JP2018133964A - Bidirectional insulation dc/dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bidirectional insulation DC/DC converter capable of constant voltage control or constant current control during reverse direction operation.SOLUTION: A bidirectional insulation DC/DC converter 1A performing forward direction operation and reverse direction operation includes an insulation transformer TR, a primary full-bridge circuit 11, a secondary full-bridge circuit 12, an LC circuit 13, and a control section 14A performing phase shift control for the primary full-bridge circuit 11, and performing synchronous rectification control for the secondary full-bridge circuit 12. During reverse direction operation, the control section 14A sets a shift period, corresponding to the time difference of phase shift amount, as the storage period of energy in the choke coil L2 of the LC circuit 16, and controls the shift period according to the voltage or current at the primary I/O end.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bidirectional insulated DC / DC converter.

  In recent years, in order to realize a recycling society as a measure against global warming, it is urgently necessary to realize energy saving and high efficiency of power supply equipment. Among them, a DC / DC converter mounted on a solar power generation device, a household storage battery, an electric vehicle or the like is used for various applications as a core of power supply equipment. In particular, the phase shift full-bridge type DC / DC converter has a medium size and high efficiency of several kilos to several tens of kilowatts and can correspond to a wide range of voltages.

  As a phase shift full bridge type DC / DC converter, for example, the one described in Non-Patent Document 1 is known. The DC / DC converter described in Non-Patent Document 1 includes a voltage type primary side circuit including a full bridge circuit, a current type secondary side circuit including a push-pull circuit and an LC circuit, and a full bridge circuit. And a control unit that performs synchronous rectification control on the push-pull circuit.

  In the forward operation in which power is supplied from the primary side to the secondary side, the control unit monitors the voltage or current at the output terminal on the secondary side and controls the phase shift amount of the full bridge circuit to thereby move forward. Controls the amount of operation (forward power conversion amount).

  FIG. 9 shows a conventional bidirectional insulated DC / DC converter 1B. For example, when the voltage at the input / output terminal T3 is equal to or lower than the target voltage, the bidirectional insulated DC / DC converter 1B performs control to increase the phase shift amount with respect to the full bridge circuit 11 of the primary side circuit. A forward power conversion operation for supplying power from the secondary side to the secondary side is performed. During the forward power conversion, the primary side circuit is phase-shift controlled so that the switching of the primary side circuit is zero-voltage switching (ZVS) with low loss. ZVS is performed by partial resonance by the resonance coil L1 and the resonance capacitors C1 to C4 when the switches Q1 to Q4 are switched. Also, reverse power conversion that supplies power from the secondary side to the primary side when a load having regenerative capacity is connected to the input / output ends T3 and T4 and the voltage at the input / output end T3 exceeds the target voltage. Perform the action.

  FIG. 10 shows a timing chart of the switches Q1 to Q8 during reverse power conversion operation of the bidirectional insulated DC / DC converter 1B shown in FIG. Although the timings of the switches Q1 to Q8 are the same as those in the forward power conversion operation, the phase shift amount TD with respect to the full bridge circuit 11 of the primary circuit is a small value during the reverse power conversion operation. In FIG. 10, the display of dead time is omitted for simplicity. 11 and 12 show current paths when the backward power conversion operation is performed according to the timing chart of FIG.

  The control unit 14B switches the switches Q1 and Q2 with opposite phases, switches the switches Q3 and Q4 with opposite phases, and further shifts the phases of the switches Q3 and Q4 with respect to the phases of the switches Q1 and Q2. The control unit 14B turns off the switch elements Q5 and Q8 in synchronization with the switch Q3 being turned on and turns on the switches Q6 and Q7, while turning on the switches Q5 and Q8 in synchronization with the switch Q4 being turned on. At the same time, the switches Q6 and Q7 are turned off.

  In the bidirectional insulated DC / DC converter 1B, the switches Q1 and Q3 are simultaneously turned on (state 2 shown in FIG. 11A) or the switches Q2 and Q4 are turned on simultaneously (state 4 shown in FIG. 12A). When energy is stored in the choke coil L2 and the switches Q2 and Q3 are simultaneously turned on (state 3 shown in FIG. 11B) or the switches Q1 and Q4 are turned on simultaneously (state 1 shown in FIG. 12B) In addition, power is transmitted from the secondary side to the primary side.

  The reverse operation amount (reverse power conversion amount) of the bidirectional insulated DC / DC converter 1B varies depending on the voltage at the input / output terminal T3, and corresponds to the time difference between the phase shift amount and 1/2 time of the switching cycle. It is automatically determined by the time obtained by subtracting the shift period TD. For this reason, the bidirectional insulated DC / DC converter 1B cannot maintain the output voltage constant during the reverse power conversion operation, in other words, cannot perform constant voltage control.

“Built-in synchronous rectification control, green mode, phase-shifting full-bridge controller”, [online], 2011, Texas Instruments Incorporated, [Retrieved November 17, 2016], Internet <URL: http: //www.tij.co.jp/product/jp/ucc28950>

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a bidirectional insulated DC / DC converter capable of constant voltage control or constant current control during reverse power conversion operation. There is.

In order to solve the above problems, a bidirectional insulated DC / DC converter according to the present invention is
A bidirectional insulated DC / DC converter that performs forward operation for supplying power from the primary side to the secondary side and reverse operation for supplying power from the secondary side to the primary side,
An insulating transformer having a primary winding and a secondary winding;
A primary full bridge circuit connected to the primary winding;
A secondary full bridge circuit connected to the secondary winding;
An LC circuit provided between the secondary side full bridge circuit and the secondary side input / output terminal;
A control unit that performs phase shift control on the primary side full bridge circuit, and performs synchronous rectification control on the secondary side full bridge circuit;
With
The controller is
The shift period corresponding to the time difference of the phase shift amount during the reverse operation is defined as an accumulation period in which energy is accumulated in the choke coil of the LC circuit, and the voltage is changed according to the voltage or current at the input / output terminal on the primary side. The shift period is controlled.

  According to this configuration, the control unit includes the primary-side full bridge circuit and the secondary side so that the shift period corresponding to the time difference of the phase shift amount during the reverse operation is the accumulation period in which energy is accumulated in the choke coil. Since each switch of the side full bridge circuit is controlled, the voltage or current at the primary side input / output terminal can be maintained at a predetermined value by controlling the shift period. Therefore, according to this configuration, constant voltage control or constant current control during reverse operation is possible.

In the bidirectional insulated DC / DC converter,
The primary side full bridge circuit has a first leg and a second leg,
The secondary full bridge circuit has a third leg and a fourth leg,
In the shift period, the control unit
The switch constituting the upper arm of the third leg, the switch constituting the lower arm of the fourth leg, the switch constituting the lower arm of the second leg, and the switch constituting the lower arm of the first leg are turned on. Or
The switch constituting the lower arm of the third leg, the switch constituting the upper arm of the fourth leg, the switch constituting the upper arm of the second leg, and the switch constituting the upper arm of the first leg are turned on. Can be configured.

In the bidirectional insulated DC / DC converter,
The controller is
When the phase shift control is started in the reverse operation, the soft-start control for gradually increasing the phase shift amount from the minimum value is performed, and then the primary input / output terminal is controlled by controlling the shift period. The voltage or current can be maintained at a predetermined value.

  According to this configuration, since the accumulation period in which energy is accumulated in the choke coil is gradually increased, the output voltage can be gradually raised without an overcurrent flowing through the switch. Further, according to this configuration, since the shift period becomes the accumulation period during the backward operation, it is possible to start up with the backward operation.

In the bidirectional insulated DC / DC converter,
The controller is
During the forward operation, the shift period is a transmission period for transmitting the energy of the choke coil from the primary side to the secondary side, and the shift period according to the voltage or current of the input / output terminal on the secondary side Is preferably controlled.

  According to this configuration, it is possible to perform constant voltage control or constant current control during both forward operation and reverse operation.

  According to the present invention, it is possible to provide a bidirectional insulated DC / DC converter capable of constant voltage control or constant current control during reverse operation.

It is a circuit diagram of the bidirectional insulation type DC / DC converter which concerns on this embodiment. It is a timing chart which shows the control timing of the switch at the time of reverse operation | movement. It is a figure which shows the electric current path in the (A) state 1 and the (B) state 2 at the time of reverse operation | movement of the bidirectional | two-way insulation type DC / DC converter which concerns on this embodiment. It is a figure which shows the electric current path in the (A) state 3 and the (B) state 4 at the time of reverse operation | movement of the bidirectional | two-way insulation type DC / DC converter which concerns on this embodiment. It is a timing chart which shows the control timing of the switch at the time of forward operation. It is a figure which shows the current pathway in the (A) state 1 and the (B) state 2 at the time of forward operation | movement of the bidirectional | two-way insulation type DC / DC converter which concerns on this embodiment. It is a figure which shows the current pathway in the (A) state 3 and the (B) state 4 at the time of forward operation | movement of the bidirectional | two-way insulation type DC / DC converter which concerns on this embodiment. It is a figure which shows the control part which concerns on a modification. It is a circuit diagram of a conventional bidirectional insulation type DC / DC converter. 10 is a timing chart showing switch control timings during reverse power conversion operation of the bidirectional insulated DC / DC converter shown in FIG. 9 proposed by the inventors of the present application. FIG. 10 is a diagram showing current paths in the (A) state 2 and the (B) state 3 during the reverse power conversion operation of the bidirectional insulated DC / DC converter shown in FIG. 9. FIG. 10 is a diagram illustrating current paths in the (A) state 4 and the (B) state 1 during the reverse power conversion operation of the bidirectional insulated DC / DC converter shown in FIG. 9.

  Embodiments of a bidirectional insulated DC / DC converter according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows a circuit diagram of a bidirectional insulated DC / DC converter 1A according to the present embodiment. The bidirectional insulation type DC / DC converter 1A includes an insulation transformer TR having a primary winding and a secondary winding, a primary side full bridge circuit 11, a secondary side full bridge circuit 12, an LC circuit 13, The controller 14A is provided, and performs a forward operation for supplying power from the primary side to the secondary side and a reverse operation for supplying power from the secondary side to the primary side.

  In the forward operation, power supplied from the primary input / output terminals T1 and T2 is supplied to a circuit connected to the secondary input / output terminals T3 and T4. In the reverse operation, power supplied from the secondary input / output terminals T3 and T4 is supplied to the primary input / output terminals T1 and T2.

  The primary side full bridge circuit 11 is provided between the primary side input / output terminals T1 and T2 and the primary winding of the insulating transformer TR. A capacitor C12 is provided between the primary side full bridge circuit 11 and the input / output terminals T1 and T2. One end of the capacitor C12 is connected to the input / output terminal T1, and the other end of the capacitor C12 is connected to the input / output terminal T2.

  As shown in FIG. 1, the primary side full bridge circuit 11 includes switches Q1 to Q4 that are connected in a full bridge. The switch Q1 constitutes the upper arm of the first leg, and the switch Q2 constitutes the lower arm of the first leg. The switch Q3 constitutes the upper arm of the second leg, and the switch Q4 constitutes the lower arm of the second leg. The connection point of the switches Q1 and Q2 is connected to one end of the primary winding of the insulation transformer TR via the coil L1, and the connection point of the switches Q3 and Q4 is connected to the other end of the primary winding of the insulation transformer TR. Is done. As the switches Q1 to Q4, for example, a power semiconductor such as IGBT or MOSFET can be used. The resonance coil L1 may be a leakage inductance of the insulating transformer TR, or may be a different coil.

  Diodes D1 to D4 are connected in reverse parallel to the switches Q1 to Q4. As the diode, a parasitic diode of the switches Q1 to Q4 or an external diode can be used. Further, capacitors C1 to C4 are connected in parallel to the switches Q1 to Q4. As the capacitors C1 to C4, parasitic capacitors of the switches Q1 to Q4 or external resonance capacitors can be used.

  The secondary side full bridge circuit 12 includes switches Q5 to Q8 connected in a full bridge. The switch Q5 constitutes the upper arm of the third leg, and the switch Q6 constitutes the lower arm of the third leg. The switch Q7 constitutes the upper arm of the fourth leg, and the switch Q8 constitutes the lower arm of the fourth leg. The connection point of the switches Q5 and Q6 is connected to one end of the secondary winding of the insulation transformer TR, and the connection point of the switches Q7 and Q8 is connected to the other end of the secondary winding of the insulation transformer TR. As the switches Q5 to Q8, for example, a power semiconductor such as IGBT or MOSFET can be used.

  Diodes D5 to D8 are connected in reverse parallel to the switches Q5 to Q8. As the diode, a parasitic diode of the switches Q5 to Q8 or an external diode can be used. Further, capacitors C5 to C8 are connected in parallel to the switches Q5 to Q8. As the capacitors C5 to C8, parasitic capacitors of the switches Q5 to Q8 or an external resonance capacitor can be used.

  The LC circuit 13 includes a coil L2 and a capacitor C34, and is provided between the secondary side full bridge circuit 12 and the input / output terminals T3 and T4 on the secondary side. More specifically, one end of the capacitor C34 is connected to the input / output terminal T3, and the other end of the capacitor C34 is connected to the input / output terminal T4. One end of the coil L2 is connected to the switches Q5 and Q7, and the other end of the coil L2 is connected to the input / output terminal T3.

  The control unit 14A is configured by a control IC such as an analog IC, a microcomputer, or an FPGA (Field-Programmable Gate Array). The controller 14A performs phase shift control on the primary side full bridge circuit 11 and performs synchronous rectification control on the secondary side full bridge circuit 12 during reverse operation and forward operation.

  Next, the control timing of the switches Q1 to Q8 during reverse operation will be described with reference to FIG. The control unit 14A outputs a control signal (for example, a phase shift synchronous rectification signal) to each of the switches Q1 to Q8, performs phase shift control on the primary side full bridge circuit 11, and performs secondary side full. Synchronous rectification control is performed on the bridge circuit 12.

  The control unit 14A sets the on-duty of the switches Q1 to Q4 to about 50%, switches the switches Q1 and Q2 in reverse phase, switches the switches Q3 and Q4 in reverse phase, and further switches the switches Q1 and Q2 The phases of the switches Q3 and Q4 are shifted with respect to the phase. The control unit 14A controls the shift period TD corresponding to the time difference of the phase shift amount according to the voltage of the input / output terminal T1 on the primary side.

  Originally, a dead time for turning off both the switches Q1 and Q2 and a dead time for turning off both the switches Q3 and Q4 for zero voltage switching are provided, but they are omitted in FIG.

  The control unit 14A turns off the switch elements Q5 and Q8 and turns on the switches Q6 and Q7 in synchronization with the turning on of the switch Q3 constituting the upper arm of the second leg that is the reference leg. Further, the control unit 14A turns on the switches Q5 and Q8 and turns off the switches Q6 and Q7 in synchronization with the turning on of the switch Q4 constituting the lower arm of the second leg.

  As shown in FIG. 2, the bidirectional insulated DC / DC converter 1A takes four states (state 1 to state 4) under the control of the control unit 14A. The current path in each state is shown in FIGS.

  In the state 1 shown in FIG. 3A, since the switches Q5 and Q8 are turned on and the switches Q2 and Q4 are turned on, a short-circuit current flows through the choke coil L2 via the insulation transformer TR. Thereby, energy is accumulated in the choke coil L2.

  In the state 2 shown in FIG. 3B, the switch Q2 is turned off and the switch Q1 is turned on. As a result, a current flows from the input / output terminal T2 to the input / output terminal T1 via the switch Q4, the primary winding of the insulating transformer TR, and the switch Q1. That is, the energy accumulated in the choke coil L2 is transmitted from the secondary side to the primary side.

  In the state 3 shown in FIG. 4A, since the switches Q6 and Q7 are turned on and the switches Q1 and Q3 are turned on, a short circuit current flows through the choke coil L2 via the insulating transformer TR. Thereby, energy is accumulated in the choke coil L2.

  In the state 4 shown in FIG. 4B, the switch Q1 is turned off and the switch Q2 is turned on. As a result, a current flows from the input / output terminal T2 to the input / output terminal T1 via the switch Q2, the primary winding of the isolation transformer TR, and the switch Q3. That is, the energy accumulated in the choke coil L2 is transmitted from the secondary side to the primary side.

  As described above, the control unit 14A controls the switches Q1 to Q8 so that the shift period TD is an accumulation period in which energy is accumulated in the choke coil L2 during reverse operation. Furthermore, the control unit 14A controls the shift period TD in accordance with the voltage at the primary input / output terminal T1. As a result, the bidirectional insulated DC / DC converter 1A can maintain the voltage at the input / output terminal T1 at a predetermined value during reverse operation, and can perform constant voltage control during reverse operation.

  Next, the control timing of the switches Q1 to Q8 during forward operation will be described with reference to FIG.

  The control unit 14A sets the on-duty of the switches Q1 to Q4 to about 50%, switches the switches Q1 and Q2 in reverse phase, switches the switches Q3 and Q4 in reverse phase, and further switches the switches Q1 and Q2 The phases of the switches Q3 and Q4 are shifted with respect to the phase. The control unit 14A controls the shift period TD corresponding to the time difference of the phase shift amount according to the voltage of the input / output terminal T3 on the secondary side.

  Originally, a dead time for turning off both the switches Q1 and Q2 and a dead time for turning off both the switches Q3 and Q4 for zero voltage switching are provided, but they are omitted in FIG.

  The control unit 14A turns off the switch elements Q5 and Q8 and turns on the switches Q6 and Q7 in synchronization with the on of the switch Q3 constituting the upper arm of the second leg. Further, the control unit 14A turns on the switches Q5 and Q8 and turns off the switches Q6 and Q7 in synchronization with the turning on of the switch Q4 constituting the lower arm of the second leg.

  As shown in FIG. 5, the bidirectional insulated DC / DC converter 1A takes four states (state 1 to state 4) under the control of the control unit 14A. The current path in each state is shown in FIGS.

  As shown in FIGS. 6 and 7, the control unit 14A switches the switch period TD corresponding to the time difference of the phase shift amount to the energy transmission period from the primary side to the secondary side during forward operation. Q1 to Q8 are controlled. Further, the control unit 14A controls the shift period TD in accordance with the voltage at the secondary input / output terminal T3. As a result, the bidirectional insulated DC / DC converter 1A can perform constant voltage control during forward operation.

  Although the embodiment of the bidirectional insulated DC / DC converter according to the present invention has been described above, the present invention is not limited to the above embodiment.

[Modification]
In the above embodiment, the control unit 14A generates the control signals (for example, phase shift synchronous rectification signals) of the switches Q1 to Q8 in each of the forward operation and the reverse operation. The number of can be reduced. For example, if the control signals of the switches Q1 to Q4 during the forward operation are A to D in sequence, the control signal during the reverse operation can be switched to C, D, B, A and used externally. The control signals of the switches Q5 and Q8 can be realized by an inverted signal of C × (D + A) during forward operation, and can be realized by an inverted signal of B × (A + C) during backward operation. The control signals for the switches Q6 and Q7 can be realized by an inverted signal of D × (B + C) during forward operation, and can be realized by an inverted signal of A × (B + D) during backward operation. “×” represents a logical product symbol, and “+” represents a logical sum symbol. FIG. 8 shows a control unit 14A ′ according to the modification.

  The control unit 14A ′ includes a switch control unit 31 that outputs only the control signals A to D of the switches Q1 to Q4, a gate unit 32, and a gate control unit 33 that controls the gate unit 32. The switch control unit 31 is configured by a phase shift control dedicated IC, for example. The switch control unit 31 controls the shift period TD according to the voltage at the input / output terminal T3 during forward operation, and controls the shift period TD according to the voltage at the input / output terminal T1 during reverse operation.

  The gate unit 32 includes direction changeover switches SW1 to SW6 and logic circuits L1 to L4. The logic circuits L1 to L4 include AND circuits AND1 to AND4, OR circuits OR1 to OR4, and NOT circuits NOT1 to NOT4. The gate control unit 33 conducts the contact 1 and the contact 3 of the direction changeover switches SW1 to SW6 during the forward operation, and conducts the contact 2 and the contact 3 of the direction changeover switches SW1 to SW6 during the reverse operation.

  As a result, the control signals A, B, C, and D are supplied to the switches Q1 to Q4 so that the dead time occurs during the forward operation, while the dead time occurs during the backward operation. Are supplied with control signals C, D, B and A. For the switches Q5 and Q8, the AND signal of the OR signal of the control signals A and D and the inverted (NOT) signal of the control signal C is supplied via the direction changeover switch SW5 during the forward operation, while the reverse direction. In operation, an AND signal of the OR signals of the control signals A and C and the inverted (NOT) signal of the control signal B is supplied via the direction switch SW5. For the switches Q6 and Q7, an AND signal of the OR signal of the control signals B and C and the inverted (NOT) signal of the control signal D is supplied via the direction changeover switch SW6 during forward operation. During reverse operation, the AND signal of the control signals B and D and the inverted signal (NOT) of the control signal A are supplied via the direction switch SW6.

  In the above embodiment, the control unit 14A can be configured to perform soft start control that gradually increases the phase shift amount (shift period TD) from the minimum value when starting in the reverse direction. Thereby, the output voltage can be gradually raised without an overcurrent flowing through the switches Q1 to Q8. In the bidirectional insulated DC / DC converter 1B shown in FIG. 9 (switch switching control during the reverse power conversion operation shown in FIG. 10), the phase shift amount becomes maximum when the reverse power conversion operation is started, and the overcurrent is increased. In some cases, the switching element is destroyed, and it is necessary to start the forward power conversion operation and to perform the reverse power conversion operation after the voltage at the input / output terminal T3 reaches the specified voltage. Since the shift period TD is the accumulation period (states 1 and 3), the bidirectional insulated DC / DC converter 1A according to the above can be started up in the reverse operation.

  Further, in the bidirectional insulated DC / DC converter 1B shown in FIG. 9, when a voltage higher than the target voltage is applied to the input / output terminal T3 at the time of startup, the output voltage (input / output terminal When the voltage (T3) becomes unstable, the forward phase shift amount (shift period TD) becomes a small value, so that a large reverse conversion voltage is generated during the reverse power conversion operation, and the secondary side full bridge circuit An overvoltage due to a surge may be applied to the 12 diodes D5 to D8, or an overcurrent may flow through the switches Q5 to Q8, leading to element destruction. On the other hand, in the bidirectional insulated DC / DC converter 1A according to the above embodiment, the soft start control can be performed even when starting in the reverse direction as described above. You can start with.

  In the above embodiment, the control unit 14A controls the shift period TD according to the voltage of the primary input / output terminal T1 during reverse operation, but according to the current of the primary input / output terminal T1. The shift period TD may be controlled. In this case, a current sensor for detecting the current at the primary input / output terminal T1 is used instead of the voltage sensor for detecting the voltage at the primary input / output terminal T1.

  In the above embodiment, the control unit 14A controls the shift period TD according to the voltage of the secondary input / output terminal T3 during forward operation, but according to the current of the secondary input / output terminal T3. The shift period TD may be controlled. In this case, a current sensor for detecting the current of the secondary input / output terminal T3 is used instead of the voltage sensor for detecting the voltage of the secondary input / output terminal T3.

  The control unit of the present invention performs phase shift control on the primary side full bridge circuit 11, while performing synchronous rectification control on the secondary side full bridge circuit 12, and sets the shift period TD to LC during reverse operation. If the accumulation period in which energy is accumulated in the choke coil L2 of the circuit 13 is set and the shift period TD is controlled according to the voltage or current of the input / output terminal T1 on the primary side, the configuration can be changed as appropriate. . The switching pattern in the phase shift control and the switching pattern in the synchronous rectification control can be changed as appropriate.

1A Bidirectional Insulation DC / DC Converter 11 Primary Full Bridge Circuit 12 Secondary Full Bridge Circuit 13 LC Circuit 14A, 14A 'Control Unit 31 Switch Control Unit 32 Gate Unit 33 Gate Control Unit

Claims (4)

A bidirectional insulated DC / DC converter that performs forward operation for supplying power from the primary side to the secondary side and reverse operation for supplying power from the secondary side to the primary side,
An insulating transformer having a primary winding and a secondary winding;
A primary full bridge circuit connected to the primary winding;
A secondary full bridge circuit connected to the secondary winding;
An LC circuit provided between the secondary side full bridge circuit and the secondary side input / output terminal;
A control unit that performs phase shift control on the primary side full bridge circuit, and performs synchronous rectification control on the secondary side full bridge circuit;
With
The controller is
The shift period corresponding to the time difference of the phase shift amount during the reverse operation is defined as an accumulation period in which energy is accumulated in the choke coil of the LC circuit, and the above-described voltage or current at the primary input / output terminal is A bidirectional insulated DC / DC converter characterized by controlling a shift period. The primary side full bridge circuit has a first leg and a second leg,
The secondary full bridge circuit has a third leg and a fourth leg,
In the shift period, the control unit
The switch constituting the upper arm of the third leg, the switch constituting the lower arm of the fourth leg, the switch constituting the lower arm of the second leg, and the switch constituting the lower arm of the first leg are turned on. Or
The switch constituting the lower arm of the third leg, the switch constituting the upper arm of the fourth leg, the switch constituting the upper arm of the second leg, and the switch constituting the upper arm of the first leg are turned on. The bidirectional insulation type DC / DC converter according to claim 1, wherein: The controller is
When the phase shift control is started in the reverse operation, the soft-start control for gradually increasing the phase shift amount from the minimum value is performed, and then the primary input / output terminal is controlled by controlling the shift period. 3. The bidirectional insulated DC / DC converter according to claim 1, wherein the voltage or the current is maintained at a predetermined value. The controller is
During the forward operation, the shift period is a transmission period for transmitting the energy of the choke coil from the primary side to the secondary side, and the shift period according to the voltage or current of the input / output terminal on the secondary side The bidirectionally insulated DC / DC converter according to claim 1, wherein the bidirectionally insulated DC / DC converter is controlled.

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