JP6350439B2 - Contactless power transmission equipment - Google Patents

Description

  The present invention relates to a contactless power transmission device, and more particularly, to a power control technique in a contactless power transmission device that transmits power to a power receiving device in a contactless manner.

  Conventionally, a non-contact power transmission system that transmits power from a power transmission device to a power reception device in a non-contact manner is known (see Patent Documents 1 to 6). The power transmission device includes a power transmission coil, and the power reception device includes a power reception coil.

  For example, in the non-contact power supply system disclosed in Japanese Patent Application Laid-Open No. 2014-207795 (Patent Document 6), the power supply apparatus includes a power transmission coil, an inverter, and a control unit. The power transmission coil transmits power in a non-contact manner to a power reception coil mounted on the vehicle. An inverter produces | generates the alternating current according to a drive frequency, and outputs it to a power transmission coil. The control unit obtains the charging power command to the battery and the output power to the battery from the vehicle side, and feedback controls the drive frequency of the inverter so that the output power follows the charging power command (see Patent Document 6).

JP2013-154815A JP2013-146154A JP2013-146148A JP 2013-110822 A JP 2013-126327 A JP 2014-207795 A

  When the inverter is a voltage-type inverter, and the transmission power corresponding to the drive frequency is supplied to the power transmission unit, the transmission power can be controlled by adjusting the duty of the inverter output voltage. Further, by adjusting the drive frequency of the inverter, it is possible to control the turn-on current indicating the inverter output current when the inverter output voltage rises.

  Here, the amount of change in the transmitted power with respect to the duty adjustment amount varies depending on the magnitude of the transmitted power. Specifically, the amount of change in the transmitted power with respect to the duty adjustment amount is larger when the transmitted power is small than when the transmitted power is large. This is because the load impedance change seen from the power receiving coil is large in the region where the transmitted power is small. Therefore, when the transmission power is small and the duty is changed, the transmission power is greatly changed compared to the case where the transmission power is large. As a result, the amount of overshoot of the transmitted power with respect to the target increases, and the control may become unstable. Such a problem and its solution are not particularly studied in the above-mentioned Patent Documents 1 to 6.

  The present invention has been made to solve such a problem, and its object is to contactlessly suppress the amount of overshoot of transmission power in consideration of the magnitude of transmission power. It is to provide a power transmission device.

  A non-contact power transmission device according to an aspect of the present invention includes a power transmission unit, an inverter, and a control unit. The power transmission unit is configured to transmit power to the power receiving device in a contactless manner. The voltage-type inverter supplies transmission power to the power transmission unit. The control unit controls the inverter. The control unit performs feedback control so as to bring the transmitted power closer to the target power by adjusting the duty of the output voltage of the inverter. The gain of feedback control is smaller when the target power is the first power than when the target power is the second power that is larger than the first power.

  In this non-contact power transmission device, when the target power is the first power, a smaller value is set as the gain of the feedback control than when the target power is the second power (> first power). Is done. Therefore, when the target power is set to the first power at which the amount of change in the transmission power with respect to the adjustment amount of the duty of the inverter output voltage is larger than when the target power is set to the second power. Also, the amount of adjustment of the duty can be suppressed. As a result, according to this non-contact power transmission device, the amount of overshoot of the transmitted power can be suppressed even when the amount of change in the transmitted power with respect to the output voltage duty adjustment amount is large.

  According to the present invention, it is possible to provide a contactless power transmission device that can appropriately suppress the amount of overshoot of transmitted power in consideration of the magnitude of transmitted power.

1 is an overall configuration diagram of a power transmission system according to an embodiment. It is the figure which showed an example of the circuit structure of a power transmission part and a power receiving part. It is a control block diagram of transmission power control and turn-on current control. It is a flowchart which shows the determination procedure of the gain in transmitted power control.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

(Configuration of contactless power transmission system)
FIG. 1 is an overall configuration diagram of a power transmission system to which a contactless power transmission device according to an embodiment of the present invention is applied. With reference to FIG. 1, the power transmission system includes a power transmission device 10 and a power reception device 20. The power receiving device 20 can be mounted on, for example, a vehicle that can travel using the electric power supplied and stored from the power transmitting device 10.

  The power transmission device 10 includes a power factor correction (PFC) circuit 210, an inverter 220, a filter circuit 230, and a power transmission unit 240. The power transmission device 10 further includes a power supply ECU (Electronic Control Unit) 250, a communication unit 260, a voltage sensor 270, and a current sensor 272.

  PFC circuit 210 rectifies and boosts AC power received from AC power supply 100 (for example, system power supply) and supplies it to inverter 220, and can improve the power factor by bringing the input current closer to a sine wave.

  Inverter 220 converts the DC power received from PFC circuit 210 into transmitted power (AC) having a predetermined transmission frequency. The transmission power generated by the inverter 220 is supplied to the power transmission unit 240 through the filter circuit 230. The inverter 220 is a voltage source inverter, and a free wheel diode is connected in antiparallel to each switching element constituting the inverter 220.

  Filter circuit 230 is provided between inverter 220 and power transmission unit 240 and suppresses harmonic noise generated from inverter 220.

  The power transmission unit 240 receives AC power (transmission power) having a transmission frequency from the inverter 220 through the filter circuit 230, and transmits power to the power reception unit 310 of the power reception device 20 in a non-contact manner through an electromagnetic field generated around the power transmission unit 240. To do.

  Voltage sensor 270 detects the output voltage of inverter 220 and outputs the detected value to power supply ECU 250. Current sensor 272 detects the output current of inverter 220 and outputs the detected value to power supply ECU 250.

  The power supply ECU 250 includes a central processing unit (CPU), a storage device, an input / output buffer, and the like (all not shown), receives signals from various sensors and devices, and controls various devices in the power transmission device 10. As an example, power supply ECU 250 performs switching control of inverter 220 so that inverter 220 generates transmission power (alternating current) when power transmission from power transmission device 10 to power reception device 20 is performed.

  As main control executed by the power supply ECU 250, the power supply ECU 250 performs feedback control (hereinafter referred to as “transmission power control”) for controlling the transmission power to the target power when executing power transmission from the power transmission device 10 to the power reception device 20. To execute). Specifically, power supply ECU 250 controls the transmitted power to the target power by adjusting the duty of the output voltage of inverter 220. The duty of the output voltage is defined as the ratio of the positive (or negative) voltage output time to the period of the output voltage waveform (rectangular wave). By changing the operation timing of the switching element (on / off duty 0.5) of the inverter 220, the duty of the inverter output voltage can be adjusted. The target power can be generated based on the power reception status of the power receiving device 20, for example. In this embodiment, in the power receiving device 20, the target power of the transmitted power is generated based on the deviation between the target value of the received power and the detected value, and transmitted from the power receiving device 20 to the power transmitting device 10.

  Further, power supply ECU 250 executes the above-described transmission power control and also executes feedback control (hereinafter also referred to as “turn-on current control”) for controlling the turn-on current in inverter 220 to a target value. Specifically, power supply ECU 250 controls the turn-on current to the target value by adjusting the drive frequency (switching frequency) of inverter 220. The turn-on current is an instantaneous value of the output current of the inverter 220 when the output voltage of the inverter 220 rises. If the turn-on current is positive, a recovery current in the reverse direction flows through the return diode of the inverter 220, and heat generation, that is, loss occurs in the return diode. Therefore, the target value (turn-on current target value) of the turn-on current control is set in a range where no recovery current is generated in the return diode of the inverter 220 and is basically set to a predetermined value of 0 or less (the power factor is good). “0” is ideal, but it may be set to a negative value by taking a margin, or may be set to a small positive value so that loss due to the recovery current does not cause a problem.) Note that the turn-on current does not necessarily have to be controlled to the target value. For example, a turn-on current limit value may be provided instead of the turn-on current target value. In this case, the turn-on current is controlled so as not to exceed the limit value.

  The communication unit 260 is configured to wirelessly communicate with the communication unit 370 of the power receiving device 20, receives a target value (target power) of transmitted power transmitted from the power receiving device 20, starts / stops power transmission, and receives the power 20 exchanges information such as the power reception status with the power receiving apparatus 20.

  On the other hand, power reception device 20 includes a power reception unit 310, a filter circuit 320, a rectification unit 330, a relay circuit 340, and a power storage device 350. Power receiving device 20 further includes a charging ECU 360, a communication unit 370, a voltage sensor 380, and a current sensor 382.

  The power receiving unit 310 receives the power (AC) output from the power transmission unit 240 of the power transmission device 10 in a non-contact manner. The power receiving unit 310 outputs the received power to the rectifying unit 330 through the filter circuit 320.

  The filter circuit 320 is provided between the power reception unit 310 and the rectification unit 330, and suppresses harmonic noise generated during power reception. Rectifier 330 rectifies the AC power received by power receiver 310 and outputs the rectified power to power storage device 350.

  The power storage device 350 is a rechargeable DC power supply, and is configured by a secondary battery such as a lithium ion battery or a nickel metal hydride battery. The power storage device 350 stores the power output from the rectifying unit 330.

  Relay circuit 340 is provided between rectifying unit 330 and power storage device 350 and is turned on when power storage device 350 is charged by power transmission device 10.

  Voltage sensor 380 detects the output voltage (power reception voltage) of rectification unit 330 and outputs the detected value to charging ECU 360. Current sensor 382 detects an output current (received current) from rectifying unit 330 and outputs the detected value to charging ECU 360.

  Charging ECU 360 includes a CPU, a storage device, an input / output buffer, and the like (all not shown), receives signals from various sensors and devices, and controls various devices in power reception device 20. The various controls are not limited to processing by software, and can be processed by dedicated hardware (electronic circuit).

  As main control executed by the charging ECU 360, the charging ECU 360 receives the target value of the transmission power in the power transmission device 10 so that the received power in the power reception device 20 becomes a desired target value during power reception from the power transmission device 10. Target power). Specifically, charging ECU 360 generates a target value of transmitted power in power transmission device 10 based on the deviation between the detected value of received power and the target value. Then, the charging ECU 360 transmits the generated target value (target power) of the transmitted power to the power transmitting apparatus 10 through the communication unit 370.

  The communication unit 370 is configured to wirelessly communicate with the communication unit 260 of the power transmission device 10, and transmits a target value (target power) of transmitted power generated in the charging ECU 360 to the power transmission device 10.

  FIG. 2 is a diagram illustrating an example of a circuit configuration of the power transmission unit 240 and the power reception unit 310 illustrated in FIG. 1. Referring to FIG. 2, power transmission unit 240 includes a primary coil 242 and a capacitor 244. Capacitor 244 is provided to compensate the power factor of transmitted power, and is connected in series to primary coil 242. The power receiving unit 310 includes a secondary coil 312 and a capacitor 314. Capacitor 314 is provided to compensate the power factor of the received power, and is connected in series to secondary coil 312.

  Referring to FIG. 1 again, in this power transmission system, transmission power (alternating current) is supplied from inverter 220 to power transmission unit 240 through filter circuit 230. Each of power transmission unit 240 and power reception unit 310 includes a coil and a capacitor, and is designed to resonate at a transmission frequency. The Q value indicating the resonance intensity of the power transmission unit 240 and the power reception unit 310 is preferably 100 or more.

  In the power transmission device 10, when transmission power is supplied from the inverter 220 to the power transmission unit 240, the power transmission unit 240 transmits power to the power reception unit 310 through an electromagnetic field formed between the coil of the power transmission unit 240 and the coil of the power reception unit 310. Energy (electric power) moves. The energy (power) transferred to the power receiving unit 310 is supplied to the power storage device 350 through the filter circuit 320 and the rectifying unit 330.

(Control block for each control)
FIG. 3 is a control block diagram of transmission power control and turn-on current control executed by power supply ECU 250. Referring to FIG. 3, power supply ECU 250 includes arithmetic units 410 and 430 and controllers 420 and 440. A feedback loop including the calculation unit 410, the controller 420, and the inverter 220 to be controlled constitutes transmission power control. On the other hand, a feedback loop including the calculation unit 430, the controller 440, and the inverter 220 constitutes turn-on current control.

  Calculation unit 410 subtracts the detected value of transmission power Ps from target power Psr indicating the target value of transmission power, and outputs the calculated value to controller 420. The detected value of the transmission power Ps can be calculated based on the detected values of the voltage sensor 270 and the current sensor 272 shown in FIG.

  The controller 420 generates a duty command value for the output voltage Vo of the inverter 220 based on the deviation between the target power Psr and the transmission power Ps. The duty of the output voltage Vo is adjusted so that the transmitted power Ps approaches the target power Psr, and the transmitted power Ps is controlled to the target power Psr.

  On the other hand, calculation unit 430 subtracts the detected value of turn-on current It from target value Itr of turn-on current, and outputs the calculated value to controller 440. Note that the target value Itr of the turn-on current is basically set to 0 or less as described above. The detected value of the turn-on current It is the detected value (instantaneous value) of the current sensor 272 (FIG. 1) when the rising of the output voltage is detected by the voltage sensor 270 (FIG. 1). Further, as described above, the turn-on current does not necessarily have to be controlled to the target value. For example, a turn-on current limit value may be provided instead of the turn-on current target value. In this case, the turn-on current is controlled so as not to exceed the limit value.

  The controller 440 generates a drive frequency (switching frequency) command value for the inverter 220 based on the deviation between the turn-on current target value Itr and the turn-on current It. The drive frequency of the inverter 220 is adjusted so that the turn-on current It approaches the target value Itr, and the turn-on current It is controlled to the target value Itr.

  In such a non-contact power transmission system in which the transmission power is controlled by adjusting the duty of the inverter output voltage, the amount of change in the transmission power with respect to the adjustment amount of the duty varies depending on the magnitude of the transmission power. Specifically, the amount of change in the transmitted power with respect to the duty adjustment amount is larger when the transmitted power is small than when the transmitted power is large. This is because the load impedance change seen from the secondary coil 312 is large in the region where the transmitted power is small.

  Therefore, when the duty is changed when the transmitted power is small, the transmitted power is greatly changed as compared with the case where the transmitted power is large. As a result, the amount of overshoot of the transmitted power with respect to the target power increases, and the control may become unstable.

  In the power transmission device 10 according to this embodiment, the gain of transmission power control (feedback control) is greater when the target power is the first power than when the target power is the second power (> first power). small.

  As a result, when the target power is set to the first power at which the amount of change in the transmission power with respect to the output voltage duty adjustment amount is larger than when the target power is set to the second power. In addition, the amount of adjustment of the duty of the output voltage of the inverter can be suppressed. As a result, according to the power transmission device 10, even when the amount of change in the transmission power with respect to the adjustment amount of the duty of the output voltage is large, the overshoot amount of the transmission power can be suppressed.

Next, how the gain for transmission power control is specifically determined will be described.
(Determination of gain)
FIG. 4 is a flowchart showing a gain determination procedure in transmission power control. The processing shown in this flowchart is executed in parallel with the above-described transmission power control. Referring to FIG. 4, power supply ECU 250 receives information related to the target power of the transmitted power from charging ECU 360 via communication units 260 and 370 (step S100).

  When information regarding the target power of the transmitted power is received, power supply ECU 250 determines whether or not the target power is equal to or less than predetermined value P1 (step S110). This is because the amount of change in the transmission power with respect to the amount of adjustment of the duty of the inverter output voltage differs depending on the magnitude of the transmission power, and thus it is necessary to change the gain in the transmission power control depending on the magnitude of the target power.

  When it is determined that the target power is larger than predetermined value P1 (NO in step S110), power supply ECU 250 sets gain G2 as a gain of the transmitted power (step S120). On the other hand, when it is determined that the target power is equal to or less than predetermined value P1 (YES in step S110), power supply ECU 250 sets gain G1 smaller than gain G2 as a gain for transmission power control (step S130).

  For example, a large constant power (second power) is transmitted for a predetermined time from the start of charging, and a small constant power (first power) is transmitted from near the full charge of the power storage device 350 after the predetermined time has elapsed. In the power transmission system, a large gain (gain G2) is set as a gain for transmission power control until a predetermined time elapses, and a small gain (gain G1) is set as a gain after the predetermined time elapses. When the process of step S120 or S130 is completed, the process proceeds to step S140.

  Thus, in the power transmission device 10, the gain of the transmission power control (feedback control) is smaller when the target power is the first power than when the target power is the second power (> first power). . Thereby, according to this power transmission device 10, even when the amount of change in the transmission power with respect to the adjustment amount of the duty of the output voltage is large, the overshoot amount of the transmission power can be suppressed.

  The power supply ECU 250 may store a function that can calculate an optimum gain for each target power in an internal memory (not shown), and calculate a gain for transmission power control for each target power based on this function. . Thereby, since an appropriate gain can be set for each target power, the control can be further stabilized.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 10 Power transmission apparatus, 20 Power receiving apparatus, 100 AC power supply, 210 PFC circuit, 220 Inverter, 230, 320 Filter circuit, 240 Power transmission part, 242 Primary coil, 244,314 Capacitor, 246,316 Resistance, 250 Power supply ECU, 260,370 Communication unit, 270, 380 Voltage sensor, 272, 382 Current sensor, 310 Power receiving unit, 312 Secondary coil, 330 Rectifier, 340 Relay circuit, 350 Power storage device, 360 Charge ECU, 410, 430 Calculation unit, 420, 440 Controller .

Claims (1)

A power transmission unit configured to transmit power to the power receiving device in a contactless manner;
A voltage-type inverter for supplying transmission power to the power transmission unit;
A control unit for controlling the inverter,
The control unit executes feedback control so as to bring the transmitted power closer to the target power by adjusting the duty of the output voltage of the inverter,
The gain of the feedback control is a non-contact power transmission device in which, when the target power is the first power, the gain is smaller than when the target power is the second power that is larger than the first power.

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