Power transmission / reception system, power transmission device, and power reception device

Abstract

A power transmission / reception system according to the present disclosure comprises a power transmission coil, a resonance capacitor, and a first rectifier circuit and a second rectifier circuit that are connected to the power transmission coil and the resonance capacitor. The first rectifier circuit and the second rectifier circuit are constituted by a combination of a plurality of legs which are provided with switching elements the switching of which is controllable. The power transmission / reception system controls the start timing of switching of the switching elements, in accordance with AC voltages or AC currents that are detected in the first rectifier circuit and the second rectifier circuit. The power transmission / reception system performs coordinated control of the duty ratios of switching of the switching elements that constitute each of the legs.

Description

Power transmission and receiving systems, power transmission equipment, and power receiving equipment Cross-references to related applications

[0001] This application is based on patent application no. 2024-167511, filed on 26 September 2024, and claims the benefit of priority thereunder. The entire contents of that patent application are incorporated herein by reference.

[0002] This disclosure relates to power transmission and reception systems, power transmission equipment, and power receiving equipment.

[0003] Patent Document 1 discloses a power transmission and reception system comprising a coil and inverter (sometimes referred to as a roadside coil and roadside inverter) located on the roadside, a coil (sometimes referred to as a vehicle-side coil) located on the vehicle side, a rectifier circuit, and a resonant circuit. 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 power transmission and reception system, the coil is connected to two-phase legs, and the timing for turning on each switch is determined by a voltage detection circuit in each leg. The power transmission and reception system achieves synchronous rectification operation by generating a gate signal based on the determination result. In addition, the power transmission and reception system prevents unnecessary switching by prohibiting switching in each leg when the output current is sufficiently low.

[0004] Japanese Patent Publication No. 2024-22249

[0005] 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 power supply while driving, multiple coils are arranged on the vehicle so that the second coil can receive power when the first coil cannot. This enables continuous power reception while the vehicle is in motion, as shown in Figure 13, for example. For example, the standard DDQ coil is configured by stacking two types of coils so that the second coil can receive power when the first coil cannot, thereby achieving continuous power transmission and reception.

[0006] 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.

[0007] 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, (1) DC current is allowed to flow until the DC current of the Q coil exceeds 10A, (2) and the low-side switching of the Q coil is started, (3) the current of the Q coil increases rapidly, and (4) an overshoot current occurs 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, causing an overshoot of the DC current. Therefore, in this field, there is a need for a technology that can smoothly switch the vehicle-side coil while keeping the power constant without causing such overshoot.

[0008] 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, turning on the upper arm switch will cause the diode's reverse current protection to fail, resulting in reverse current flow and unstable control. Additionally, power control may be necessary depending on the charging status and acceleration state. Power control is also possible through inverter control on the power transmission side. However, from a safety standpoint, it is desirable to be able to control power on the vehicle side as well. This disclosure provides a technology that enables power control even when switching the vehicle-side coil.

[0009] A first aspect of the present disclosure is a power transmission and reception system comprising a plurality of coil windings, a plurality of resonant circuits, and a plurality of rectifier circuits connected to the coil windings and the resonant circuits. Each of the rectifier circuits is composed of a plurality of legs, each equipped with a switching element capable of controlling switching. The power transmission and reception system is configured to control the timing at which the switching of the switching elements is initiated in accordance with the AC voltage or AC current detected in each of the rectifier circuits. Furthermore, the power transmission and reception system is configured to coordinately control the switching duty cycle of the switching elements constituting each of the legs.

[0010] Here, the leg is composed of two switching elements combined. The power transmission and reception system is preferably configured to control the timing at which one of the two switching elements constituting the leg starts switching, according to the AC voltage or the AC current.

[0011] Furthermore, it is preferable that the power transmission and reception system is configured to control the timing at which the first switching element starts switching and the timing at which the second switching element starts switching, among the two switching elements constituting the leg, are staggered.

[0012] Furthermore, it is preferable that the power transmission and reception system be configured to maintain a constant total amount of transmitted and received power even when the coil windings are switched.

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

[0014] Furthermore, it is preferable that the plurality of coil windings be configured to include coil windings connected between the legs included in different rectifier circuits.

[0015] A second aspect of the present disclosure is a power transmission device comprising a plurality of coil windings, a plurality of resonant circuits, and a plurality of rectifier circuits connected to the coil windings and the resonant circuits. Each of the rectifier circuits is composed of a plurality of legs, each equipped with a switching element capable of controlling switching. The power transmission device is configured to control the timing at which the switching of the switching elements is initiated in response to the AC voltage or AC current detected in each of the rectifier circuits, and to coordinately control the switching duty cycle of the switching elements constituting each of the legs.

[0016] A third aspect of the present disclosure is a power receiving device comprising a plurality of coil windings, a plurality of resonant circuits, and a plurality of rectifier circuits connected to the coil windings and the resonant circuits. Each of the rectifier circuits is composed of a plurality of legs, each equipped with a switching element capable of controlling switching. The power receiving device is configured to control the timing at which the switching of the switching elements is initiated in response to the AC voltage or AC current detected in each of the rectifier circuits, and to coordinately control the switching duty cycle of the switching elements constituting each of the legs.

[0017] According to this disclosure, 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.

[0018] This figure shows a first configuration example of the power transmission and receiving system according to the first embodiment. This figure shows the control logic of the power transmission and receiving system according to the first embodiment. This figure shows the results of the operation simulation of the power transmission and receiving system according to the first embodiment. This figure shows the results of the operation simulation of the power transmission and receiving system according to the first embodiment. This figure shows a second configuration example of the power transmission and receiving system according to the first embodiment. This figure shows a first configuration example of the power transmission and receiving system according to the second embodiment. This figure shows an example of the configuration of the power transmission coil in the power transmission and receiving system according to the second embodiment. This figure shows the control logic of the power transmission and receiving system according to the second embodiment. This figure shows the results of the operation simulation of the power transmission and receiving system according to the second embodiment. This figure shows a second configuration example of the power transmission and receiving system according to the second embodiment. This figure shows a third configuration example of the power transmission and receiving system according to the second embodiment. This figure shows a fourth configuration example of the power transmission and receiving system according to the second embodiment. This figure shows the results of the operation simulation of a conventional power transmission and receiving system. This figure shows the results of the operation simulation of a conventional power transmission and receiving system.

[0019] Embodiments of the present disclosure 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 the directions in the drawings. These terms are for convenience to clarify the description and do not limit the orientation of each component when it is positioned.

[0020] As shown in Figure 1, the power transmission and receiving 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.

[0021] 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 between the device and 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, by switching their configurations. That is, the power converter 104 can function as either a power transmission device or a power receiving device.

[0022] The power transmission device 102 is comprised of a DC voltage source 10, an input capacitor 12, a switching bridge 14, a resonant capacitor 16, and a transmission coil 18.

[0023] 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 has a configuration in which switching elements 14-1 and 14-2 connected in series and switching elements 14-3 and 14-4 connected in series are connected in parallel. 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). The configuration in which two MOSFETs are connected in series is one in which the source of the second MOSFET is connected to the drain of the first MOSFET. The configuration in which two IGBTs are connected in series is one in which the collector of the second IGBT is connected to the emitter of the first IGBT. The diagram shows that each of the switching elements 14-1 to 14-4 has the function of a recirculating diode.

[0024] The input capacitor 12 and the switching bridge 14 are connected in parallel to the DC voltage source 10. The first terminal of the resonant capacitor 16 is connected to the connection point between switching elements 14-3 and 14-4. The first terminal of the transmission coil 18 is connected to the second terminal of the resonant capacitor 16. The second terminal of the transmission coil 18 is connected to the connection point between switching elements 14-1 and 14-2.

[0025] Although Figure 1 shows a configuration of the power transmission device 102 equipped with only one set of resonant capacitor 16 and transmission coil 18, the device is not limited to this configuration. The power transmission device 102 may be configured in which multiple sets of resonant capacitor 16 and transmission coil 18 are connected in parallel. Alternatively, the power transmission device 102 may be configured in which multiple sets of resonant capacitor 16 and transmission coil 18 are connected in series. Furthermore, the power transmission device 102 may be equipped with multiple sets of resonant capacitor 16 and transmission coil 18, with a first set connected in parallel and a second set connected in series to the first set connected in parallel. By arranging multiple sets of resonant capacitor 16 and transmission coil 18 along the road, the power transmission and receiving system 100 can charge and discharge batteries even when a vehicle equipped with the power converter 104 is traveling on the road.

[0026] The power conversion device 104 is comprised of 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.

[0027] Of the two ends of the power transmission coil 20 (20a, 20b), the terminal indicated by the black dot in the figure 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, of the two ends of the power transmission coil 20 (20a, 20b), the terminal opposite to the reference end is called the dependent end (the terminal located opposite the black dot). However, the terms reference end and dependent end are merely convenient terms used to distinguish the polarity of the windings. The terms reference end and dependent end do not limit the structure of the windings, such as the winding method.

[0028] 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.

[0029] In this embodiment, it is preferable that the power transmission coil 20a and the power transmission coil 20b be coils of different types, forms, shapes, and sizes. For example, the power transmission coil 20a is a DD coil composed of eight-shaped coils. The power transmission coil 20b is a Q coil made up of multiple coils. In this embodiment, different types, forms, shapes, and sizes of coils are applied to the power transmission coil 20a and the power transmission coil 20b. This increases the possibility that the power transmission and reception system 100 can transmit and receive power using the second coil (for example, the power transmission coil 20b) even when the first coil (for example, the power transmission coil 20a) is unable to transmit or receive power.

[0030] The first rectifier circuit 26a is configured with leg A and leg B connected in parallel. Leg A is configured with switching elements 26a-1 and 26a-2 connected in series. Leg B is configured with switching elements 26a-3 and 26a-4 connected in series. 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). The configuration in which two MOSFETs are connected in series is one in which the source of the second MOSFET is connected to the drain of the first MOSFET. The configuration in which two IGBTs are connected in series is one in which the collector of the second IGBT is connected to the emitter of the first IGBT. Note that the drawings show each of the switching elements 26a-1 to 26a-4 having the function of a recirculating diode.

[0031] The reference terminal of the power transmission coil 20a is connected to the first terminal of the resonant capacitor 24a. The second terminal of the resonant capacitor 24a is connected to the connection point of the first rectifier circuit 26a that connects switching elements 26a-1 and 26a-2. The dependent terminal of the power transmission coil 20a is connected to the connection point of the first rectifier circuit 26a that connects switching elements 26a-3 and 26a-4.

[0032] Furthermore, the first rectifier circuit 26a is connected in parallel to the smoothing capacitor 28a and the battery 30. That is, the first terminal of the smoothing capacitor 28a and the positive terminal of the battery 30 are connected to the connection point of the first rectifier circuit 26a that connects switching elements 26a-1 and 26a-3. The second terminal of the smoothing capacitor 28a and the negative terminal of the battery 30 are connected to the connection point of the first rectifier circuit 26a that connects switching elements 26a-2 and 26a-4.

[0033] The second rectifier circuit 26b is configured with legs C and D connected in parallel. Leg C is configured with switching elements 26b-1 and 26b-2 connected in series. Leg D is configured with switching elements 26b-3 and 26b-4 connected in series. 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). The configuration in which two MOSFETs are connected in series is one in which the source of the second MOSFET is connected to the drain of the first MOSFET. The configuration in which two IGBTs are connected in series is one in which the collector of the second IGBT is connected to the emitter of the first IGBT. Note that the drawings show each of the switching elements 26b-1 to 26b-4 having the function of a recirculating diode.

[0034] The reference terminal of the power transmission coil 20b is connected to the first terminal of the resonant capacitor 24b. The second terminal of the resonant capacitor 24b is connected to the connection point of the second rectifier circuit 26b that connects switching elements 26b-1 and 26b-2. The dependent terminal of the power transmission coil 20b is connected to the connection point of the second rectifier circuit 26b that connects switching elements 26b-3 and 26b-4.

[0035] Furthermore, the second rectifier circuit 26b is connected in parallel to the smoothing capacitor 28b and the battery 30. Specifically, the first terminal of the smoothing capacitor 28b and the positive terminal of the battery 30 are connected to the connection point of the second rectifier circuit 26b that connects switching elements 26b-1 and 26b-3. The second terminal of the smoothing capacitor 28b and the negative terminal of the battery 30 are connected to the connection point of the second rectifier circuit 26b that connects switching elements 26b-2 and 26b-4.

[0036] The battery 30 may be connected in parallel to the load device. The load device includes, for example, a circuit that drives a motor to propel a vehicle such as an electric car. Alternatively, the load device may be connected instead of the battery 30.

[0037] 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 using a timing signal S. ａ－１ ~S ａ－４ The control unit 106 generates a timing signal S that controls the timing of switching control of the switching elements 26b-1 to 26b-4 in the second rectifier circuit 26b. ｂ－１ ~S ｂ－４ The control unit 106 generates the timing signal S generated. ａ－１ ~S ａ－４ , S ｂ－１ ~S ｂ－４The control unit 106 outputs the generated duty cycles to the power converter 104. The control unit 106 also generates duty cycle signals DutyA and DutyB to control the switching duty cycles in legs A and B of the first rectifier circuit 26a. The control unit 106 generates duty cycle signals DutyC and DutyD to control the switching duty cycles in legs C and D of the second rectifier circuit 26b. The control unit 106 outputs the generated duty cycle signals DutyA, DutyB, DutyC, and DutyD to the power converter 104.

[0038] 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 behind the switching phase of switching elements 14-1 and 14-2 by 180°-δ, where δ is a phase angle smaller than 180°.

[0039] When the phase angle is between 0° and 180° - δ (the first period), the switching elements 14-1 and 14-4 are on, and the switching elements 14-2 and 14-3 are off. During this first period, the voltage Vdc is applied to the resonance capacitor 16 and the transmission coil 18. When the phase angle is between 180° - δ and 180° (the second period), the switching elements 14-1 and 14-3 are on, and the switching elements 14-2 and 14-4 are off. During this second period, the voltage applied to the resonance capacitor 16 and the transmission coil 18 is 0. When the phase angle is between 180° and 360° - δ (the third period), the switching elements 14-1 and 14-4 are off, and the switching elements 14-2 and 14-3 are on. During this third period, the voltage -Vdc is applied to the resonance capacitor 16 and the transmission coil 18. When the phase angle is between 360° - δ and 360° (the fourth period), the switching elements 14-1 and 14-3 are off, and the switching elements 14-2 and 14-4 are on. During this fourth period, the voltage applied to the resonance 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 resonance capacitor 16 and the transmission coil 18 is repeated as Vdc, 0, -Vdc, 0, Vdc, 0, -Vdc,... over time.

[0040] FIG. 2 shows the control logic (configuration example of a control circuit) of the switching control of the power conversion device 104 by the control unit 106.

[0041] The control unit 106 is configured to generate timing signals S ＤＳＡ , S ＤＳＢ such that the switching elements 26a-2 and 26a-4 on the low side of the first rectifier circuit 26a can be switched on / off during a period when the detected voltages V ＴＨ１ exceed the threshold voltage V (13) ａ－２ , S ａ－４ . The control unit 106 is configured to generate timing signals S ＤＳＣ , S ＤＳＤ such that the switching elements 26b-2 and 26b-4 on the low side of the second rectifier circuit 26b can be switched on / off during a period when the detected voltages V ＤＳＣ , V ＤＳＤ exceed the threshold voltage VＴＨ１ The timing signal S is set to enable on / off switching control during the period exceeding this time. ｂ－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.

[0042] That is, the detected voltage V between the connection point connecting switching elements 26a-1 and 26a-2 of leg A and ground. ＤＳＡ The threshold voltage V ＴＨ１ During the period exceeding this time, the control unit 106 provides a timing signal S that enables the switching of the switching element 26a-2. ａ－２ This generates the detected voltage V between the connection point connecting switching elements 26a-3 and 26a-4 of leg B and ground. ＤＳＢ The threshold voltage V ＴＨ１ During the period exceeding this time, the control unit 106 provides a timing signal S that enables the switching of the switching element 26a-4. ａ－４ It generates a detection voltage V between the connection point connecting 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 control unit 106 provides a timing signal S that enables the switching of the switching element 26b-2. ｂ－２ It generates a detection voltage V between the connection point connecting switching elements 26b-3 and 26b-4 of leg D and ground. ＤＳＤ The threshold voltage V ＴＨ１During the period exceeding this time, the control unit 106 provides a timing signal S that enables the 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.

[0043] The control unit 106 applies a detected voltage V to the high-side switching elements 26a-1 and 26a-3 of the first rectifier circuit 26a. ＤＳＡ , V ＤＳＢ The threshold voltage V ＴＨ２ The timing signal S is set to enable on / off switching control during the period exceeding this time. ａ－１ S ａ－３ The control unit 106 generates the detected voltage V to the high-side switching elements 26b-1 and 26b-3 of the second rectifier circuit 26b. ＤＳＣ , V ＤＳＤ The threshold voltage V ＴＨ２ The timing signal S is set to enable on / off switching control during the period exceeding this time. 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.

[0044] That is, the detected voltage V between the connection point connecting switching elements 26a-1 and 26a-2 of leg A and ground. ＤＳＡ The threshold voltage V ＴＨ２ During the period exceeding this time, the control unit 106 provides a timing signal S that enables the switching of the switching element 26a-1. ａ－１ This generates the detected voltage V between the connection point connecting switching elements 26a-3 and 26a-4 of leg B and ground. ＤＳＢ The threshold voltage V ＴＨ２ During the period exceeding this time, the control unit 106 provides a timing signal S that enables the switching of the switching element 26a-3. ａ－３ This generates the following: Also, the detected voltage V between the connection point connecting switching elements 26b-1 and 26b-2 of leg C and ground. ＤＳＣThe threshold voltage V ＴＨ２ During the period exceeding this time, the control unit 106 provides a timing signal S that enables the switching of the switching element 26b-1. ｂ－１ It generates a detection voltage V between the connection point connecting switching elements 26b-3 and 26b-4 of leg D and ground. ＤＳＤ The threshold voltage V ＴＨ２ During the period exceeding this time, the control unit 106 provides a timing signal S that enables the switching of the switching element 26b-3. ｂ－３ This generates the threshold voltage V. ＴＨ２ The detected voltage V in leg A may be set to a different value for each leg. Furthermore, during periods when switching control is not possible, each switching element is not switched and rectified by the recirculating diode. Thus, the detected voltage V in leg A is set to a different value for each leg. ＤＳＡ The threshold voltage V ＴＨ１ During the period exceeding this limit, the timing signal S ａ－２ This controls the timing at which the switching of the switching element 26a-2 begins. Also, the detected voltage V in leg A ＤＳＡ The threshold voltage V ＴＨ２ During the period exceeding this limit, the timing signal S ａ－１ The timing at which switching of switching element 26a-1 begins is controlled by this. With this configuration, the timing at which switching of the high-side switching element 26a-1 constituting leg A begins is later than the timing at which switching of the low-side switching element 26a-2 constituting leg A begins. This is because the threshold voltage V ＴＨ２ The threshold voltage V ＴＨ１ This is because it is larger. In other words, the control unit 106 controls the switching start timing of the two switching elements 26a-1 and 26a-2 that constitute leg A to be staggered. The same applies to legs B to D. The power transmission and reception system 100 can control the timing at which the switching of the switching elements starts according to the AC voltage.

[0045] Furthermore, the control unit 106 controls the DC current I flowing through the battery 30. ＤＣAccording to this, the duty ratio of switching in each leg is controlled. The control unit 106 controls the duty ratio of the detected direct current I ＤＣ and the target current I ＤＣ which is the target value of the direct current I ＤＣ ＊ to generate duty signals DutyA, DutyB, DutyC, DutyD for controlling the duty ratios in legs A to D. Note that the target current I ＤＣ ＊ is obtained from the accelerator opening degree of the vehicle or the like. Specifically, the control unit 106 applies PI control to the difference value between the detected direct current I ＤＣ and the target current I ＤＣ ＊ to generate the duty signals DutyA, DutyB, DutyC, DutyD. Thereby, the control unit 106 generates a duty signal DutyA for controlling the duty ratios of the switching elements 26a-1 and 26a-2 constituting leg A of the first rectifier circuit 26a and outputs it to the power conversion device 104. The control unit 106 generates a duty signal DutyB for controlling the duty ratios of the switching elements 26a-3 and 26a-4 constituting leg B of the first rectifier circuit 26a and outputs it to the power conversion device 104. The control unit 106 generates a duty signal DutyC for controlling the duty ratios of the switching elements 26b-1 and 26b-2 constituting leg C of the second rectifier circuit 26b and outputs it to the power conversion device 104. The control unit 106 generates a duty signal DutyD for controlling the duty ratios of the switching elements ۲۶b-۳ and ۲۶b-۴ constituting leg D of the second rectifier circuit 26b and outputs it to the power conversion device 104. In this way, the power transmission and reception system 100 can cooperate to control the duty ratio of the switching of the switching elements constituting each leg.

[0046] Note that it is not essential to control the duty ratios in legs A to D to be the same. They may be controlled to have different duty ratios according to the amount of power transmitted and received by the power transmission coil 20a and the power transmission coil 20b.

[0047] 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 being performed in the first rectifier circuit 26a to which the power transmission coil 20a is connected, and switching control of leg A is being carried out. In this state, a current i ＡＣａ is flowing through the power transmission coil 20a. Therefore, 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. The electromagnetic coupling between the transmission coil 18 and the power transmission coil 20a starts to switch to the electromagnetic coupling between the transmission coil 18 and the power transmission coil 20b, and the detected voltage V ＤＳＣ becomes equal to or higher than the threshold voltage V ＴＨ１ . As a result, 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). When 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, in the power transmission and reception system 100, it is 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).

[0048] 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 iＡＣｂ The transition between the two is smooth. As a result, the current I flowing through the battery 30 ＤＣ The main component is the current i of the power transmission coil 20a. ＡＣａ Current I based on ＤＣａ and the current i of the power transmission coil 20b ＡＣｂ Current I based on ＤＣｂ It can be smoothly switched between the two. And the current I ＤＣ It is maintained at approximately a constant level.

[0049] Figure 5 shows the current I flowing through power transmission coils 20a and 20b. ＡＣａ (Current i Ｌ１ ) and current I ＡＣｂ (Current i Ｌ２ A second configuration example of a power transmission and reception system 100 that controls the switching of the power converter 104 by means of ) is shown.

[0050] The control unit 106 controls the detected current I to the low-side switching elements 26a-2 and 26a-4 of the first rectifier circuit 26a. ＡＣａ The threshold current I ＴＨ１ The timing signal S is set to enable on / off switching control during the period exceeding this time. ａ－２ S ａ－４ The control unit 106 generates the detected current I to the low-side switching elements 26b-2 and 26b-4 of the second rectifier circuit 26b. ＡＣｂ The threshold current I ＴＨ１ A timing signal S is used to enable on / off switching control during the period exceeding a certain threshold. ｂ－２ S ｂ－４ It generates the detected current I. ＡＣａ , I ＡＣｂ is an alternating current i ＡＣａ i ＡＣｂ This shows the absolute value of the amplitude. However, the detected current I ＡＣａ , I ＡＣｂ is an alternating current i ＡＣａ i ＡＣｂ It may also be the average of the absolute values.

[0051] In other words, the detected current I of the power transmission coil 20a ＡＣａ The threshold current IＴＨ１ During the period exceeding this time, the control unit 106 provides a timing signal S that enables switching of switching elements 26a-2 and 26a-4. ａ－２ and timing signal S ａ－４ It generates the detected current I of the power transmission coil 20b. ＡＣｂ The threshold current I ＴＨ１ During the period exceeding this time, the control unit 106 provides a timing signal S that 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.

[0052] The control unit 106 controls the high-side switching elements 26a-1 and 26a-3 of the first rectifier circuit 26a to detect current I ＡＣａ The threshold current I ＴＨ２ The timing signal S is set to enable on / off switching control during the period exceeding this time. ａ－１ S ａ－３ The control unit 106 generates the detected current I to the high-side switching elements 26b-1 and 26b-3 of the second rectifier circuit 26b. ＡＣｂ The threshold current I ＴＨ２ The timing signal S is set to enable on / off switching control during the period exceeding this time. 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.

[0053] In other words, the detected current I of the power transmission coil 20a ＡＣａ The threshold current I ＴＨ２ During the period exceeding this time, the control unit 106 provides a timing signal S that enables switching of switching elements 26a-1 and 26a-3. ａ－１ and timing signal S ａ－３ This generates the detected current I of the power transmission coil 20b. ＡＣｂ The threshold current IＴＨ２ During the period exceeding this time, the control unit 106 provides a timing signal S that enables switching of switching elements 26b-1 and 26b-3. ｂ－１ and timing signal S 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 is not switched and rectified by the recirculating diode. In this way, the power transmission and reception system 100 can control the timing of when the switching of the switching elements begins in accordance with the AC current.

[0054] 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. ＤＣ The threshold current I ＴＨ２ The timing signal S is set to enable on / off switching control during the period exceeding this time. ａ－１ S ａ－３ The control unit 106 may generate a DC current I to the high-side switching elements 26b-1 and 26b-3 of the second rectifier circuit 26b. ＤＣ The threshold current I ＴＨ２ The timing signal S is set to enable on / off switching control during the period exceeding this time. ｂ－１ S ｂ－３ It may also be configured to generate a DC current I flowing through the battery 30. ＤＣ The threshold current I ＴＨ２ During the period exceeding this time, the control unit 106 provides a timing signal S that enables the 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 necessary components]. Furthermore, during periods when switching control is not possible, each switching element is not controlled by switching control, and rectification is performed by a recirculating diode.

[0055] Even in this configuration, the power transmission and reception system 100 receives current I from the battery 30. ＤＣ This makes it possible to smoothly transition from power transmission coil 20a to power transmission coil 20b in order to maintain the total current at approximately a constant level.

[0056] As shown in Figure 6, the power transmission and receiving system 110 in the second embodiment includes a power transmission device 112, a power conversion device 114, and a control unit 116.

[0057] 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 between the device and the power transmission device 112.

[0058] 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.

[0059] The power conversion device 114 is comprised of 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.

[0060] The first rectifier circuit 26a is configured with leg A and leg B connected in parallel. Leg A is configured with switching elements 26a-1 and 26a-2 connected in series. Leg B is configured with switching elements 26a-3 and 26a-4 connected in series. 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). The configuration in which two MOSFETs are connected in series is one in which the source of the second MOSFET is connected to the drain of the first MOSFET. The configuration in which two IGBTs are connected in series is one in which the collector of the second IGBT is connected to the emitter of the first IGBT. Note that the drawings show each of the switching elements 26a-1 to 26a-4 having the function of a recirculating diode.

[0061] Furthermore, the first rectifier circuit 26a is connected in parallel to the smoothing capacitor 28a and the battery 30. That is, the first terminal of the smoothing capacitor 28a and the positive terminal of the battery 30 are connected to the connection point of the first rectifier circuit 26a that connects switching elements 26a-1 and 26a-3. The second terminal of the smoothing capacitor 28a and the negative terminal of the battery 30 are connected to the connection point of the first rectifier circuit 26a that connects switching elements 26a-2 and 26a-4.

[0062] The second rectifier circuit 26b is configured with legs C and D connected in parallel. Leg C is configured with switching elements 26b-1 and 26b-2 connected in series. Leg D is configured with switching elements 26b-3 and 26b-4 connected in series. 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). The configuration in which two MOSFETs are connected in series is one in which the source of the second MOSFET is connected to the drain of the first MOSFET. The configuration in which two IGBTs are connected in series is one in which the collector of the second IGBT is connected to the emitter of the first IGBT. Note that the drawings show each of the switching elements 26b-1 to 26b-4 having the function of a recirculating diode.

[0063] Furthermore, the second rectifier circuit 26b is connected in parallel to the smoothing capacitor 28b and the battery 30. Specifically, the first terminal of the smoothing capacitor 28b and the positive terminal of the battery 30 are connected to the connection point of the second rectifier circuit 26b that connects switching elements 26b-1 and 26b-3. The second terminal of the smoothing capacitor 28b and the negative terminal of the battery 30 are connected to the connection point of the second rectifier circuit 26b that connects switching elements 26b-2 and 26b-4.

[0064] The battery 30 may be connected in parallel to the load device. The load device includes, for example, a circuit that drives a motor to propel a vehicle such as an electric car. Alternatively, the load device may be connected instead of the battery 30.

[0065] Of the ends of the power transmission coil 20 (20a, 20b, 20c, 20d), the terminals indicated by black dots in the figure are the reference ends. The reference ends are defined as terminals where 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, of the ends of the power transmission coil 20 (20a, 20b, 20c, 20d), the terminals opposite to the reference ends are referred to as the dependent ends. However, the terms reference end and dependent end are merely convenient terms used to distinguish the polarity of the windings. The terms reference end and dependent end do not limit the structure of the windings, such as the winding method.

[0066] In this embodiment, the power transmission coils 20 (20a, 20b, 20c, 20d) are preferably flat, stackless coils formed in a rectangular loop shape. Figure 7 shows an example of the configuration of the power transmission coils 20 (20a, 20b, 20c, 20d) as a circuit diagram. Each power transmission coil 20a to 20d is formed by a conductor in a rectangular loop shape and is flat. The power transmission coils 20a to 20d are arranged in a predetermined direction so that the areas around which the conductors circulate 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 circulates counterclockwise in a rectangular shape with the same number of turns 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.

[0067] 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. In this embodiment, coils of different types, forms, shapes, and sizes are applied to the power transmission coils 20 (20a, 20b, 20c, 20d). This increases the possibility that the power transmission and reception system 110 can transmit and receive power using the second coil even when the first coil cannot transmit or receive power.

[0068] The reference terminal of the power transmission coil 20a (the terminal shown as a black dot in Figure 6) is connected to the first terminal of the resonant capacitor 24a. The second terminal of the resonant capacitor 24a is connected to connection point Ta, which connects switching elements 26a-1 and 26a-2 of the first rectifier circuit 26a. The dependent terminal of the power transmission coil 20b (the terminal located on the opposite side of the black dot) is connected to the first terminal of the resonant capacitor 24b. The second terminal of the resonant capacitor 24b is connected to connection point Tb, which connects switching elements 26a-3 and 26a-4 of the first rectifier circuit 26a.

[0069] The reference terminal of the power transmission coil 20c is connected to the first terminal of the resonant capacitor 24c. The second terminal of the resonant capacitor 24c is connected to the connection point Tc that connects 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 the first terminal of the resonant capacitor 24d. The second terminal of the resonant capacitor 24d is connected to the connection point Td that connects switching elements 26b-3 and 26b-4 of the second rectifier circuit 26b.

[0070] 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.

[0071] 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 in the first rectifier circuit 26a and leg C in the second rectifier circuit 26b.

[0072] 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 using a timing signal S. ａ－１ ~S ａ－４ The control unit 116 generates a timing signal S that controls the timing of switching control of the switching elements 26b-1 to 26b-4 in the second rectifier circuit 26b. ｂ－１ ~S ｂ－４ The control unit 116 generates the timing signal S generated. ａ－１ ~S ａ－４ , S ｂ－１ ~S ｂ－４ The control unit 116 outputs the generated duty cycles to the power converter 114. The control unit 116 also generates duty cycle signals DutyA and DutyB to control the switching duty cycles in legs A and B of the first rectifier circuit 26a. The control unit 116 generates duty cycle signals DutyC and DutyD to control the switching duty cycles in legs C and D of the second rectifier circuit 26b. The control unit 116 outputs the generated duty cycle signals DutyA, DutyB, DutyC, and DutyD to the power converter 114.

[0073] Figure 8 shows the control logic (an example of the control circuit configuration) for the switching control of the power converter 114 by the control unit 116.

[0074] The control unit 116 applies a detected voltage V to the low-side switching elements 26a-2 and 26a-4 of the first rectifier circuit 26a. ＤＳＡ , V ＤＳＢ The threshold voltage V ＴＨ１ The timing signal S is set to enable on / off switching control during the period exceeding this time. ａ－２ S ａ－４ The control unit 116 generates the detected voltage V to the low-side switching elements 26b-2 and 26b-4 of the second rectifier circuit 26b. ＤＳＣ , V ＤＳＤ The threshold voltage V ＴＨ１The timing signal S is set to enable on / off switching control during the period exceeding this time. ｂ－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.

[0075] That is, the detected voltage V between the connection point connecting switching elements 26a-1 and 26a-2 of leg A and ground. ＤＳＡ The threshold voltage V ＴＨ１ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the switching of the switching element 26a-2. ａ－２ This generates the detected voltage V between the connection point connecting switching elements 26a-3 and 26a-4 of leg B and ground. ＤＳＢ The threshold voltage V ＴＨ１ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the switching of the switching element 26a-4. ａ－４ It generates a detection voltage V between the connection point connecting 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 control unit 116 provides a timing signal S that enables the switching of the switching element 26b-2. ｂ－２ It generates a detection voltage V between the connection point connecting switching elements 26b-3 and 26b-4 of leg D and ground. ＤＳＤ The threshold voltage V ＴＨ１During the period exceeding this time, the control unit 116 provides a timing signal S that enables the 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.

[0076] The control unit 116 applies a detected voltage V to the high-side switching elements 26a-1 and 26a-3 of the first rectifier circuit 26a. ＤＳＡ , V ＤＳＢ 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 The control unit 116 generates the detected voltage V to the high-side switching elements 26b-1 and 26b-3 of the second rectifier circuit 26b. ＤＳＣ , V ＤＳＤ The threshold voltage V ＴＨ２ The timing signal S is set to enable on / off switching control during the period exceeding this time. 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.

[0077] That is, the detected voltage V between the connection point connecting switching elements 26a-1 and 26a-2 of leg A and ground. ＤＳＡ The threshold voltage V ＴＨ２ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the switching of the switching element 26a-1. ａ－１ This generates the detected voltage V between the connection point connecting switching elements 26a-3 and 26a-4 of leg B and ground. ＤＳＢ The threshold voltage V ＴＨ２ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the switching of the switching element 26a-3. ａ－３ It generates a detection voltage V between the connection point connecting switching elements 26b-1 and 26b-2 of leg C and ground. ＤＳＣThe threshold voltage V ＴＨ２ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the switching of the switching element 26b-1. ｂ－１ It generates a detection voltage V between the connection point connecting switching elements 26b-3 and 26b-4 of leg D and ground. ＤＳＤ The threshold voltage V ＴＨ２ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the switching of the switching element 26b-3. ｂ－３ This 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 performs rectification with a recirculating diode without switching control. In this way, the power transmission and reception system 110 can control the timing at which the switching of the switching elements begins.

[0078] Furthermore, the control unit 116 controls the DC current I flowing through the battery 30. ＤＣ Accordingly, the duty cycle of the switching in each leg is controlled. The control unit 116 controls the detected DC current I ＤＣ and DC current I 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. ＤＣ ＊ This is obtained from the vehicle's accelerator opening, etc. Specifically, the control unit 116 receives the detected DC current I ＤＣ and target current I ＤＣ ＊PI control is applied to the difference value to generate duty signals DutyA, DutyB, DutyC, and DutyD. As a result, the control unit 116 generates duty signal DutyA, which controls the duty cycle of switching elements 26a-1 and 26a-2 that constitute leg A of the first rectifier circuit 26a, and outputs it to the power converter 114. The control unit 116 generates duty signal DutyB, which controls the duty cycle of switching elements 26a-3 and 26a-4 that constitute leg B of the first rectifier circuit 26a, and outputs it to the power converter 114. The control unit 116 generates duty signal DutyC, which controls the duty cycle of switching elements 26b-1 and 26b-2 that constitute leg C of the second rectifier circuit 26b, and outputs it to the power converter 114. The control unit 116 generates a duty signal DutyD that controls the duty cycle of the switching elements 26b-3 and 26b-24 that constitute leg D of the second rectifier circuit 26b, and outputs it to the power converter 114. In this way, the power transmission and reception system 110 can coordinately control the switching duty cycle of the switching elements that constitute each leg.

[0079] It is not mandatory to control the duty cycles in Legs A to D to be the same. The duty cycles may be controlled to be different for each other depending on the amount of power transmitted and received by power transmission coils 20a and 20b.

[0080] Figure 9 shows the results of an operation simulation of the power transmission and reception system 110 when the power transmission coil 20a and power transmission coil 20b are repeatedly switched. Each time the coils are switched, the current i flows through the power transmission coils 20a to 20d. ＡＣａ ~i ＡＣｄ The switching is smooth. As a result, current I ＤＣ It is maintained at approximately a constant level.

[0081] Figure 10 shows the current I flowing through the power transmission coils 20a to 20d. ＡＣａ From current I ＡＣｄ A second configuration example of a power transmission and reception system 110 that performs switching control of the power converter 114 is shown.

[0082] The control unit 116 controls the detected current I to the low-side switching elements 26a-2 and 26a-4 of the first rectifier circuit 26a. ＡＣａ , I ＡＣｂ The threshold current I ＴＨ１ The timing signal S is set to enable on / off switching control during the period exceeding this time. ａ－２ S ａ－４ The control unit 116 generates the detected current I to the low-side switching elements 26b-2 and 26b-4 of the second rectifier circuit 26b. ＡＣｃ , I ＡＣｄ The threshold current I ＴＨ１ The timing signal S is set to enable on / off switching control during the period exceeding this time. 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.

[0083] In other words, the detected current I of the power transmission coil 20a ＡＣａ The threshold current I ＴＨ１ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the switching of the switching element 26a-2. ａ－２ It generates the detected current I of the power transmission coil 20b. ＡＣｂ The threshold current I ＴＨ１ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the 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 IＴＨ１ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the switching of the switching element 26b-2. ｂ－２ It generates the detected current I of the power transmission coil 20d. ＡＣｄ The threshold current I ＴＨ１ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the 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.

[0084] The control unit 116 detects current I for the high-side switching elements 26a-1 and 26a-3 of the first rectifier circuit 26a. ＡＣａ , I ＡＣｂ The threshold current I ＴＨ２ The timing signal S is set to enable on / off switching control during the period exceeding this time. ａ－１ S ａ－３ The control unit 116 generates the detected current I to the high-side switching elements 26b-1 and 26b-3 of the second rectifier circuit 26b. ＡＣｃ , I ＡＣｄ The threshold current I ＴＨ２ The timing signal S is set to enable on / off switching control during the period exceeding this time. 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.

[0085] In other words, the detected current I of the power transmission coil 20a ＡＣａ The threshold current I ＴＨ２ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the switching of the switching element 26a-1. ａ－１ It generates the detected current I of the power transmission coil 20b. ＡＣｂ The threshold current I ＴＨ２ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the switching of the switching element 26a-3. ａ－３It generates the detection current I of the power transmission coil 20c. ＡＣｃ The threshold current I ＴＨ２ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the switching of the switching element 26b-1. ｂ－１ It generates the detected current I of the power transmission coil 20d. ＡＣｄ The threshold current I ＴＨ２ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the 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 is not switched and rectified by the recirculating diode.

[0086] 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. 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 The control unit 116 may generate a DC current I to the high-side switching elements 26b-1 and 26b-3 of the second rectifier circuit 26b. ＤＣ The threshold current I ＴＨ２ The timing signal S is set to enable on / off switching control during the period exceeding this time. ｂ－１ S ｂ－３ It may also be configured to generate a DC current I flowing through the battery 30. ＤＣ The threshold current I ＴＨ２ During the period exceeding this time, the control unit 116 provides a timing signal S that enables the 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 necessary components]. Furthermore, during periods when switching control is not possible, each switching element is not controlled by switching control, and rectification is performed by a recirculating diode.

[0087] Even in this configuration, the power transmission and reception system 110 receives current I from 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.

[0088] As shown in Figure 11, the power transmission and reception system 110 has a terminal voltage V of the high-side switching element 26a-1 of leg A included in the power converter 114. ＤＳＡ The terminal voltage V of the high-side switching element 26a-3 of leg B ＤＳＢ The terminal voltage V of the high-side switching element 26b-1 of leg C ＤＳＣ , and the terminal voltage V of the high-side switching element 26b-3 of leg D ＤＳＤ Similar control can be achieved using [this method].

[0089] Furthermore, as shown in Figure 12, the power transmission and reception system 110 transmits 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 from the midpoint X to the connection point Tc of leg C. ＤＳＣ The voltage V from the midpoint X to the connection point Td of leg D. ＤＳＤ Similar control can be achieved using [this method].

[0090] [Configuration of the Disclosure] [Configuration 1] 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 the switching, wherein the timing for starting the switching of the switching element is controlled in accordance with the AC voltage or AC current detected in each rectifier circuit, and the duty cycle of the switching of the switching elements constituting each leg is controlled in a coordinated manner. [Configuration 2] The power transmission and reception system according to Configuration 1, wherein the leg is formed by combining two of the switching elements, and the timing for starting the switching of one of the two switching elements constituting the leg is controlled in accordance with the AC voltage or AC current. [Configuration 3] The power transmission and reception system according to Configuration 2, wherein the timing for starting the switching of the first switching element and the timing for starting the switching of the second switching element among the two switching elements constituting the leg are controlled to be staggered. [Configuration 4] A power transmission and reception system according to Configuration 1, wherein the system is configured to maintain a constant total amount of transmitted and received power even when the coil windings are switched. [Configuration 5] A power transmission and reception system according to any one of Configurations 1 to 4, wherein the plurality of coil windings are configured to include coil windings connected between the legs included in each of the rectifier circuits. [Configuration 6] A power transmission and reception system according to Configuration 5, wherein the plurality of coil windings are configured to include coil windings connected between the legs included in different rectifier circuits.[Configuration 7] A power transmission device comprising: a plurality of coil windings; a plurality of resonant circuits; and a plurality of rectifier circuits, each comprising a plurality of legs connected to the coil windings and the resonant circuits and equipped with switching elements capable of controlling switching, wherein the power transmission device is configured to control the timing at which the switching of the switching elements is started in accordance with the AC voltage or AC current detected in each rectifier circuit, and to coordinately control the switching duty cycle of the switching elements constituting each leg. [Configuration 8] A power receiving device comprising: a plurality of coil windings; a plurality of resonant circuits; and a plurality of rectifier circuits, each comprising a plurality of legs connected to the coil windings and the resonant circuits and equipped with switching elements capable of controlling switching, wherein the power receiving device is configured to control the timing at which the switching of the switching elements is started in accordance with the AC voltage or AC current detected in each rectifier circuit, and to coordinately control the switching duty cycle of the switching elements constituting each leg.

Claims

1. A power transmission and reception system comprising: a plurality of coil windings; a plurality of resonant circuits; and a plurality of rectifier circuits, each comprising a plurality of legs connected to the coil windings and the resonant circuits and equipped with switching elements capable of controlling switching, wherein the system is configured to control the timing at which the switching of the switching elements is initiated in accordance with the AC voltage or AC current detected in each rectifier circuit, and to coordinately control the switching duty cycle of the switching elements constituting each leg.

2. A power transmission and reception system according to claim 1, wherein the leg is configured by combining two of the switching elements, and is configured to control the timing at which switching of one of the two switching elements constituting the leg is initiated in accordance with the AC voltage or the AC current.

3. A power transmission and reception system according to claim 2, wherein the system is configured to control the timing at which the first switching element starts switching and the timing at which the second switching element starts switching, among the two switching elements constituting the leg, are staggered.

4. A power transmission and reception system according to claim 1, wherein the system is configured to maintain 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, wherein the plurality of coil windings are configured to 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, wherein the plurality of coil windings are configured to include coil windings connected between the legs included in different rectifier circuits.

7. A power transmission device comprising: a plurality of coil windings; a plurality of resonant circuits; and a plurality of rectifier circuits, each comprising a plurality of legs connected to the coil windings and the resonant circuits and equipped with switching elements capable of controlling switching, wherein the power transmission device is configured to control the timing at which the switching of the switching elements is started in accordance with the AC voltage or AC current detected in each of the rectifier circuits, and to coordinately control the switching duty cycle of the switching elements constituting each of the legs.

8. A power receiving device comprising: a plurality of coil windings; a plurality of resonant circuits; and a plurality of rectifier circuits, each comprising a plurality of legs connected to the coil windings and the resonant circuits and equipped with switching elements capable of controlling switching, wherein the power receiving device is configured to control the timing at which the switching of the switching elements is started in accordance with the AC voltage or AC current detected in each of the rectifier circuits, and to coordinately control the switching duty cycle of the switching elements constituting each of the legs.

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