JP6579622B2 - Bi-directional isolated DC / DC converter - Google Patents

Description

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

  As an insulation type DC / DC converter, the thing of patent document 1 is known, for example. As shown in FIG. 9, an insulated DC / DC converter 100B described in Patent Document 1 includes a transformer Ts, a full bridge circuit 13 provided on the primary side of the transformer Ts, and an LLC resonance circuit (a coil L11, a capacitor). C12 and a resonance circuit composed of the primary winding of the transformer Ts), a synchronous rectification switch circuit 14 provided on the secondary side of the transformer Ts, a rectification smoothing circuit including coils L21 and L22, and a capacitor C21, and control Circuit 15.

  Further, the insulation type DC / DC converter 100B includes clamping diodes D11 and D12 on the primary side. The clamp diode D11 has an anode connected to the other end of the primary winding of the transformer Ts and a cathode connected to the input terminal T1 on the high potential side, and the potential of the other end of the primary winding of the transformer Ts It is provided to clamp to the high potential side potential. The clamping diode D12 has a cathode connected to the other end of the primary winding of the transformer Ts, an anode connected to the input terminal T1 ′ on the low potential side, and a potential at the other end of the primary winding of the transformer Ts. Is clamped to a potential on the low potential side. This prevents an overvoltage from occurring in the switch elements Q15 and Q16 of the secondary side synchronous rectification switch circuit 14.

  The isolated DC / DC converter 100B is intended to supply power from the primary side to the secondary side. For this reason, the control circuit 15 controls the full bridge circuit 13 by LLC resonance to reduce the switching loss of the full bridge circuit 13.

  In the case where the primary side has a circuit configuration corresponding to phase shift control, the control circuit 15 performs phase shift control on the primary side full bridge circuit, thereby forming a switch constituting the primary side full bridge circuit. The switching loss of the primary-side full bridge circuit can be reduced by the partial resonance of the element parasitic capacitor or the external resonance capacitor and the resonance coil.

JP 2014-197942 A

  As described above, the conventional isolated DC / DC converter 100B can reduce the switching loss by LLC resonance or partial resonance when power is supplied from the primary side to the secondary side. However, when the conventional isolated DC / DC converter 100B supplies power from the secondary side to the primary side in the reverse direction, LLC resonance or partial resonance does not work, and switching loss due to zero current switching or zero voltage switching does not occur. There was a problem that it could not be reduced. Specifically, when switching the switch element constituting the primary-side full bridge circuit, in addition to the switching loss, the charge of the parasitic capacitor of the switch element or the external resonance capacitor is released, thereby causing voltage oscillation. There was a problem that a loss would occur.

  This invention is made | formed in view of the said situation, The place made into the subject performs efficiently the electric power supply from the primary side to the secondary side, and the electric power supply from the secondary side to the primary side. It is an object of the present invention to provide a bi-directional insulated DC / DC converter that is capable of performing the above.

In order to solve the above-described problems, a bidirectional insulated DC / DC converter according to the present invention includes:
An insulating transformer having a primary winding and a secondary winding;
A voltage type primary side DC / DC converter part including a full bridge circuit provided on the primary side of the insulation transformer part;
A current-type secondary side DC / DC converter unit provided on the secondary side of the insulating transformer unit;
A control circuit that performs phase shift control on the primary DC / DC converter unit, and performs synchronous rectification control on the secondary DC / DC converter unit;
A bi-directional isolated DC / DC converter comprising:
The primary side DC / DC converter unit includes:
A first coil having one end connected to a connection point of the first switch element and the second switch element constituting the first leg of the full bridge circuit, and the other end connected to one end of the primary winding;
A second coil having one end connected to a connection point of the third switch element and the fourth switch element constituting the second leg of the full bridge circuit, and the other end connected to the other end of the primary winding;
A first rectifying element having an anode connected to the other end of the first coil and a cathode connected to one end of the first leg;
A second rectifying element having an anode connected to the other end of the first leg and a cathode connected to the other end of the first coil;
A third rectifying element having an anode connected to the other end of the second coil and a cathode connected to one end of the second leg;
The anode is connected to the other end of the second leg, and a fourth rectifier element having a cathode connected to the other end of the second coil, only including,
In the control circuit, the third switch element and the fourth switch element with respect to the phases of the first switch element and the second switch element during a reverse power conversion operation for supplying power from the secondary side to the primary side Is set to a minimum value that can be set in the control circuit,
The control circuit controls the shift amount so that the amount of power supplied from the primary side to the secondary side is minimized or zero during the reverse power conversion operation .

  According to this configuration, the first coil and the second coil provide an impedance between the full bridge circuit and the insulating transformer, and the first to fourth rectifier elements form a current path that bypasses the first to fourth switch elements. Then, by making it difficult for the current to flow through the first to fourth switch elements during the reverse power conversion operation, the parasitic capacitors of the first to fourth switch elements or the externally attached capacitors are switched during the switching of the first to fourth switch elements. It is possible to suppress voltage oscillation that occurs when the electric charge of the resonant capacitor is released.

  According to the present invention, a bidirectional insulated DC / DC converter capable of efficiently performing power supply from the primary side to the secondary side and power supply from the secondary side to the primary side is provided. Can do.

1 is a circuit diagram of a bidirectional insulated DC / DC converter according to an embodiment of the present invention. It is a timing chart of the switch element at the time of reverse direction power conversion operation. It is a figure which shows the current pathway of the bidirectional | two-way insulation type DC / DC converter in each state of FIG. 2, (A) is the state 2-1, (B) is the state 2-2, (C) is the state 3-1. (D) is a figure corresponding to the state 3-2. It is a figure which shows the electric current path | route of the bidirectional | two-way insulation type DC / DC converter in each state of FIG. 2, (A) is the state 4-1, (B) is the state 4-2, (C) is the state 1-1. (D) is a figure corresponding to the state 1-2. It is a timing chart of the switch element at the time of forward power conversion operation. It is a figure which shows the current pathway of the bidirectional | two-way insulation type DC / DC converter in each state of FIG. 5, Comprising: (A) is the state 1-2, (B) is the state 2-1, (C) is the state 2-2. (D) is a figure corresponding to the state 3-1. It is a figure which shows the current pathway of the bidirectional | two-way insulation type DC / DC converter in each state of FIG. 5, Comprising: (A) is the state 3-2, (B) is the state 4-1, and (C) is the state 4-2. (D) is a figure corresponding to the state 1-1. It is a circuit diagram of the bidirectional | two-way insulation type DC / DC converter which concerns on the modification of this invention. It is a circuit diagram of the conventional insulation type DC / DC converter.

  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 bidirectional insulated DC / DC converter 100A according to an embodiment of the present invention. The bidirectional insulated DC / DC converter 100A performs a forward power conversion operation for supplying power from the primary side to the secondary side and a reverse power conversion operation for supplying power from the secondary side to the primary side. .

  The bidirectional insulated DC / DC converter 100A includes a transformer TR1 corresponding to the “insulating transformer” of the present invention, and a voltage-type primary DC / DC converter unit 1 provided on the primary winding side of the transformer TR1. And a current type secondary DC / DC converter section 2 provided on the secondary winding side of the transformer TR1 and a control circuit 5.

  The primary side DC / DC converter unit 1 includes a smoothing capacitor C1, a primary side full bridge circuit 3, a first coil L1, a second coil L2, and first to fourth rectifying elements D1 to D4. ing.

  The smoothing capacitor C1 has one end connected to the high-potential side input / output terminal T1 and the other end connected to the low-potential side input / output terminal T1 '.

  The primary side full bridge circuit 3 includes a first switch element Q1, a second switch element Q2, a third switch element Q3, and a fourth switch element Q4. The first switch element Q1 constitutes the upper arm of the first leg, and the second switch element Q2 constitutes the lower arm of the first leg. The third switch element Q3 constitutes the upper arm of the second leg, and the fourth switch element Q4 constitutes the lower arm of the second leg. The first to fourth switch elements Q1 to Q4 perform a switching operation under the control of the control circuit 5. As the first to fourth switch elements Q1 to Q4, power elements that perform a switching operation such as an IGBT and a MOSFET can be used.

  A diode is connected in antiparallel to each of the first to fourth switch elements Q1 to Q4. As the diode, each parasitic diode of the first to fourth switching elements Q1 to Q4 or a diode element different from the parasitic diode can be used. Furthermore, a capacitor is connected in parallel to each of the first to fourth switch elements Q1 to Q4. As the capacitor, the parasitic capacitors of the first to fourth switch elements Q1 to Q4 or an external resonant capacitor different from the parasitic capacitor can be used. In the present embodiment, a resonance capacitor Ca is connected in parallel to the third switch element Q3, and a resonance capacitor Cb is connected in parallel to the fourth switch element Q4.

  The first coil L1 has one end connected to the connection point of the first switch element Q1 and the second switch element Q2 constituting the first leg of the primary side full bridge circuit 3, and the other end connected to the primary winding of the transformer TR1. It is connected to one end. The second coil L2 has one end connected to the connection point of the third switch element Q3 and the fourth switch element Q4 constituting the second leg of the primary side full bridge circuit 3, and the other end connected to the primary winding of the transformer TR1. Is connected to the other end. That is, at the time of forward power conversion operation, the parasitic capacitors of the first coil L1, the second coil L2, and the first to fourth switch elements Q1 to Q4 and the external resonance capacitors Ca and Cb are primary side full bridge circuits. A partial resonance circuit is configured at the time of switching of each of the three switching elements Q1 to Q4, and switching loss is reduced by zero voltage switching.

  The first rectifier element D <b> 1 is formed of a diode, and has an anode connected to the other end of the first coil L <b> 1 and a cathode connected to one end of the first leg of the primary side full bridge circuit 3. That is, the first rectifier element D1 is connected in parallel to the first switch element Q1 via the first coil L1, and has a current path that bypasses the first coil L1 and the first switch element Q1 during switching in the reverse power conversion operation. Form.

  The second rectifying element D <b> 2 is formed of a diode, and has a cathode connected to the other end of the first coil L <b> 1 and an anode connected to the other end of the first leg of the primary side full bridge circuit 3. That is, the second rectifier element D2 is connected in parallel to the second switch element Q2 via the first coil L1, and has a current path that bypasses the first coil L1 and the second switch element Q2 during switching in the reverse power conversion operation. Form.

  The third rectifier element D3 is formed of a diode, and has an anode connected to the other end of the second coil L2 and a cathode connected to one end of the second leg of the primary side full bridge circuit 3. That is, the third rectifier element D3 is connected in parallel to the third switch element Q3 via the second coil L2, and has a current path that bypasses the second coil L2 and the third switch element Q3 during switching in the reverse power conversion operation. Form.

  The fourth rectifying element D4 is formed of a diode, and has a cathode connected to the other end of the second coil L2 and an anode connected to the other end of the second leg of the primary side full bridge circuit 3. That is, the fourth rectifier element D4 is connected in parallel to the fourth switch element Q4 via the second coil L2, and has a current path that bypasses the second coil L2 and the fourth switch element Q4 during switching in the reverse power conversion operation. Form.

  The secondary side DC / DC converter unit 2 includes a secondary side full bridge circuit 4 and a secondary side LC circuit including a coil L3 and a smoothing capacitor C2.

  Secondary-side full bridge circuit 4 includes a fifth switch element Q5, a sixth switch element Q6, a seventh switch element Q7, and an eighth switch element Q8. The fifth switch element Q5 constitutes the upper arm of the first leg, and the sixth switch element Q6 constitutes the lower arm of the first leg. The seventh switch element Q7 constitutes the upper arm of the second leg, and the eighth switch element Q8 constitutes the lower arm of the second leg. The fifth to eighth switch elements Q5 to Q8 perform a switching operation under the control of the control circuit 5. As the fifth to eighth switch elements Q5 to Q8, a power element that performs a switching operation such as an IGBT or a MOSFET can be used.

  A diode is connected in antiparallel to each of the fifth to eighth switch elements Q5 to Q8. As the diode, each of the parasitic diodes of the fifth to eighth switch elements Q5 to Q8 or a diode element different from the parasitic diode can be used. Furthermore, a capacitor is connected in parallel to each of the fifth to eighth switch elements Q5 to Q8. As the capacitor, the parasitic capacitors of the fifth to eighth switch elements Q5 to Q8 or an external resonance capacitor different from the parasitic capacitor can be used. In the present embodiment, a resonance capacitor Cc is connected in parallel to the fifth switch element Q5, and a resonance capacitor Cd is connected in parallel to the sixth switch element Q6.

  The control circuit 5 is configured by a control IC (integrated circuit) such as a microcomputer or FPGA (field programmable gate array). The control circuit 5 controls the primary side full bridge circuit 3 and the secondary side full bridge circuit 4. Specifically, the control circuit 5 performs phase shift control to shift the phases of the first to fourth switch elements Q1 to Q4 with respect to the primary side full bridge circuit 3, and the secondary side full bridge circuit 4 On the other hand, synchronous rectification control is performed in which the switching operation of the fifth to eighth switch elements Q5 to Q8 is synchronized with the switching operation of the primary side full bridge circuit 3.

  Next, a control method of the control circuit 5 during the reverse power conversion operation will be described with reference to FIGS. As shown in FIG. 2, it is assumed that the PWM duty of the primary side full bridge circuit 3 (PWM duty of the first switch element Q1 and the fourth switch element Q4) is set to 50%.

The control circuit 5 performs control corresponding to the reverse power conversion operation when the voltage between the terminals T2 and T2 ′ on the secondary side rises from a predetermined voltage defined in advance by an external power source or the like during the forward power conversion operation. That is, the control circuit 5 performs phase shift control on the primary side full bridge circuit 3 during the reverse power conversion operation. Specifically, the control circuit 5 makes the OFF time of the second switch element Q2 slightly longer than the ON time of the first switch element Q1, and both the first switch element Q1 and the second switch element Q2 are in the OFF state. The phases of the first switch element Q1 and the second switch element Q2 are inverted so as to include the dead time (time t _{2 to} t _{3 in} FIG. 2). Similarly, the control circuit 5 makes the OFF time of the third switch element Q3 slightly longer than the ON time of the fourth switch element Q4, and both the third switch element Q3 and the fourth switch element Q4 are turned off. to include a dead time (time _t 4 ~t ₅ in FIG. 2) inverts the third switching element Q3 the phase of the fourth switching element Q4.

  Further, the control circuit 5 shifts the phases of the third switch element Q3 and the fourth switch element Q4 with respect to the phases of the first switch element Q1 and the second switch element Q2. The amount of phase shift during the reverse power conversion operation is minimized because it is controlled to minimize the amount of power conversion in the forward direction. In other words, the phase shift amount during the reverse power conversion operation is set to the minimum value that can be set in the control circuit 5. The minimum value may be a value including zero phase shift amount.

  The control circuit 5 performs synchronous rectification control on the secondary full bridge circuit 4 during the reverse power conversion operation. Specifically, the control circuit 5 turns off the sixth switch element Q6 and the seventh switch element Q7 only when both the first switch element Q1 and the fourth switch element Q4 are in the ON state, and the second switch element Q2 Only when both the third switch element Q3 and the third switch element Q3 are in the ON state, the fifth switch element Q5 and the eighth switch element Q8 are in the OFF state.

State of the bidirectional insulated DC / DC converter 100A at time _t 2 ~t ₅ (state 2-1, state 2-2, state 3-1) are shown in Figure 3 (A) ~ (C) . In the state 2-1, the state 2-2, and the state 3-1, since the four switch elements Q5 to Q8 of the secondary side full bridge circuit 4 are in the ON state, a current flows through the secondary winding of the transformer TR1. Current flows through the coil L3 of the secondary LC circuit, and energy is accumulated in the coil L3.

State of the bidirectional insulated DC / DC converter 100A at time _t 5 ~t ₆ (state 3-2) is as Figure 3 (D). In the state 3-2, the fifth switch element Q5 and the eighth switch element Q8 are turned off, so that a current flows through the secondary winding of the transformer TR1 and power is supplied to the primary side. On the primary side, the third switch element Q3 is turned on and the second switch element Q2 and the third switch element Q3 are turned on, but no current flows through the second switch element Q2 and the third switch element Q3. A current flows through the second rectifying element D2 and the third rectifying element D3. For this reason, when the third switch element Q3 is turned on, the voltage oscillation generated by the discharge of the parasitic capacitor of the third switch element Q3 and the external resonance capacitor Ca is suppressed.

State of the bidirectional insulated DC / DC converter 100A at time _t 6 ~t ₉ (state 4-1, state 4-2, state 1-1) are shown in Figure 4 (A) ~ (C) . In the state 4-1, the state 4-2, and the state 1-1, the four switch elements Q5 to Q8 of the secondary side full bridge circuit 4 are turned on, so that a current flows through the secondary winding of the transformer TR1. Current flows through the coil L3 of the secondary LC circuit, and energy is accumulated in the coil L3.

State (state 2) of the time _t 9 _{~t 10} bidirectional insulated DC / DC converter 100A in is as FIG. 4 (D). In the state 1-2, since the sixth switch element Q6 and the seventh switch element Q7 are in the OFF state, a current in the direction opposite to that in the state 3-2 flows in the secondary winding of the transformer TR1, and the current flows to the primary side. Power is supplied. On the primary side, the fourth switch element Q4 is turned on and the first switch element Q1 and the fourth switch element Q4 are turned on, but no current flows through the first switch element Q1 and the fourth switch element Q4. A current flows through the first rectifying element D1 and the fourth rectifying element D4. For this reason, when the fourth switch element Q4 is turned on, the voltage oscillation generated by the discharge of the parasitic capacitor of the fourth switch element Q4 and the external resonance capacitor Cb is suppressed.

  Next, a control method of the control circuit 5 during the forward power conversion operation will be described with reference to FIGS. The control circuit 5 performs phase shift control on the primary side full bridge circuit 3 and performs synchronous rectification control on the secondary side full bridge circuit 4 during forward power conversion operation.

  The phase shift control during the forward power conversion operation is common to the phase shift control during the reverse power conversion operation, except for the phase shift amount. Since the amount of phase shift during the forward power conversion operation is controlled by the amount of power conversion in the forward direction, as can be seen from a comparison between FIG. 5 and FIG. 2, generally the amount of phase shift during the reverse power conversion operation. Is set to a larger value. On the other hand, the synchronous rectification control during the forward power conversion operation is common to the synchronous rectification control during the reverse power conversion operation.

State of the bidirectional insulated DC / DC converter 100A at time _t 1 ~t ₂ (state 1-2) are shown in Figure 6 (A). In the state 1-2, the first switch element Q1, the fourth switch element Q4, the fifth switch element Q5, and the eighth switch element Q8 are turned on, current flows through the primary winding of the transformer TR1, and the secondary side Power is supplied.

State of the bidirectional insulated DC / DC converter 100A at time _{t 2} (state 2-1) are shown in Figure 6 (B). In the state 2-1, the first switch element Q1 is turned OFF by zero voltage switching, the sixth switch element Q6 and the seventh switch element Q7 are turned ON by hard switching, and the parasitic capacitor of the first switch element Q1 is charged. As a result, the parasitic capacitor of the second switch element Q2 is discharged.

State of the bidirectional insulated DC / DC converter 100A at time _{t 3} (condition 2-2) is shown in Figure 6 (C). In the state 2-2, the second switch element Q2 is turned on by zero voltage switching.

State of the bidirectional insulated DC / DC converter 100A (Condition 3-1) at time _{t 4} is shown in Figure 6 (D). In the state 3-1, the fourth switch element Q4 is turned OFF by zero voltage switching, the parasitic capacitor and the resonance capacitor Cb of the fourth switch element Q4 are charged, and the parasitic capacitor and the resonance capacitor Ca of the third switch element Q3 are charged. Discharge.

State of the bidirectional insulated DC / DC converter 100A at time _{t 5} (state 3-2) are shown in Figure 7 (A). In the state 3-2, the third switch element Q3 is turned on by zero voltage switching, and a current in the opposite direction flows to the primary winding of the transformer TR1 and power is supplied to the secondary side. The

State of the bidirectional insulated DC / DC converter 100A (Condition 4-1) at time _{t 6} is shown in Figure 7 (B). In state 4-1, the second switch element Q2 is turned OFF by zero voltage switching, the fifth switch element Q5 and the eighth switch element Q8 are turned ON by hard switching, and the parasitic capacitor of the second switch element Q2 is charged. As a result, the parasitic capacitor of the first switch element Q1 is discharged.

State of the bidirectional insulated DC / DC converter 100A at time _{t 7} (state 4-2) are shown in Figure 7 (C). In state 4-2, the first switch element Q1 is turned on by zero voltage switching.

State of the bidirectional insulated DC / DC converter 100A at time _{t 8} (state 1-1) are shown in Figure 7 (D). In the state 1-1, the third switch element Q3 is turned OFF by zero voltage switching, the parasitic capacitor and the resonance capacitor Ca of the third switch element Q3 are charged, and the parasitic capacitor and the resonance capacitor Cb of the fourth switch element Q4 are charged. Discharge.

  Eventually, according to the bidirectional insulated DC / DC converter 100A, the first coil L1 and the second coil L2 provide impedance between the primary side full bridge circuit 3 and the transformer TR1, so that the forward power conversion operation can be performed. The first coil L1, the second coil L2, the first to fourth switch elements Q1 to Q4, the parasitic capacitors and the external resonant capacitors Ca and Cb are connected to the switch elements Q1 to Q4 of the primary side full bridge circuit 3, respectively. A partial resonance circuit can be formed at the time of switching, and switching loss can be reduced by zero voltage switching. Furthermore, a current path that bypasses the first to fourth switch elements Q1 to Q4 is formed by the first to fourth rectifier elements D1 to D4, and the first to fourth switch elements Q1 to Q4 are connected to each other during reverse power conversion operation. By making the current difficult to flow, the charges of the parasitic capacitors of the first to fourth switch elements Q1 to Q4 and / or the external resonance capacitors Ca and Cb are released when the first to fourth switch elements Q1 to Q4 are switched. Thus, the voltage oscillation generated can be suppressed. Therefore, according to the bidirectional insulated DC / DC converter 100A, it is possible to efficiently perform power supply from the primary side to the secondary side and power supply from the secondary side to the primary side.

  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 1]
FIG. 8 shows a circuit diagram of a bidirectional insulated DC / DC converter 100A ′ according to the first modification of the present invention. The bidirectional insulated DC / DC converter 100A ′ is different from the bidirectional insulated DC / DC converter 100A according to the above embodiment in that the coil L3 ′, the open / close means S1 and S2, the fourth coil L4, and the fifth coil L5. And fifth to eighth rectifying elements D5 to D8 are added.

  The opening / closing means S1 and S2 are configured by relays, power elements such as IGBTs and MOSFETs that perform a switching operation, and are switched between a conductive state and a non-conductive state under the control of the control circuit 5. The opening / closing means S1 is connected in parallel to the primary side coil L3 ', and the opening / closing means S2 is connected in parallel to the secondary side coil L3.

  When the switching means S1 is in a conductive state and the switching means S2 is in a non-conductive state, the circuit topology of the primary side DC / DC converter unit 1 is a voltage type and the secondary side DC / DC converter unit 2 as in the above embodiment. The circuit topology is a current type. The bidirectionally isolated DC / DC converter 100A ′ having the circuit topology normally performs a forward power conversion operation for supplying power from the primary side to the secondary side, and the voltage between the terminals T2 and T2 ′ on the secondary side is increased. When the voltage rises above a specified voltage specified in advance by an external power source or the like, a reverse power conversion operation is performed. The first to fourth rectifying elements D1 to D4 during the reverse power conversion operation form a current path that bypasses the first to fourth switch elements Q1 to Q4.

  On the other hand, when the switching means S1 is in a non-conductive state and the switching means S2 is in a conductive state, the circuit topology of the primary side DC / DC converter unit 1 is a current type, and the circuit topology of the secondary side DC / DC converter unit 2 is a voltage. Become a mold. The bidirectionally isolated DC / DC converter 100A ′ having the circuit topology normally performs a forward power conversion operation for supplying power from the secondary side to the primary side, and the voltage between the terminals T1 and T1 ′ on the primary side is When the voltage rises above a specified voltage that is specified in advance by an external power source or the like, a reverse power conversion operation for supplying power from the primary side to the secondary side is performed. The fifth to eighth rectifier elements D5 to D8 during the reverse power conversion operation form a current path that bypasses the fifth to eighth switch elements Q5 to Q8.

[Other variations]
In the present invention, at least one of the switching pattern in the phase shift control or the switching pattern in the synchronous rectification control can be appropriately changed. For example, the phase shift is performed between the rise of the first switch element Q1 and the fall of the fourth switch element Q4, and the sixth and seventh switch elements are turned on when the first and fourth switch elements Q1 and Q4 are simultaneously turned on. Q6 and Q7 may be turned off to perform synchronous rectification.

  The primary DC / DC converter unit 1 has a voltage topology circuit topology, a primary full bridge circuit 3, a first coil L1, a second coil L2, and first to fourth rectifying elements D1 to D4. Can be changed as appropriate.

  If the circuit topology of the secondary side DC / DC converter unit 2 is a current type and bi-directional power supply to the primary side DC / DC converter unit 1 is possible, the configuration can be changed as appropriate. it can.

  The insulation transformer unit may be composed of a plurality of transformers, for example.

DESCRIPTION OF SYMBOLS 1 Primary side DC / DC converter part 2 Secondary side DC / DC converter part 3 Primary side full bridge circuit 4 Secondary side full bridge circuit 5 Control circuit 100A, 100A 'Bidirectional insulation type DC / DC converter

Claims (1)

An insulating transformer having a primary winding and a secondary winding;
A voltage type primary side DC / DC converter part including a full bridge circuit provided on the primary side of the insulation transformer part;
A current-type secondary side DC / DC converter unit provided on the secondary side of the insulating transformer unit;
A control circuit that performs phase shift control on the primary DC / DC converter unit, and performs synchronous rectification control on the secondary DC / DC converter unit;
A bi-directional isolated DC / DC converter comprising:
The primary side DC / DC converter unit includes:
A first coil having one end connected to a connection point of the first switch element and the second switch element constituting the first leg of the full bridge circuit, and the other end connected to one end of the primary winding;
A second coil having one end connected to a connection point of the third switch element and the fourth switch element constituting the second leg of the full bridge circuit, and the other end connected to the other end of the primary winding;
A first rectifying element having an anode connected to the other end of the first coil and a cathode connected to one end of the first leg;
A second rectifying element having an anode connected to the other end of the first leg and a cathode connected to the other end of the first coil;
A third rectifying element having an anode connected to the other end of the second coil and a cathode connected to one end of the second leg;
The anode is connected to the other end of the second leg, and a fourth rectifier element having a cathode connected to the other end of the second coil, only including,
In the control circuit, the third switch element and the fourth switch element with respect to the phases of the first switch element and the second switch element during a reverse power conversion operation for supplying power from the secondary side to the primary side Is set to a minimum value that can be set in the control circuit,
The control circuit controls the shift amount so that the amount of power supplied from the primary side to the secondary side is minimized or zero during the reverse power conversion operation. DC / DC converter.

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