JP6565808B2 - Power transmission device and power transmission system - Google Patents

Description

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

  There is known a power transmission system that transmits power from a power transmission device to a power reception device in a contactless manner (see, for example, Patent Documents 1 to 6). About such an electric power transmission system, Unexamined-Japanese-Patent No. 2014-207795 (patent document 1) discloses the non-contact electric power feeding system which carries out non-contact electric power feeding from a power feeding apparatus (power transmission apparatus) to a vehicle (power receiving apparatus). In this non-contact power supply system, 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 1).

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

  In the power transmission system as described above, the power transmission efficiency between the power transmission coil and the power reception coil is adjusted by adjusting the frequency of the transmission power so that the current flowing through the power transmission coil is minimized while the power is maintained. Can be increased.

  By using the known extreme value search control that searches for the extreme value of the controlled variable by giving a vibration signal to the controlled object, the frequency of the transmission power generated by the inverter is vibrated, so that the current flowing through the power transmission coil is minimized. It is possible to search for an optimal frequency. However, the vibration operation that vibrates the frequency and the frequency movement operation (control operation) based on the search result of the extreme value search control interfere with each other, so that a change in the current of the power transmission coil due to the vibration operation is erroneously detected. There is a possibility that the frequency is erroneously operated.

  The present invention has been made to solve such a problem, and an object of the present invention is to optimally minimize a current flowing through a power transmission coil in a power transmission device that transmits power to a power receiving device in a contactless manner and a power transmission system including the power transmission device. It is to improve the accuracy of extreme value search control for searching for a frequency.

  A power transmission device according to the present invention includes a power transmission coil that transmits power to a power receiving device in a contactless manner, an inverter that generates AC transmission power and supplies the power to the power transmission coil, and a frequency control that adjusts the frequency of the transmission power by controlling the inverter. The control part which performs is provided. The frequency control includes extreme value search control for searching for a frequency at which the current flowing through the power transmission coil is minimized by vibrating the frequency. The control unit operates the frequency so that the frequency movement operation based on the search result of the extreme value search control does not overlap the frequency vibration operation.

  The power transmission system according to the present invention includes a power transmission device and a power reception device. The power transmission device executes a power transmission coil that transmits power to the power receiving device in a contactless manner, an inverter that generates AC transmission power and supplies the power to the power transmission coil, and frequency control that adjusts the frequency of the transmission power by controlling the inverter. And a control unit. The frequency control includes extreme value search control for searching for a frequency at which the current flowing through the power transmission coil is minimized by vibrating the frequency. The control unit operates the frequency so that the frequency movement operation based on the search result of the extreme value search control does not overlap the frequency vibration operation.

  In this power transmission device and power transmission system, extreme value search control for searching for an optimum frequency that minimizes the current flowing in the power transmission coil is performed by vibrating the frequency of the transmitted power. And since the frequency is operated so that the frequency movement operation based on the search result of the extreme value search control does not overlap with the frequency vibration operation, it is possible to accurately detect a change in the current of the power transmission coil due to the frequency vibration operation. . Therefore, according to this power transmission device and power transmission system, the accuracy of the extreme value search control can be improved, and as a result, the power transmission efficiency between the power transmission coil and the power reception coil can be increased.

  According to the present invention, in a power transmission device that transmits power to a power receiving device in a contactless manner and a power transmission system including the power transmission device, it is possible to improve the accuracy of extreme value search control that searches for an optimum frequency that minimizes the current flowing through the power transmission coil. it can. As a result, the power transmission efficiency between the power transmission coil and the power reception coil can be increased.

1 is an overall configuration diagram of a power transmission system to which a power transmission device according to an embodiment of the present invention is applied. It is a circuit diagram explaining the structure of the power transmission part and power receiving part which are shown in FIG. It is a control block diagram of transmission power control and transmission coil current control executed by the power supply ECU. It is a timing chart explaining the execution period of the vibration operation of the frequency, and the execution period of the movement operation of the frequency based on the result of the vibration operation. It is the figure which showed an example of the vibration operation of the frequency based on the vibration signal produced | generated by the vibration signal production | generation part, and the movement operation of the frequency based on the output of a controller. In power transmission coil current control, it is a reference figure which shows an example of frequency operation in case frequency vibration operation and frequency movement operation based on a control result overlap. It is a flowchart for demonstrating the process sequence of the extreme value search control performed by power supply ECU.

  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.

  FIG. 1 is an overall configuration diagram of a power transmission system to which a 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 is 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. Power transmission device 10 further includes a power supply ECU (Electronic Control Unit) 250, a communication unit 260, a voltage sensor 270, and current sensors 272 and 274.

  The PFC circuit 210 rectifies and boosts the power received from the AC power supply 100 such as a commercial power supply and supplies it to the inverter 220, and improves the power factor by bringing the input current closer to a sine wave. Various known PFC circuits can be adopted as the PFC circuit 210. Instead of the PFC circuit 210, a rectifier that does not have a power factor improvement function may be employed.

  Inverter 220 is controlled by power supply ECU 250 and converts DC power received from PFC circuit 210 into transmitted power (AC) having a predetermined frequency (for example, several tens of kHz). Inverter 220 can adjust the frequency of transmitted power by changing the switching frequency in accordance with a control signal from power supply ECU 250. The transmission power generated by the inverter 220 is supplied to the power transmission unit 240 through the filter circuit 230. Inverter 220 is formed of, for example, a single-phase full bridge circuit.

  Filter circuit 230 is provided between inverter 220 and power transmission unit 240 and suppresses harmonic noise generated from inverter 220. The filter circuit 230 is configured by, for example, an LC filter including an inductor and a capacitor.

  The power transmission unit 240 receives AC power (transmitted power) generated by the inverter 220 from the inverter 220 through the filter circuit 230 and transmits power to the power reception unit 310 of the power reception device 20 through a magnetic field generated around the power transmission unit 240 in a contactless manner. To do. The power transmission unit 240 includes a resonance circuit (not shown) for transmitting power to the power reception unit 310 in a contactless manner. The resonance circuit may be configured by a coil and a capacitor. However, when a desired resonance state is formed only by the coil, the capacitor may not be provided.

  Voltage sensor 270 detects output voltage V of inverter 220 and outputs the detected value to power supply ECU 250. Current sensor 272 detects current flowing through inverter 220, that is, output current Iinv of inverter 220, and outputs the detected value to power supply ECU 250. Note that the transmission power supplied from the inverter 220 to the power transmission unit 240 can be detected based on the detection values of the voltage sensor 270 and the current sensor 272. Current sensor 274 detects current Is flowing through power transmission unit 240 and outputs the detected value to power supply ECU 250.

  The power supply ECU 250 includes a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores processing programs, a RAM (Random Access Memory) that temporarily stores data, an input / output port for inputting and outputting various signals, and the like. (All not shown), and receives signals from the above-described sensors and the like, and executes control of various devices in the power transmission device 10. For example, power supply ECU 250 executes 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. Various controls are not limited to processing by software, and can be processed by dedicated hardware (electronic circuit).

  In power transmission device 10 according to the present embodiment, as main control executed by power supply ECU 250, power supply ECU 250 performs control for setting the transmission power to the target power when executing power transmission from power transmission device 10 to power reception device 20. (Hereinafter also referred to as “transmission power control”). 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 of the inverter 220 is defined as the ratio of the positive (or negative) voltage output time to the cycle of the output voltage waveform (rectangular wave). The duty of the inverter output voltage can be adjusted by changing the operation timing of the switching element (on / off period ratio 0.5) of the inverter 220. The target power of the transmitted power is 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.

  Furthermore, the power supply ECU 250 executes the above-described transmission power control, and performs control for minimizing a current Is flowing in a power transmission coil (described later) included in the power transmission unit 240 while the transmission power is maintained (hereinafter referred to as “ Also referred to as “power transmission coil current control”). Although details will be described later, the power transmission efficiency between the power transmission unit 240 (power transmission coil) and the power reception unit 310 (power reception coil) increases as the current flowing through the power transmission coil decreases with transmission power maintained. . Therefore, the power supply ECU 250 adjusts the drive frequency of the inverter 220 (the switching frequency of the inverter 220 and also the frequency of transmission power) so that the current Is flowing through the transmission coil is minimized while executing transmission power control. To do. Power supply ECU 250 can adjust the drive frequency of inverter 220, that is, the frequency of transmitted power, in a predetermined frequency band (which can be determined by a standard or the like), and does not adjust the frequency outside this frequency band.

  The communication unit 260 is configured to wirelessly communicate with the communication unit 370 of the power receiving device 20. The communication unit 260 receives a target of transmission power (target power) transmitted from the power receiving device 20, exchanges information about start / stop of power transmission with the power receiving device 20, and receives power reception status (power reception) of the power receiving device 20. Voltage, received current, received power, etc.) from the power receiving device 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 reception unit 310 receives the power (alternating current) output from the power transmission unit 240 of the power transmission device 10 in a non-contact manner through a magnetic field. Power reception unit 310 includes, for example, a resonance circuit for receiving power from power transmission unit 240 in a contactless manner (not shown). The resonance circuit may be configured by a coil and a capacitor. However, when a desired resonance state is formed only by the coil, the capacitor may not be provided.

  The filter circuit 320 is provided between the power reception unit 310 and the rectification unit 330, and suppresses harmonic noise generated when the power reception unit 310 receives power. The filter circuit 320 is configured by an LC filter including an inductor and a capacitor, for example. Rectifier 330 rectifies the AC power received by power receiver 310 and outputs the rectified power to power storage device 350. The rectification unit 330 includes a smoothing capacitor together with a rectifier.

  The power storage device 350 is a rechargeable DC power source, and includes 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. Then, power storage device 350 supplies the stored power to a load driving device or the like (not shown). Note that an electric double layer capacitor or the like can also be employed as the power storage device 350.

  Relay circuit 340 is provided between rectifying unit 330 and power storage device 350. Relay circuit 340 is turned on (conductive state) 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. Based on the detection values of the voltage sensor 380 and the current sensor 382, the power received by the power receiving unit 310 (corresponding to the charging power of the power storage device 350) can be detected. The voltage sensor 380 and the current sensor 382 may be provided between the power receiving unit 310 and the rectifying unit 330 (for example, between the filter circuit 320 and the rectifying unit 330).

  Charging ECU 360 includes a CPU, a ROM, a RAM, an input / output port, and the like (all not shown), receives signals from the above-described sensors and the like, 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 of transmission power (target power) in the power transmission device 10 so that the received power in the power reception device 20 becomes a desired target during power reception from the power transmission device 10. ) Is generated. Specifically, charging ECU 360 generates a target of transmitted power in power transmission device 10 based on the deviation between the target of received power and the detected value. Then, the charging ECU 360 transmits the generated transmission power target (target power) to the power transmission device 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. The communication unit 370 transmits the target (target power) of the transmission power generated in the charging ECU 360 to the power transmission device 10, exchanges information about start / stop of power transmission with the power transmission device 10, and receives power from the power reception device 20. The situation (power reception voltage, power reception current, power reception power, etc.) is transmitted to the power transmission device 10.

  In this power transmission system, AC transmission power is supplied from the inverter 220 to the power transmission unit 240 through the filter circuit 230 in the power transmission device 10. Each of power transmission unit 240 and power reception unit 310 includes a resonance circuit and is designed to resonate at the frequency of transmitted power.

  When AC power is supplied from the inverter 220 to the power transmission unit 240 through the filter circuit 230, a magnetic field formed between the coil that configures the resonance circuit of the power transmission unit 240 and the coil that configures the resonance circuit of the power reception unit 310. Through this, energy (electric power) moves from the power transmission unit 240 to the power reception unit 310. 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.

  FIG. 2 is a circuit diagram illustrating the configuration of power transmission unit 240 and power reception unit 310 shown in FIG. Referring to FIG. 2, power transmission unit 240 includes a power transmission coil 242 and a capacitor 244. The capacitor 244 is connected in series with the power transmission coil 242 to form a resonance circuit with the power transmission coil 242. Capacitor 244 is provided to adjust the resonance frequency of power transmission unit 240. The Q value indicating the resonance strength of the resonance circuit constituted by the power transmission coil 242 and the capacitor 244 is preferably 100 or more. In the circuit diagram, in the power transmission device 10, the filter circuit 230 (FIG. 1) between the inverter 220 and the power transmission unit 240 is omitted.

  Power reception unit 310 includes a power reception coil 312 and a capacitor 314. The capacitor 314 is connected in series with the power receiving coil 312 to form a resonance circuit with the power receiving coil 312. The capacitor 314 is provided to adjust the resonance frequency of the power reception unit 310. The Q value of the resonance circuit constituted by the power receiving coil 312 and the capacitor 314 is also preferably 100 or more.

  Although not particularly illustrated, the structures of the power transmission coil 242 and the power reception coil 312 are not particularly limited. For example, when the power transmission unit 240 and the power reception unit 310 face each other, a spiral coil or a spiral coil wound around an axis along the direction in which the power transmission unit 240 and the power reception unit 310 are aligned is used as the power transmission coil 242 and the power reception coil 312. Can be adopted for each of the above. Alternatively, when the power transmission unit 240 and the power reception unit 310 face each other, a coil formed by winding an electric wire around a ferrite plate whose normal direction is the direction in which the power transmission unit 240 and the power reception unit 310 are arranged is a power transmission coil 242 and a power reception coil. Each of 312 may be adopted.

  Here, it is assumed that the inductance of the power receiving coil 312 is L2, and the capacitance of the capacitor 314 is C2. The electrical load 390 is the filter circuit 320, the rectifier 330, and the power storage device 350 (FIG. 1) after the power receiving unit 310. The impedance 395 indicates the equivalent impedance of the electric load 390, and the impedance value is RL. That is, impedance 395 is a load impedance after power receiving unit 310 (hereinafter, equivalent impedance RL of electric load 390 is also referred to as “load impedance RL”). Note that the load impedance RL includes the circuit configuration of the electric load 390, the power received by the electric load 390 (received power), and the voltage of the power storage device 350 (FIG. 1) included in the electric load 390 (the voltage of the electric load 390 is stored) Restrained by the device 350).

  In such a circuit configuration, the power transmission efficiency η between the power transmission coil 242 and the power reception coil 312 is expressed by the following equation.

  Here, I1 indicates a current flowing through the power transmission coil 242 (that is, current Is), and I2 indicates a current flowing through the power receiving coil 312. R1 represents the winding resistance of the power transmission coil 242, and r2 represents the winding resistance of the power reception coil 312. Since the voltage of the electrical load 390 is constrained by the power storage device 350 (FIG. 1), the current I2 and the load impedance RL become substantially constant when power is maintained. Therefore, it is understood from the equation (1) that the power transmission efficiency η is inversely proportional to the square of the current I1. That is, the smaller the current I1 flowing through the power transmission coil 242, the higher the power transmission efficiency η.

  Therefore, in power transmission device 10 according to this embodiment, power transmission coil current control is performed to minimize current Is (FIG. 1) flowing through power transmission coil 242 while transmission power is maintained. For this power transmission coil current control, extreme value search control for searching for an extreme value of a controlled variable by applying a vibration signal to a controlled object is applied. That is, although details of the control will be described later, the power supply ECU 250 searches for an optimum frequency at which the current Is flowing through the power transmission coil 242 is minimized by oscillating the frequency of the transmitted power using the extreme value search control.

  This extreme value search control detects a change in the current Is of the power transmission coil 242 due to the vibration of the frequency of the transmission power and moves (operates) the frequency in a direction in which the current Is decreases. The operation of vibrating (vibration operation) interferes with the frequency operation based on the search result of the extreme value search control (moving operation based on the control), so that a change in the current Is of the power transmission coil 242 due to the frequency vibration operation is erroneously detected. As a result, the frequency may be erroneously manipulated.

  Therefore, in power transmission device 10 according to the present embodiment, power supply ECU 250 causes frequency movement operation (movement operation based on control) based on a search result of extreme value search control to be a frequency vibration operation for calculating the movement operation amount. Operate the frequency so that it does not overlap. Thereby, the change of the current Is of the power transmission coil 242 due to the frequency vibration operation can be accurately detected. Therefore, according to this power transmission system, the accuracy of the extreme value search control can be improved, and as a result, the power transmission efficiency between the power transmission coil 242 and the power reception coil 312 can be increased.

  FIG. 3 is a control block diagram of transmission power control and transmission coil current control executed by the power supply ECU 250. Referring to FIG. 3, power supply ECU 250 includes a first control unit 400 that executes transmission power control, and a second control unit 500 that executes transmission coil current control.

  The first control unit 400 includes a subtraction unit 410 and a controller 420. Subtraction unit 410 subtracts the detected value of transmission power Ps from target power Psr indicating the target of transmission power, and outputs the calculated value to controller 420. The detection value of the transmission power Ps is calculated based on, for example, the detection values of the voltage sensor 270 and the current sensor 272 shown in FIG. For example, the target power Psr is generated in the power receiving device 20 based on the power reception status of the power receiving device 20, and is transmitted from the power receiving device 20 to the power transmitting device 10.

  The controller 420 generates a duty command value for the inverter output voltage based on the deviation between the target power Psr and the transmission power Ps. For example, the controller 420 calculates an operation amount by executing PI control (proportional integral control) with a deviation (output of the subtraction unit 410) between the target power Psr and the transmission power Ps as an input, and calculates the calculated operation. The amount is the duty command value.

  The second control unit 500 includes a vibration signal generation unit 510, a high pass filter (HPF (High Pass Filter)) 520, a multiplication unit 530, a low pass filter (LPF (Low Pass Filter)) 540, a controller 550, An adder 560 and a timing adjuster 570 are included.

  The vibration signal generation unit 510 generates a vibration signal having a sufficiently small amplitude and a low frequency. In the extreme value search control, by using such a vibration signal, the transition of the frequency f of the transmission power to the optimum frequency (the frequency at which the current Is flowing through the power transmission coil 242 is minimized) is monitored.

  The HPF 520 receives the detected value of the current Is flowing through the power transmission coil 242 and outputs a signal from which the DC component of the current Is is removed. The HPF 520 extracts the slope (differential coefficient) of the current Is when the frequency f of the transmission power is vibrated based on the vibration signal generated by the vibration signal generation unit 510.

  The multiplier 530 multiplies the signal (differential coefficient of the current Is) output from the HPF 520 by the vibration signal generated by the vibration signal generator 510, and calculates a correlation coefficient between the vibration signal and the current Is. This correlation coefficient indicates the increase / decrease direction of the current Is when the frequency f is changed.

  The LPF 540 extracts the direct current component of the correlation coefficient calculated by the multiplication unit 530. The output of the LPF 540 indicates the operation direction (increase / decrease direction) of the frequency f for shifting the frequency f to the optimum frequency. The LPF 540 can be omitted.

  The controller 550 calculates an operation amount (change amount) of the frequency f for shifting the frequency f to the optimal frequency based on the output of the LPF 540. For example, the controller 550 calculates an operation amount of the frequency f by executing I control (integration control) using the output signal of the LPF 540 as an input. The adder 560 adds the output of the controller 550 and the vibration signal generated by the vibration signal generator 510, and uses the calculated value as the final operation amount of the frequency f.

  The timing adjustment unit 570 adjusts the generation timing of the vibration signal by the vibration signal generation unit 510 and the output timing of the frequency movement operation amount calculated by the controller 550. Specifically, the timing adjustment unit 570 includes a vibration signal generation unit so that the frequency movement operation based on the output of the controller 550 does not overlap the frequency vibration operation based on the vibration signal generated by the vibration signal generation unit 510. The operation timings of 510 and controller 550 are adjusted.

  FIG. 4 is a timing chart for explaining the execution period of the frequency vibration operation and the execution period of the frequency movement operation based on the result of the vibration operation. Referring to FIG. 4, the horizontal axis indicates time, and the vertical axis indicates frequency. The period T1 is a period in which a vibration operation with a frequency based on the vibration signal generated by the vibration signal generation unit 510 is executed. A period T2 following the period T1 is a period in which a frequency moving operation based on the output of the controller 550 is executed. The period T1 during which the frequency oscillating operation is performed and the period T2 during which the frequency moving operation is performed are alternately set so as not to overlap each other.

  In this extreme value search control, since it is necessary to detect a change in the current Is of the power transmission coil 242 due to the frequency vibration operation while the transmission power is maintained, the period T1 during which the frequency vibration operation is executed is determined. It is preferable to secure a time of + α when the power change due to the frequency change is settled. On the other hand, the period T2 during which the operation of moving the frequency based on the output of the controller 550 is executed does not necessarily require the power to be maintained, and can be set to a time shorter than the period T1 (for example, the period T1 = power For settling time + α, period T2 = power settling time).

  FIG. 5 is a diagram illustrating an example of a frequency vibration operation based on the vibration signal generated by the vibration signal generation unit 510 and a frequency movement operation based on the output of the controller 550. Referring to FIG. 5, in a period T1 from time t1, a vibration operation (amplitude A1) of a frequency based on the vibration signal generated by vibration signal generation unit 510 is executed. Thereafter, in a period T2 from time t2, a frequency movement operation (operation amount B1) by the controller 550 based on a change in the current Is of the power transmission coil 242 due to the vibration operation in the period T1 is executed. Since the execution timing of the frequency vibration operation and the movement operation is adjusted so that the period T1 during which the frequency vibration operation is performed and the period T2 during which the frequency movement operation is performed are not overlapped, the frequency vibration is performed. It is possible to accurately detect a change in the current Is of the power transmission coil 242 due to the operation, and as a result, it is possible to improve the calculation accuracy of the frequency moving operation amount by the controller 550.

  As a reference example, FIG. 6 is a reference diagram illustrating an example of a frequency operation when a frequency vibration operation and a frequency movement operation based on a control result overlap in power transmission coil current control. Referring to FIG. 6, a frequency oscillation operation (amplitude A1) is executed in a period T1 from time t11. Thereafter, at time t12 after the elapse of period T1 from time t11, the frequency oscillation operation (amplitude A1) is executed again. Further, at this timing, a frequency movement operation (operation amount B1) based on a change in the power transmission coil current due to the vibration operation in the period T1 from time t11 to time t12 is also executed. Thereby, the frequency is operated by A2 (= A1 + B1).

  Then, in the period T1 from time t12 to time t13, the change in the power transmission coil current due to the vibration operation with the frequency of the amplitude A1 cannot be detected, and the change in the power transmission coil current due to the frequency vibration operation is erroneously detected ( Detection of a change in the power transmission coil current with respect to a change in the frequency of A2. Therefore, at time t13, based on the erroneously detected current change, a frequency movement operation (operation amount B2) is executed, and the operation amount (A1) for the vibration operation is further superimposed on this movement operation amount.

  Thus, if the frequency vibration operation and the frequency movement operation based on the control result overlap, it is impossible to accurately detect the change in the current of the power transmission coil due to the frequency vibration operation, and the accuracy of the extreme value search control May be reduced.

  On the other hand, in the power transmission device 10 according to this embodiment, as shown in FIGS. 4 and 5, the frequency vibration operation and the movement operation are not overlapped. The change of the current Is can be detected accurately, and as a result, the search accuracy by the extreme value search control can be increased.

  FIG. 7 is a flowchart for explaining a processing procedure of extreme value search control executed by power supply ECU 250. The process shown in this flowchart is called from the main routine and executed every predetermined time or when a predetermined condition is satisfied.

  Referring to FIG. 7, power supply ECU 250 controls inverter 220 to execute a vibration operation that vibrates the frequency of transmitted power (step S <b> 10). Note that the vibration operation executed in step S10 is one vibration operation in the period T1 shown in FIGS.

  Next, power supply ECU 250 determines whether or not the vibration operation period has elapsed (step S20). This vibration operation period is the period T1 shown in FIGS. If it is determined in step S20 that the vibration operation period has elapsed (YES in step S20), power supply ECU 250 receives the detected value of current Is flowing in power transmission coil 242 from current sensor 274, and the detection result of current Is. Is used to calculate the correlation coefficient between the frequency vibration operation (vibration signal) and the current Is (step S30). As described above, this correlation coefficient indicates the increase / decrease direction of the current Is when the frequency is changed.

  Subsequently, the power supply ECU 250 uses the correlation coefficient calculated in step S30 to calculate a frequency moving operation amount for shifting the frequency to the optimum frequency (step S40). For example, power supply ECU 250 extracts the DC component of the correlation coefficient, and calculates the amount of movement operation of the frequency by executing I control using the calculation result as an input. Then, power supply ECU 250 controls inverter 220 to execute a frequency movement operation based on the calculated movement operation amount (step S50).

  Next, power supply ECU 250 determines whether or not the frequency moving operation period has elapsed (step S60). This moving operation period is the period T2 shown in FIGS. If it is determined in step S60 that the moving operation period has elapsed (YES in step S60), power supply ECU 250 shifts the process to return.

  As described above, in this embodiment, the extreme value search control for searching for the optimum frequency at which the current Is flowing through the power transmission coil 242 is minimized is performed by vibrating the frequency of the transmitted power. And since the frequency is operated so that the frequency movement operation based on the search result of the extreme value search control does not overlap with the frequency vibration operation, it is possible to accurately detect the change in the current Is of the power transmission coil 242 due to the frequency vibration operation. Can do. Therefore, according to this embodiment, the accuracy of the extreme value search control can be improved, and as a result, the power transmission efficiency between the power transmission coil 242 and the power reception coil 312 can be increased.

  In the above embodiment, the controller 420 of the first control unit 400 that executes transmission power control executes PI control. However, instead of PI control, I control or P control (proportional control) is used. ) May be executed.

  In the above description, the controller 550 of the second control unit 500 that executes the power transmission coil current control is assumed to execute the I control. However, instead of the I control, PI control or P You may make it perform control.

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

  DESCRIPTION OF SYMBOLS 10 Power transmission device, 20 Power receiving device, 100 AC power supply, 210 PFC circuit, 220 Inverter, 230, 320 Filter circuit, 240 Power transmission part, 242, 312 Coil, 244, 314 Capacitor, 250 Power supply ECU, 260, 370 Communication part, 270 , 380 Voltage sensor, 272, 274, 382 Current sensor, 310 Power receiving unit, 330 Rectifying unit, 340 Relay circuit, 350 Power storage device, 360 Charging ECU, 390 Electric load, 395 Impedance, 400 First control unit, 410 Subtracting unit , 420, 550 controller, 500 second control unit, 510 vibration signal generation unit, 520 HPF, 530 multiplication unit, 540 LPF, 560 addition unit, 570 timing adjustment unit.

Claims (2)

A power transmission coil for non-contact power transmission to the power receiving device;
An inverter for generating AC transmission power and supplying the transmission coil to the transmission coil;
A control unit that executes frequency control for adjusting the frequency of the transmission power by controlling the inverter;
The frequency control includes extreme value search control for searching for a frequency at which a current flowing through the power transmission coil is minimized by vibrating the frequency.
The said control part is a power transmission apparatus which operates the said frequency so that the movement operation of the said frequency by the search result of the said extreme value search control may not overlap with the vibration operation of the said frequency. A power transmission device;
A power receiving device,
The power transmission device is:
A power transmission coil for transmitting power to the power receiving device in a contactless manner;
An inverter for generating AC transmission power and supplying the transmission coil to the transmission coil;
A control unit that performs frequency control for adjusting the frequency of the transmission power by controlling the inverter;
The frequency control includes extreme value search control for searching for a frequency at which a current flowing through the power transmission coil is minimized by vibrating the frequency.
The said control part is an electric power transmission system which operates the said frequency so that the movement operation of the said frequency by the search result of the said extreme value search control may not overlap with the vibration operation of the said frequency.

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