Powered Device

Abstract

To perform an optimal power transmission control regardless of individual difference between a power transmission device and a power reception device, positional relationship between them, and the like.SOLUTION: A power supply device 30 includes: a power reception part (power supply side coil 31 and resonance circuit 32) that receives a power transmitted from an in-vehicle device 10 by a contactless power transmission; a variable capacitor 34 that can be charged by the power received by the power reception part and that can supply accumulated power to a load; a voltage detection circuit 35 that detects a terminal voltage of the variable capacitor 34; and a power supply-side control part 40 that controls a capacitance of the variable capacitor 34 based on the amount of change in a terminal voltage detected by the voltage detection circuit 35.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology of the present disclosure relates to a power receiving device. [Background technology]

[0002] In recent years, research and development has been conducted into charging mobility vehicles equipped with secondary batteries that contribute to energy efficiency, in order to ensure that more people have access to affordable, reliable, sustainable, and advanced energy.

[0003] For example, research and development into charging and power supply is being conducted on contactless power transmission, which transmits power between two devices without contact.

[0004] Patent Document 1 describes a contactless power supply device including a power supply unit and a power receiving unit. The power supply unit includes a power supply coil and an AC power supply that supplies AC power to the power supply coil. The power receiving unit includes a power receiving coil that receives AC power contactlessly by electromagnetically coupling with the power supply coil when facing the power supply coil, a power receiving-side resonant capacitor that is connected to the power receiving coil to form a power receiving-side resonant circuit, a power receiving circuit that converts the AC power received by the power receiving coil to generate a receiving voltage and outputs it to an electrical load, and an overvoltage protection circuit that shifts the power receiving-side resonant frequency of the power receiving-side resonant circuit when the receiving voltage exceeds a threshold voltage that determines whether an overvoltage state exists.

[0005] Patent Document 2 describes a wireless power receiving device that is mounted on a moving body that obtains driving force from power stored in a battery and that can receive power wirelessly while the moving body is moving or stopped.

[0006] Patent Document 3 describes a power receiving device that receives power transferred from a power transmitting device in a non-contact manner by electromagnetic resonance.

[0007] Patent document 4 describes a contactless charging system equipped with a relay device, which is capable of preventing overcurrent and overvoltage in the inverter output even when the mutual inductance between the relay coil and the receiving coil fluctuates greatly. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-147849 [Patent Document 2] Japanese Patent Application Publication No. 2017-175703 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-005615 [Patent Document 4] Japanese Patent Publication No. 2022-039628 Summary of the Invention [Problem to be solved by the invention]

[0009] The technology disclosed herein aims to perform optimal power transmission control regardless of individual differences between power transmitting devices and power receiving devices, their relative positions, and the like. [Means for solving the problem]

[0010] A power receiving device according to an aspect of the present disclosure includes a power receiving unit that receives power transmitted from a power transmitting device through contactless power transmission, and a power receiving unit that receives the power from the power receiving unit. Charged and configured to supply the stored power to a load. Includes a variable capacitor a power supply unit, a detection unit for detecting a terminal voltage of the power supply unit, and a voltage detection unit for detecting a change in the terminal voltage detected by the detection unit. variable capacitor and a control unit that controls the capacity of the [Effects of the Invention]

[0011] According to the technology of the present disclosure, optimal power transmission control can be performed regardless of individual differences between the power transmitting device and the power receiving device, their relative positions, and the like. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing a contactless power transmission system 100 according to an embodiment of the disclosed technique. [Figure 2] FIG. 2 is a schematic diagram illustrating the operating state of the contactless power transfer system 100 while the in-vehicle device 10 is executing power supply control. [Figure 3] FIG. 3 is a diagram showing an example of the configuration of the variable capacitor 34. As shown in FIG. [Figure 4] FIG. 4 is a diagram showing a modified example of the variable capacitor 34. In FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] 1 is a schematic diagram showing a contactless power transfer system 100 according to an embodiment of the technology of the present disclosure. The contactless power transfer system 100 includes an on-board device 10 mounted on a vehicle or the like, and a power supply device 30 installed in a parking lot, a facility, a house, or the like. The contactless power transfer system 100 is configured to enable first power transfer from the on-board device 10 to the power supply device 30. The on-board device 10 and the power supply device 30 transfer power contactlessly using magnetic coupling between coils, for example, using a magnetic field resonance method or an electromagnetic induction method.

[0014] The vehicle on which the in-vehicle device 10 is mounted includes a secondary battery 17 (denoted as BAT in the drawing) such as a lithium ion battery or a nickel-metal hydride battery, and an electric motor as a drive source that is driven using the power of the secondary battery 17. This vehicle is, for example, an automobile having drive wheels driven by the power of the electric motor and wheels including steerable wheels (neither of which is shown).

[0015] The vehicle-mounted device 10 includes a vehicle-side coil 11, a resonant circuit 12 connected to the vehicle-side coil 11, a first power conversion circuit 13 connected to the resonant circuit 12, a filter 14 provided between the first power conversion circuit 13 and a secondary battery 17, a first communication unit 18, and a vehicle-side control unit 20.

[0016] The resonant circuit 12 includes, for example, a capacitor connected in series to the vehicle-side coil 11. During the first power transmission, the vehicle-side coil 11 and the resonant circuit 12 form a power transmission unit that transmits power to the power supply device 30 by contactless power transmission.

[0017] During the first power transmission, the first power conversion circuit 13 uses power from the secondary battery 17 to generate supply power to be supplied to the vehicle-side coil 11 and the resonant circuit 12, and supplies this supply power to the vehicle-side coil 11 and the resonant circuit 12. The first power conversion circuit 13 includes switching elements such as transistors, and during the first power transmission, it operates, for example, as an inverter that converts direct current supplied from the secondary battery 17 into high-frequency alternating current. The high-frequency alternating current converted by the first power conversion circuit 13 is input to the vehicle-side coil 11, and high-frequency alternating current is induced by electromagnetic induction in the power supply-side coil 31 of the power supply device 30 that faces the vehicle-side coil 11 with a gap therebetween.

[0018] A filter 14 is provided to stabilize the power and remove noise.

[0019] The first communication unit 18 is an interface for performing short-distance wireless communication, which can be achieved using, for example, Wi-Fi (registered trademark) or Bluetooth (registered trademark).

[0020] The vehicle-side control unit 20 includes a processor such as a CPU (Central Processing Unit) and a memory, and performs various controls related to power transmission.

[0021] The power supply device 30 includes a power supply side coil 31, a resonant circuit 32 connected to the power supply side coil 31, a second power conversion circuit 33 connected to the resonant circuit 32, a variable capacitor 34 with a variable capacitance connected to the second power conversion circuit 33, a voltage detection circuit 35 that detects the terminal voltage Vc of the variable capacitor 34, a third power conversion circuit 36 ​​connected to the variable capacitor 34, a second communication unit 37, and a power supply side control unit 40.

[0022] The resonant circuit 32 includes, for example, a capacitor connected in series to the power supply side coil 31. During the first power transmission, the power supply side coil 31 and the resonant circuit 32 form a power receiving unit that receives power transmitted from the in-vehicle device 10 by contactless power transmission.

[0023] The second power conversion circuit 33 operates as a rectifier during the first power transmission, and converts the high-frequency AC input from the power supply side coil 31 into DC.

[0024] The variable capacitor 34 is charged by the direct current converted by the second power conversion circuit 33. During the first power transmission, the variable capacitor 34 is configured to be able to supply the stored power to a load connected to the third power conversion circuit 36.

[0025] The third power conversion circuit 36 ​​operates as an inverter during the first power transmission, converting the DC discharged from the variable capacitor 34 into AC at the frequency of the commercial power supply. The AC at the commercial frequency converted by the third power conversion circuit 36 ​​is supplied to a power distribution network or a load such as a home appliance.

[0026] The second communication unit 37 is an interface for performing short-distance wireless communication, which can be achieved using, for example, Wi-Fi (registered trademark) or Bluetooth (registered trademark).

[0027] The power supply side control unit 40 includes a processor such as a CPU (Central Processing Unit) and a memory, and performs overall control of the power supply device 30.

[0028] During the first power transmission, the vehicle-side control unit 20 acquires the terminal voltage Vc of the variable capacitor 34 of the power supply device 30, and performs power supply control to control the supply power supplied to the vehicle-side coil 11 and the resonant circuit 12 via the first power conversion circuit 13 so that this terminal voltage Vc becomes a predetermined target voltage.

[0029] In this way, the vehicle-side control unit 20 controls (feedback control) the input power of the control object, which is a system that charges the variable capacitor 34 with power transmitted from the in-vehicle device 10 (a charging system including the resonant circuit 12, the vehicle-side coil 11, the power supply-side coil 31, the resonant circuit 32, and the second power conversion circuit 33, which are provided between the first power conversion circuit 13 and the variable capacitor 34). The output voltage (synonymous with the terminal voltage Vc) of the control object is set to a target voltage. Hereinafter, the transfer function of the control object will be referred to as transfer function G(s).

[0030] 2 is a schematic diagram illustrating the operating state of the contactless power transfer system 100 while the in-vehicle device 10 is performing power supply control. When the power supply control is started, the power supply-side control unit 40 acquires the terminal voltage Vc from the voltage detection circuit 35 and performs control to transmit the acquired terminal voltage Vc from the second communication unit 37 to the in-vehicle device 10. The terminal voltage Vc transmitted from the second communication unit 37 is received by the first communication unit 18 and acquired by the vehicle-side control unit 20.

[0031] 2, the vehicle-side control unit 20 includes a comparator 21, a compensator 22, and a pulse generating unit 23. These are configured by hardware, software, or a combination thereof. The comparator 21 compares the terminal voltage Vc acquired via the first communication unit 18 with a target voltage, and outputs the deviation.

[0032] The compensator 22 determines the input power to the controlled object required to optimize the output of the controlled object represented by the transfer function G(s) (to achieve a state with good responsiveness and no oscillation) based on the deviation input from the comparator 21 and various preset setting values ​​(for example, information on the P term, I term, and D term in the case of a PID compensator).

[0033] Specifically, the compensator 22 determines the input power to the controlled object so that the phase margin between the input and output of the controlled object is equal to or greater than 0 degrees. The pulse generator 23 generates a drive pulse and supplies it to the first power converter circuit 13 so that the power output from the first power converter circuit 13 becomes the input power determined by the compensator 22.

[0034] The setting value of compensator 22 that makes the phase margin between the input and output of the controlled object 0 degrees or more can be determined based on the values ​​(frequencies) of the poles and zeros in transfer function G(s) if they are determined.

[0035] The transfer function G(s) can be uniquely determined if the combination of the on-vehicle device 10 and the power supply device 30 is fixed. However, even with this combination, the transfer function G(s) can change depending on the positional relationship between the vehicle-side coil 11 and the power supply-side coil 31, individual differences between the devices, the external environment, and the like. The capacitance of the variable capacitor 34 of the power supply device 30 is required to be set to an appropriate value depending on the transfer function G(s) determined by the combination of the on-vehicle device 10 and the power supply device 30. However, as described above, if there is a change in the transfer function G(s), which is uniquely determined by the design information of the on-vehicle device 10 and the power supply device 30, the capacitance of the variable capacitor 34 may not be appropriate. Therefore, in this embodiment, the capacitance of the variable capacitor 34 can be set to an appropriate value by using the output of the controlled object when the controlled object is operated under specific conditions.

[0036] Before the above-mentioned power supply control is executed, i.e., before the comparator 21 and the compensator 22 determine the power to be supplied to the vehicle-side coil 11 and the resonant circuit 12, the vehicle-side control unit 20 generates a drive pulse of a predetermined pattern (a pattern with fixed pulse width and frequency) using the pulse generation unit 23, and controls the first power conversion circuit 13 according to this drive pulse, thereby executing capacity setting control to control the power to be supplied to the vehicle-side coil 11 and the resonant circuit 12 to a predetermined power (constant value).

[0037] Fig. 3 is a diagram showing an example of the configuration of the variable capacitor 34, and shows an enlarged portion of the power supply device 30 in Fig. 1. As shown in Fig. 3, the variable capacitor 34 includes a first capacitor 341, at least one second capacitor 342 (two in the example of Fig. 3) provided in parallel with the first capacitor 341, and a switch 343 provided between the second capacitor 342 and a load connected to the third power conversion circuit 36.

[0038] The power supply side control unit 40 changes the capacitance of the variable capacitor 34 by controlling the on / off of the switch 343. In the example of Fig. 3, when both switches 343 are on, the capacitance of the variable capacitor 34 is the sum of the capacitance of the first capacitor 341 and the capacitance of each of the two second capacitors 342. When one of the two switches 343 is on and the other is off, the capacitance of the variable capacitor 34 is the sum of the capacitance of the first capacitor 341 and the capacitance of one of the second capacitors 342. When both of the two switches 343 are off, the capacitance of the first capacitor 341 is the capacitance of the variable capacitor 34.

[0039] For example, in an initial state, the power supply-side control unit 40 controls the two switches 343 to be off. When the vehicle-side control unit 20 executes capacity setting control in this initial state, a constant amount of power is transmitted from the in-vehicle device 10 to the power supply device 30, and this power charges the variable capacitor 34, causing the terminal voltage Vc to increase. After the capacity setting control starts, the power supply-side control unit 40 acquires the terminal voltage Vc of the variable capacitor 34 detected by the voltage detection circuit 35 and determines the amount of change in this terminal voltage Vc (the gradient of the change in the terminal voltage Vc over time). Based on this amount of change, the power supply-side control unit 40 determines the capacitance of the variable capacitor 34 that should be set during power supply control.

[0040] For example, when the change in the terminal voltage Vc is equal to or greater than a threshold, the power supply side control unit 40 controls the necessary number of switches 343 to be on according to the magnitude of the change, thereby increasing the capacitance of the variable capacitor 34 from its initial state.

[0041] In the initial state, two switches 343 may be controlled to be on. In this case, when the amount of change in the terminal voltage Vc is less than the threshold, the power supply side control unit 40 controls the necessary number of switches 343 to be off according to the magnitude of the amount of change, thereby reducing the capacitance of the variable capacitor 34 from that in the initial state.

[0042] Alternatively, in the initial state, one of the two switches 343 may be controlled to be on. In this case, when the amount of change in the terminal voltage Vc is equal to or greater than the threshold, the power supply side control unit 40 controls the switch 343 that is off to be on, thereby increasing the capacitance of the variable capacitor 34 compared to that in the initial state. Furthermore, when the amount of change in the terminal voltage Vc is less than the threshold, the power supply side control unit 40 controls the switch 343 that is on to be off, thereby decreasing the capacitance of the variable capacitor 34 compared to that in the initial state.

[0043] After the capacitance of the variable capacitor 34 is controlled in this manner, the vehicle-side control unit 20 executes power supply control.

[0044] As described above, according to the contactless power transfer system 100, the capacitance of the variable capacitor 34 during power transfer control is determined based on the amount of change in the terminal voltage of the variable capacitor 34 when a predetermined amount of power is transferred from the in-vehicle device 10 to the power supply device 30 before the start of power transfer control. Therefore, changes in the transfer function G(s) caused by individual differences between the in-vehicle device 10 and the power supply device 30, the positional relationship between the vehicle-side coil 11 and the power supply-side coil 31, etc. can be absorbed by adjusting the capacitance of the variable capacitor 34, enabling optimal power transfer control.

[0045] Even if the capacitance of the variable capacitor 34 is appropriately determined in the capacitance setting control, the transfer function G(s) may change during execution of the power supply control. For example, if the target current value output to the load is changed, or if the external environment, such as temperature, changes, the values ​​of the poles and zeros of the transfer function G(s) may change. Therefore, the power supply side controller 40 may monitor the terminal voltage Vc detected by the voltage detection circuit 35 during execution of the power supply control, and if the fluctuation of the terminal voltage Vc is large, change the capacitance of the variable capacitor 34 to absorb such changes in the poles and zeros. In this way, power transmission can be stably performed during the power supply control.

[0046] In this way, when the capacitance of variable capacitor 34 is changed during power supply control, it is preferable to provide resistor 344 in parallel with switch 343 in variable capacitor 34, as shown in Fig. 4. By providing resistor 344, it is possible to prevent inrush current when switch 343 switches from off to on, thereby improving the safety of the circuit.

[0047] This specification describes at least the following items. Note that the components in parentheses correspond to those in the above-described embodiment, but are not limited to these.

[0048] (1) a power receiving unit (a power supply side coil 31 and a resonant circuit 32) that receives power transmitted from a power transmitting device (an in-vehicle device 10) by contactless power transmission; a variable capacitance power supply unit (variable capacitor 34) that can be charged with the power received by the power receiving unit and can supply the stored power to a load; a detection unit (voltage detection circuit 35) that detects the terminal voltage of the power supply unit; and a control unit (power supply side control unit 40) that controls the capacity of the power supply unit based on the amount of change in the terminal voltage detected by the detection unit. Power receiving device (power supply device 30).

[0049] According to (1), the optimal capacity of the power supply unit can be determined based on the amount of change in the terminal voltage of the power supply unit charged by the power transmitted from the power transmitting device. As a result, optimal power transmission control becomes possible regardless of individual differences between the power transmitting device and the power receiving device, their relative positions, etc.

[0050] (2) The power receiving device according to (1), the power transmitting device is capable of performing power supply control to control power supplied from the power transmitting device to the power receiving unit so that a terminal voltage (terminal voltage Vc) of the power supply unit becomes a target voltage; the control unit controls a capacity of the power supply unit during the power supply control based on a change amount of the terminal voltage of the power supply unit when a predetermined power is transmitted from the power transmission device to the power receiving device before the power transmission control is performed by the power transmission device. Power receiving device.

[0051] According to (2), optimal power transmission control becomes possible regardless of individual differences between the power transmitting device and the power receiving device, their relative positions, and the like.

[0052] (3) (2) The power receiving device according to the present invention, When a change amount of the terminal voltage when the predetermined power is received in a state in which the capacity of the power supply unit is controlled to a predetermined capacity is equal to or greater than a threshold value, the control unit controls the capacity of the power supply unit during the power supply control to a capacity larger than the predetermined capacity. Power receiving device.

[0053] According to (3), optimal power transmission control becomes possible regardless of individual differences between the power transmitting device and the power receiving device, their relative positions, and the like.

[0054] (4) (2) The power receiving device according to the present invention, When a change amount of the terminal voltage when the predetermined power is received in a state in which the capacity of the power supply unit is controlled to a predetermined capacity is less than a threshold value, the control unit controls the capacity of the power supply unit during the power supply control to a capacity smaller than the predetermined capacity. Power receiving device.

[0055] According to (4), optimal power transmission control becomes possible regardless of individual differences between the power transmitting device and the power receiving device, their relative positions, and the like.

[0056] (5) A power receiving device according to any one of (1) to (4), The control unit further controls a capacity of the power supply unit based on a terminal voltage of the power supply unit while the power supply control is being performed. Power receiving device.

[0057] According to (5), even after power supply control has started, the capacity of the power supply unit can be appropriately controlled in accordance with changes in the transfer function of the system that charges the power supply, which may change depending on the load state, the external environment, etc.

[0058] (6) A power receiving device according to any one of (1) to (5), the power supply unit includes a first capacitor (first capacitor 341), at least one second capacitor (second capacitor 342) connected in parallel to the first capacitor, and a switch (switch 343) connected between the load and the second capacitor; The control unit controls the on / off of the switch to control the capacity of the power supply unit. Power receiving device.

[0059] (7) (6) The power receiving device according to the present invention, The power supply unit has a resistor (resistor 344) connected in parallel to the switch. Power receiving device.

[0060] According to (7), it is possible to prevent an inrush current when changing the capacity of the power supply unit during power supply control, thereby improving safety. [Explanation of symbols]

[0061] 10 Onboard equipment 11 Vehicle side coil 12,32 resonant circuit 13 First power conversion circuit 14 Filters 17 Secondary battery 18 First Communications Department 20 Vehicle side control unit 21 Comparator 22 Compensator 23 Pulse generation unit 30 Power supply 31 Power supply coil 33 Second power conversion circuit 34 Variable Capacitor 341 First Capacitor 342 Second Capacitor 343 Switch 344 resistor 35 Voltage detection circuit 36 Third power conversion circuit 37 Second Communications Department 40 Power supply side control unit 100 Contactless power transmission system

Claims

1. a power receiving unit that receives power transmitted from the power transmitting device by wireless power transmission; a power supply unit including a variable capacitor that is charged by the power received by the power receiving unit and is configured to be able to supply the stored power to a load; a detection unit that detects a terminal voltage of the power supply unit; a control unit that controls the capacitance of the variable capacitor based on the amount of change in the terminal voltage detected by the detection unit. Power receiving device.

2. The power receiving device according to claim 1 , the power transmitting device is capable of performing power supply control to control power supplied from the power transmitting device to the power receiving unit so that a terminal voltage of the power supply unit becomes a target voltage; the control unit controls the capacitance of the variable capacitor during the power supply control based on a change in the terminal voltage of the power supply unit when a predetermined power is transmitted from the power transmission device to the power receiving device before the power transmission control is performed by the power transmission device. Power receiving device.

3. The power receiving device according to claim 2, When a change amount of the terminal voltage when the predetermined power is received in a state in which the capacitance of the variable capacitor is controlled to a predetermined capacitance is equal to or greater than a threshold value, the control unit controls the capacitance of the variable capacitor during the power supply control to a capacitance larger than the predetermined capacitance. Power receiving device.

4. The power receiving device according to claim 2, When a change amount of the terminal voltage when the predetermined power is received in a state in which the capacitance of the variable capacitor is controlled to a predetermined capacitance is less than a threshold value, the control unit controls the capacitance of the variable capacitor during the power supply control to a capacitance smaller than the predetermined capacitance. Power receiving device.

5. The power receiving device according to claim 2, The control unit further controls the capacitance of the variable capacitor based on a terminal voltage of the power supply unit while the power supply control is being performed. Power receiving device.

6. The power receiving device according to any one of claims 1 to 5, the variable capacitor includes a first capacitor, at least one second capacitor connected in parallel to the first capacitor, and a switch connected between the load and the second capacitor; The control unit controls the on / off of the switch to control the capacitance of the variable capacitor. Power receiving device.

7. The power receiving device according to claim 6, The variable capacitor has a resistor connected in parallel with the switch. Power receiving device.

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