternating current i ACa i ACb i ACc i ACd This shows the absolute value of the amplitude. However, the detected current I ACa , I ACb , I ACc , I ACd is an alternating current i ACa i ACb i ACc i ACd It may also be the average of the absolute values.

[0082] In other words, the detection current I of the power transmission coil 20a ACa The threshold current I TH1 During the period exceeding this time, a timing signal S enables switching of the switching element 26a-2. a-2 It generates the detection current I of the power transmission coil 20b. ACb The threshold current I TH1 During the period exceeding this time, a timing signal S enables switching of the switching element 26a-4. a-4 It generates the detection current I of the power transmission coil 20c. ACc The threshold current I TH1 During the period exceeding this time, the timing signal S enables switching of the switching element 26b-2. b-2 It generates the detection current I of the power transmission coil 20d. ACd The threshold current I TH1 During the period exceeding this time, a timing signal S enables switching of the switching element 26b-4. b-4 This generates the threshold current I. TH1 This can be set to a different value for each leg.

[0083] The control unit 116 detects a current I for the high-side switching elements 26a-1 and 26a-3 of the first rectifier circuit 26a and the high-side switching elements 26b-1 and 26b-3 of the second rectifier circuit 26b. ACa , I ACb , I ACc , I ACd The threshold current I TH2 A timing signal S is used to enable on / off switching control during the period exceeding a certain threshold. a-1 S a-3 S b-1 S b-3 This generates the threshold current I. TH2 The threshold current I TH1 It is preferable to set it to a larger value.

[0084] In other words, the detection current I of the power transmission coil 20a ACa The threshold current I TH2During the period exceeding this time, a timing signal S enables switching of the switching element 26a-1. a-1 It generates the detection current I of the power transmission coil 20b. ACb The threshold current I TH2 During the period exceeding this time, a timing signal S enables switching of the switching element 26a-3. a-3 It generates the detection current I of the power transmission coil 20c. ACc The threshold current I TH2 During the period exceeding this time, a timing signal S enables switching of the switching element 26b-1. b-1 It generates the detection current I of the power transmission coil 20d. ACd The threshold current I TH2 During the period exceeding this time, a timing signal S enables switching of the switching element 26b-3. b-3 This generates the threshold current I. TH2 This can be set to a different value for each leg. Also, during periods when switching control is not possible, each switching element rectifies using a recirculating diode without switching control.

[0085] Furthermore, the control unit 116 supplies a DC current I to the high-side switching elements 26a-1 and 26a-3 of the first rectifier circuit 26a and the high-side switching elements 26b-1 and 26b-3 of the second rectifier circuit 26b. DC The threshold current I TH2 A timing signal S is used to enable on / off switching control during the period exceeding a certain threshold. a-1 S a-3 S b-1 S b-3 It may also be possible to generate a DC current I flowing through the battery 30. DC The threshold current I TH2 During the period exceeding this time, a timing signal S enables switching of switching elements 26a-1, 26a-3, 26b-1, and 26b-3. a-1 S a-3 S b-1 S b-3This generates [the specified value]. Furthermore, during periods when switching control is not possible, each switching element performs rectification using a recirculating diode without switching control.

[0086] Even in this configuration, the current I flowing through the battery 30 DC This makes it possible to smoothly transition between power transmission coils 20a and 20d so as to maintain the total current at approximately a constant level.

[0087] As shown in Figure 11, the terminal voltage V of the switching element 26a-1 on the high-side of leg A included in the power converter 114 DSA The terminal voltage V of switching element 26a-3 on the high-side of leg B DSB The terminal voltage V of switching element 26b-1 on the high-side of leg C DSC The terminal voltage V of switching element 26b-3 on the high-side of leg D DSD Similar control can be performed using [this method].

[0088] Furthermore, as shown in Figure 12, the voltage V from the midpoint X of the output voltage to the connection point Ta of leg A DSA The voltage V from the midpoint X to the connection point Tb of leg B. DSB The voltage V across the connection point Tc of leg C from the midpoint X. DSC The voltage V from the midpoint X to the connection point Td of leg D. DSD Similar control can be performed using [this method].

[0089] [Configuration of the present invention] [Configuration 1] Multiple coil windings, Multiple resonant circuits, A power transmission and reception system comprising: a coil winding and a plurality of rectifier circuits, each comprising a plurality of legs connected to the resonant circuit and equipped with a switching element capable of controlling the switching; The rectifier circuit controls the timing at which the switching element starts switching in accordance with the detected AC voltage or AC current. A power transmission and reception system characterized by coordinating and controlling the switching duty cycles of the switching elements constituting a plurality of the aforementioned legs. [Configuration 2] The power transmission and reception system described in Configuration 1, The leg is composed of two of the switching elements, A power transmission and reception system characterized by controlling the timing at which switching of one of the switching elements constituting the leg is initiated according to the AC voltage or the AC current. [Configuration 3] The power transmission and reception system described in Configuration 2, A power transmission and reception system characterized by controlling the timing at which the switching of one of the switching elements constituting the leg starts to switch and the timing at which the switching of the other switching element constituting the leg starts to switch. [Structure 4] The power transmission and reception system described in Configuration 1, A power transmission and reception system characterized by maintaining a constant total amount of transmitted and received power even when the coil windings are switched. [Composition 5] A power transmission and reception system described in any one of items 1 to 4, A power transmission and reception system characterized in that the plurality of coil windings include coil windings connected between the legs included in each of the rectifier circuits. [Composition 6] The power transmission and reception system described in Configuration 5, A power transmission and reception system characterized in that the plurality of coil windings include coil windings connected between the legs included in different rectifier circuits. [Composition 7] Multiple coil windings, Multiple resonant circuits, A power transmission device comprising: a coil winding and a plurality of rectifier circuits, each comprising a plurality of legs connected to the resonant circuit and equipped with a switching element capable of controlling the switching; The rectifier circuit controls the timing at which the switching element starts switching in accordance with the detected AC voltage or AC current. A power transmission device characterized by coordinating and controlling the switching duty cycles of the switching elements constituting a plurality of legs. [Structure 8] Multiple coil windings, Multiple resonant circuits, A power receiving device comprising: a coil winding and a plurality of rectifier circuits, each comprising a plurality of legs connected to the resonant circuit and equipped with a switching element capable of controlling the switching; The rectifier circuit controls the timing at which the switching element starts switching in accordance with the detected AC voltage or AC current. A power receiving device characterized by coordinating and controlling the switching duty cycles of the switching elements constituting a plurality of the aforementioned legs. [Explanation of symbols]

[0090] 10 DC voltage source, 12 input capacitor, 14 switching bridge, 14-1 to 14-4 switching elements, 16 resonant capacitor, 18 transmission coil, 20 (20a, 20b, 20c, 20d) power transmission coil, 24 (24a, 24b, 24c, 24d) resonant capacitor, 26a first rectifier circuit, 26b second rectifier circuit, 26a-1 to 26a-4 switching elements, 26b-1 to 26b-4 switching elements, 28 (28a, 28b) smoothing capacitor, 30 battery, 100 power transmission and reception system, 102 power transmission device, 104 power converter, 106 control unit, 110 power transmission and reception system, 112 power transmission device, 114 power converter, 116 control unit.

Claims

1. Multiple coil windings, Multiple resonant circuits, A power transmission and reception system comprising: a coil winding and a plurality of rectifier circuits, each comprising a plurality of legs connected to the resonant circuit and equipped with a switching element capable of controlling the switching; The rectifier circuit controls the timing at which the switching element starts switching in accordance with the detected AC voltage or AC current. A power transmission and reception system characterized by coordinating and controlling the switching duty cycles of the switching elements constituting a plurality of the aforementioned legs.

2. A power transmission and reception system according to claim 1, The leg is composed of two of the switching elements, A power transmission and reception system characterized by controlling the timing at which one of the switching elements constituting the leg starts switching according to the AC voltage or the AC current.

3. A power transmission and reception system according to claim 2, A power transmission and reception system characterized by controlling the timing at which the switching of one of the switching elements constituting the leg starts to switch and the timing at which the switching of the other switching element constituting the leg starts to switch.

4. A power transmission and reception system according to claim 1, A power transmission and reception system characterized by maintaining a constant total amount of transmitted and received power even when the coil windings are switched.

5. A power transmission and reception system according to any one of claims 1 to 4, A power transmission and reception system characterized in that the plurality of coil windings include coil windings connected between the legs included in each of the rectifier circuits.

6. A power transmission and reception system according to claim 5, A power transmission and reception system characterized in that the plurality of coil windings include coil windings connected between the legs included in different rectifier circuits.

7. Multiple coil windings, Multiple resonant circuits, A power transmission device comprising: a coil winding and a plurality of rectifier circuits, each comprising a plurality of legs connected to the resonant circuit and equipped with a switching element capable of controlling the switching; The rectifier circuit controls the timing at which the switching element starts switching in accordance with the detected AC voltage or AC current. A power transmission device characterized by coordinating and controlling the switching duty cycles of the switching elements constituting a plurality of legs.

8. Multiple coil windings, Multiple resonant circuits, A power receiving device comprising: a coil winding and a plurality of rectifier circuits, each comprising a plurality of legs connected to the resonant circuit and equipped with a switching element capable of controlling the switching; The rectifier circuit controls the timing at which the switching element starts switching in accordance with the detected AC voltage or AC current. A power receiving device characterized by coordinating and controlling the switching duty cycles of the switching elements constituting a plurality of the aforementioned legs.

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