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

Abstract

A power transmission / reception system according to the present disclosure comprises a plurality of coils and a plurality of rectifier circuits. The plurality of rectifier circuits are each configured to include a switching element that can control a rectifying operation by switching. This system is configured to perform control to switch combinations of coils and rectifier circuits in accordance with a power transmission / reception state.

Description

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

[0001] This application is based on patent application no. 2024-167350, filed on 26 September 2024, and claims the benefit of that priority, and all the contents of that patent application are incorporated herein by reference.

[0002] This disclosure relates to a power transmission and reception system, a power transmission device, and a power receiving device.

[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, depending on the detected value of the output power.

[0004] Japanese Patent Publication No. 2024-22249

[0005] In conventional configurations, the high-side switch must be turned on after the high-side diode has been activated. However, before sufficient current flows, i.e., in discontinuous current modes at low power, it is difficult to detect the timing of diode activation. Furthermore, in this mode, since no power is being received, the loss in the diode is small, and the effect of synchronous rectification control is minimal.

[0006] Therefore, in this field, it is desirable to improve efficiency by synchronous rectification control, and it is preferable to improve safety by controlling the power charged by the current. This disclosure provides a technology that can improve the efficiency of a power transmission and reception system and controls power by controlling the time that semiconductor elements are turned on.

[0007] A first aspect of this disclosure is a power transmission and reception system comprising a plurality of coils and a plurality of rectifier circuits. Each of the plurality of rectifier circuits is configured to include a switching element capable of controlling the rectification operation by switching. The power transmission and reception system is configured to perform control to switch the combination of the coils and the rectifier circuits according to the power transmission and reception state.

[0008] In this context, the power transmission and reception system is preferably configured to include a sensor for detecting the state of power transmission and reception, and to perform control to switch the combination of the coil and the rectifier circuit according to the output of the sensor.

[0009] Furthermore, it is preferable that the power transmission and reception system is equipped with multiple sensors and configured to control the combination of the coil and the rectifier circuit according to the difference in output between the sensors.

[0010] Furthermore, the sensor is a current sensor provided in each of the plurality of rectifier circuits and detects DC current. The power transmission and reception system is preferably configured to perform control to switch the combination of the coil and the rectifier circuit according to the difference in output between the current sensors.

[0011] Furthermore, the sensor is a current sensor provided in each of the plurality of rectifier circuits and detects alternating current. The power transmission and reception system is preferably configured to perform control to switch the combination of the coil and the rectifier circuit according to the difference in output between the current sensors.

[0012] Furthermore, the sensor is a voltage sensor provided in each of the plurality of rectifier circuits and detects voltage. The power transmission and reception system is preferably configured to perform control to switch the combination of the coil and the rectifier circuit according to the difference in output between the voltage sensors.

[0013] Furthermore, each of the plurality of rectifier circuits is composed of a plurality of legs in which the switching elements are connected in series. Preferably, the plurality of coils are configured to include a first coil connected between the legs included in each of the plurality of rectifier circuits, and a second coil connected between the legs included in different rectifier circuits.

[0014] A second aspect of this disclosure is a power transmission device comprising a plurality of coils and a plurality of rectifier circuits. Each of the plurality of rectifier circuits is configured to include a switching element capable of controlling the rectification operation by switching. The power transmission device is configured to perform control to switch the combination of the coils and the rectifier circuits according to the power transmission and reception state.

[0015] A third aspect of this disclosure is a power receiving device comprising a plurality of coils and a plurality of rectifier circuits. Each of the plurality of rectifier circuits is configured to include a switching element capable of controlling the rectification operation by switching. The power receiving device is configured to perform control to switch the combination of the coils and the rectifier circuits according to the power transmission and reception state.

[0016] According to this disclosure, the efficiency of the power transmission and reception system can be improved, and power can be controlled by controlling the time that semiconductor elements are turned on.

[0017] This diagram shows the configuration of a power transmission and reception system in an embodiment of the present disclosure. This diagram shows the configuration of a power transmission and reception system to which control using a direct current (DC) current sensor is applied in the first embodiment of the present disclosure. This diagram shows the flow of control using a direct current (DC) current sensor in the first embodiment of the present disclosure. This diagram shows the modes and conditions of control using a direct current (DC) current sensor in the first embodiment of the present disclosure. This diagram shows the simulation results of control using a direct current (DC) current sensor in the first embodiment of the present disclosure. This diagram shows the configuration of a power transmission and reception system to which control using an alternating current (AC) current sensor is applied in the second embodiment of the present disclosure. This diagram shows the flow of control using an alternating current (AC) current sensor in the second embodiment of the present disclosure. This diagram shows the modes and conditions of control using an alternating current (AC) current sensor in the second embodiment of the present disclosure. This diagram shows the simulation results of control using an alternating current (AC) current sensor in the second embodiment of the present disclosure. This diagram shows the configuration of a power transmission and reception system to which control using a voltage sensor is applied in the third embodiment of the present disclosure. This diagram shows the flow of control using a voltage sensor in the third embodiment of the present disclosure. This diagram shows the modes and conditions of control using a voltage sensor in the third embodiment of the present disclosure. This diagram shows the simulation results of control using a voltage sensor in the third embodiment of the present disclosure. This figure shows a modified example of the configuration of the power transmission and reception system in the embodiment of the present disclosure.

[0018] The power transmission and reception system 100 in the embodiment of the present disclosure is configured to include a primary circuit 102 and a secondary circuit 104. The primary circuit 102 is configured to include an AC power supply 10, a primary capacitor 12, and a primary inductor (primary coil) 14. The secondary circuit 104 is configured to include a first synchronous rectifier circuit 20a, a second synchronous rectifier circuit 20b, secondary inductors (secondary coils) 16 (16a, 16b, 16c, 16d), secondary capacitors 18 (18a, 18b, 18c, 18d), smoothing capacitors 22 (22a, 22b), and a storage battery 24.

[0019] The power transmission and reception system 100 is mainly composed of a synchronous rectifier circuit and is used to convert AC in the primary circuit 102 to DC and charge and discharge the battery 24 in the secondary circuit 104. The power transmission and reception system 100 uses switching elements and recirculation diodes to improve rectification efficiency. In the power transmission and reception system 100, the primary circuit 102 can be the transmitting side and the secondary circuit 104 can be the receiving side. Alternatively, the power transmission and reception system 100 can be reversed so that the primary circuit 102 is the receiving side and the secondary circuit 104 is the transmitting side.

[0020] The first synchronous rectifier circuit 20a is composed of switching elements (parallel-connected recirculating diodes) 20a-1, 20a-2, 20a-3, and 20a-4. The switching elements 20a-1, 20a-2, 20a-3, and 20a-4 rectify AC power and efficiently convert it to DC. The recirculating diodes are connected in parallel with the switching elements to improve rectification efficiency.

[0021] The second synchronous rectifier circuit 20b is composed of switching elements (parallel-connected recirculating diodes) 20b-1, 20b-2, 20b-3, and 20b-4. The switching elements 20b-1, 20b-2, 20b-3, and 20b-4 rectify AC power and efficiently convert it to DC. The recirculating diodes are connected in parallel with the switching elements to improve rectification efficiency.

[0022] Each of the secondary inductors 16 (16a, 16b, 16c, 16d) is combined with each of the secondary capacitors 18 (18a, 18b, 18c, 18d) to form a resonant circuit. In the following description, the secondary inductors 16 (16a, 16b, 16c, 16d) or their inductances may be represented as L1, L2, L3, and L4, respectively. The secondary inductors 16 (16a, 16b, 16c, 16d) and secondary capacitors 18 (18a, 18b, 18c, 18d) perform the functions of storing and releasing electrical energy.

[0023] The smoothing capacitors 22 (22a, 22b) smooth the DC voltage and reduce ripple. As a result, the battery 24 is charged and discharged with a stable DC output.

[0024] In the primary circuit 102, AC power is supplied to the primary inductor 14 through the primary capacitor 12.

[0025] In the first synchronous rectifier circuit 20a, the drain terminal of switching element 20a-1 is connected to the first terminal of the smoothing capacitor 22a and the positive terminal of the battery 24. The source terminal of switching element 20a-1 is connected to the drain terminal of switching element 20a-2. The source terminal of switching element 20a-2 is connected to the second terminal of the smoothing capacitor 22a and the negative terminal of the battery 24. Hereinafter, the pair of switching elements 20a-1 and 20a-2 will be referred to as Leg A. The drain terminal of switching element 20a-3 is connected to the first terminal of the smoothing capacitor 22a and the positive terminal of the battery 24. The source terminal of switching element 20a-3 is connected to the drain terminal of switching element 20a-4. The source terminal of switching element 20a-4 is connected to the second terminal of the smoothing capacitor 22a and the negative terminal of the battery 24. Hereinafter, the pair of switching elements 20a-3 and 20a-4 will be referred to as Leg B.

[0026] Furthermore, the first terminal of the resonant circuit composed of the secondary inductor 16a and the secondary capacitor 18a is connected to the connection point between the source terminal of switching element 20a-1 and the drain terminal of switching element 20a-2. In addition, the first terminal of the resonant circuit composed of the secondary inductor 16b and the secondary capacitor 18b is connected to the connection point between the source terminal of switching element 20a-3 and the drain terminal of switching element 20a-4.

[0027] In the second synchronous rectifier circuit 20b, the drain terminal of switching element 20b-1 is connected to the first terminal of the smoothing capacitor 22b and the positive terminal of the battery 24. The source terminal of switching element 20b-1 is connected to the drain terminal of switching element 20b-2. The source terminal of switching element 20b-2 is connected to the second terminal of the smoothing capacitor 22b and the negative terminal of the battery 24. Hereinafter, the pair of switching elements 20b-1 and 20b-2 will be referred to as Leg C. The drain terminal of switching element 20b-3 is connected to the first terminal of the smoothing capacitor 22b and the positive terminal of the battery 24. The source terminal of switching element 20b-3 is connected to the drain terminal of switching element 20b-4. The source terminal of switching element 20b-4 is connected to the second terminal of the smoothing capacitor 22b and the negative terminal of the battery 24. Hereinafter, the pair of switching elements 20b-3 and 20b-4 will be referred to as Leg D.

[0028] Furthermore, the first terminal of the resonant circuit composed of the secondary inductor 16c and the secondary capacitor 18c is connected to the connection point between the source terminal of switching element 20b-1 and the drain terminal of switching element 20b-2. In addition, the first terminal of the resonant circuit composed of the secondary inductor 16d and the secondary capacitor 18d is connected to the connection point between the source terminal of switching element 20b-3 and the drain terminal of switching element 20b-4.

[0029] The secondary inductor 16a and secondary capacitor 18a, the secondary inductor 16b and secondary capacitor 18b, the secondary inductor 16c and secondary capacitor 18c, and the secondary inductor 16d and secondary capacitor 18d are connected in parallel.

[0030] [First Embodiment: Control using DC Current Sensors] Figure 2 shows the configuration of a power transmission and reception system 100 to which control using DC current sensors 30a and 30b is applied. The power transmission and reception system 100 has a first synchronous rectifier circuit 20a with current I ｄｃ１ A DC sensor 30a is provided to measure the current I of the second synchronous rectifier circuit 20b in the power transmission and reception system 100. ｄｃ２A DC direct current sensor 30b for measurement is provided. In the control unit 106, the current I of the first synchronous rectifier circuit 20a ｄｃ１ and the current I of the second synchronous rectifier circuit 20b ｄｃ２ are input. The control unit 106 performs switching control of the first synchronous rectifier circuit 20a and the second synchronous rectifier circuit 20b according to the input currents I ｄｃ１ and current I ｄｃ２ . Note that the control unit 106 is a control device having a specific circuit such as a logic IC, and may be configured to perform switching control by hardware. Further, the control unit 106 is a control device having a computer including, for example, one or more memories and one or more processors, and may be configured to perform switching control by software. Here, the memory includes, for example, ROM, RAM, etc. Further, the processor includes a general-purpose processor (for example, CPU), or a dedicated processor (for example, GPU, ASIC, FPGA, programmable logic device, etc.). Software corresponds to a program including instructions for realizing switching control. The program is stored in a non-transitory tangible recording medium and is read and executed by a processor via a memory. Further, the control unit 106 is a control device having a specific circuit and a computer, and may be configured to perform switching control by the cooperation of the above-mentioned hardware and the above-mentioned software.

[0031] FIG. 3 is a diagram showing a control flow using DC (direct current) current sensors 30a and 30b. Further, FIG. 4 is a diagram showing conditions (conditions for determining the power transmission and reception state) for each mode in this control.

[0032] When all of a plurality of conditions shown in the following conditions 1-1, 1-2, and 1-3 are satisfied, the control unit 106 determines that the state is in mode 1 in which the primary inductor 14 of the primary side circuit 102 is most strongly electromagnetically coupled with the secondary inductors 16a and 16b (L1, L2) of the secondary side circuit 104. Condition 1-1 is that the absolute value of the difference between current I ｄｃ１ and current I ｄｃ２ , |I ｄｃ１ -I ｄｃ２ | is the maximum current I ｍａｘIt is greater than a constant β times. Condition 1-2 is that the current I ｄｃ１ Current I ｄｃ２ It is greater than. Conditions 1-3 are for current I ｄｃ１ The maximum current I ｍａｘ It is greater than a constant α times. In mode 1, the control unit 106 synchronously switches leg A and leg B and turns off leg C and leg D, thereby performing rectification using leg A and leg B.

[0033] Furthermore, the control unit 106 determines that the state is Mode 2, in which the primary inductor 14 of the primary circuit 102 is most strongly electromagnetically coupled with the secondary inductors 16c, 16d (L3, L4) of the secondary circuit 104, when all of the conditions shown in the following conditions 2-1, 2-2, and 2-3 are met. Condition 2-1 is current I ｄｃ１ and current I ｄｃ２ The absolute value of the difference between | I ｄｃ１ -I ｄｃ２ | indicates the maximum current I ｍａｘ It is greater than a constant β times. Condition 2-2 is that the current I ｄｃ２ Current I ｄｃ１ It is greater than. Condition 2-3 is current I ｄｃ２ The maximum current I ｍａｘ It is greater than a constant α times. In mode 2, the control unit 106 turns off legs A and B and performs rectification using legs C and D by synchronous switching control of legs C and D.

[0034] Furthermore, the control unit 106 determines that the state is Mode 3, in which the primary inductor 14 of the primary circuit 102 is most strongly electromagnetically coupled with the secondary inductors 16b, 16c (L2, L3) of the secondary circuit 104, when all of the conditions shown in conditions 3-1 and 3-3 below are met. Condition 3-1 is current I ｄｃ１ and current I ｄｃ２ The absolute value of the difference between | I ｄｃ１ -I ｄｃ２ | indicates the maximum current I ｍａｘ It is smaller than a constant β times. Condition 3-3 is that the current I ｄｃ１ The maximum current I ｍａｘ The current I is greater than a constant α times ｄｃ２ The maximum current I ｍａｘIt is greater than a constant α times. In mode 3, the control unit 106 turns off legs A and D and performs rectification using legs B and C by synchronous switching control of legs B and C.

[0035] Furthermore, if none of the above conditions are met, the control unit 106 determines that the device is in mode 4 and stops charging and discharging by turning off all of legs A, B, C, and D.

[0036] Furthermore, it is preferable to set constants α and β to different values. For example, it is preferable to set them such that constant α > constant β. Specifically, for example, constant α is set to 0.10 and constant β is set to 0.05. By setting constants α and β in this way, it is possible to suppress the occurrence of chattering, in which the leg being used frequently switches, near the reference value of the above conditions.

[0037] Figure 5 shows the results of a simulation of the charging and discharging of the battery 24 in a moving vehicle, when the primary circuit 102 is configured as the power transmission side and the secondary circuit 104 is configured as the power reception side and mounted on the vehicle. In Figure 5, the horizontal axis represents the time when the vehicle is traveling at 130 km / h.

[0038] During vehicle operation, the mutual inductance changes depending on the relative position of the primary circuit 102 and the secondary circuit 104. Therefore, among the secondary inductors 16 (16a, 16b, 16c, 16d), power is charged and discharged starting with the coil with the highest mutual inductance with the primary inductor 14.

[0039] According to the power transmission and reception system 100, the current 1 (I) changes with the change in mutual inductance. ｄｃ１ ) and current 2 (I ｄｃ２ The relative magnitudes of the two components are switched, and modes 1 to 3 are switched appropriately. In other words, by applying the power transmission and reception system 100, each leg included in the first synchronous rectifier circuit 20a and the second synchronous rectifier circuit 20b is switched appropriately and rectification is performed. Furthermore, the occurrence of chattering during switching is also suppressed.

[0040] [Second Embodiment: Control using AC Current Sensors] Figure 6 shows the configuration of a power transmission and reception system 100 to which control using AC current sensors 32a and 32b is applied. The power transmission and reception system 100 has a first synchronous rectifier circuit 20a with current I ａｃ１ An AC / DC sensor 32a is provided to measure the current I of the second synchronous rectifier circuit 20b in the power transmission / reception system 100. ａｃ２ A DC sensor 32b is provided to measure the current I of the first synchronous rectifier circuit 20a. ａｃ１ and the current I of the second synchronous rectifier circuit 20b ａｃ２ The input is received. The control unit 106 receives the input current I ａｃ１ and current I ａｃ２ Accordingly, switching control of the first synchronous rectifier circuit 20a and the second synchronous rectifier circuit 20b is performed.

[0041] Figure 7 shows the control flow using AC current sensors 32a and 32b. Figure 8 shows the conditions for each mode in this control (conditions for determining the state of power transmission and reception). In the following explanation, the current value represents the average value of the AC current.

[0042] The control unit 106 determines that the state is Mode 1, in which the primary inductor 14 of the primary circuit 102 is most strongly electromagnetically coupled with the secondary inductors 16a and 16b (L1 and L2) of the secondary circuit 104, when all of the following conditions 1-1, 1-2, and 1-3 are met. Condition 1-1 is current I ａｃ１ and current I ａｃ２ The absolute value of the difference between | I ａｃ１ -I ａｃ２ | indicates the maximum current I ｍａｘ It is greater than a constant β times. Condition 1-2 is that the current I ａｃ１ Current I ａｃ２ It is greater than. Conditions 1-3 are for current I ａｃ１ The maximum current I ｍａｘ It is greater than a constant α times. In mode 1, the control unit 106 synchronously switches leg A and leg B and turns off leg C and leg D, thereby performing rectification using leg A and leg B.

[0043] Furthermore, the control unit 106 determines that the state is Mode 2, in which the primary inductor 14 of the primary circuit 102 is most strongly electromagnetically coupled with the secondary inductors 16c, 16d (L3, L4) of the secondary circuit 104, when all of the conditions shown in the following conditions 2-1, 2-2, and 2-3 are met. Condition 2-1 is current I ａｃ１ and current I ａｃ２ The absolute value of the difference between | I ａｃ１ -I ａｃ２ | indicates the maximum current I ｍａｘ It is greater than a constant β times. Condition 2-2 is that the current I ａｃ２ Current I ａｃ１ It is greater than. Condition 2-3 is current I ａｃ２ The maximum current I ｍａｘ It is greater than a constant α times. In mode 2, legs A and B are turned off, and legs C and D are controlled by synchronous switching, thereby using legs C and D to perform rectification.

[0044] Furthermore, the control unit 106 determines that the state is Mode 3, in which the primary inductor 14 of the primary circuit 102 is most strongly electromagnetically coupled with the secondary inductors 16b, 16c (L2, L3) of the secondary circuit 104, when all of the conditions shown in conditions 3-1 and 3-3 below are met. Condition 3-1 is current I ａｃ１ and current I ａｃ２ The absolute value of the difference between | I ａｃ１ -I ａｃ２ | indicates the maximum current I ｍａｘ It is smaller than a constant β times. Condition 3-3 is that the current I ａｃ１ The maximum current I ｍａｘ The current I is greater than a constant α times ａｃ２ The maximum current I ｍａｘ It is greater than a constant α times. In mode 3, legs A and D are turned off, and legs B and C are controlled by synchronous switching, thereby performing rectification using legs B and C.

[0045] Furthermore, if none of the above conditions are met, the control unit 106 determines that the device is in mode 4 and stops charging and discharging by turning off all of legs A, B, C, and D.

[0046] In this embodiment as well, it is preferable to set the constant α and constant β to different values, similar to the above embodiment. For example, it is preferable to set them such that constant α > constant β. Specifically, for example, constant α is set to 0.10 and constant β is set to 0.05. By setting constants α and β in this way, it is possible to suppress the occurrence of chattering, in which the leg being used frequently switches, near the reference value of the above conditions.

[0047] Figure 9 shows the results of a simulation of the charging and discharging of the battery 24 in a moving vehicle, when the primary circuit 102 is configured as the power transmission side and the secondary circuit 104 is configured as the power reception side and mounted on the vehicle. In Figure 9, the horizontal axis represents the time when the vehicle is traveling at 130 km / h.

[0048] During vehicle operation, the mutual inductance changes depending on the relative positions of the primary circuit 102 and the secondary circuit 104. Consequently, the current 1(I) ａｃ１ ) and current 2 (I ａｃ２ The relative magnitude of ) switches, and Mode 1 to Mode 3 are switched appropriately. In Mode 1, the current 1 (I ａｃ１ Only current 2 (I) is detected. ａｃ２ ) is current 1 (I ａｃ１ It is sufficiently small compared to ). In mode 2, the current 2 (I ａｃ２ Only current 1 (I) is detected. ａｃ１ ) is current 2 (I ａｃ２ It is sufficiently small compared to ). In mode 3, the current is 1 (I ａｃ１ ) and current 2 (I ａｃ２ ) is of roughly the same level.

[0049] In this embodiment as well, similar to the above embodiment, by applying the power transmission and reception system 100, each leg included in the first synchronous rectifier circuit 20a and the second synchronous rectifier circuit 20b is appropriately switched and rectification is performed. Furthermore, the occurrence of chattering during switching is also suppressed.

[0050] [Third Embodiment: Control by Voltage Sensors] FIG. 10 shows the configuration of a power transmission and reception system 100 to which control using voltage sensors 34a and 34b is applied. In the power transmission and reception system 100, a voltage sensor 34a for measuring the voltage V １２ of the first synchronous rectifier circuit 20a is provided. In the power transmission and reception system 100, a voltage sensor 34b for measuring the voltage V ３４ of the second synchronous rectifier circuit 20b is provided. The control unit 106 receives the voltage V １２ of the first synchronous rectifier circuit 20a and the voltage V ３４ of the second synchronous rectifier circuit 20b. The control unit 106 performs switching control of the first synchronous rectifier circuit 20a and the second synchronous rectifier circuit 20b according to the input voltages V １２ and V ３４ .

[0051] FIG. 11 is a diagram showing the flow of control using the voltage sensors 34a and 34b. FIG. 12 is a diagram showing the conditions (conditions for determining the power transmission and reception state) for each mode in this control. In the following description, the voltage values and current values indicate the AC average values.

[0052] When all of a plurality of conditions shown in the following conditions 1-1, 1-2, and 1-3 are satisfied, the control unit 106 determines that the state is Mode 1 in which the primary inductor 14 of the primary circuit 102 is most strongly electromagnetically coupled to the secondary inductors 16a and 16b (L1, L2) of the secondary circuit 104. Condition 1-1 is that the absolute value |V １２ −V ３４ | of the difference between V １２ and V ３４ is greater than a constant β times the maximum voltage V ｍａｘ . Condition 1-2 is that the voltage V １２ is greater than the voltage V ３４ . Condition 1-3 is that the voltage V １２ is greater than a constant α times the maximum voltage V ｍａｘ . In the case of Mode 1, the control unit 106 performs synchronous switching control of leg A and leg B and turns off leg C and leg D, thereby performing rectification using leg A and leg B.

[0053] Further, when all of the plurality of conditions shown in the following conditions 2-1, 2-2, and 2-3 are satisfied, the control unit 106 determines that the state is Mode 2 in which the primary inductor 14 of the primary side circuit 102 is most strongly coupled to the secondary inductors 16c and 16d (L3, L4) of the secondary side circuit 104. Condition 2-1 is that the absolute value of the difference between the voltage V １２ and the voltage V ３４ |V １２ - V ３４ | is greater than a constant β times the maximum voltage V ｍａｘ . Condition 2-2 is that the voltage V ３４ is greater than the voltage V １２ . Condition 2-3 is that the voltage V ３４ is greater than a constant α times the maximum voltage V ｍａｘ . In the case of Mode 2, the control unit 106 turns off Leg A and Leg B, and performs rectification using Leg C and Leg D by performing synchronous switching control on Leg C and Leg D.

[0054] Further, when all of the plurality of conditions shown in the following conditions 3-1 and 3-3 are satisfied, the control unit 106 determines that the state is Mode 3 in which the primary inductor 14 of the primary side circuit 102 is most strongly electromagnetically coupled to the secondary inductors 16b and 16c (L2, L3) of the secondary side circuit 104. Condition 3-1 is that the absolute value of the difference between the voltage V １２ and the voltage V ３４ |V １２ - V ３４ | is less than a constant β times the maximum voltage V ｍａｘ . Condition 3-3 is that the voltage V １２ is greater than a constant α times the maximum voltage V ｍａｘ , and the voltage V ３４ is greater than a constant α times the maximum voltage V ｍａｘ . In the case of Mode 3, Leg A and Leg D are turned off, and Leg B and Leg C are used for rectification by performing synchronous switching control on Leg B and Leg C.

[0055] Further, when none of the above conditions are satisfied, the control unit 106 determines that the state is Mode 4, and stops charging and discharging by turning off all of Leg A, Leg B, Leg C, and Leg D.

[0056] In this embodiment as well, it is preferable to set the constant α and constant β to different values, similar to the above embodiment. For example, it is preferable to set them such that constant α > constant β. Specifically, for example, constant α is set to 0.10 and constant β is set to 0.05. By setting constants α and β in this way, it is possible to suppress the occurrence of chattering, in which the leg used frequently switches around the reference value of the above conditions.

[0057] Figure 13 shows the results of a simulation of the charging and discharging of the battery 24 in a moving vehicle, when the primary circuit 102 is configured as the power transmission side and the secondary circuit 104 is configured as the power reception side and mounted on the vehicle. In Figure 13, the horizontal axis represents the time when the vehicle is traveling at 130 km / h.

[0058] During vehicle operation, the mutual inductance changes depending on the relative positions of the primary circuit 102 and the secondary circuit 104. Consequently, the voltage V １２ (Current 1) and Voltage V ３４ The relative magnitude of (current 2) switches, and modes 1 to 3 are switched appropriately. In mode 1, voltage V １２ Voltage V ３４ Larger. In mode 2, the voltage V ３４ Voltage V １２ Larger. In mode 3, the voltage V １２ and voltage V ３４ They are of roughly the same level.

[0059] In this embodiment as well, similar to the above embodiment, by applying the power transmission and reception system 100, each leg included in the first synchronous rectifier circuit 20a and the second synchronous rectifier circuit 20b is appropriately switched and rectification is performed. Furthermore, the occurrence of chattering during switching is also suppressed.

[0060] [Modified Version] This embodiment is a power transmission and reception system comprising a plurality of coils and a plurality of rectifier circuits. Each of the rectifier circuits is configured to include a switching element capable of controlling the rectification operation by switching. The power transmission and reception system can be configured to perform control by switching the combination of coils and rectifier circuits according to the power transmission and reception state.

[0061] As a variation, the power transmission and reception system 200 may be configured without secondary inductors 16b, 16d and secondary capacitors 18b, 18d, as shown in Figure 14.

[0062] In the power transmission and reception system 200, control using a direct current (DC) sensor, control using an alternating current (AC) sensor, or control using a voltage sensor can be applied. In any case, as with the power transmission and reception system 100, current sensors and voltage sensors are provided and control is performed according to the output of the sensors.

[0063] In the case of the power transmission and reception system 200, only the conditions of Mode 1 and Mode 2 described above are applied to switch each leg. That is, when the conditions of Mode 1 are met, the power transmission and reception system 200 performs rectification using Leg A and Leg B by synchronously switching Leg A and Leg B and turning Leg C and Leg D to the OFF state. Also, when the conditions of Mode 2 are met, the power transmission and reception system 200 performs rectification using Leg C and Leg D by synchronously switching Leg C and Leg D and turning Leg A and Leg B to the OFF state. If none of the above conditions are met, the power transmission and reception system 200 turns off Leg A, Leg B, Leg C, and Leg D and stops charging and discharging.

[0064] In the power transmission and reception system 200, each leg included in the first synchronous rectifier circuit 20a and the second synchronous rectifier circuit 20b is appropriately switched to perform rectification, and the occurrence of chattering during switching can also be suppressed.

[0065] In addition, the number of leg sets may be further increased in the above embodiments and modifications. In this case as well, the legs can be selected and rectification control performed based on the relative magnitudes of the current or voltage flowing through each synchronous rectifier circuit.

[0066] As described above, the power transmission and reception system in the above embodiment and its modified examples has lower diode losses compared to rectification using diodes. Therefore, efficiency can be improved by synchronous rectification control in this system. Furthermore, the power transmission and reception system in the above embodiment and its modified examples can always perform synchronous rectification control even when the coil receiving power is switched, under conditions where the positional relationship between the coils of the primary circuit and the secondary circuit changes. Therefore, when the power transmission and reception system is applied to a vehicle or the like, the overall system efficiency during operation can be improved.

[0067] Furthermore, according to the power transmission and reception system in the above embodiment and its modified form, the power charged by the current can be controlled by controlling the time the active semiconductor element is turned on. Therefore, this system can prevent overcharging of the battery when charging is not necessary. As a result, safety can be improved in this system.

[0068] [Configuration of the Disclosure] [Configuration 1] A power transmission and reception system comprising a plurality of coils and a plurality of rectifier circuits, each of the plurality of rectifier circuits comprising a switching element capable of controlling the rectification operation by switching, and configured to perform control to switch the combination of the coil and the rectifier circuit according to the power transmission and reception state. [Configuration 2] The power transmission and reception system according to Configuration 1, comprising a sensor for detecting the power transmission and reception state, and configured to perform control to switch the combination of the coil and the rectifier circuit according to the output of the sensor. [Configuration 3] The power transmission and reception system according to Configuration 2, comprising a plurality of the sensors, and configured to perform control to switch the combination of the coil and the rectifier circuit according to the difference in output between the sensors. [Configuration 4] The power transmission and reception system according to Configuration 3, wherein the sensor is a current sensor provided in each of the plurality of rectifier circuits for detecting DC current, and configured to perform control to switch the combination of the coil and the rectifier circuit according to the difference in output between the current sensors. [Configuration 5] A power transmission and reception system according to Configuration 3, wherein the sensor is a current sensor provided in each of the plurality of rectifier circuits for detecting alternating current, and the system is configured to perform control to switch the combination of the coil and the rectifier circuit according to the difference in output between the current sensors. [Configuration 6] A power transmission and reception system according to Configuration 3, wherein the sensor is a voltage sensor provided in each of the plurality of rectifier circuits for detecting voltage, and the system is configured to perform control to switch the combination of the coil and the rectifier circuit according to the difference in output between the voltage sensors. [Configuration 7] A power transmission and reception system according to any one of Configurations 1 to 6, wherein each of the plurality of rectifier circuits is configured to include a plurality of legs in which the switching elements are connected in series, and the plurality of coils is configured to include a first coil connected between the legs included in each of the plurality of rectifier circuits, and a second coil connected between the legs included in different rectifier circuits.[Configuration 8] A power transmission device comprising a plurality of coils and a plurality of rectifier circuits, each of the plurality of rectifier circuits being configured to include a switching element capable of controlling the rectification operation by switching, and configured to perform control to switch the combination of the coils and the rectifier circuits according to the power transmission and reception state. [Configuration 9] A power receiving device comprising a plurality of coils and a plurality of rectifier circuits, each of the plurality of rectifier circuits being configured to include a switching element capable of controlling the rectification operation by switching, and configured to perform control to switch the combination of the coils and the rectifier circuits according to the power transmission and reception state.

Claims

1. A power transmission and reception system comprising a plurality of coils and a plurality of rectifier circuits, each of the plurality of rectifier circuits being configured to include a switching element capable of controlling the rectification operation by switching, and configured to perform control to switch the combination of the coils and the rectifier circuits according to the power transmission and reception state.

2. A power transmission and reception system according to claim 1, comprising a sensor for detecting the state of power transmission and reception, and configured to perform control to switch the combination of the coil and the rectifier circuit according to the output of the sensor.

3. A power transmission and reception system according to claim 2, comprising a plurality of sensors, and configured to perform control to switch the combination of the coil and the rectifier circuit according to the difference in output between the sensors.

4. A power transmission and reception system according to claim 3, wherein the sensor is a current sensor provided in each of the plurality of rectifier circuits for detecting a DC current, and the system is configured to perform control to switch the combination of the coil and the rectifier circuit according to the difference in output between the current sensors.

5. A power transmission and reception system according to claim 3, wherein the sensor is a current sensor provided in each of the plurality of rectifier circuits for detecting alternating current, and the system is configured to perform control to switch the combination of the coil and the rectifier circuit according to the difference in output between the current sensors.

6. A power transmission and reception system according to claim 3, wherein the sensor is a voltage sensor provided in each of the plurality of rectifier circuits for detecting voltage, and the system is configured to perform control to switch the combination of the coil and the rectifier circuit according to the difference in output between the voltage sensors.

7. A power transmission and reception system according to any one of claims 1 to 6, wherein each of the plurality of rectifier circuits is configured to include a plurality of legs in which the switching elements are connected in series, and the plurality of coils is configured to include a first coil connected between the legs included in each of the plurality of rectifier circuits, and a second coil connected between the legs included in different rectifier circuits.

8. A power transmission device comprising a plurality of coils and a plurality of rectifier circuits, each of the plurality of rectifier circuits being configured to include a switching element capable of controlling the rectification operation by switching, and configured to perform control to switch the combination of the coils and the rectifier circuits according to the power transmission and reception state.

9. A power receiving device comprising a plurality of coils and a plurality of rectifier circuits, each of the plurality of rectifier circuits being configured to include a switching element capable of controlling the rectification operation by switching, and configured to perform control to switch the combination of the coils and the rectifier circuits according to the power transmission and reception state.

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