Power transmission and reception system

Abstract

This system prevents the voltage conversion ratio from becoming excessively large, thereby providing a miniaturized and highly efficient power transmission and reception system. [Solution] A power transmission and receiving system 110 is provided which is capable of charging and discharging a battery 30 and comprises a plurality of power transmission coils 20a to 20d, resonant capacitors 24a to 24d, a first rectifier circuit 26a and a second rectifier circuit 26b, wherein the switching ratio of the first rectifier circuit 26a and the second rectifier circuit 26b is controlled according to the DC current of the battery 30 and the detected current in each of the plurality of power transmission coils 20a to 20d.

Description

[Technical Field]

[0001] This invention relates to a power transmission and reception system. [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] When synchronous rectification control is applied to control a power transmission and reception system with multiple vehicle-side coils, current flows only to the vehicle-side coils that have a strong magnetic coupling with the roadside coils. In other words, only some of the vehicle-side coils are used, which leads to technical problems such as the power receiving current being concentrated in some coils, resulting in reduced efficiency, or a large current flowing through some coils, leading to a large leakage magnetic field. [Means for solving the problem]

[0005] One aspect of the present invention is a power transmission and reception system capable of charging and discharging a battery, comprising a plurality of coil windings, a plurality of resonant circuits, and a plurality of rectifier circuits formed by combining a plurality of legs connected to the coil windings and the resonant circuits and equipped with switching elements capable of controlling switching, wherein the switching ratio of the rectifier circuits is controlled according to the DC current of the battery and the detected current in each of the plurality of coil windings.

[0006] Here, it is preferable that the switching ratio of the rectifier circuit be controlled to satisfy the conditions set for both efficiency and leakage magnetic field.

[0007] Furthermore, it is preferable that the switching ratio is controlled according to the difference between the DC current and the target DC current, which is the target value of the DC current; the difference between each of the detected currents and the average value of the detected currents; and the target value of the difference.

[0008] Furthermore, each of the rectifier circuits preferably includes a plurality of legs in which the switching elements are connected in series, and the plurality of coil windings preferably include coil windings connected between the legs included in each of the rectifier circuits.

[0009] Furthermore, it is preferable that the plurality of coil windings include coil windings connected between different legs included in the rectifier circuit. [Effects of the Invention]

[0010] According to the present invention, it is possible to prevent the voltage conversion ratio from becoming excessively large and to provide a power transmission and reception system that is miniaturized and highly efficient. [Brief explanation of the drawing]

[0011] [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 block of the power transmission and reception system according to the first embodiment. [Figure 3] This diagram shows the configuration of the power transmission and reception system according to the second embodiment. [Figure 4] 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 5] This diagram shows the control block of the power transmission and reception system according to the second embodiment. [Figure 6] This figure shows the effects of controlling the power transmission and reception system according to the second embodiment. [Figure 7] This figure shows another example of a control block for a power transmission and reception system according to the second embodiment. [Modes for carrying out the invention]

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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 are connected in series when the drain of one MOSFET is connected to the source of the other MOSFET. Two IGBTs are connected in series when the emitter of one IGBT is connected to the collector of the other IGBT. Note that each of the switching elements 14-1 to 14-4 also has a circulating diode shown.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] The first rectifier circuit 26a is configured by connecting in parallel a series-connected switching element 26a-1 and switching element 26a-2, and a series-connected switching element 26a-3 and switching element 26a-4. 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 are connected in series when the drain of one MOSFET is connected to the source of the other MOSFET. Two IGBTs are connected in series when the emitter of one IGBT is connected to the collector of the other IGBT. Note that each of the switching elements 26a-1 to 26a-4 also has a recirculation diode shown.

[0024] 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. In other words, the power transmission coil 20a is connected between the legs included in the first rectifier circuit 26a.

[0025] 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.

[0026] The second rectifier circuit 26b is configured by connecting in parallel the series-connected switching elements 26b-1 and 26b-2, and the series-connected switching elements 26b-3 and 26b-4. The 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 are connected in series when the drain of one MOSFET is connected to the source of the other MOSFET. Two IGBTs are connected in series when the emitter of one IGBT is connected to the collector of the other IGBT. Note that each of the switching elements 26b-1 to 26b-4 also has a recirculation diode shown.

[0027] 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. In other words, the power transmission coil 20b is connected between the legs included in the second rectifier circuit 26b.

[0028] 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.

[0029] 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.

[0030] 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°.

[0031] During the phase angle between 0° and 180°-δ, switching elements 14-1 and 14-4 are on, and switching elements 14-2 and 14-3 are off. During this first period, a voltage Vdc is applied to the resonant capacitor 16 and the transmission coil 18. During the phase angle between 180°-δ and 180°, switching elements 14-1 and 14-3 are on, and switching elements 14-2 and 14-4 are off. During this second period, the voltage applied to the resonant capacitor 16 and the transmission coil 18 is 0. During the phase angle between 180° and 360°-δ, switching elements 14-1 and 14-4 are off, and switching elements 14-2 and 14-3 are on. During this third period, a voltage -Vdc is applied to the resonant capacitor 16 and the transmission coil 18. During the phase angle between 360°-δ and 360°, switching elements 14-1 and 14-3 are off, and switching elements 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. In this way, the switching of switching elements 14-1 to 14-4 causes the voltage Vin applied to the resonant capacitor 16 and the transmission coil 18 to repeat over time as Vdc, 0, -Vdc, 0, Vdc, 0, -Vdc, ...

[0032] 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 DC current I flowing through the battery 30. DC and the detected current I in each of the coil windings of power transmission coil 20a and power transmission coil 20b AC1 and detected current I AC2 The switching ratio (duty cycle) Duty1 of the first rectifier circuit 26a and the switching ratio (duty cycle) Duty2 of the second rectifier circuit 26b are controlled accordingly.

[0033] Note that the detection current I AC1 and detected current I AC2 This refers to the alternating current i flowing through the coil windings of power transmission coil 20a and power transmission coil 20b, respectively. AC1and alternating current i AC2 indicates the absolute value of the amplitude.

[0034] FIG. 2 shows a control block for controlling the control unit 106. The control block of the control unit 106 includes an alternating current control block unit and a direct current control block unit.

[0035] The alternating current control block unit processes the detection currents I AC1 and detection current I AC2 inputted in each of the coil windings of the power transmission coils 20a and 20b. First, the average value I AC1 of the detection current I AC2 and the detection current I ave is obtained, and the difference values (I AC1 - I ave ) between the detection current I AC1 and the average value I ave and the difference values (I AC2 - I ave ) between the detection current I AC2 and the average value I ave are calculated. Further, the difference value (I AC1 - I ave ) between the detection current I AC1 and the average value I ave ) and its target value (I AC1 - I ave ) * and the difference value between the difference value of the detection current I AC2 and the average value I ave (I AC2 - I ave ) and its target value (I AC2 - I ave ) * are calculated. The alternating current control block unit applies PI control to these values and outputs them.

[0036] The direct current control block unit processes the direct current I DC flowing through the battery 30 as an input. First, the difference value (I DC - I DC * ) between the direct current I DC and its target value I DC *The DC control block calculates the value. The DC control block then applies PI control to this value and outputs the result.

[0037] The control unit 106 adds the output of the AC control block and the output of the DC control block to generate and output the switching ratio Duty1 of the first rectifier circuit 26a and the switching ratio Duty2 of the second rectifier circuit 26b. Specifically, the detected current I AC1 and the average value I ave The difference value (I AC1 -I ave ) and its target value (I AC1 -I ave ) * The difference between the PI control value and the DC current I DC Its target value I DC * The difference value (I DC -I DC * The PI control value of ) is added to and the switching ratio Duty1 of the first rectifier circuit 26a is generated and output according to the added value. Also, the detected current I AC2 and the average value I ave The difference value (I AC2 -I ave ) and its target value (I AC2 -I ave ) * The difference between the PI control value and the DC current I DC Its target value I DC * The difference value (I DC -I DC * The PI control value of ) is added to and the switching ratio Duty2 of the second rectifier circuit 26b is generated and output according to the added value.

[0038] The control unit 106 controls the switching of the switching elements 26a-1 to 26a-4 of the first rectifier circuit 26a of the power converter 104 according to the switching ratio Duty 1 of the first rectifier circuit 26a. The control unit 106 also controls the switching of the switching elements 26b-1 to 26b-4 of the second rectifier circuit 26b of the power converter 104 according to the switching ratio Duty 2 of the second rectifier circuit 26b.

[0039] As shown in Figure 3, 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] The first rectifier circuit 26a is configured by connecting in parallel a series-connected switching element 26a-1 and switching element 26a-2, and a series-connected switching element 26a-3 and switching element 26a-4. 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 are connected in series when the drain of one MOSFET is connected to the source of the other MOSFET. Two IGBTs are connected in series when the emitter of one IGBT is connected to the collector of the other IGBT. Note that each of the switching elements 26a-1 to 26a-4 also has a recirculation diode shown.

[0044] In other words, the first rectifier circuit 26a includes a first leg in which switching elements 26a-1 and 26a-2 are connected in series, and a second leg in which switching elements 26a-3 and 26a-4 are connected in series.

[0045] 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.

[0046] The second rectifier circuit 26b is configured by connecting in parallel the series-connected switching elements 26b-1 and 26b-2, and the series-connected switching elements 26b-3 and 26b-4. The 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 are connected in series when the drain of one MOSFET is connected to the source of the other MOSFET. Two IGBTs are connected in series when the emitter of one IGBT is connected to the collector of the other IGBT. Note that each of the switching elements 26b-1 to 26b-4 also has a recirculation diode shown.

[0047] In other words, the second rectifier circuit 26b includes a third leg in which switching elements 26b-1 and 26b-2 are connected in series, and a fourth leg in which switching elements 26b-3 and 26b-4 are connected in series.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] In this embodiment, the power transmission coils 20 (20a, 20b, 20c, 20d) are preferably stackless coils formed in a flat rectangular loop shape. Figure 4 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.

[0052] 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.

[0053] 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 between 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 between switching elements 26a-3 and 26a-4 of the first rectifier circuit 26a.

[0054] The reference end of the power transmission coil 20c is connected to one end of the resonant capacitor 24c. The other end of the resonant capacitor 24c is connected to the connection point between switching elements 26b-1 and 26b-2 of the second rectifier circuit 26b. The dependent end of the power transmission coil 20d is connected to one end of the resonant capacitor 24d. The other end of the resonant capacitor 24d is connected to the connection point between switching elements 26b-3 and 26b-4 of the second rectifier circuit 26b.

[0055] 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.

[0056] Specifically, power transmission coils 20a and 20b are connected between the first and second legs of the first rectifier circuit 26a. Power transmission coils 20c and 20d are connected between the third and fourth legs of the second rectifier circuit 26b. Power transmission coils 20b and 20c are connected between the second and third legs of different first and second rectifier circuits 26a and 26b.

[0057] 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 DC current I flowing through the battery 30. DC and the detected current I in each of the coil windings of power transmission coils 20a to 20d AC1 ~Detection current I AC4According to this, the switching time ratio (duty ratio) Duty1 of the first leg composed of the switching element 26a-1 and the switching element 26a-2 of the first rectifier circuit 26a, the switching time ratio (duty ratio) Duty2 of the second leg composed of the switching element 26a-3 and the switching element 26a-4 of the first rectifier circuit 26a, the switching time ratio (duty ratio) Duty3 of the third leg composed of the switching element 26b-1 and the switching element 26b-2 of the second rectifier circuit 26b, and the switching time ratio (duty ratio) Duty4 of the fourth leg composed of the switching element 26b-3 and the switching element 26b-4 of the second rectifier circuit 26b are controlled.

[0058] FIG. 5 shows a control block for performing the control of the control unit 116. The control block of the control unit 116 includes an AC control block unit and a DC control block unit.

[0059] The AC control block unit performs processing with the detected current I AC1 ~ the detected current I AC4 input to each of the coil windings of the power transmission coils 20a to 20d. First, the average value I AC1 ~ the detected current I AC4 is obtained, and the difference value (I ave -I AC1 ) between the detected current I ave and the average value I AC1 , the difference value (I ave -I AC2 ) between the detected current I ave and the average value I AC2 , the difference value (I ave -I AC3 ) between the detected current I ave and the average value I AC3 , and the difference value (I ave -I AC4 ) between the detected current I ave and the average value I AC4 are calculated. Further, the difference value (I ave -I AC1 ) between the detected current I ave and the average value I AC1 and its target value (I ave -I AC1 -I ave )* The difference value from, detected current I AC2 and the average value I ave The difference value (I AC2 -I ave ) and its target value (I AC2 -I ave ) * The difference value from, detected current I AC3 and the average value I ave The difference value (I AC3 -I ave ) and its target value (I AC3 -I ave ) * The difference value from, detected current I AC4 and the average value I ave The difference value (I AC4 -I ave ) and its target value (I AC4 -I ave ) * The difference between these values ​​is calculated. The AC control block applies PI control to these values ​​and outputs the result.

[0060] The DC control block controls the DC current I flowing through the battery 30. DC The following is processed as input: First, the DC current I DC Its target value I DC * The difference value (I DC -I DC * The DC control block calculates the value. The DC control block then applies PI control to this value and outputs the result.

[0061] The control unit 116 adds the output of the AC control block and the output of the DC control block, and generates and outputs switching ratios Duty1 to Duty4 according to the added value. Specifically, the detected current I AC1 and the average value I ave The difference value (I AC1 -I ave ) and its target value (I AC1 -I ave ) * The difference between the PI control value and the DC current I DC Its target value I DC * The difference value (I DC-I DC * The PI control value of ) is added to and the switching ratio Duty1 is generated and output according to the added value. Also, the detected current I AC2 and the average value I ave The difference value (I AC2 -I ave ) and its target value (I AC2 -I ave ) * The difference between the PI control value and the DC current I DC Its target value I DC * The difference value (I DC -I DC * The PI control value of ) is added to and the switching ratio Duty2 is generated and output according to the added value. Also, the detected current I AC3 and the average value I ave The difference value (I AC3 -I ave ) and its target value (I AC3 -I ave ) * The difference between the PI control value and the DC current I DC Its target value I DC * The difference value (I DC -I DC * The PI control value of ) is added to and a switching ratio Duty3 is generated and output according to the added value. Also, the detected current I AC4 and the average value I ave The difference value (I AC4 -I ave ) and its target value (I AC4 -I ave ) * The difference between the PI control value and the DC current I DC Its target value I DC * The difference value (I DC -I DC * The PI control value of ) is added to and a switching ratio Duty4 is generated and output according to the added value.

[0062] The control unit 116 controls the switching of switching elements 26a-2 and 26a-4 of the first rectifier circuit 26a of the power converter 114 according to the switching ratio Duty 1. The control unit 116 also controls the switching of switching elements 26a-3 and 26a-4 of the first rectifier circuit 26a of the power converter 114 according to the switching ratio Duty 2. The control unit 116 also controls the switching of switching elements 26b-1 and 26b-2 of the second rectifier circuit 26b of the power converter 114 according to the switching ratio Duty 3. The control unit 116 also controls the switching of switching elements 26b-3 and 26b-4 of the second rectifier circuit 26b of the power converter 114 according to the switching ratio Duty 4.

[0063] Figure 6 shows the results of a simulation of the control of the power transmission and reception system 110 in the second embodiment. In Figure 6, the case where the balance control in this embodiment is not applied is shown up to 8 ms, and the case where the balance control in this embodiment is applied is shown from 8 ms onward.

[0064] In other words, when balance control is not applied, switching control is performed by completely separating the following states: the state in which the first legs of switching elements 26a-1 and 26a-2 are used in combination with the second legs of switching elements 26a-3 and 26a-4; the state in which the second legs of switching elements 26a-3 and 26a-4 are used in combination with the third legs of switching elements 26b-1 and 2ba-2; and the state in which the third legs of switching elements 26b-1 and 26b-2 are used in combination with the fourth legs of switching elements 26b-3 and 26b-4.

[0065] On the other hand, when balance control is applied, the DC current I flowing through the battery 30 is as shown in Figure 5. DC and the detected current I in each of the coil windings of power transmission coils 20a to 20d AC1~Detection current I AC4 Accordingly, the switching ratios Duty1 for the first leg, Duty2 for the second leg, Duty3 for the third leg, and Duty4 for the fourth leg are set, and switching control is performed to balance the current flowing through power transmission coils 20a to 20d.

[0066] As shown in Figure 6, without balance control, current flows only through power transmission coils 20b and 20c, and the current amplitude increases to about 100A. In contrast, when balance control is applied, current flows evenly through power transmission coils 20a to 20d, and the current amplitude is about 63A. In other words, by applying balance control, the charge and discharge current to the battery 30 is kept constant while reducing the amplitude of the coil current flowing through power transmission coils 20a to 20d by 37%. In this way, by distributing the current from two coils to four coils, the current peak is reduced, and copper loss in the coil windings of the vehicle-side coils can be reduced by 21% (=(63^2×4) / (100^2×2)). In addition, the magnetic field due to the additional power receiving current weakens the leakage magnetic field, so a reduction in the leakage magnetic field can also be expected.

[0067] Figure 7 shows another example of a control block for controlling the control unit 116. The control block of the control unit 116 includes an AC control block section and a DC control block section.

[0068] The AC control block has a detection current I AC1 , detection current I AC2 , detection current I AC3 and detected current I AC4 The switching duty cycles (duty cycles) Duty1, Duty2, Duty3, and Duty4 are used as input values, and the detected current I AC1 and the average value I ave The target value of the difference (I AC1 -I ave ) * , detection current I AC2 and the average value I aveThe target value of the difference (I AC2 -I ave ) * , detection current I AC3 and the average value I ave The target value of the difference (I AC3 -I ave ) * , detection current I AC4 and the average value I ave The target value of the difference (I AC4 -I ave ) * A reference table (reference database) is set up that associates these values ​​as output values. These input and output values ​​are set in advance to ensure that either or both of the leakage magnetic field and circuit losses of the power transmission and reception system 110 remain below an upper limit.

[0069] Detected current I in power transmission and reception system 110 AC1 , detection current I AC2 , detection current I AC3 and detected current I AC4 When the switching ratios (duty cycles) Duty1, Duty2, Duty3, and Duty4 are input values, the target value (I) of the difference value associated with those input values ​​is retrieved from the reference table (reference database). AC1 -I ave ) * , (I AC2 -I ave ) * , (I AC3 -I ave ) * , (I AC4 -I ave ) * Read the data and retrieve the target value of the difference (I AC1 -I ave ) * , (I AC2 -I ave ) * , (I AC3 -I ave ) * , (I AC4 -I ave ) *By using this for control, either or both of the leakage magnetic field and circuit losses of the power transmission and reception system 110 can be kept below the upper limit.

[0070] [Configuration of the present invention] [Configuration 1] A power transmission and reception system capable of charging and discharging a battery comprises multiple coil windings, multiple resonant circuits, and multiple rectifier circuits formed by combining multiple legs, each having a switching element that can control the switching and connected to the coil windings and the resonant circuits, and is capable of charging and discharging a battery. A power transmission and reception system characterized in that the rectifier circuit controls the switching ratio according to the DC current of the battery and the detected current in each of the plurality of coil windings. [Configuration 2] The power transmission and reception system described in Configuration 1, A power transmission and reception system characterized in that the switching ratio of the rectifier circuit is controlled to satisfy conditions set for both efficiency and leakage magnetic field. [Configuration 3] The power transmission and reception system described in Configuration 1, The difference between the aforementioned DC current and the target DC current, which is the target value of the aforementioned DC current, The difference between each of the detected currents and the average value of the detected currents, and the target value of the difference, A power transmission and reception system characterized in that the switching ratio is controlled accordingly. [Structure 4] A power transmission and reception system as described in any one of items 1 to 3, Each of the rectifier circuits includes a plurality of legs in which the switching elements are connected in series. 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 5] The power transmission and reception system described in Configuration 4, A power transmission and reception system characterized in that the plurality of coil windings include coil windings connected between legs included in different rectifier circuits. [Explanation of Symbols]

[0071] 10 DC voltage source, 12 input capacitor, 14 switching bridge, 14-1~14-4 switching element, 16 resonant capacitor, 18 transmission coil, 20 (20a, 20b, 20c, 20d) power transmission coil, 24 (24a, 24b, 24c, 24d) resonant capacitor, 26a-1~26a-4, 26b-1~26b-4 switching element, 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. A power transmission and reception system capable of charging and discharging a battery comprises multiple coil windings, multiple resonant circuits, and multiple rectifier circuits formed by combining multiple legs, each having a switching element that can control the switching and connected to the coil windings and the resonant circuits, and is capable of charging and discharging a battery. A power transmission and reception system characterized in that the rectifier circuit controls the switching ratio according to the DC current of the battery and the detected current in each of the plurality of coil windings.

2. A power transmission and reception system according to claim 1, A power transmission and reception system characterized in that the switching ratio of the rectifier circuit is controlled to satisfy conditions set for both efficiency and leakage magnetic field.

3. A power transmission and reception system according to claim 1, The difference between the aforementioned DC current and the target DC current, which is the target value of the aforementioned DC current, The difference between each of the detected currents and the average value of the detected currents, and the target value of the difference, A power transmission and reception system characterized in that the switching ratio is controlled accordingly.

4. A power transmission and reception system according to any one of claims 1 to 3, Each of the rectifier circuits includes a plurality of legs in which the switching elements are connected in series. 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.

5. A power transmission and reception system according to claim 4, A power transmission and reception system characterized in that the plurality of coil windings include coil windings connected between legs included in different rectifier circuits.

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