JP2015231306A - Non-contact power reception device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact power reception device capable of suppressing harmonic noise caused by resonance generated between a matching device and a rectifier.SOLUTION: The non-contact power reception device 10 includes: a power reception section 110, a rectifier 170, and a load 105 connected with the rectifier to receive electric power from an external power supply 400 in a non-contact mode. The power reception section includes a power reception coil 111 for receiving electric power from external power. The rectifier includes a plurality of diodes D11-D14 to rectify electric power received by the power reception section. The rectifier further includes capacitors C11-C14 connected in parallel to each of the plurality of diodes.

Description

  The present invention relates to a non-contact power receiving apparatus, and more particularly to a technique for reducing harmonic noise generated in a non-contact power receiving apparatus that receives power from an external power source in a non-contact manner.

  In recent years, contactless wireless power transmission without using a power cord or a power transmission cable has attracted attention, and an electric vehicle that can charge an in-vehicle power storage device with power from a power source outside the vehicle (hereinafter also referred to as “external power source”), Application to hybrid vehicles has been proposed.

  As the wireless power transmission technology, as a promising technology, for example, three technologies of power transmission using electromagnetic induction, power transmission using electromagnetic waves such as microwaves, and power transmission using a resonance method are known.

  JP 2013-251974 A (Patent Document 1) and JP 2012-105503 A (Patent Document 2) are non-contact power receiving devices (vehicles) that can receive power in a non-contact manner. A configuration is disclosed in which AC power received by contact is rectified to DC power by a rectifier including a diode bridge and supplied to a load.

JP2013-251974A JP 2012-105503 A JP2013-154815A JP2013-146154A JP2013-146148A JP 2013-110822 A JP 2013-126327 A

  In a non-contact power receiving device, generally, received AC power is rectified by a rectifier and stored in a power storage device or an electric device is driven. In such a device, current resonance may occur between the circuit from the receiving coil to the rectifier and the circuit inside the rectifier due to the difference in impedance due to the coil component and the capacitor component including the parasitic capacitance. The resonance frequency of such current does not coincide with the frequency of the electromagnetic field used for power transmission (hereinafter also referred to as “system frequency”), and in many cases can be several times higher than the system frequency. Then, an oscillating current variation called ringing occurs in the input current of the rectifier due to the influence of current resonance due to the difference in impedance.

  When such current fluctuation occurs, the harmonic component of the input current of the rectifier increases, which may cause electromagnetic radiation noise from a power supply coil or the like.

  The present invention has been made to solve such a problem, and an object thereof is to reduce harmonic noise caused by a rectifier in a non-contact power receiving apparatus.

  A non-contact power receiving device according to the present invention is a device for receiving power from an external power source in a non-contact manner, and includes a power receiving unit, a rectifier, and a load connected to the rectifier. The power receiving unit includes a power receiving coil that receives power from an external power source. The rectifier includes a plurality of diodes and rectifies the power received by the power receiving unit. The rectifier further includes a capacitor connected in parallel to each of the plurality of diodes.

  By adopting such a circuit configuration for the rectifier and appropriately setting the capacitance of the capacitor provided in parallel to the diode, the difference in impedance between the circuit on the power receiving coil side and the rectifier can be reduced. Therefore, ringing of the input current of the rectifier can be reduced, and thereby harmonic noise generated due to the rectifier can be reduced.

It is a whole block diagram of the non-contact electric power feeding system according to this Embodiment. It is a figure for demonstrating the structure of the rectifier in a comparative example. It is a figure which shows an example of the waveform of the rectifier input current in a comparative example. It is a figure for demonstrating the structure of the rectifier in this Embodiment. It is a figure which shows an example of the waveform of the rectifier input current in this Embodiment. It is a figure which shows the simulation result of the harmonic component waveform of the rectifier input current in a comparative example. It is a figure which shows an example of the harmonic component of the rectifier input current measured in the circuit of the comparative example. It is a figure which shows the simulation result of the harmonic component waveform of the rectifier input current in this Embodiment. It is a figure which shows an example of the harmonic component of the rectifier input current measured in this Embodiment. It is a figure for demonstrating the structure of a modification. It is a figure which shows an example of the waveform of the rectifier input current in a modification. It is a figure which shows the simulation result of the harmonic component waveform of the rectifier input current in a modification. It is a figure which shows an example of the harmonic component of the rectifier input current measured in the modification.

  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 wireless power supply system]
FIG. 1 is an overall configuration diagram of a non-contact power feeding system 10 according to the present embodiment. Referring to FIG. 1, contactless power supply system 10 includes a vehicle 100 and a power transmission device 200. In the present embodiment, the case where the “non-contact power receiving device” is the vehicle 100 configured to be able to receive power without contact will be described as an example, but any device capable of receiving power without contact will be described. For example, it may be an electric device other than the vehicle.

  Referring to FIG. 1, power transmission device 200 includes a power supply device 210 and a power transmission unit 220. The power supply device 210 generates AC power having a predetermined frequency. As an example, the power supply device 210 receives electric power from the commercial power supply 400 to generate high-frequency AC power, and supplies the generated AC power to the power transmission unit 220. Then, the power transmission unit 220 outputs electric power in a non-contact manner to the power reception unit 110 of the vehicle 100 via an electromagnetic field generated around the power transmission unit 220.

  Power supply device 210 includes a communication unit 230, a power transmission ECU 240 that is a control device, and a power supply unit 250. The power transmission unit 220 includes a resonance coil 221 and a capacitor 222.

  Power supply unit 250 is controlled by control signal MOD from power transmission ECU 240, and converts power received from an AC power supply such as commercial power supply 400 into high-frequency power. The power supply unit 250 supplies the converted high frequency power to the resonance coil 221.

  In addition, power supply unit 250 outputs power transmission voltage Vtr and power transmission current Itr detected by a voltage sensor and a current sensor (not shown) to power transmission ECU 240, respectively.

  The resonance coil 221 transfers the electric power transmitted from the power supply unit 250 to the resonance coil 111 included in the power reception unit 110 of the vehicle 100 in a non-contact manner. The resonance coil 221 and the capacitor 222 constitute an LC resonance circuit.

  Communication unit 230 is a communication interface for performing wireless communication between power transmission device 200 and vehicle 100, and exchanges information INFO with communication unit 195 on vehicle 100 side. The communication unit 230 receives vehicle information transmitted from the communication unit 195 on the vehicle 100 side, a signal instructing start and stop of power transmission, and the like, and outputs the received information to the power transmission ECU 240. Communication unit 230 transmits information such as power transmission voltage Vtr and power transmission current Itr from power transmission ECU 240 to vehicle 100.

  Although not shown in FIG. 1, the power transmission ECU 240 includes a CPU (Central Processing Unit), a storage device, and an input / output buffer, and inputs signals from each sensor and outputs control signals to each device. Each device in the power supply device 210 is controlled. Note that these controls are not limited to processing by software, and can be processed by dedicated hardware (electronic circuit).

  Vehicle 100 includes a power receiving unit 110, a matching unit 160, a rectifier 170, a load 105, a vehicle ECU (Electronic Control Unit) 300 that is a control device, and a communication unit 195. The load 105 includes a DC / DC converter 180, a charging relay CHR185, a power storage device 190, a system main relay SMR115, a power control unit PCU (Power Control Unit) 120, a motor generator 130, a power transmission gear 140, Drive wheel 150.

  Power receiving unit 110 is provided, for example, near the floor panel of vehicle 100 and includes a resonance coil 111 and a capacitor 112.

  The resonance coil 111 receives power from the resonance coil 221 included in the power transmission device 200 in a contactless manner. The resonance coil 111 and the capacitor 112 constitute an LC resonance circuit.

  The power received by the resonance coil 111 is output to the rectifier 170 via the matching unit 160. Matching device 160 is typically configured to include a reactor and a capacitor, and adjusts the input impedance of a load to which the power received by resonance coil 111 is supplied.

  Rectifier 170 rectifies the AC power received from resonant coil 111 via matching device 160 and outputs the rectified DC power to power storage device 190.

  DC / DC converter 180 is controlled by control signal PWD from vehicle ECU 300, and converts the DC voltage rectified by rectifier 170 into a desired voltage. Note that the DC / DC converter 180 is not necessarily essential, and a configuration without the DC / DC converter 180 may be employed.

  CHR 185 is electrically connected between DC / DC converter 180 and power storage device 190. CHR185 is controlled by a control signal SE2 from vehicle ECU 300, and switches between supply and interruption of power from DC / DC converter 180 to power storage device 190.

  The power storage device 190 is a power storage element configured to be chargeable / dischargeable. The power storage device 190 includes, for example, a secondary battery such as a lithium ion battery or a nickel metal hydride battery, and a power storage element such as an electric double layer capacitor.

  The power storage device 190 stores the power from the DC / DC converter 180. The power storage device 190 is also connected to the PCU 120 via the SMR 115. Power storage device 190 supplies power for generating vehicle driving force to PCU 120. Further, power storage device 190 stores the electric power generated by motor generator 130.

  Although not shown, power storage device 190 is provided with a voltage sensor and a current sensor for detecting voltage VB of power storage device 190 and input / output current IB, respectively. These detection values are output to vehicle ECU 300. Vehicle ECU 300 calculates the state of charge of power storage device 190 (also referred to as “SOC (State Of Charge)”) based on voltage VB and current IB.

  SMR 115 is electrically connected between power storage device 190 and PCU 120. SMR 115 is controlled by control signal SE <b> 1 from vehicle ECU 300, and switches between supply and interruption of power between power storage device 190 and PCU 120.

  The PCU 120 is configured to include a converter and an inverter (not shown). The converter is controlled by a control signal PWC from vehicle ECU 300 to convert the voltage from power storage device 190. The inverter is controlled by a control signal PWI from vehicle ECU 300 and drives motor generator 130 using electric power converted by the converter.

  Motor generator 130 is an AC rotating electric machine, for example, a permanent magnet type synchronous motor including a rotor in which permanent magnets are embedded. The output torque of motor generator 130 is transmitted to drive wheel 150 via power transmission gear 140. The vehicle 100 travels using this torque. The motor generator 130 can generate power by the rotational force of the drive wheels 150 during regenerative braking of the vehicle 100. Then, the generated power is converted by PCU 120 into charging power for power storage device 190.

  Further, in a hybrid vehicle equipped with an engine (not shown) in addition to motor generator 130, necessary vehicle driving force is generated by operating engine and motor generator 130 in a coordinated manner. In this case, the power storage device 190 can be charged using the power generated by the rotation of the engine.

  The communication unit 195 is a communication interface for performing wireless communication between the vehicle 100 and the power transmission device 200, and exchanges information INFO with the communication unit 230 of the power transmission device 200.

  Although not shown in FIG. 1, vehicle ECU 300 includes a CPU, a storage device, and an input / output buffer, and inputs a signal from each sensor and outputs a control signal to each device. Control. Note that these controls are not limited to processing by software, and can be processed by dedicated hardware (electronic circuit).

  FIG. 2 is a diagram showing a detailed configuration of matching unit 160 and rectifier 170 in FIG. 1 in a comparative example compared with the present embodiment.

  Referring to FIG. 2, matching device 160 is a so-called three-stage LC filter including reactors L1 to L6 and capacitors C1 and C2, and a reactor is connected to one power line from power receiving unit 110 (FIG. 1). L1, L3, and L5 are connected in series, and reactors L2, L4, and L6 are connected in series to the other power line. Capacitor C1 is connected between the connection node of reactors L1 and L3 and the connection node of reactors L2 and L4. Capacitor C2 is connected between the connection node of reactors L3 and L5 and the connection node of reactors L4 and L6. Matching device 160 appropriately adjusts the reactances of reactors L1 to L6 and the capacitances of capacitors C1 and C2, thereby matching the impedance of power reception unit 110 with the impedance of rectifier 170 and the subsequent.

  The rectifier 170 includes a diode bridge 171 composed of diodes D11 to D14, and a filter circuit F10. The rectifier 170 performs full-wave rectification on the AC power passed through the matching unit 160 by the diode bridge 171, smoothes the rectified waveform by the filter circuit F 10, and supplies the rectified waveform to the DC / DC converter 180.

  In such a circuit, between the circuit from the power receiving unit 110 to the matching device 160 and the circuit inside the rectifier 170, the matching device 160, the rectifier 170, and the like due to the difference in impedance due to the coil component and the capacitor component including the parasitic capacitance. Current resonance may occur between the two. The resonance frequency of such a current can be several times higher than the frequency (system frequency) of the electromagnetic field used for power transmission between the power reception unit 110 and the power transmission unit 220. As a result, an oscillating current fluctuation called “ringing” occurs in the input current of the rectifier 170 as shown in FIG. 3 due to the influence of a resonance current having a frequency different from the system frequency. When such current fluctuation occurs, the harmonic component of the input current of the rectifier 170 increases, which may cause radiation noise from a resonance coil or the like.

  Therefore, in the present embodiment, a method for preventing ringing between the matching device and the rectifier by changing the configuration of the rectifier will be described.

  FIG. 4 is a diagram for explaining the configuration of the rectifier in the present embodiment. Referring to FIG. 4, rectifier 170A in the present embodiment includes a bridge circuit 171A and a filter circuit F10A.

  The bridge circuit 171A has a configuration in which capacitors C11 to C14 are connected in parallel to the diodes D11 to D14 in a diode bridge composed of the diodes D11 to D14. By appropriately setting the capacitances of the capacitors C11 to C14, the resonance frequency of the current generated between the matching device 160 and the circuit inside the rectifier 170 and the system frequency can be matched (tuned). By setting it as such a circuit, as FIG. 5 shows, the ringing in a rectifier input current can be suppressed and it can be set as the rectifier input current waveform nearer to a sine wave.

  In addition, since the current fluctuation component of the rectifier input current is reduced, the filter circuit F10A can be configured more simply.

  The harmonic components (normal mode noise) of the current in the present embodiment and the comparative example will be compared using FIGS. 6 and 7 show the simulation result of the current harmonic component in the comparative example and the measurement result in the actual machine, respectively. FIG. 8 and FIG. 9 show the simulation result of the current harmonic component in this embodiment and the measurement result in the actual machine, respectively. 6 to 9, solid lines LN10, LN20, LN30, and LN40 indicate current waveforms, and broken lines LN11, LN21, LN22, LN31, LN41, and LN42 indicate peak envelopes of harmonic components (odd order and even order). Show. In the simulations of FIGS. 6 and 8, only odd-order harmonic components are described.

  With reference to FIGS. 6 to 9, in both the simulation result and the actual measurement result, the case where the rectifier of the present embodiment is used is particularly higher in the higher-order harmonic components than the case of the comparative example. It can be seen that the peak value is small. That is, harmonic noise can be reduced by adopting the rectifier configuration as in the present embodiment.

[Modification]
As described above, ringing in the rectifier input current waveform can be reduced by connecting an appropriate capacitor in parallel to each diode of the diode bridge of the rectifier to tune the resonant frequency of the current and the system frequency, resulting in smoothness. It was found that a simple input current waveform can be obtained.

  Therefore, it can be expected that the matching device for matching the impedances of the power receiving unit and the load is further simplified by adopting the rectifier configuration as in the present embodiment.

  Therefore, in the modified example, as shown in FIG. 10, the rectifier is a circuit similar to the rectifier 170A of the present embodiment shown in FIG. 4 described above, while the matching devices are reactors L21 and L22. An example in which matching unit 160A having a single-stage LC filter including only capacitor C21 is used will be described.

  The waveform of the rectifier input current, the waveform of the simulation result of the harmonic component waveform, and the waveform of the actually measured harmonic component in the case of the circuit of the modification shown in FIG. 10 are shown in FIGS.

  As shown in FIG. 11, it can be seen that a smooth rectifier input current in which ringing is suppressed is obtained even in the modification having the matching device 160A of the one-stage LC filter.

  Furthermore, the simulation result of the harmonic component waveform shown in FIG. 12 and the harmonic component of the actually measured current waveform shown in FIG. 13 are also higher frequency components than the waveforms (FIGS. 6 and 7) in the comparative example described above. It can be seen that the peak value of is small.

  Compared with the simulation waveform (FIG. 8) and the measured current waveform (FIG. 9) in the configuration of FIG. 4 using the matching unit 160 using the three-stage LC filter, a substantially equivalent reduction in high-frequency components is realized. Yes.

  Thus, by using the rectifier as in this embodiment having a bridge circuit in which capacitors are connected in parallel to each diode, high-frequency noise can be reduced even when the matching device has a simpler configuration. As a result, the matching unit can be reduced in size and mounted on the vehicle, and the vehicle weight can be reduced, the fuel consumption can be improved, and the cost can be reduced.

  In the present embodiment, the power receiving unit and the power transmission unit in FIG. 1 have been described by way of example only of a resonance coil to which a capacitor is connected. However, the power reception unit and the power transmission unit are added to the resonance coil. The electromagnetic induction coil may be further provided to supply power to the resonance coil by electromagnetic induction or to extract power.

  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 Non-contact electric power feeding system, 100 Vehicle, 105 Load, 110 Power receiving part, 111, 221 Resonant coil, 112, 222, C1, C2, C11-C14, C21 Capacitor, 115 SMR, 120 PCU, 130 Motor generator, 140 Power transmission Gear, 150 driving wheel, 160, 160A matching device, 170, 170A rectifier, 171 diode bridge, 171A bridge circuit, 180 DC / DC converter, 185 CHR, 190 power storage device, 195, 230 communication unit, 200 power transmission device, 210 power supply Device, 220 power transmission unit, 240 power transmission ECU, 250 power supply unit, 300 vehicle ECU, 400 commercial power supply, D11 to D14 diode, F10, F10A filter circuit, L1, L2, L3, L4, L5, L6, L21, L 2 reactor.

Claims (1)

A non-contact power receiving device for receiving power from an external power source in a non-contact manner,
A power receiving unit that includes a power receiving coil and receives power from the external power source;
A rectifier that includes a plurality of diodes and rectifies the power received by the power receiving unit;
A load connected to the rectifier,
The non-contact power receiving device, wherein the rectifier further includes a capacitor connected in parallel to each of the plurality of diodes.

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