JP7356104B2 - Two-way wireless power supply device - Google Patents

Description

The present invention relates to a bidirectional wireless power supply device.

Conventional V2H (Vehicle to Home) systems or V2G (Vehicle to Grid) systems, which bidirectionally connect the power of electric vehicles such as electric vehicles and plug-in hybrid vehicles with the power of homes and power distribution systems for mutual interchange, are Although it is useful for leveling consumption and natural energy generation, it is time-consuming because it requires connecting the power supply device and the electric vehicle with a cable.

The two-way wireless power supply device described in Patent Document 1 performs power transmission using coupling of magnetic fields by coils, and thus eliminates the need for cable connection. However, the bidirectional wireless power supply device described in Patent Document 1 has the problem that it is expensive and large because each power supply device is configured with a bridge converter that operates with a plurality of power semiconductors.

On the other hand, the bidirectional wireless power feeding device described in Non-Patent Document 1 is configured with a single-stone converter that operates with a single power semiconductor, so that the bidirectional wireless power feeding device described in Patent Document 1 is It is possible to significantly reduce the cost and size compared to the previous model.

Patent No. 6038386

Hideki Omori and 7 others “A Wireless V2H Apparatus with a New SiC-MOSFET and Unique Bidirectional Controlled Single-Ended Converter”, [online], July 27, 2017, IEEE, [Retrieved October 24, 2018] , Internet <URL: https://umexpert.um.edu.my/file/publication/00005361_159948_71519.pdf>

However, the bidirectional wireless power supply device described in Non-Patent Document 1 has two problems for practical use. One is the stability of transmission characteristics against circuit variations, and since transmission power fluctuates significantly due to constant variations that normally occur in transmission coils and resonant capacitors, mass production and compatibility become problems.

Another issue is the controllability of the transmitted power. Single-stone converters use a frequency control method that varies the transmitted power by changing the frequency, but the standard frequency band specified by international standards is generally not wide enough. Therefore, the problem is that a predetermined transmission power variable range cannot be obtained.

The present invention has been made in view of the above circumstances, and its object is to reduce the cost and size of the device while improving the stability of transmission characteristics and the controllability of transmitted power. An object of the present invention is to provide a bidirectional wireless power supply device.

In order to solve the above problems, a bidirectional wireless power supply device according to the present invention includes:
a first power supply device connected to a first DC power supply;
a second power supply device connected to a second DC power supply;
A control unit that controls the first power supply device and the second power supply device,
A bidirectional wireless power supply device that transmits power between the first power supply device and the second power supply device,
The first power supply device includes:
a first transmission coil;
a first switching element connected in series to the first transmission coil;
a first resonant capacitor connected in parallel to at least one of the first transmission coil and the first switching element;
The second power supply device includes:
a second transmission coil;
a second switching element connected in series to the second transmission coil;
a second resonant capacitor connected in parallel to at least one of the second transmission coil and the second switching element,
The control unit includes:
a first turn-on control circuit that controls turn-on of the first switching element in synchronization with a resonant voltage generated by the first transmission coil and the first resonant capacitor so that the first switching element performs a zero-voltage switching operation;
a second turn-on control circuit that controls turn-on of the second switching element in synchronization with a resonant voltage generated by the second transmission coil and the second resonant capacitor so that the second switching element performs a zero-voltage switching operation;
The present invention is characterized by comprising a mutual phase shift control circuit that controls the switching of the first switching element and the switching of the second switching element to have a predetermined phase difference.

According to this configuration, the first power supply device is configured with a single-stone converter that operates with the first switching element, and the second power supply device is configured with a single-stone converter that operates with the second switching element. Cost reduction and miniaturization can be achieved.

Furthermore, according to this configuration, the first switching element and the second switching element perform a zero voltage switching operation, and the switching of the first switching element and the switching of the second switching element are controlled to have a predetermined phase difference. Therefore, the stability of transmission characteristics and the controllability of transmission power can be improved.

In the above two-way wireless power supply device,
It is preferable that the mutual phase shift control circuit performs control such that the turn-off of the first switching element and the turn-off of the second switching element have the phase difference.

In the above two-way wireless power supply device,
Preferably, the phase difference is between 45 degrees and 315 degrees.

In the above two-way wireless power supply device,
The mutual phase shift control circuit includes:
a phase difference detector that directly or indirectly detects the phase difference;
a phase difference command device that directly or indirectly commands the target value of the phase difference;
a feedback control unit that performs feedback control of the phase difference by comparing the detection value of the phase difference detector and the target value of the phase difference command device;
It can be configured to include a conduction time variable section that changes the conduction time of the second switching element according to the output of the feedback control section.

In the above two-way wireless power supply device,
The phase difference detector indirectly detects the phase difference by detecting transmitted power,
The phase commander may be configured to indirectly command the target value by commanding the transmitted power.

In the above two-way wireless power supply device,
The mutual phase shift control circuit can be configured to include a detection element that magnetically or electrically detects a change in the voltage of the first transmission coil in a non-contact manner.

In the above two-way wireless power supply device,
The mutual phase shift control circuit can be configured to include a conduction time control circuit that controls the conduction time of the first switching element so that the operating frequency of the first power supply device becomes a predetermined value.

In the above two-way wireless power supply device,
The mutual phase shift control circuit can be configured to control the phase difference so that the transmission power between the first transmission coil and the second transmission coil becomes a predetermined value.

In the above two-way wireless power supply device,
The mutual phase shift control circuit includes a timing transmitting circuit that transmits the switching timing of the first switching element using light or radio waves, and a timing receiving circuit that receives the light or radio waves transmitted from the timing transmitting circuit. It can be configured as follows.

In the above two-way wireless power supply device,
The second switching element includes a transistor and an anti-parallel diode connected in anti-parallel to the transistor,
The mutual phase shift control circuit includes:
a phase difference detector that directly or indirectly detects the phase difference;
a phase difference command device that directly or indirectly commands the target value of the phase difference;
a feedback control unit that performs feedback control of the phase difference by comparing the detection value of the phase difference detector and the target value of the phase difference command device;
a resonant current detector that detects a zero-crossing point of the current flowing through the second transmission coil;
The conduction time variable section may be configured to control the on time of the transistor after the anti-parallel diode is turned off in accordance with the detection result of the resonant current detector and the output of the feedback control section.

According to the present invention, it is possible to provide a bidirectional wireless power feeding device that achieves lower cost and smaller size of the device, and improves the stability of transmission characteristics and the controllability of transmitted power.

FIG. 1 is a diagram showing a bidirectional wireless power supply device according to a first embodiment. 3 is a timing chart of each part of the bidirectional wireless power supply device according to the first embodiment. FIG. 3 is a diagram showing the relationship among phase difference, transmission power, and operating frequency. FIG. 7 is a diagram showing a bidirectional wireless power supply device according to a second embodiment. FIG. 7 is a diagram illustrating the operating principle of a bidirectional wireless power supply device according to a second embodiment. FIG. 7 is a diagram showing a bidirectional wireless power supply device according to a third embodiment. 7 is a timing chart of each part of a bidirectional wireless power supply device according to a third embodiment.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a bidirectional wireless power supply device according to the present invention will be described with reference to the accompanying drawings.

[First embodiment]
FIG. 1 shows a bidirectional wireless power supply device 1A according to a first embodiment of the present invention. The bidirectional wireless power supply device 1A includes a first power supply device 10 connected to a first DC power supply 2, a second power supply device 20 connected to a second DC power supply 3, and a control unit 30, Power is transferred between the power source 2 and the second DC power source 3.

The first DC power supply 2 includes a first battery _E1 , a first capacitor _C3 , and a first coil _L3 . The first battery _E1 is, for example, a storage battery installed at home. The first capacitor _C3 has one end connected to the high potential side of the first battery _E1 via the first coil _L3 , and the other end connected to the low potential side of the first battery _E1 .

The second DC power supply 3 includes a second battery _E2 , a second capacitor _C4 , and a second coil _L4 . The second battery _E2 is, for example, a storage battery mounted on an electric vehicle. The second capacitor _C4 has one end connected to the high potential side of the second battery _E2 via the second coil _L4 , and the other end connected to the low potential side of the second battery _E2 .

The first power supply device 10 is a single-stone converter that includes a first transmission coil _L1 , a first switching element _SW1 configured with an IGBT (insulated gate transistor), and a first resonant capacitor _C1 . The first transmission coil _L1 has one end connected to the high potential side of the first battery _E1 via the first coil _L3 , and the other end connected to the first battery E1 via the current path of the first switching element _SW1 . Connected to the low potential side of ₁ . The first resonant capacitor C ₁ is connected in parallel to at least one of the first transmission coil L ₁ and the first switching element SW ₁ (in this embodiment, the first transmission coil L ₁ ).

The second power supply device 20 is a single-stone converter that includes a second transmission coil _L2 , a second switching element _SW2 configured with an IGBT (insulated gate transistor), and a second resonant capacitor _C2 . The second transmission coil _L2 has one end connected to the high potential side of the second battery _E2 via the second coil _L4 , and the other end connected to the second battery E2 via the current path of the second switching element _SW2. Connected to the low potential side of ₂ . The second resonant capacitor C ₂ is connected in parallel to at least one of the second transmission coil L ₂ and the second switching element SW ₂ (in this embodiment, the second transmission coil L ₂ ).

The first transmission coil _L1 and the second transmission coil _L2 are magnetically coupled with a coupling coefficient of 0.5 or less. Further, in this embodiment, IGBTs are used for the first switching element SW ₁ and the second switching element SW ₂ , but switching elements having a self-turn-off function such as MOSFETs and bipolar transistors may also be used.

The control section 30 includes a first turn-on control circuit (31, 32), a second turn-on control circuit (33, 34), and mutual phase shift control circuits (35 to 39).

The first turn-on control circuit includes a first resonant voltage detection circuit 31 and a first synchronization circuit 32. The first resonant voltage _detection circuit 31 measures the voltage V _R1 across the first transmission coil L ₁ (first resonant capacitor C ₁ ), thereby detecting _the first configured to detect a resonant voltage. The first synchronous circuit 32 is configured to control turn-on of the first switching element SW ₁ in synchronization with the first resonant voltage so that the first switching element SW ₁ performs a zero voltage switching operation.

The second turn-on control circuit includes a second resonant voltage detection circuit 33 and a second synchronization circuit 34. The _second resonant voltage detection circuit 33 measures the voltage V _{R2 across} the second transmission coil L ₂ (second resonant capacitor C ₂ ), thereby detecting the second configured to detect a resonant voltage. The second synchronous circuit 34 is configured to control turn-on of the second switching element SW ₂ in synchronization with the second resonant voltage so that the second switching element SW ₂ performs a zero voltage switching operation.

The mutual phase shift control circuit includes a timing transmission circuit 35, a timing reception circuit 36, a detection circuit 37, a comparison circuit 38, and a turn-off phase difference control circuit 39.

The timing transmitting circuit 35 is configured to transmit a timing signal for switching the first switching element _SW1 using light or radio waves. Timing receiving circuit 36 is configured to receive the timing signal transmitted from the timing transmitting circuit. In this embodiment, the timing transmitting circuit 35 includes a light emitting diode, and the timing receiving circuit 36 includes a phototransistor.

The detection circuit 37 is configured to detect the current flowing between the second power supply device 20 and the second DC power supply 3 and output a signal (for example, a voltage signal) according to the detection result to the comparison circuit 38.

The comparison circuit 38 is configured to output a phase difference control command value so that the transmission power between the first transmission coil L ₁ and the second transmission coil L ₂ reaches a predetermined target value. The comparison circuit 38 includes, for example, a differential amplifier, the reference voltage V _ref corresponding to the target value of transmission power is input to the inverting input terminal of the differential amplifier, and the reference voltage V ref corresponding to the target value of transmission power is input to the non-inverting input terminal of the differential amplifier from the detection circuit 37. signal is input. The comparison circuit 38 outputs a signal corresponding to the difference between the two to the turn-off phase difference control circuit 39 as a phase difference control command value.

The turn-off phase difference control circuit 39 controls the turn-off of the first switching element SW ₁ and the turn-off of the second switching element SW ₂ to have a predetermined phase difference based on the output of the timing receiving circuit 36 and the output of the comparison circuit 38. Then, a control signal is output to the second synchronization circuit 34 (phase shift control). The second synchronization circuit 34 turns off the second switching element _SW2 in response to this control signal.

Next, with reference to FIG. 2, control of the bidirectional wireless power supply device 1A will be described. In FIG. 2, (A) is the waveform of the voltage _VSW1 across the first switching element _SW1 , (B) is the waveform of the current _ISW1 flowing through the first switching element _SW1 , and (C) is the waveform of the first transmission coil _L1. ( _D ) is the waveform of the gate voltage _Vg1 of the first switching element _SW1 , (E) is the waveform of the gate voltage Vg2 of the second switching element _SW2 , (F) is the waveform of the gate voltage _Vg2 of the second switching element SW2. The waveform of the voltage _VR2 across the transmission coil _L2 , (G) the waveform of the current _ISW2 flowing through the second switching element _SW2 , and (H) the waveform of the voltage _VSW2 across the second switching element _SW2 .

During the period T _OFF1 in which the first switching element SW ₁ is OFF, the voltage V _R1 across the first transmission coil L ₁ is a first resonance voltage generated by the first transmission coil L ₁ and the first resonance capacitor C ₁ . .

The voltage _VSW1 across the first switching element _SW1 traces an arc of resonance, rises gently, then falls slowly and reaches zero. When the voltage V _SW1 reaches zero at time t ₁ , the first antiparallel diode D ₁ constituting the first switching element SW ₁ automatically becomes conductive, and the first switching element SW ₁ becomes conductive.

When the first resonant voltage detection circuit 31 detects the zero cross point _t0 where the voltage _VR1 crosses zero, the first synchronization circuit 32 connected to the first resonant voltage detection circuit 31 detects the zero cross point t0 of the first resonant voltage. At time _t2 synchronized with ₀ , the gate voltage _Vg1 of the first switching element _SW1 is switched from a low level to a high level to turn on the first transistor _Q1 constituting the first switching element _SW1 . That is, the first synchronous circuit 32 turns on the first switching element _SW1 to perform a zero voltage switching operation.

Here, the voltage V _SW1 across the first switching element SW ₁ may have a small amplitude and may not reach zero depending on the state of the load (for example, the first DC power supply ₂ ); The waveform of the voltage across both ends _VR1 crosses zero regardless of the magnitude of the amplitude. Therefore, in this embodiment, the first resonant voltage detection circuit 31 is configured to detect the zero cross point _t0 .

Further, in order to realize the zero voltage switching operation of the first switching element SW ₁ , the first switching element SW ₁ may be turned on at time t ₁ , but the timing at time t ₁ may be shifted depending on the load condition. There is. Therefore, in this embodiment, some margin is provided by turning on the first switching element SW ₁ at time t _{2 after time t 1 .}

During the period _TON1 in which the first switching element _SW1 is conductive, the DC voltage of the first battery _E1 is applied to the first transmission coil _L1 , so the current I flowing through the first switching element _{SW1 SW1} increases linearly. When the current _ISW1 commutates from negative to positive, the current flowing through the first anti-parallel diode _D1 smoothly flows to the first transistor _Q1 , and the first switching element _SW1 continues to be conductive.

The first synchronization circuit 32 switches the gate voltage V _g1 of the switching element SW ₁ from a high level to a low level at a time t ₆ after a preset time T _ON1 has elapsed, thereby cutting off the first transistor Q ₁ . As a result, the first switching element _SW1 is turned off, and the current stored in the first transmission coil _L1 flows into the first resonant capacitor _C1 , resulting in a resonant state, and oscillation continues.

During the period T _OFF2 in which the second switching element SW ₂ is OFF, the voltage V _R2 across the second transmission coil L ₂ is a second resonance voltage generated by the second transmission coil L ₂ and the second resonance capacitor C ₂ . .

The voltage _VSW2 across the second switching element _SW2 traces a resonance arc, rises gently, then falls slowly and reaches zero. When the voltage V _SW2 reaches zero at time t ₄ , the second antiparallel diode D ₂ constituting the second switching element SW ₂ automatically becomes conductive, and the second switching element SW ₂ becomes conductive.

When the second resonant voltage detection circuit ₃₃ detects the zero cross point t3 where the voltage _VR2 crosses zero, the second synchronization circuit 34 connected to the second resonant voltage detection circuit 33 detects the zero cross point t3 of the second resonant voltage. At time _t5 synchronized with ₃ , the gate voltage _Vg2 of the second switching element _SW2 is switched from low level to high level to make the second transistor _Q2 constituting the second switching element _SW2 conductive. That is, the second synchronous circuit 34 turns on the second switching element _SW2 to perform a zero voltage switching operation.

During the period T _ON2 in which the second switching element SW ₂ is conductive, the DC voltage of the second battery E ₂ is applied to the second transmission coil L ₂ , so the current I flowing through the second switching element SW _{2 SW2} increases linearly. When the current _ISW2 commutates from negative to positive, the current flowing through the second anti-parallel diode _D2 smoothly flows to the second transistor _Q2 , and the second switching element _SW2 continues to be conductive.

At time _t6 , when the gate voltage _Vg1 of the first switching element _SW1 changes from high level to low level and the first switching element _SW1 is turned off, a timing signal is sent from the timing transmitting circuit 35 to the timing receiving circuit 36. .

The turn-off phase difference control circuit 39 connected to the timing receiving circuit 36 causes the second synchronization circuit 34 to adjust the gate voltage V _g2 of the second switching element SW ₂ at time t ₇ delayed by the phase shift time T _φ from time t ₆ . A control signal is output to the second synchronization circuit 34 so as to switch from a high level to a low level and turn off the second switching element _SW2 . When the second switching element _SW2 is turned off, the current stored in the second transmission coil _L2 flows into the second resonant capacitor _C2 , resulting in a resonant state, and oscillation continues.

According to the present embodiment, with the above operation, the first switching element SW ₁ and the second switching element SW ₂ maintain zero voltage switching with small switching loss, while changing the turn-off phase of the second switching element SW 2 to the second switching element SW ₂ . It is possible to shift the turn-off phase of one switching element _SW1 by a time T _φ (by a phase angle of φ=2πT _φ /T _o (T _o : operation period)).

After all, according to the bidirectional wireless power supply device 1A according to the present embodiment, the first power supply device 10 is configured with a single-stone converter that operates with the first switching element _SW1 , and the second power supply device 20 is configured with the second switching element SW1. Since it is composed of a single-stone converter that operates with SW ₂ , the device can be made lower in cost and smaller in size than a bridge converter type bidirectional power supply device that uses a plurality of power semiconductors.

In addition, according to the bidirectional wireless power supply device 1A according to the present embodiment, the phase difference in the transmission power between the first power supply device 10 and the second power supply device 20, which is the main cause of transmission power fluctuation due to variations in circuit constants, can be reduced. As a result of compensation by the phase shift control of the turn-off phase difference control circuit 39, the fluctuation is extremely small, and sufficient mass productivity and compatibility can be obtained. That is, according to this embodiment, the stability of transmission characteristics can be improved.

FIG. 3 shows the relationship among phase difference, transmission power, and operating frequency. The solid line is the transmitted power (left axis), and the broken line is the operating frequency (right axis). As can be seen from the figure, according to this embodiment, the transmission power can be controlled from 0 to the maximum value (4.8 kW in FIG. 3) while keeping the operating frequency substantially constant. That is, according to this embodiment, controllability of transmission power can be improved.

In addition, as can be seen from Figure 3, the phase range for phase shift control can control the entire transmission power range bidirectionally, and from 45 degrees to 315 degrees, the change in transmission power is gradual with respect to the phase difference, so it is stable. Easy to control. In particular, in the case of instantaneous control in which the second switching element SW ₂ is turned off with a delay of time T _φ after detecting the turn-off of the first switching element SW ₁ as in the present embodiment, the The phase difference region is an uncontrollable region, but if it is from 45 degrees to 315 degrees, the entire region (the entire transmission power range) can be stably controlled. Furthermore, from the viewpoint of stable control at a desired operating point, it is preferable to perform phase shift control in a phase range of 60 degrees to 300 degrees.

[Second embodiment]
FIG. 4 shows a bidirectional wireless power supply device 1B according to a second embodiment of the present invention. The bidirectional wireless power supply device 1B includes a first power supply device 10 connected to the first DC power supply 2, a second power supply device 20 connected to the second DC power supply 3, and a control unit 40, Power is transferred between the power source 2 and the second DC power source 3.

The configurations of the first DC power supply 2, the first power supply device 10, the second DC power supply 3, and the second power supply device 20 are the same as those in the first embodiment, so the description thereof will be omitted here.

The control section 40 includes a first turn-on control circuit (31, 32), a second turn-on control circuit (33, 34), and a mutual phase shift control circuit (41-44). The first turn-on control circuit (31, 32) and the second turn-on control circuit (33, 34) are common to the first embodiment.

The first turn-on control circuit includes a first resonant voltage detection circuit 31 and a first synchronization circuit 32. The first resonant voltage detection circuit 31 is configured to detect _{the first resonant voltage caused by the first transmission coil L 1 and} the first resonant capacitor C ₁ by measuring the voltage V _R1 across the first transmission coil L 1 . Ru. The first synchronous circuit 32 controls the turn-on of the first switching element SW ₁ in synchronization with the first resonance voltage so that the first switching element SW 1 performs a zero voltage switching operation, and also controls the turn-on of the first switching element SW ₁ at a predetermined level. It is configured to maintain the conduction time _TON1 .

The second turn-on control circuit includes a second resonant voltage detection circuit 33 and a second synchronization circuit 34. The second resonance voltage detection circuit 33 is configured to detect the second resonance voltage caused by the second transmission coil L _{2 and} the second resonance capacitor C ₂ by measuring the voltage V _R2 across the second transmission coil L 2 . Ru. The second synchronous circuit 34 is configured to control turn-on of the second switching element SW ₂ in synchronization with the second resonant voltage so that the second switching element SW ₂ performs a zero voltage switching operation.

The mutual phase shift control circuit includes a phase difference detector 41, a phase difference command device 42, a differential amplifier 43 (corresponding to the "feedback control section" of the present invention), and a conduction time variable section 44.

The phase difference detector 41 is configured to indirectly detect the phase difference by detecting the transmitted power between the first transmission coil L ₁ and the second transmission coil L ₂ . Since the transmitted power has a correlation with the phase difference (see FIG. 3), the phase difference can be indirectly detected and controlled using the transmitted power. Note that in place of the phase difference detector 41, a phase difference detector configured to directly detect a phase difference may be used.

The phase difference command device 42 is configured to indirectly command the target value of the phase difference by commanding the target value of the transmission power between the first transmission coil _L1 and the second transmission coil _L2 . . Note that instead of the phase difference command device 42, a phase difference command device configured to directly command the target value of the phase difference may be used.

The differential amplifier 43 is configured to compare the detection value detected by the phase difference detector 41 and the target value commanded by the phase difference command device 42, and perform feedback control of the phase difference. In this embodiment, the detected value is input to the non-inverting input terminal of the differential amplifier 43, and the target value is input to the inverting input terminal. The differential amplifier 43 outputs a signal corresponding to the difference between the two to the conduction time variable section 44 as a phase difference control command value.

The conduction time variable section 44 controls the second synchronous circuit 34 according to the signal input from the differential amplifier 43, and changes the conduction time of the second switching element _SW2 . Specifically, the conduction time variable section 44 outputs a control signal to the second synchronization circuit 34 so that the turn-off of the first switching element SW ₁ and the turn-off of the second switching element SW ₂ have a predetermined phase difference. (phase shift control). The second synchronization circuit 34 turns off the second switching element _SW2 in response to this control signal.

FIG. 5 shows a diagram of the operating principle of the bidirectional wireless power supply device 1B. The bidirectional wireless power supply device 1B can be represented by a first calculation section 51, a filter section 52, a second calculation section 53, a gain setting section 54, and a voltage control transmission section 55.

The first calculation unit 51 represents the phase difference detector 41 and calculates the phase difference ΔΦ between the phase Φ ₁ on the first power supply device 10 side and the phase Φ ₂ on the second power supply device 20 side determined from the transmitted power. The phase difference ΔΦ between the phase Φ ₁ on the first power supply device 10 side and the phase Φ ₂ on the second power supply device 20 side obtained from something other than the transmitted power may be calculated. The filter section 52, that is, the transfer function F(S) represents a low-pass filter included in the phase difference detector 41 for system stabilization.

The second calculation unit 53 calculates the difference between the output of the filter unit 52 and the phase difference command ΔΦ _r . The second calculation unit 53 represents the differential amplifier 43, and the phase difference command ΔΦ _r represents the target value of the phase difference output from the phase difference command unit 42. The gain setting unit 54, ie, the block K, represents the aggregated gains of the entire control loop.

The voltage control transmitter 55, ie, the 1/S block, represents a combination of the conduction time variable section 44, the second synchronous circuit 34, and the second power supply device 20. The voltage controlled oscillator 55 becomes a voltage controlled oscillator whose operating frequency changes as a result of the change in the conduction time of the second switching element _SW2 , and thus functions as an integrator for the operating phase.

From FIG. 5, the phase Φ ₂ of the second power supply device 20 can be expressed by the following equation.

As can be seen from equation (1), in the bidirectional wireless power supply device 1B, the phase difference ΔΦ between the phase Φ ₂ on the second power supply device 20 side and the phase Φ ₁ on the first power supply device 10 side is steadily It operates so that the command ΔΦ _r (target value of phase difference) is achieved.

The bidirectional wireless power supply device 1B according to the present embodiment does not have instantaneous control like the first embodiment, so there is a delay in response, but the timing transmitting circuit 35 and timing receiving circuit 36 of the first embodiment are not required. , low cost, and strong against disturbance noise.

[Third embodiment]
FIG. 6 shows a bidirectional wireless power supply device 1C according to a third embodiment of the present invention. The bidirectional wireless power supply device 1C includes a first power supply device 10 connected to the first DC power supply 2, a second power supply device 20 connected to the second DC power supply 3, and a control unit 60, Power is transferred between the power source 2 and the second DC power source 3.

The configurations of the first DC power supply 2, the first power supply device 10, the second DC power supply 3, and the second power supply device 20 are the same as those in the second embodiment, so the description thereof will be omitted here.

The control section 60 includes a first turn-on control circuit (31, 32), a second turn-on control circuit (33, 34), and a mutual phase shift control circuit (41-43, 61-63). The configurations of the first turn-on control circuit (31, 32) and the second turn-on control circuit (33, 34) are the same as in the second embodiment.

The mutual phase shift control circuit includes a phase difference detector 41 , a phase difference command device 42 , a differential amplifier 43 , a resonant current detection element 61 , a resonant current detection circuit 62 , and a conduction time variable section 63 . The configurations of the phase difference detector 41, phase difference command device 42, and differential amplifier 43 are the same as in the second embodiment.

The resonant current detection element 61 and the resonant current detection circuit 62 correspond to the "resonant current detector" of the present invention. The resonant current detection element 61 detects the current flowing through the second transmission coil L ₂ and outputs the detection result to the resonant current detection circuit 62 . The resonant current detection circuit 62 detects the zero-cross point of the current flowing through the second transmission coil L ₂ based on the detection result of the resonant current detection element 61 and outputs the detection result (zero-cross signal) to the conduction time variable section 63 .

At least during the period when the second switching element SW ₂ is conductive, the current flowing through the second transmission coil L ₂ and the current I _SW2 flowing through the second switching element SW ₂ are equal. Therefore, detecting the zero-crossing point of the current flowing through the second transmission coil _L2 is the same as detecting the zero-crossing point of the current _ISW2 of the second switching element _SW2 .

In the second switching element _SW2 , when the current _ISW2 reaches the zero cross point, the second anti-parallel diode _D2 is turned off, and the current flowing through the second anti-parallel diode _D2 flows to the second transistor _Q2 . That is, the zero-crossing point of the current I _SW2 is the timing at which the second anti-parallel diode D ₂ is turned off. Note that the second anti-parallel diode _D2 is a built-in (parasitic) diode of the second transistor _Q2 or a diode independent of the second transistor _Q2 .

The conduction time variable unit 63 is configured to control the on time of the second transistor Q ₂ after the second anti-parallel diode D ₂ is turned off. The conduction time variable section 63 receives a zero-crossing signal from the resonance current detection circuit 62 and receives a phase difference control command value (more specifically, a transmission power control command value that has a correlation with the phase difference) from the differential amplifier 43. ) is input. The control command value is a command value (for feedback control) for bringing the detection value detected by the phase difference detector 41 closer to the target value commanded by the phase difference command device 42.

Based on these signals, the conduction time variable section 63 calculates the on time of the second transistor Q ₂ after the second anti-parallel diode D ₂ is turned off. Further, the conduction time variable section 63 generates a timing signal for turning off the second transistor _Q2 when the on-time has elapsed. The timing signal is output to the second synchronization circuit 34.

The second synchronization circuit 34 turns off the second transistor _Q2 based on the timing signal. As a result, phase shift control is performed in which the turn-off of the first switching element SW ₁ and the turn-off of the second switching element SW ₂ have a predetermined phase difference.

FIG. 7 shows a timing chart of each part of the bidirectional wireless power supply device 1C. In FIG. 7, the waveforms (A) to (H) indicate the same signals as in FIG. 2, and the waveform (I) is the timing signal T for controlling the on-time of the second transistor _Q2 . This is _{a MOS} waveform.

When the voltage V _SW2 reaches zero at time t ₄ , the second anti-parallel diode D ₂ of the second switching element SW ₂ is turned on, and the second switching element SW ₂ becomes conductive. During the period T _ON2 in which the second switching element SW ₂ is conductive, the current I _SW2 of the second switching element SW ₂ increases linearly.

When the current I _SW2 reaches zero at time _t5 ', the second anti-parallel diode _D2 is turned off, and the current flowing through the second anti-parallel diode _D2 flows into the second transistor _Q2 . In the control section 60 , the resonance current detection circuit 62 outputs a zero-cross signal to the conduction time variable section 63 .

The conduction time variable section 63 determines the on time T of the second transistor Q ₂ after the second anti-parallel diode D ₂ is turned off based on the zero cross signal and the signal related to the control command value input from the differential amplifier 43. and generates a timing signal _TMOS regarding the on-time T. The conduction time variable section 63 outputs the generated timing signal _TMOS to the second synchronization circuit 34.

The second synchronization circuit 34 switches the gate voltage V _g2 of the second transistor Q ₂ from high level to low level at the timing when the timing signal T _MOS switches from high level to low level at time t ₇ . Turn off ₂ . The subsequent control is the same as that shown in FIG.

Similar to the second embodiment, the bidirectional wireless power supply device 1C according to the present embodiment eliminates the need for the timing transmitting circuit 35 and the timing receiving circuit 36, so it is low in cost and resistant to disturbance noise.

Furthermore, since the bidirectional wireless power supply device 1C according to the present embodiment controls the on time of the second transistor _Q2 after the second anti-parallel diode _D2 is turned off, the on time (conductivity) of the second switching element SW2 is controlled. When compared with a normal method of controlling time), it is possible to stably control the second power supply device 20.

A method of controlling the on-time of the second switching element _SW2 is to control the sum of the on-time of the second anti-parallel diode _D2 and the on-time of the second transistor _Q2 . In this case, for one sum, there are multiple combinations of the on-time of the second anti-parallel diode _D2 and the on-time of the second transistor _Q2 , so the on-time of the second transistor _Q2 can be uniquely determined. cannot be determined.

For example, even if the conduction time variable unit 63 calculates the on-time of the second switching element SW ₂ and turns off the second switching element SW ₂ according to the on-time, the on-time of the second transistor Q ₂ is outside the appropriate range. If so, the operation of the second power supply device 20 becomes unstable. When the operation of the second power supply device 20 becomes unstable, the phase difference between the first power supply device 10 and the second power supply device 20 becomes unstable, and an excessive voltage is generated in the second switching element _SW2 . A current flows.

On the other hand, in the present embodiment, the conduction time variable section 63 calculates the on time T of the second transistor _Q2 after the second antiparallel diode D2 is turned off, so that the on time T can _be uniquely determined. . Therefore, in this embodiment, the on-time T of the second transistor _Q2 can be kept within an appropriate range according to the target value of the phase difference (target value of transmission power), and the second power supply device 20 can be stably controlled. be able to.

[Modified example]
Although the embodiments of the bidirectional wireless power supply device according to the present invention have been described above, the present invention is not limited to the above embodiments.

For example, in the first embodiment, the timing transmitting circuit 35 and the timing receiving circuit 36 may be omitted.

In the first embodiment, instead of the timing transmitting circuit 35 and the timing receiving circuit 36, a detecting element that magnetically or electrically detects a change in the voltage of the first transmission coil _L1 in a non-contact manner may be used. The detection element is preferably installed in a central part of the second transmission coil _L2 where there is no winding in order to make it less susceptible to noise.

In the first embodiment, the conduction time T _ON1 of the first switching element SW ₁ is set to a fixed value, but instead of this, a conduction time control circuit of the first switching element SW ₁ is provided, and the conduction time T ON1 of the first switching element SW 1 is set to a fixed value. The conduction time of the first switching element SW ₁ may be controlled so that the operating frequency of the first power supply device 10 becomes a predetermined value.

In the first and second embodiments, the turn-off of _the first switching element SW ₁ and the turn-off of the second switching element SW ₂ are controlled to have a predetermined phase difference. It may be controlled such that there is a predetermined phase difference between the turn-on of the second switching element _SW2 and the turn-on of the second switching element SW2. That is, the mutual phase shift control circuit of the present invention can be configured to perform control so that the switching of the first switching element _SW1 and the switching of the second switching element _SW2 have a predetermined phase difference. However, at the turn-on timing, it is necessary to control the phase difference so that the first and second switching elements SW ₁ and SW ₂ each perform a zero-voltage switching operation, whereas at the turn-off timing, such a Since there is no restriction, there is a high degree of freedom in controlling the phase difference, and from the viewpoint of transmitting the desired power, it is necessary to ensure that the turn-off of the first switching element SW ₁ and the turn-off of the second switching element SW ₂ have a predetermined phase difference. It is preferable to control.

The control unit 30 in the first embodiment includes mutual phase shift control circuits (35 to 39) for transmitting power from the first power supply device 10 to the second power supply device 20. It may further include a mutual phase shift control circuit for transmitting power from to the first power supply device 10.

Similarly, the control unit 40 in the second embodiment and the control unit 60 in the third embodiment further include a mutual phase shift control circuit for transmitting power from the second power supply device 20 to the first power supply device 10. It's okay.

Further, the bidirectional wireless power feeding devices 1A to 1C of the first to third embodiments are configured as wireless power feeding devices that perform bidirectional power transmission between the first power feeding device 10 and the second power feeding device 20. However, it can be used as a wireless power supply device that performs unidirectional power transmission between the first power supply device 10 and the second power supply device 20.

1A, 1B, 1C Bidirectional wireless power supply device 2 First DC power supply 3 Second DC power supply 10 First power supply device 20 Second power supply device 30, 40, 60 Control section 31 First resonance voltage detection circuit 32 First synchronization circuit 33 Second resonant voltage detection circuit 34 Second synchronization circuit 35 Timing transmission circuit 36 Timing reception circuit 37 Detection circuit 38 Comparison circuit 39 Turn-off phase difference control circuit 41 Phase difference detector 42 Phase difference command unit 43 Differential amplifier 44 Conduction time variable section 51 First calculation section 52 Filter section 53 Second calculation section 54 Gain setting section 55 Voltage control transmission section 61 Resonance current detection element 62 Resonance current detection circuit 63 Conduction time variable section

Claims (8)

a first power supply device connected to a first DC power supply;
a second power supply device connected to a second DC power supply;
A control unit that controls the first power supply device and the second power supply device,
A bidirectional wireless power supply device that transmits power between the first power supply device and the second power supply device,
The first power supply device includes:
a first transmission coil;
a first switching element connected in series to the first transmission coil;
a first resonant capacitor connected in parallel to at least one of the first transmission coil and the first switching element,
The second power supply device includes:
a second transmission coil;
a second switching element connected in series to the second transmission coil;
a second resonant capacitor connected in parallel to at least one of the second transmission coil and the second switching element,
The control unit includes:
a first turn-on control circuit that controls turn-on of the first switching element in synchronization with a resonant voltage generated by the first transmission coil and the first resonant capacitor so that the first switching element performs a zero-voltage switching operation;
a second turn-on control circuit that controls turn-on of the second switching element in synchronization with a resonant voltage generated by the second transmission coil and the second resonant capacitor so that the second switching element performs a zero-voltage switching operation;
a mutual phase shift control circuit that controls the switching of the first switching element and the switching of the second switching element to have a predetermined phase difference ,
The first turn-on control circuit turns off the first switching element after a predetermined time has elapsed since the first switching element was turned on;
The mutual phase shift control circuit includes:
a detection circuit that detects an output from the second power supply device to the second DC power supply;
a comparison circuit that generates a control command for the phase difference based on a difference between a signal value corresponding to the output and a reference signal value corresponding to the target value so that the electric power reaches a predetermined target value;
a turn-off phase difference that generates a control signal for turning off the second switching element so that the turn-off of the first switching element and the turn-off of the second switching element have the phase difference based on the control command; comprising a control circuit;
The second turn-on control circuit turns off the second switching element in response to the control signal.
A two-way wireless power supply device characterized by: The bidirectional wireless power supply device according to claim 1 , wherein the phase difference is 45 degrees to 315 degrees. a first power supply device connected to a first DC power supply;
a second power supply device connected to a second DC power supply;
A control unit that controls the first power supply device and the second power supply device,
A bidirectional wireless power supply device that transmits power between the first power supply device and the second power supply device,
The first power supply device includes:
a first transmission coil;
a first switching element connected in series to the first transmission coil;
a first resonant capacitor connected in parallel to at least one of the first transmission coil and the first switching element,
The second power supply device includes:
a second transmission coil;
a second switching element connected in series to the second transmission coil;
a second resonant capacitor connected in parallel to at least one of the second transmission coil and the second switching element,
The control unit includes:
a first turn-on control circuit that controls turn-on of the first switching element in synchronization with a resonant voltage generated by the first transmission coil and the first resonant capacitor so that the first switching element performs a zero-voltage switching operation;
a second turn-on control circuit that controls turn-on of the second switching element in synchronization with a resonant voltage generated by the second transmission coil and the second resonant capacitor so that the second switching element performs a zero-voltage switching operation;
A mutual phase shift control circuit that controls the switching of the first switching element and the switching of the second switching element to have a predetermined phase difference.
The first turn-on control circuit turns off the first switching element after a predetermined time has elapsed since the first switching element was turned on;
The mutual phase shift control circuit includes:
a phase difference detector that directly or indirectly detects the phase difference;
a phase difference command device that directly or indirectly commands the target value of the phase difference;
a feedback control unit that performs feedback control of the phase difference by comparing the detection value of the phase difference detector and the target value of the phase difference command device;
a conduction time variable section that generates a control signal for changing the conduction time of the second switching element according to the output of the feedback control section ;
The second turn-on control circuit turns off the second switching element in response to the control signal.
A two-way wireless power supply device characterized by: The phase difference detector indirectly detects the phase difference by detecting transmitted power,
The bidirectional wireless power supply device according to claim 3 , wherein the phase difference command device indirectly commands the target value by commanding transmission power. 2. The bidirectional wireless power supply device according to claim 1, wherein the mutual phase shift control circuit includes a detection element that magnetically or electrically detects a change in voltage of the first transmission coil in a non-contact manner. 2. The mutual phase shift control circuit according to claim 1, wherein the mutual phase shift control circuit includes a conduction time control circuit that controls the conduction time of the first switching element so that the operating frequency of the first power supply device becomes a predetermined value. The described two-way wireless power supply device. The mutual phase shift control circuit includes a timing transmitting circuit that transmits the switching timing of the first switching element using light or radio waves, and a timing receiving circuit that receives the light or radio waves transmitted from the timing transmitting circuit. The bidirectional wireless power supply device according to claim 1, characterized in that: a first power supply device connected to a first DC power supply;
a second power supply device connected to a second DC power supply;
A control unit that controls the first power supply device and the second power supply device,
A bidirectional wireless power supply device that transmits power between the first power supply device and the second power supply device,
The first power supply device includes:
a first transmission coil;
a first switching element connected in series to the first transmission coil;
a first resonant capacitor connected in parallel to at least one of the first transmission coil and the first switching element,
The second power supply device includes:
a second transmission coil;
a second switching element connected in series to the second transmission coil;
a second resonant capacitor connected in parallel to at least one of the second transmission coil and the second switching element,
The control unit includes:
a first turn-on control circuit that controls turn-on of the first switching element in synchronization with a resonant voltage generated by the first transmission coil and the first resonant capacitor so that the first switching element performs a zero-voltage switching operation;
a second turn-on control circuit that controls turn-on of the second switching element in synchronization with a resonant voltage generated by the second transmission coil and the second resonant capacitor so that the second switching element performs a zero-voltage switching operation;
A mutual phase shift control circuit that controls the switching of the first switching element and the switching of the second switching element to have a predetermined phase difference.
The first turn-on control circuit turns off the first switching element after a predetermined time has elapsed since the first switching element was turned on;
The second switching element includes a transistor and an anti-parallel diode connected in anti-parallel to the transistor,
The mutual phase shift control circuit includes:
a phase difference detector that directly or indirectly detects the phase difference;
a phase difference command device that directly or indirectly commands the target value of the phase difference;
a feedback control unit that performs feedback control of the phase difference by comparing the detection value of the phase difference detector and the target value of the phase difference command device;
a resonant current detector that detects a zero-crossing point of the current flowing through the second transmission coil;
a conduction time variable section that generates a control signal for controlling the on time of the transistor after the anti-parallel diode is turned off, according to the detection result of the resonant current detector and the output of the feedback control section; Prepare ,
The second turn-on control circuit turns off the second switching element in response to the control signal.
A two-way wireless power supply device characterized by:

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