WO2015170460A1

WO2015170460A1 - Wireless power supply device and wireless power supply system using same

Info

Publication number: WO2015170460A1
Application number: PCT/JP2015/002238
Authority: WO
Inventors: 田村　秀樹
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2014-05-07
Filing date: 2015-04-24
Publication date: 2015-11-12
Also published as: JP2017123699A

Abstract

The present invention addresses the problem of enabling charging with a sufficient power-supply efficiency even when the relative position between a primary coil and a secondary coil is shifted. A wireless power-supply device (2) of the present invention comprises an inverter circuit (21), a capacitance adjustment circuit (22) having a primary side capacitor (C11), a control circuit (23), and a primary side coil (L1). The control circuit (23) starts up so that first drive signals (G11, G14 (G12, G13)) applied to first switching elements (S11 to S14) and second drive signals (G22, G23 (G21, G24)) applied to second switching elements (S21 to S24) match each other in phase. After the start-up, the control circuit (23) performs control so that the phase of the second drive signals (G21, G24 (G22, G23)) advances compared to the phase of the first drive signals (G12, G13 (G11, G14)).

Description

Non-contact power supply device and non-contact power supply system using the same

The present invention generally relates to a non-contact power supply device, a non-contact power supply system, and more particularly to a non-contact power supply device that supplies power to a load in a non-contact manner and a non-contact power supply system using the same.

2. Description of the Related Art Conventionally, a non-contact power supply device that supplies electric power to a moving body in a non-contact manner using electromagnetic induction is known, for example, disclosed in Document 1 (Japanese Patent Application Publication No. 2013-243929). The non-contact power feeding device described in Document 1 includes a power feeding coil (primary side coil) and a power feeding side control unit. The primary side coil supplies electric power to the non-contact power receiving device provided in the electric vehicle by generating a magnetic field. The power supply side control unit controls the start and stop of the power supply of the primary side coil, and controls the magnitude of the power supplied from the primary side coil.

The non-contact power receiving device includes a power receiving coil (secondary coil), a rectifier circuit, and a storage battery (load). The secondary coil can receive power from the primary coil by electromagnetic induction. And the electric power which the secondary side coil received by electromagnetic induction is input into a rectifier circuit, is converted into direct current, and is output to a load.

However, in the above conventional example, when the electric vehicle is stopped by shifting from the specified stop position, the relative positions of the primary side coil and the secondary side coil may be shifted. In this case, there is a possibility that the coupling efficiency between the primary side coil and the secondary side coil changes and the power supply efficiency is lowered.

The present invention has been made in view of the above points, and a non-contact power feeding device that can feed power with sufficient power feeding efficiency even when the relative positions of the primary side coil and the secondary side coil are shifted, and It aims at providing the non-contact electric power feeding system using it.

The contactless power supply device of the present invention includes an inverter circuit, a primary side coil, a capacity adjustment circuit, and a control circuit. The inverter circuit has a plurality of first switch elements, and converts the DC power into AC power by switching on / off of the plurality of first switch elements, and outputs the AC power. The primary coil receives the AC power output from the inverter circuit and generates a magnetic field. The capacitance adjusting circuit is electrically connected between the inverter circuit and the primary side coil, and includes a plurality of second switch elements and a primary side capacitor. In addition, the capacitance adjusting circuit switches a path through the primary side capacitor and a path not through the primary side capacitor by switching on / off of the plurality of second switch elements. The control circuit controls on / off of the plurality of first switch elements and the plurality of second switch elements, respectively. The primary side coil forms a resonance circuit together with the primary side capacitor. The control circuit starts so that the phase of the first drive signal applied to the plurality of first switch elements matches the phase of the second drive signal applied to the plurality of second switch elements. The control circuit controls the second drive signal so that the phase of the second drive signal advances from the phase of the first drive signal after startup.

The contactless power supply system of the present invention includes the contactless power supply device and a power receiving device that receives power supplied from the contactless power supply device. The power receiving device includes a secondary coil that generates AC power in response to a magnetic field generated by the primary coil, and a secondary capacitor that forms a resonance circuit together with the secondary coil.

It is a circuit schematic diagram showing a non-contact power feeding system and a non-contact power feeding apparatus according to an embodiment. FIG. 2A is a waveform diagram of each drive signal in the non-contact power feeding apparatus according to the embodiment. FIG. 2B is a waveform diagram of each drive signal when the phase is shifted in the non-contact power feeding apparatus according to the embodiment. It is the schematic which shows the usage example of the non-contact electric power feeding system which concerns on embodiment. FIG. 4A is a correlation diagram between the switching frequency and the output power when the resonance characteristic shows a bimodal characteristic. FIG. 4B is a correlation diagram between the switching frequency and the output power when the resonance characteristic shows a single peak characteristic. It is a figure which shows the correlation with the phase difference of a 1st drive signal and a 2nd drive signal, and output electric power in the non-contact electric power supply which concerns on embodiment. It is a wave form diagram which shows the operation | movement in slow phase mode in the non-contact electric power supply which concerns on embodiment. In the non-contact electric power feeder which concerns on embodiment, it is a circuit schematic diagram at the time of further adding a capacitor | condenser. In the non-contact electric power feeder which concerns on embodiment, it is the circuit schematic diagram at the time of arrange | positioning the added capacitor in the back | latter stage of a capacity | capacitance adjustment circuit. In the non-contact electric power feeder which concerns on embodiment, it is the circuit schematic diagram at the time of arrange | positioning the added capacitor | condenser in the front | former stage of a capacity | capacitance adjustment circuit. It is a circuit schematic diagram showing other composition of the capacity adjustment circuit in the non-contact electric power supply concerning an embodiment. FIG. 11A and FIG. 11B are correlation diagrams of the switching frequency and the output power when the resonance characteristics show a bimodal characteristic.

The contactless power supply device 2 of the present embodiment has the following first feature.

In the first feature, the non-contact power feeding device 2 includes an inverter circuit 21, a capacity adjustment circuit 22, a control circuit 23, and a primary coil L1, as shown in FIG. The inverter circuit 21 has a plurality of first switch elements S11 to S14. The inverter circuit 21 converts the DC power into AC power and outputs AC power by switching on / off the plurality of first switch elements S11 to S14.

The primary coil L1 receives the AC power output from the inverter circuit 21 and generates a magnetic field. The capacity adjustment circuit 22 is electrically connected between the inverter circuit 21 and the primary side coil L1. The capacitance adjusting circuit 22 includes a plurality of second switch elements S21 to S24 and a primary side capacitor C11. The capacitance adjusting circuit 22 switches the path through the primary side capacitor C11 and the path not through the primary side capacitor C11 by switching on / off of the plurality of second switch elements S21 to S24.

The control circuit 23 controls on / off of the plurality of first switch elements S11 to S14 and the plurality of second switch elements S21 to S24, respectively. The primary side coil L1 forms a resonance circuit (primary side resonance circuit) together with the primary side capacitor C11.

As shown in FIG. 2A, the control circuit 23 starts so that the phases of the first drive signals G11 and G14 (G12 and G13) coincide with the phases of the second drive signals G22 and G23 (G21 and G24). . The first drive signals G11 to G14 are signals given to the plurality of first switch elements S11 to S14. The second drive signals G21 to G24 are signals given to the plurality of second switch elements S21 to S24. After the start-up, as shown in FIG. 2B, the control circuit 23 advances the phase of the second drive signals G21, G24 (G22, G23) from the phase of the first drive signals G12, G13 (G11, G14). To control.

Further, the non-contact power feeding device 2 of the present embodiment may have the following second feature in addition to the first feature.

In the second feature, the non-contact power feeding device 2 includes a capacitor C12 connected in series to the capacitance adjusting circuit 22 between the inverter circuit 21 and the primary side coil L1, as shown in FIGS. Prepare.

In addition to the second feature, the non-contact power feeding device 2 of the present embodiment may have the following third feature.

In the third feature, the capacitor C12 is connected between the capacitance adjusting circuit 22 and the primary coil L1, as shown in FIGS.

Further, the non-contact power feeding device 2 of the present embodiment may have the following fourth feature in addition to any of the first to third features.

In the fourth feature, the plurality of second switch elements are a first bidirectional switch Q1 and a second bidirectional switch Q2, as shown in FIG. The capacity adjustment circuit 22 connects the first bidirectional switch Q1 in series with the primary side capacitor C11, and connects the second bidirectional switch Q2 in parallel with the series circuit of the primary side capacitor C11 and the first bidirectional switch Q1. Configured.

In addition to the fourth feature, the non-contact power feeding device 2 of the present embodiment may have the following fifth feature.

In the fifth feature, each of the first bidirectional switch Q1 and the second bidirectional switch Q2 is a gallium nitride based semiconductor element.

Further, the non-contact power feeding system 1 of the present embodiment has the following sixth feature.

In the sixth feature, the non-contact power feeding system 1 includes a non-contact power feeding device 2 having any one of the first to fifth features and a power receiving device 3 as shown in FIG. The power receiving device 3 receives a magnetic field generated by the primary coil L1 and generates a secondary circuit L2 that generates AC power, and a secondary circuit that forms a resonance circuit (secondary resonance circuit) together with the secondary coil L2. Side capacitor C21.

The contactless power supply device 2 of the present embodiment can supply power with sufficient power supply efficiency even when the relative positions of the primary side coil L1 and the secondary side coil L2 shift.

Further, the non-contact power supply system 1 of the present embodiment can supply power with sufficient power supply efficiency even if the relative positions of the primary side coil L1 and the secondary side coil L2 shift.

Hereinafter, the non-contact power feeding device 2 and the non-contact power feeding system 1 of the present embodiment will be described in detail. However, the configuration described below is only an example of the present invention, and the present invention is not limited to the following embodiment, and the technical idea according to the present invention is not deviated from this embodiment. Various changes can be made in accordance with the design or the like as long as they are not.

In the following, as illustrated in FIG. 3, a case where power is supplied to the storage battery 101 of the electric vehicle 100 using the non-contact power supply device 2 and the non-contact power supply system 1 of the present embodiment is illustrated, but the present invention is limited to this example. It is not the purpose. That is, the contactless power supply device 2 and the contactless power supply system 1 of the present embodiment may be configured to supply power to the load 4 in a contactless manner, and the load 4 is not limited to the storage battery 101 of the electric vehicle 100.

The contactless power supply system 1 of the present embodiment includes a contactless power supply device 2 and a power reception device 3 as shown in FIG. As shown in FIG. 1, the non-contact power feeding device 2 includes an inverter circuit 21, a capacity adjustment circuit 22, a control circuit 23, and a primary coil L1. As shown in FIG. 1, the power receiving device 3 includes a rectifier circuit 31, a secondary coil L2, and a secondary capacitor C21.

In the non-contact power feeding system 1 of the present embodiment, the non-contact power feeding device 2 is installed on the floor or the ground as shown in FIG. The non-contact power feeding device 2 may be arranged not only on the floor or the ground but also embedded in the floor or the ground, for example. In the non-contact power feeding device 2, only the primary side coil L1 is arranged at a position where it can face the secondary side coil L2, and other parts, circuits, etc. are arranged away from the primary side coil L1. It may be configured.

In the non-contact power feeding system 1 of the present embodiment, the power receiving device 3 is installed in the vehicle of the electric vehicle 100 as shown in FIG. The power receiving device 3 is electrically connected to the storage battery 101 of the electric vehicle 100. The storage battery 101 is constituted by, for example, a nickel metal hydride battery, a lithium ion battery, or a high-capacity capacitor. The storage battery 101 is used as a power source for an electric motor included in the electric vehicle 100. In addition, the storage battery 101 is used as a power source for electronic devices such as a car navigation system, a car audio, and a power window included in the electric vehicle 100.

First, the non-contact power feeding device 2 will be described.

The inverter circuit 21 is a full-bridge inverter composed of four first switch elements S11 to S14 as shown in FIG. In the contactless power supply device 2 of the present embodiment, each of the first switch elements S11 to S14 is an n-channel enhancement type MOSFET (Metal-Oxide-Semiconductor-Field-Effect-Transistor). Each of the first switch elements S11 to S14 may be composed of other semiconductor switching elements such as bipolar transistors and IGBTs (Insulated Gate Bipolar Transistors).

In the inverter circuit 21, a series circuit of two first switch elements S11 and S12 and a series circuit of two first switch elements S13 and S14 are connected in parallel. The drains of the first switch elements S11 and S13 are electrically connected to the output terminal on the high potential side of the DC power supply DC1. The sources of the first switch elements S12 and S14 are electrically connected to the output terminal on the low potential side of the DC power supply DC1. A connection point between the source of the first switch element S13 and the drain of the first switch element S14 is the first output terminal of the inverter circuit 21. The connection point between the source of the first switch element S11 and the drain of the first switch element S12 is the second output terminal of the inverter circuit 21.

In FIG. 1, the diodes electrically connected between the drains and sources of the first switch elements S11 to S14 are parasitic diodes of the first switch elements S11 to S14.

The inverter circuit 21 operates when the first drive signals G11 to G14 are supplied to the first switch elements S11 to S14, respectively. Specifically, the inverter circuit 21 operates so as to alternately switch the ON period of the first switch elements S11 and S14 and the ON period of the first switch elements S12 and S13 by the first drive signals G11 to G14. (See FIG. 2A). In the ON period of the first switch elements S11 and S14, the inverter circuit 21 outputs a negative voltage. Further, during the ON period of the first switch elements S12 and S13, the inverter circuit 21 outputs a positive voltage. Therefore, the inverter circuit 21 alternately outputs a positive voltage and a negative voltage.

That is, the inverter circuit 21 includes a plurality of first switch elements S11 to S14. The inverter circuit 21 converts the DC power supplied from the DC power source DC1 (see FIG. 1) into AC power by switching on / off of the plurality of first switch elements S11 to S14, and converts the AC power into AC power. It is configured to output.

As shown in FIG. 1, the capacity adjustment circuit 22 includes a primary capacitor C11 and four second switch elements S21 to S24. In the contactless power supply device 2 of the present embodiment, the second switch elements S21 to S24 are n-channel enhancement type MOSFETs. Each of the second switch elements S21 to S24 may be composed of other semiconductor switching elements such as bipolar transistors and IGBTs.

In the capacity adjustment circuit 22, a series circuit of two second switch elements S21 and S22 and a series circuit of two second switch elements S23 and S24 are connected in parallel. A connection point between the source of the second switch element S21 and the drain of the second switch element S22 is electrically connected to the first output terminal of the inverter circuit 21. The connection point between the source of the second switch element S23 and the drain of the second switch element S24 is electrically connected to one end of the primary side coil L1. And the primary side capacitor | condenser C11 is electrically connected between the connection point of each source of 2nd switch element S21, S23, and the connection point of each drain of 2nd switch element S22, S24.

In FIG. 1, the diodes electrically connected between the drain terminals and the source terminals of the second switch elements S21 to S24 are parasitic diodes of the second switch elements S21 to S24.

The capacity adjustment circuit 22 operates when the second drive signals G21 to G24 are supplied to the second switch elements S21 to S24, respectively. Specifically, the capacitance adjustment circuit 22 operates so as to alternately switch the on period of the second switch elements S21, 24 and the on period of the second switch elements S22, S23 by the second drive signals G21 to G24. (See FIG. 2A).

In the ON period of the second switch elements S21 and S24, a voltage is applied to the primary side capacitor C11 during a period in which the inverter circuit 21 outputs a positive voltage. That is, a path between the input and output of the capacitance adjustment circuit 22 is a path through the primary capacitor C11. On the other hand, during the ON period of the second switch elements S21 and S24, the current passes through the parasitic diode of the second switch element S23 and the second switch element S21 during the period in which the inverter circuit 21 outputs a negative voltage. Flows. That is, the path between the input and output of the capacity adjustment circuit 22 is a path that does not pass through the primary side capacitor C11. In other words, between the input and output of the capacitance adjustment circuit 22 is a path that bypasses the input and output.

Similarly, in a period in which the inverter circuit 21 outputs a positive voltage during the ON period of the second switch elements S22 and S23, a path passing through the second switch element S22 and the parasitic diode of the second switch element S24. Current flows. That is, the path between the input and output of the capacity adjustment circuit 22 is a path that does not pass through the primary side capacitor C11. On the other hand, during the ON period of the second switch elements S22 and S23, the voltage is applied to the primary capacitor C11 during the period in which the inverter circuit 21 outputs a negative voltage. That is, a path between the input and output of the capacitance adjustment circuit 22 is a path through the primary capacitor C11.

That is, the capacity adjustment circuit 22 is electrically connected between the inverter circuit 21 and the primary coil L1, and includes a plurality of second switch elements S21 to S24 and a primary capacitor C11. Has been. Then, the capacitance adjusting circuit 22 switches the path through the primary side capacitor C11 and the path not through the primary side capacitor C11 by switching on / off of the plurality of second switch elements S21 to S24. It is configured. In this way, by changing the period in which the primary side capacitor C11 is connected between the input and output and the period in which the primary side capacitor C11 is not connected between the input and output, the capacitance of the capacitance adjusting circuit 22 is changed. The capacity can be adjusted.

The control circuit 23 includes a main control circuit 231, a first drive circuit 232, and a second drive circuit 233. The main control circuit 231 is constituted by, for example, a microcomputer (microcomputer). The main control circuit 231 outputs a binary first control signal for switching on / off of each of the first switch elements S11 to S14 of the inverter circuit 21. In the contactless power supply device 2 of the present embodiment, the main control circuit 231 switches the on / off of the first switch elements S12, S13 and the control signal for switching on / off of the first switch elements S11, S14. The control signal is output as the first control signal.

The main control circuit 231 outputs a binary second control signal for switching on / off of each of the second switch elements S21 to S24 of the capacitance adjustment circuit 22. In the non-contact power feeding device 2 of the present embodiment, the main control circuit 231 switches the on / off of the second switch elements S22, S23 and the control signal for switching on / off of the second switch elements S21, S24. Are output as the second control signal.

The first drive circuit 232 is a driver that amplifies the level of the first control signal output from the main control circuit 231 to a level capable of driving the first switch elements S11 to S14 of the inverter circuit 21. The first control signal amplified by the first drive circuit 232 is input to the gates of the first switch elements S11 to S14 as the first drive signals G11 to G14, respectively. Accordingly, the first switch elements S11 to S14 are switched on / off by the first drive signals G11 to G14, respectively.

The second drive circuit 233 is a driver that amplifies the level of the second control signal output from the main control circuit 231 to a level capable of driving the second switch elements S21 to S24 of the capacitance adjustment circuit 22. The second control signal amplified by the second drive circuit 233 is input to the gates of the second switch elements S21 to S24 as the second drive signals G21 to G24, respectively. Accordingly, the second switch elements S21 to S24 are switched on / off by the second drive signals G21 to G24, respectively.

That is, the control circuit 23 is configured to control ON / OFF of the plurality of first switch elements S11 to S14 and the plurality of second switch elements S21 to S24, respectively.

Here, the first drive circuit 232 outputs a voltage based on the circuit ground as the first drive signals G12 and G14. The first drive circuit 232 outputs a voltage based on the sources of the first switch elements S11 and S13 as the first drive signals G11 and G13. On the other hand, the second drive circuit 233 outputs voltages based on the sources of the second switch elements S21 to S24 as the second drive signals G21 to G24. The second drive circuit 233 is applied with a higher voltage than the first drive circuit 232. For this reason, in the non-contact electric power feeder 2 of this embodiment, the 1st drive circuit 232 and the 2nd drive circuit 233 are mutually electrically insulated.

The primary coil L1 is electrically connected to a pair of output terminals of the inverter circuit 21 via the capacity adjustment circuit 22. The primary coil L1 generates a magnetic field when an alternating current output from the inverter circuit 21 flows. That is, the primary coil L1 receives the AC power output from the inverter circuit 21 and generates a magnetic field. The primary coil L1 forms a resonance circuit (primary resonance circuit) together with the primary capacitor C11 included in the capacitance adjustment circuit 22.

Next, the power receiving device 3 will be described.

As shown in FIG. 3, the secondary coil L2 is provided so as to be positioned in the vicinity of the primary coil L1 when the electric vehicle 100 stops at a specified stop position. When the secondary coil L2 receives a magnetic field generated by the primary coil L1, an alternating current flows by electromagnetic induction. That is, the secondary coil L2 receives the magnetic field generated by the primary coil L1 and generates AC power. As shown in FIG. 1, a secondary capacitor C21 is electrically connected to one end of the secondary coil L2. For this reason, the secondary coil L2 forms a resonance circuit (secondary resonance circuit) together with the secondary capacitor C21.

The rectifier circuit 31 includes four diodes D1 to D4 and a smoothing capacitor C3 as shown in FIG. Each of the diodes D1 to D4 constitutes a diode bridge. The diode bridge converts the alternating current generated in the secondary coil L2 into a pulsating current and outputs the pulsating current. The smoothing capacitor C3 is electrically connected to a pair of output terminals of the diode bridge. The smoothing capacitor C3 smoothes the pulsating current output from the diode bridge and outputs a direct current. That is, the rectifier circuit 31 rectifies and outputs the AC power generated by the secondary coil L2 to DC power. The DC power output from the rectifier circuit 31 is supplied to the load 4 (here, the storage battery 101).

Hereinafter, a power feeding method in the contactless power feeding system 1 of the present embodiment will be described. In the non-contact power feeding system 1 of the present embodiment, power is transmitted from the primary coil L1 to the secondary coil L2 by a resonance method using a magnetic resonance phenomenon. That is, in the non-contact power feeding system 1 of the present embodiment, the output of the non-contact power feeding device 2 is utilized by utilizing the resonance phenomenon caused by the primary side resonance circuit formed by the primary side coil L1 and the primary side capacitor C11. Amplifying power. And in the non-contact electric power feeding system 1 of this embodiment, the magnetic resonance of the secondary side resonance circuit formed by the secondary side coil L2 and the secondary side capacitor C21 and the primary side resonance circuit is used. Thus, the output power of the non-contact power feeding device 2 is efficiently transmitted to the power receiving device 3. Therefore, it is desirable that the resonance characteristics of the primary-side resonance circuit and the secondary-side resonance circuit match each other.

Here, the resonance characteristics in the non-contact power feeding system 1 of the present embodiment will be described. In the non-contact power feeding system 1 of the present embodiment, when the coupling between the primary side coil L1 and the secondary side coil L2 is close, as shown in FIG. 4A, the primary side resonance circuit (resonance on the secondary side) Circuit) exhibits so-called bimodal characteristics. In this resonance characteristic, a “crest” at which the output is maximized at the first resonance frequency fr1, a “valley” at which the output is minimized at the second resonance frequency fr2, and a “mountain” at which the output is maximized at the third resonance frequency fr3. "And appears. Resonance frequencies fr1 to fr3 are expressed by the following equations, where the inductance of the primary side resonance circuit (secondary side resonance circuit) is represented by 'L', the capacitance is represented by 'C', and the mutual inductance is represented by 'M'. It is represented by

In the non-contact power feeding system 1 of the present embodiment, when the coupling between the primary side coil L1 and the secondary side coil L2 is sparse, as shown in FIG. 4B, the primary side resonance circuit (secondary side) The resonance characteristic of the resonance circuit of FIG. In this resonance characteristic, a “mountain” where the output becomes maximum at the fourth resonance frequency fr4 appears. The fourth resonance frequency fr4 is represented by the following expression when the inductance of the primary side resonance circuit (secondary side resonance circuit) is represented as ‘L’ and the capacitance is represented as ‘C’.

Even when the power receiving device 3 does not include the secondary side capacitor C21 (that is, when the secondary side resonance circuit is not formed), the resonance characteristic of the primary side resonance circuit shows a single peak characteristic.

Here, as shown in FIGS. 4A and 4B, the inverter circuit 21 operates in either the slow phase mode or the fast phase mode according to the correlation between the switching frequency f1 of the inverter circuit 21 and the resonance frequencies fr1 to fr4. Operate in mode. The switching frequency f1 corresponds to the frequency of each of the first drive signals G11 to G14 and the second drive signals G21 to G24.

The phase advance mode is an operation mode in which the inverter circuit 21 operates in a state in which the phase of the output current of the inverter circuit 21 is advanced from the output voltage of the inverter circuit 21. In the phase advance mode, the switching operation of the inverter circuit 21 is so-called hard switching. Accordingly, the phase advance mode is not preferable because loss due to switching of each of the first switch elements S11 to S14 may increase or excessive stress may be applied to each of the first switch elements S11 to S14.

On the other hand, the slow phase mode is an operation mode in which the inverter circuit 21 operates in a state in which the phase of the current flowing through the primary side coil L1 (that is, the primary side current) is delayed from the phase of the output voltage of the inverter circuit 21. is there. In the slow phase mode, the switching operation of the inverter circuit 21 is so-called soft switching. Therefore, in the slow phase mode, loss due to switching of each of the first switch elements S11 to S14 can be reduced, and excessive stress can be prevented from being applied to each of the first switch elements S11 to S14. . That is, in the non-contact power feeding device 2 of the present embodiment, it is preferable that the inverter circuit 21 operates in the slow phase mode.

When the resonance characteristic shows a bimodal characteristic, as shown in FIG. 4A, when the switching frequency f1 is lower than the first resonance frequency fr1 (f1 <fr1), the inverter circuit 21 operates in the phase advance mode. As shown in FIG. 4A, when the switching frequency f1 is between the second resonance frequency fr2 and the third resonance frequency fr3 (fr2 <fr1 <fr3), the inverter circuit 21 operates in the phase advance mode. On the other hand, as shown in FIG. 4A, when the switching frequency f1 is between the first resonance frequency fr1 and the second resonance frequency fr2 (fr1 <f1 <fr2), the inverter circuit 21 operates in the slow phase mode. As shown in FIG. 4A, when the switching frequency f1 is larger than the third resonance frequency fr3 (f1> fr3), the inverter circuit 21 operates in the slow phase mode.

When the resonance characteristic shows a single peak characteristic, as shown in FIG. 4B, when the switching frequency f1 is lower than the fourth resonance frequency fr4 (f1 <fr4), the inverter circuit 21 operates in the phase advance mode. As shown in FIG. 4B, when the switching frequency f1 is higher than the fourth resonance frequency fr4 (f1> fr4), the inverter circuit 21 operates in the slow phase mode.

In the contactless power supply device 2 of the present embodiment, the control circuit 23 controls the switch elements S11 to S14 of the inverter circuit 21 so that the switching frequency f1 falls between the first resonance frequency fr1 and the second resonance frequency fr2. is doing. This configuration is preferable because the phase of the current flowing through the primary side coil L1 and the phase of the current flowing through the secondary side coil L2 are shifted from each other by nearly 180 degrees, so that unnecessary radiation can be reduced.

By the way, in the non-contact electric power feeding system 1 of this embodiment, the relative position of the primary side coil L1 and the secondary side coil L2 may shift | deviate. For example, if the stop position of the electric vehicle 100 deviates from a predetermined stop position, the relative positions of the primary coil L1 and the secondary coil L2 are shifted. When the relative positions of the primary side coil L1 and the secondary side coil L2 are shifted in this way, the coupling state between the primary side coil L1 and the secondary side coil L2 changes, and mutual inductance or primary side is changed. There is a possibility that the inductance of the resonance circuit (secondary side resonance circuit) of the first and second resonance circuits changes.

In this case, since the resonance frequencies fr1 to fr4 change, the resonance characteristics also change. Then, the output power of the non-contact power feeding device 2 decreases with the change in the resonance characteristics, and there is a possibility that power cannot be fed with sufficient power feeding efficiency. Further, depending on the change in the resonance characteristics, the switching frequency f1 may enter the phase advance mode region. In this case, if the inverter circuit 21 is operated at the preset switching frequency f1, the inverter circuit 21 operates in the phase advance mode.

If the method of changing the switching frequency f1 is used, the output power of the non-contact power feeding device 2 can be changed. However, since a usable frequency band is regulated by laws such as the Radio Law, a method of changing the switching frequency f1 is not preferable. Further, in the method of changing the switching frequency f1, the inverter circuit 21 may still operate in the phase advance mode.

Here, as shown in FIG. 5, the inventors of the present application simulate that the output power of the non-contact power feeding device 2 changes by changing the phase difference θ without changing the switching frequency f <b> 1 (experiment). ) In FIG. 5, the characteristic when the switching frequency f1 is 93 kHz is indicated by a solid line, and the characteristic when the switching frequency f1 is 91 kHz is indicated by a broken line. 2B, the phase difference θ is the difference between the phase of the first drive signals G11 and G14 and the phase of the second drive signals G22 and G23, or the phase of the first drive signals G12 and G13 and the second phase. This is the difference from the phases of the drive signals G21 and G24. That is, the phase difference θ is a difference between the phases of the first drive signals G11 and G14 (G12 and G13) and the phases of the second drive signals G22 and G23 (G21 and G24).

Further, as shown in FIG. 5, the inventors of the present application have confirmed by simulation (experiment) that the output power of the non-contact power feeding device 2 can be started when the phase difference θ is zero. Yes. Further, as shown in FIG. 5, the inventors of the present application have shown by simulation (experiment) that the operation mode of the inverter circuit 21 (that is, the phase advance mode or the phase delay mode) changes according to the phase difference θ. I'm sure.

Therefore, in the non-contact power feeding device 2 of the present embodiment, the control circuit 23 starts so that the first period T1 and the second period T2 coincide as shown in FIG. 2A. The first period T1 is a period in which the inverter circuit 21 outputs a negative AC voltage. The second period T2 is a period during which the capacitance adjustment circuit 22 is switched to a path through the primary capacitor C11. Specifically, the control circuit 23 performs control so that the timing at which the first drive signals G11 and G14 are output coincides with the timing at which the second drive signals G22 and G23 are output at the time of starting. Similarly, at the time of start-up, the control circuit 23 performs control so that the timing for outputting the first drive signals G12 and G13 coincides with the timing for outputting the second drive signals G21 and G24. That is, the control circuit 23 starts so that the phases of the first drive signals G11, G14 (G12, G13) and the phases of the second drive signals G22, G23 (G21, G24) coincide.

By the above control of the control circuit 23, the inverter circuit 21 starts operating when the first period T1 and the second period T2 coincide, that is, the phase difference θ is zero. Therefore, the output power of the non-contact power feeding device 2 of the present embodiment becomes zero at the start (see FIG. 5). The state where the phase difference θ is zero hits the boundary between the phase of the slow phase mode and the region of the fast phase mode as shown in FIG. 5, so that the inverter circuit 21 can be prevented from operating in the fast phase mode. it can. Of course, if the control circuit 23 performs control as described above, even if the relative displacement between the primary side coil L1 and the secondary side coil L2 occurs, the inverter circuit 21 is in a state where the phase difference θ is zero. Operate.

Further, as shown in FIG. 2B, the control circuit 23, after starting, the phase of the second drive signals G21, G24 (G22, G23) advances from the phase of the first drive signals G12, G13 (G11, G14). To control. Specifically, the control circuit 23 advances the timing for outputting the second drive signals G21, G24 (G22, G23) earlier than the timing for outputting the first drive signals G12, G13 (G11, G14).

By the above control of the control circuit 23, the phase difference θ becomes smaller than zero, and the output power of the non-contact power feeding device 2 increases (see FIG. 5). Then, when the phase difference θ is smaller than zero, as shown in FIG. 5, it corresponds to the phase of the slow phase mode, so that the inverter circuit 21 operates in the slow phase mode. That is, the control of the control circuit 23 can prevent the inverter circuit 21 from operating in the phase advance mode. Of course, if the control circuit 23 controls as described above, the phase difference θ becomes smaller than zero even when the relative displacement between the primary coil L1 and the secondary coil L2 occurs, and the inverter circuit 21 operates in the slow phase mode.

As described above, in the contactless power supply device 2 of the present embodiment, the control circuit 23 is configured to output the phases of the first drive signals G11 and G14 (G12 and G13) and the second drive signals G22 and G23 (G21 and G24). Start to match the phase. Then, the control circuit 23 performs control so that the phases of the second drive signals G21 and G24 (G22 and G23) are ahead of the phases of the first drive signals G12 and G13 (G11 and G14). For this reason, in the non-contact electric power feeder 2 of this embodiment, even if the relative position of the primary side coil L1 and the secondary side coil L2 shifts, the non-contact electric power feeder 2 does not change the switching frequency f1. Output power can be increased. Therefore, the contactless power supply device 2 of the present embodiment can supply power with sufficient power supply efficiency even if the relative positions of the primary side coil L1 and the secondary side coil L2 shift.

Further, in the non-contact power feeding device 2 of the present embodiment, the inverter circuit 21 starts operating in a state where the phase difference θ is zero, and the phase difference θ becomes small after starting, so the inverter circuit 21 operates in the phase advance mode. Can be prevented. Of course, the same effect can be obtained also in the non-contact power feeding system 1 of the present embodiment using the non-contact power feeding device 2 of the present embodiment.

Here, if the phase difference θ is reduced, the operation mode of the inverter circuit 21 may be switched from the slow phase mode to the fast phase mode. Therefore, in the contactless power supply device 2 of the present embodiment, the control circuit 23 may be configured to monitor the amount of change per unit time of the output power of the contactless power supply device 2. In this case, the control circuit 23 determines that the output power has reached a maximum when the amount of change per unit time in the output power is below a predetermined threshold or becomes a negative value. Therefore, in this configuration, it is possible to determine the timing at which the inverter circuit 21 switches from the slow phase mode to the fast phase mode.

In addition, the control circuit 23 may be configured to monitor the phase difference θ1 between the phase of the output voltage of the inverter circuit 21 and the phase of the current (primary side current) flowing through the primary side coil L1 ( (See FIG. 6). In this configuration, the control circuit 23 monitors whether or not the phase difference θ1 exceeds a predetermined threshold, so that it is possible to determine the timing at which the operation mode of the inverter circuit 21 is switched from the slow phase mode to the fast phase mode.

In addition, as shown in FIG. 7, the contactless power supply device 2 of the present embodiment includes a capacitor C <b> 12 connected in series to the capacity adjustment circuit 22 between the inverter circuit 21 and the primary coil L <b> 1. preferable. In this configuration, since the voltage applied between the inverter circuit 21 and the primary coil L1 is divided by the primary capacitor C11 and the capacitor C12, the voltage applied to the primary capacitor C11 is Can be small. That is, in this configuration, the voltage applied to the capacitance adjusting circuit 22 can be reduced, so that the breakdown voltage required for each of the second switch elements S21 to S24 can be reduced.

Here, as already described, the first drive circuit 232 and the second drive circuit 233 are electrically insulated from each other, but the required withstand voltage is the circuit ground and the first output of the inverter circuit 21. It is determined by the voltage V1 between the ends (see FIGS. 8 and 9). As shown in FIG. 9, when the capacitor C12 is connected between the inverter circuit 21 and the capacity adjustment circuit 22, the maximum voltage of the voltage V1 is equal to the power supply voltage of the DC power supply DC1 and the voltage across the capacitor C12. It becomes the voltage which added. In this case, since it is necessary to increase the dielectric strength with respect to the voltage across the capacitor C12, it is difficult to design the insulation between the first drive circuit 232 and the second drive circuit 233.

Therefore, as shown in FIG. 8, the capacitor C12 is preferably connected between the capacitance adjusting circuit 22 and the primary coil L1. In this configuration, the maximum voltage V1 is the power supply voltage of the DC power supply DC1, so that the required withstand voltage can be reduced as compared with the configuration shown in FIG. That is, this configuration has an advantage that the design of insulation between the first drive circuit 232 and the second drive circuit 233 is easier than the configuration shown in FIG.

In the configurations shown in FIGS. 8 and 9, the non-contact power feeding device 2 further includes a capacitor C13 in the primary-side resonance circuit, but whether or not the capacitor C13 is included is arbitrary. 8 and 9, the power receiving device 3 further includes a capacitor C22 in the secondary-side resonance circuit, but whether or not the capacitor C22 is included is arbitrary.

By the way, in the non-contact power feeding device 2 of the present embodiment, the capacitance adjustment circuit 22 is configured by using the four second switch elements S21 to S24, but the capacitance adjustment circuit 22 may have other configurations. For example, as shown in FIG. 10, the capacity adjustment circuit 22 may be configured by a primary side capacitor C11, a first bidirectional switch Q1, and a second bidirectional switch Q2. The first bidirectional switch Q1 and the second bidirectional switch Q2 are used instead of the plurality of second switch elements S21 to S24.

The first bidirectional switch Q1 is composed of a semiconductor element having a double gate structure having two gate terminals GT1 and GT2. The first bidirectional switch Q1 is connected in series with the primary capacitor C11. The second bidirectional switch Q2 is composed of a semiconductor element having a double gate structure having two gate terminals GT3 and GT4. The second bidirectional switch Q2 is connected in parallel with the series circuit of the first bidirectional switch Q1 and the primary side capacitor C11.

In the first bidirectional switch Q1, when an ON signal is input to the gate terminal GT1 and an OFF signal is input to the gate terminal GT2, the direction from the first output end of the inverter circuit 21 toward one end of the primary coil L1 (first direction) ). The first bidirectional switch Q1 conducts in a direction opposite to the first direction (second direction) when an off signal is input to the gate terminal GT1 and an on signal is input to the gate terminal GT2. Further, the first bidirectional switch Q1 conducts in both the first direction and the second direction when an ON signal is input to each of the gate terminals GT1 and GT2. The first bidirectional switch Q1 becomes non-conductive in both the first direction and the second direction when an off signal is input to each of the gate terminals GT1 and GT2.

The second bidirectional switch Q2 conducts in the first direction when an ON signal is input to the gate terminal GT3 and an OFF signal is input to the gate terminal GT4. The second bidirectional switch Q2 conducts in the second direction when an off signal is input to the gate terminal GT3 and an on signal is input to the gate terminal GT4. Further, the second bidirectional switch Q2 conducts in both the first direction and the second direction when an ON signal is input to each of the gate terminals GT3 and GT4. The second bidirectional switch Q2 becomes non-conductive in both the first direction and the second direction when an off signal is input to each of the gate terminals GT3 and GT4.

The second drive signal G21 is input to the gate terminal GT1 of the first bidirectional switch Q1, and the second drive signal G22 is input to the gate terminal GT2. The second drive signal G23 is input to the gate terminal GT3 of the second bidirectional switch Q2, and the second drive signal G24 is input to the gate terminal GT4. The capacitance adjustment circuit 22 configured in this way operates in the same manner as the capacitance adjustment circuit 22 having a plurality of second switch elements S21 to S24 as shown in FIG.

The first bidirectional switch Q1 and the second bidirectional switch Q2 are preferably gallium nitride (GaN) based semiconductor elements. With this configuration, it is possible to improve the pressure resistance and temperature resistance of each bidirectional switch Q1, Q2. In addition, the first bidirectional switch Q1 (second bidirectional switch Q2) may be configured by connecting two series circuits of diodes and IGBTs in parallel so that their polarities are opposite to each other. The first bidirectional switch Q1 (second bidirectional switch Q2) may be configured by connecting an n-channel enhancement type MOSFET and a p-channel enhancement type MOSFET in series.

In the contactless power supply device 2 and the contactless power supply system 1 of the present embodiment, power is supplied from the primary side coil L1 to the secondary side coil L2 by the resonance method, but power is supplied by the electromagnetic induction method. It may be a configuration. In this configuration, since it is not necessary to form a resonance circuit in the power receiving device 3, the secondary side capacitor C21 is not necessary.

By the way, the primary side coil L1 and the secondary side coil L2 are not limited to solenoid type coils (the conductive wire is spirally wound around the core), but the conductive wire is wound in a spiral shape on a plane. A spiral coil may be used. Spiral type coils have the advantage that unwanted radiation noise is less likely to occur than solenoid type coils. Further, the use of the spiral type coil has an advantage that the range of the switching frequency f1 usable in the inverter circuit 21 is expanded as a result of reducing unnecessary radiation noise. Hereinafter, this point will be described in detail.

That is, the resonance characteristics in the non-contact power feeding system 1 of the present embodiment change according to the coupling coefficient between the primary side coil L1 and the secondary side coil L2, as described above. The resonance characteristic shows a so-called bimodal characteristic in which two maximum values are generated in the output as shown in FIGS. 11A and 11B under certain conditions. In this resonance characteristic (bimodal characteristic), as shown in FIG. 11A and FIG. 11B, two “mountains” in which the output is maximized at each of the first resonance frequency fr1 and the third resonance frequency fr3 are generated. Between these two “mountains”, a “valley” in which the output is minimized at the second resonance frequency fr2 occurs. Here, the first resonance frequency fr1, the second resonance frequency fr2, and the third resonance frequency fr3 are in a relationship of fr1 <fr2 <fr3. Hereinafter, with reference to the second resonance frequency fr2, the frequency region lower than the second resonance frequency fr2 is referred to as “low frequency region”, and the frequency region higher than the second resonance frequency fr2 is referred to as “high frequency region”.

In such a resonance characteristic, a region where the inverter circuit 21 operates in the slow phase mode (hereinafter referred to as a “slow phase region”) is provided for each of the “crest” in the low frequency region and the “crest” in the high frequency region. ) Occurs. Therefore, the inverter circuit 21 can operate in the slow phase mode even when the switching frequency f1 is at any of the two “mountains”.

Here, assuming that the switching frequency f1 of the inverter circuit 21 is ‘f0’, the case where the frequency f0 is in the “mountain” in the low frequency region and the case in the “mountain” of the high frequency region are compared. Then, unnecessary radiation noise becomes smaller when the frequency f0 is in the “mountain” of the low frequency region. That is, in the “mountain” of the high frequency region, the current flowing through the primary coil L1 and the current flowing through the secondary coil L2 have the same phase. On the other hand, in the “mountain” in the low frequency region, the current flowing through the primary coil L1 and the current flowing through the secondary coil L2 are in opposite phases. Therefore, in the “mountains” in the low frequency region, the unnecessary radiation noise generated in the primary side coil L1 and the unnecessary radiation noise generated in the secondary side coil L2 cancel each other. Unnecessary radiation noise is reduced when viewed from the entire contact power supply system 1.

Therefore, even when a solenoid type coil is employed, if the switching frequency f1 of the inverter circuit 21 is in the “mountain” slow phase region (fr1 to fr2) of the low frequency region, the inverter circuit 21 operates in the slow phase mode. In addition, unnecessary radiation noise is also reduced. However, since the slow phase region of the “mountain” in the low frequency region changes according to the coupling coefficient between the primary side coil L1 and the secondary side coil L2, the inverter circuit 21 is brought into such an uncertain slow phase region. Therefore, it is necessary to control so that the switching frequency f1 is reduced.

On the other hand, in the case of a spiral type coil, even if the switching frequency f1 of the inverter circuit 21 is in the “mountain” slow phase region (higher frequency side than fr3) of the high frequency region, compared to the solenoid type coil. Unwanted radiation noise is greatly reduced. In other words, by using the spiral type coil, the switching frequency f1 of the inverter circuit 21 is not limited to the “hill” slow-phase region in the low frequency region, and the range of the switching frequency f1 usable in the inverter circuit 21 is expanded. Will be. Although the slow phase region of the “mountain” in the high frequency region is also an uncertain region, if the switching frequency f1 of the inverter circuit 21 is swept from a sufficiently high frequency to a low frequency side, the switching frequency f1 becomes the high frequency region. Since it passes through the “mountain” slow-phase region, no complicated control is required.

Claims

An inverter circuit which has a plurality of first switch elements and converts the DC power into AC power by switching on / off of the plurality of first switch elements, and outputs the AC power;
A primary coil that receives the AC power output from the inverter circuit and generates a magnetic field;
A plurality of second switch elements and a primary capacitor are electrically connected between the inverter circuit and the primary coil, and the plurality of second switch elements are switched on / off. A capacitance adjusting circuit that switches a path through the primary side capacitor and a path not through the primary side capacitor;
A control circuit for controlling on / off of each of the plurality of first switch elements and the plurality of second switch elements;
The primary coil forms a resonance circuit with the primary capacitor,
The control circuit starts so that the phase of the first drive signal applied to the plurality of first switch elements coincides with the phase of the second drive signal applied to the plurality of second switch elements, and after the start The non-contact power feeding apparatus is controlled so that a phase of the second drive signal is advanced than a phase of the first drive signal.
The non-contact power feeding device according to claim 1, further comprising a capacitor connected in series with the capacity adjustment circuit between the inverter circuit and the primary coil.
3. The non-contact power feeding device according to claim 2, wherein the capacitor is connected between the capacitance adjusting circuit and the primary coil.
The plurality of second switch elements are a first bidirectional switch and a second bidirectional switch,
The capacitance adjusting circuit connects the first bidirectional switch in series with the primary side capacitor, and connects the second bidirectional switch in parallel with the series circuit of the primary side capacitor and the first bidirectional switch. The non-contact power feeding device according to claim 1, wherein the non-contact power feeding device is configured as described above.
The contactless power feeding device according to claim 4, wherein each of the first bidirectional switch and the second bidirectional switch is a gallium nitride based semiconductor element.
A contactless power supply device according to any one of claims 1 to 5, and a power receiving device that receives power supplied from the contactless power supply device,
The power receiving device is:
A secondary coil that generates AC power in response to a magnetic field generated by the primary coil;
A non-contact power feeding system comprising: a secondary side capacitor that forms a resonance circuit together with the secondary side coil.