JP6481558B2 - 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 feeding system disclosed in Japanese Patent Application Laid-Open No. 2014-207795 (Patent Document 6), the power feeding device 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.

  In a voltage type inverter, it is known that when an output current (positive turn-on current) having the same sign as the output voltage flows at the rise of the output voltage, a recovery current is generated in the freewheeling diode of the inverter. When the recovery current is generated, the freewheeling diode generates heat and the loss increases. Therefore, for example, by adjusting the drive frequency of the inverter, the turn-on current is controlled to a target value (for example, a value of 0 or less).

  However, when the duty of the inverter output voltage is set to a small value, the drive frequency band of the inverter in which the positive turn-on current does not occur becomes narrower than when the duty is set to a large value. Therefore, when the target power is set to a small power and a small value is set as the duty of the inverter output voltage, a possibility that a positive turn-on current is generated increases. 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 an object of the invention is contactless power transmission that can suppress generation of a positive turn-on current even if a small value is set as a target power. Is to provide a device.

  A contactless power transmission device according to an aspect of the present invention includes a power transmission unit, a voltage-type inverter, a booster circuit, 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 booster circuit rectifies and boosts the AC power supplied from the AC power supply and supplies it to the inverter. The control unit controls the inverter and the booster circuit. The control unit can execute the first control and the second control. In the first control, the transmission power is controlled to the target power by adjusting the duty of the output voltage of the inverter. In the second control, the transmission power is controlled to the target power by adjusting the boost ratio of the booster circuit. The control unit executes the first control when the target power is the first power, and performs the second control when the target power is the second power smaller than the first power. Execute control.

  In this non-contact power transmission device, when the second power (<first power) is set as the target power, the transmission power is controlled to the target power by adjusting the boost ratio of the booster circuit. The Since the step-up ratio is lowered in order to control the transmitted power to a small electric power (second electric power), a larger value is set as the duty of the output voltage of the inverter than when the step-up ratio is not lowered. When a large value is set as the duty, the drive frequency band of the inverter that does not generate a positive turn-on current is wider than when a small value is set as the duty. Therefore, the possibility of generating a positive turn-on current is reduced.

  Further, as the step-up ratio decreases, the drive frequency band of the inverter that can control the turn-on current to a value of 0 or less, for example, is widened. Therefore, the possibility of generating a positive turn-on current is reduced.

  Therefore, according to this non-contact power transmission apparatus, even if a small value is set as the target power, generation of a positive turn-on current can be suppressed.

  According to this invention, even if a small value is set as the target power, it is possible to provide a contactless power transmission device that can suppress the generation of a positive turn-on current.

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 1st transmitted power control and turn-on current control. It is a control block diagram of 2nd transmission power control and turn-on current control. It is a flowchart which shows the switching control of 1st and 2nd transmission 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 portions 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. The PFC circuit 210 can change the boost ratio. Although details will be described later, when a small power is set as the target power of the transmission power by the power transmission device 10, the transmission power is controlled to the target power by adjusting the step-up ratio of the PFC circuit 210. Here, the small electric power refers to electric power that increases the possibility of generating a positive turn-on current, which will be described later, when the transmitted power is controlled to the target power by adjusting the duty of the output voltage of the inverter 220, which will be described later.

  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 “turn-on current”) to control the turn-on current in the inverter 220 to a target value when executing power transmission from the power transmitting apparatus 10 to the power receiving apparatus 20. Control "). 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.

  Further, the power supply ECU 250 executes the above-described turn-on current control and adjusts the duty of the output voltage of the inverter 220 to adjust the transmission power to the target power (hereinafter referred to as “first control”). Also referred to as “transmission power control”. 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, the power supply ECU 250 executes the above-described turn-on current control and adjusts the step-up ratio of the PFC circuit 210 to thereby control the transmission power to the target power (hereinafter referred to as “second transmission power control”). (Also referred to as “)”. When the first transmission power control is executed when the small power is set as the target power of the transmission power by the power transmission device 10, a small value is set as the duty of the output voltage of the inverter 220. When the duty of the inverter output voltage is set to a small value, the drive frequency band of the inverter in which the positive turn-on current does not occur becomes narrower than when the duty is set to a large value. Therefore, when the target power is set to a small power, if a small value is set as the duty of the inverter output voltage, a positive turn-on current is likely to occur. Therefore, the power transmission device 10 of this embodiment can execute the second transmission power control for the case where the target power is set to a small power.

  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.

(Description of control block for each control)
FIG. 3 is a control block diagram of first transmission power control and turn-on current control executed by the 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 the first transmission power control. On the other hand, a feedback loop constituted by the arithmetic unit 430, the controller 440, and the inverter 220 constitutes turn-on current control.

  Operation unit 410 subtracts the detected value of transmitted power Ps from target power Psr indicating the target value of transmitted 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 of the inverter 220 based on the deviation between the target power Psr and the transmission power Ps. The duty of the output voltage 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, the calculation unit 430 subtracts the detected value of the turn-on current It from the target value Itr of the turn-on current, and outputs the calculated value to the controller 440. Note that the turn-on current target value Itr is basically set to 0 or less as described above. The detected value of the turn-on current It is a detected value (instantaneous value) of the current sensor 272 (both see FIG. 1) when the voltage sensor 270 detects the rising of the output voltage Vo. 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.

  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.

  When the small power is set as the target power of the transmission power of the power transmission device 10, the second transmission power control is executed instead of the first transmission power control. FIG. 4 is a control block diagram of second transmission power control and turn-on current control executed by the power supply ECU 250. Here, the difference between the second transmission power control and the first transmission power control will be described. Referring to FIG. 4, a feedback loop constituted by calculation unit 410, controller 420, and PFC circuit 210 to be controlled constitutes second transmission power control.

  In the first transmission power control, the transmission power is controlled to the target power by adjusting the duty of the output voltage of the inverter 220. In the second transmission power control, unlike the first transmission power control, the transmission power is controlled to the target power by adjusting the step-up ratio of the PFC circuit 210.

  Specifically, in the second transmission power control, the controller 420 generates a command value for the step-up ratio of the PFC circuit 210 based on the deviation between the target power Psr and the transmission power Ps. The step-up ratio 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.

  In the first transmission power control, when the duty of the output voltage of the inverter 220 is set to a small value, the drive frequency band of the inverter 220 in which a positive turn-on current does not occur is set compared to the case where the duty is set to a large value. Narrow. Therefore, when the target power is set to a small power, if the transmission power is controlled to the target power by reducing the duty, the possibility of a positive turn-on current is increased.

  Therefore, in power transmission device 10 according to this embodiment, when the target power is the first power, the first transmission power control (duty control of the inverter output voltage) is executed, and the target power is the second power. In the case of electric power (<first electric power), second transmission electric power control (step-up ratio control of the PFC circuit) is executed.

  When the second power (<first power) is set as the target power, the step-up ratio of the PFC circuit 210 is reduced by the second transmission power control. A large value is set as the duty of 220 output voltage. When a large value is set as the duty, the drive frequency band of the inverter 220 in which a positive turn-on current does not occur is wider than when a small value is set as the duty. Therefore, the possibility of generating a positive turn-on current is reduced.

  Further, since the step-up ratio of the PFC circuit 210 is reduced, even if the output voltage of the inverter 220 is the same, the drive frequency band of the inverter 220 that can control the turn-on current to a value of 0 or less, for example Becomes wider. Therefore, the possibility of generating a positive turn-on current is reduced.

  Therefore, according to power transmission device 10 according to this embodiment, even if a small value is set as the target power, generation of a positive turn-on current can be suppressed. Next, transmission power control (switching control between the first and second transmission power controls) in the power transmission device 10 will be described.

(Transmission power control)
FIG. 5 is a flowchart for explaining the switching control between the first and second transmission power controls in the power transmission device 10. Referring to FIG. 5, 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 greater than a predetermined value P1 (step S110). The reason for making such a determination will be described next. When a small value is set as the duty of the output voltage of the inverter 220, the drive frequency band of the inverter 220 in which no positive turn-on current is generated becomes narrow. Therefore, when a small power is set as the target power, a positive turn-on current may occur if transmission power control (first transmission power control) is performed by setting a small value as the duty. Becomes higher. Therefore, in the power transmission device 10, whether or not the target power is equal to or less than the predetermined value P1 to determine whether to execute the first transmission power control or the second transmission power control without adjusting the duty. Judging.

  When it is determined that the target power is greater than or equal to predetermined value P1 (YES in step S110), power supply ECU 250 executes first transmission power control. That is, power supply ECU 250 controls the transmission power to the target power by adjusting the duty of the output voltage of inverter 220 (step S120). On the other hand, when it is determined that the target power is smaller than predetermined value P1 (NO in step S110), power supply ECU 250 executes the second transmission power control. That is, power supply ECU 250 controls the transmitted power to the target power by adjusting the step-up ratio of PFC circuit 210 (step S130).

  For example, after the start of charging, a large constant power (first power) is transmitted until the power storage device 350 is about to be fully charged. In the power transmission system in which the power of the power storage device 350 is transmitted, the first transmission power control is executed until the power storage device 350 is almost fully charged, and the second power is transmitted after the power storage device 350 is about to be fully charged. The transmission power control is executed. When the process of step S120 or S130 is executed, the process proceeds to step S140.

  Thus, in power transmission device 10 according to this embodiment, when the target power is the first power, the first transmission power control (inverter output voltage duty control) is executed, and the target power is the first power. When the power is 2 (<first power), second transmission power control (step-up ratio control of the PFC circuit) is executed. Thereby, even if a small value is set as the target power, generation of a positive turn-on current can be suppressed.

  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 booster circuit that rectifies and boosts AC power supplied from an AC power source and supplies the AC power to the inverter;
A control unit for controlling the inverter and the booster circuit;
The controller is
A first control for controlling the transmitted power to a target power by adjusting a duty of an output voltage of the inverter;
Without adjusting the duty, it is possible to execute a second control for controlling the transmitted power to the target power by adjusting the boost ratio of the booster circuit,
The control unit executes the first control when the target power is the first power, and when the target power is the second power smaller than the first power, A contactless power transmission device that executes the second control.

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