JP2017005782A - Resonance type bidirectional dc/dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resonance type bidirectional DC/DC converter performing bidirectional voltage conversion.SOLUTION: A resonance type bidirectional DC/DC converter includes a first bridge circuit 1 where switch elements Q1-Q4 connecting diodes D1-D4 and capacitors C1-C4 in parallel constitute a bridge, a second bridge circuit 2 where switch elements Q5-Q8 connecting diodes D5-D8 and capacitors C5-C8 in parallel constitute a bridge, a smoothing reactor L having one end connected in series with the second bridge circuit, an isolation transformer T1 having a primary winding for connection with the first bridge circuit and a secondary winding for connection with the second bridge circuit, a series circuit where the primary winding P2 of an auxiliary resonance transformer T2 and a first auxiliary resonance switch Q10 are connected in series across the first bridge circuit, and a series circuit where an auxiliary resonance reactor Lr and the secondary winding S2 of the auxiliary resonance transformer and a second auxiliary resonance switch Q9 are connected in series across the second bridge circuit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a resonant bidirectional DC / DC converter that reduces switching loss by performing zero voltage and zero current switching.

  Conventionally, what was described in patent document 1 is known as this kind of resonance type DC / DC converter. FIG. 9 is a circuit configuration diagram of the resonant DC / DC converter described in Patent Document 1. In FIG. The resonant DC / DC converter shown in FIG. 9 converts the direct current voltage of the direct current power supply 115 into another direct current voltage and supplies it to a load by a conversion unit including four switch elements Q11 to Q14 configured by a full bridge. .

  An auxiliary resonance circuit including an auxiliary winding 118 magnetically coupled to the inductor 116, an auxiliary inductance 120, a backflow prevention diode 119, and an auxiliary switch QA is connected in parallel to the converter.

  Prior to turning on the two switch elements arranged at the diagonal positions, the auxiliary switch QA is turned on, and the charges of the switch elements Q11 to Q14 are extracted using the reactor energy of the auxiliary winding 118. Thereby, the zero voltage switching of the switch elements Q11 to Q14 can be realized.

JP 2000-224855 A

  However, the above-described conventional resonance type DC / DC converter cannot perform bidirectional voltage conversion of step-down conversion and step-up conversion by performing only one voltage conversion.

  An object of the present invention is to provide a resonant bidirectional DC / DC converter capable of performing bidirectional voltage conversion.

  In order to solve the above problems, a resonant bidirectional DC / DC converter according to the present invention includes a first bridge having a plurality of first switch elements in which a first diode and a first capacitor are connected in parallel. A second bridge circuit comprising a plurality of second switch elements in which a second diode and a second capacitor are connected in parallel, and a smoothing reactor having one end connected in series to the second bridge circuit; An insulation transformer in which a primary winding is connected to the first bridge circuit and a secondary winding is connected to the second bridge circuit; and a primary winding and an auxiliary resonance transformer at both ends of the first bridge circuit; A first series circuit in which one auxiliary resonance switch is connected in series; an auxiliary resonance reactor; a secondary winding of the auxiliary resonance transformer; and a second coil at both ends of the second bridge circuit. And a co resonance switch is characterized in that it comprises a second series circuit connected in series.

  According to the present invention, the isolation transformer connected to the first bridge circuit and the second bridge circuit is provided, and the primary winding of the auxiliary resonance transformer and the first auxiliary resonance switch are connected in series to both ends of the first bridge circuit. By connecting the auxiliary resonance reactor, the secondary winding of the auxiliary resonance transformer, and the second auxiliary resonance switch in series at both ends of the second bridge circuit, zero voltage switching can be performed by bidirectional voltage conversion.

It is a figure which shows the structure of the resonance type bidirectional | two-way DC / DC converter which concerns on Example 1 of this invention. It is a wave form diagram of a gate drive signal of each switch of a resonance type bidirectional DC / DC converter concerning Example 1 of the present invention. It is a figure which shows the step-down conversion simulation waveform of the resonance type bidirectional DC / DC converter which concerns on Example 1 of this invention. It is an operation | movement transition diagram at the time of the pressure | voltage fall of the resonance type bidirectional | two-way DC / DC converter which concerns on Example 1 of this invention. It is an operation | movement transition diagram at the time of the pressure | voltage fall of the resonance type bidirectional | two-way DC / DC converter which concerns on Example 1 of this invention. It is a figure which shows the step-up conversion simulation waveform of the resonance type bidirectional DC / DC converter which concerns on Example 1 of this invention. It is an operation | movement transition diagram at the time of pressure | voltage rise of the resonance type bidirectional | two-way DC / DC converter which concerns on Example 1 of this invention. It is an operation | movement transition diagram at the time of voltage boost of the resonance type bidirectional | two-way DC / DC converter which concerns on Example 1 of this invention. It is a circuit block diagram of the conventional resonance type DC / DC converter.

  Hereinafter, a resonant bidirectional DC / DC converter according to an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a resonant bidirectional DC / DC converter according to Embodiment 1 of the present invention. This resonant bidirectional DC / DC converter can perform bidirectional voltage conversion of step-down conversion and step-up conversion, and can realize zero voltage switching (ZVS) when the switch element is turned on in both forward conversion and reverse conversion. This is a high-efficiency, isolated DC / DC converter that supports a wide input and uses an auxiliary resonance method.

  The resonant bidirectional DC / DC converter includes a high-voltage DC power supply V1, a low-voltage DC power supply V2, a first bridge circuit 1, a second bridge circuit 2, a smoothing reactor L, an insulating transformer T1, an auxiliary resonant transformer T2, and a first auxiliary. A resonance switch Q10 and a second auxiliary resonance switch Q9 are provided. The voltage of the high-voltage DC power supply V1 is higher than the voltage of the low-voltage DC power supply V2.

  The insulating transformer T1 has a primary winding P1 and a secondary winding S1 that is electromagnetically coupled to the primary winding P1. The auxiliary resonant transformer T2 has a primary winding P2 and a secondary winding S2 that is electromagnetically coupled to the primary winding P2.

  The first bridge circuit 1 includes a switch element Q1 in which a diode D1 and a capacitor C1 are connected in parallel, a switch element Q2 in which a diode D2 and a capacitor C2 are connected in parallel, a diode D3, and a capacitor C3. A switching element Q4 in which Q3, a diode D4, and a capacitor C4 are connected in parallel forms a bridge. Both ends of the output of the first bridge circuit 1 are connected to both ends of the high-voltage side DC power source V1.

  The second bridge circuit 2 includes a switch element Q5 in which a diode D5 and a capacitor C5 are connected in parallel, a switch element Q6 in which a diode D6 and a capacitor C6 are connected in parallel, a diode D7, and a capacitor C7. A switching element Q8 in which Q7, a diode D8, and a capacitor C8 are connected in parallel forms a bridge. Both ends of the output of the second bridge circuit 2 are connected to both ends of a series circuit of the smoothing reactor L and the low-voltage side DC power source V2.

  One end of the smoothing reactor L is connected to the drains of the switching elements Q5 and Q7, and the other end of the smoothing reactor L is connected to the positive electrode of the low-voltage DC power supply V2.

  In the insulation transformer T1, one end of the primary winding P1 is connected to a connection point between the switch element Q1 and the switch element Q2 of the first bridge circuit 1, and the other end of the primary winding P1 is the switch element Q3 of the first bridge circuit 1. Is connected to a connection point between the switch element Q4 and the switch element Q4. One end of the secondary winding S1 of the isolation transformer T1 is connected to a connection point between the switch element Q5 and the switch element Q6 of the second bridge circuit 2, and the other end of the secondary winding S1 is connected to the second bridge circuit 2. It is connected to a connection point between the switch element Q7 and the switch element Q8.

  The primary winding P2 of the auxiliary resonance transformer T2 and the first auxiliary resonance switch Q10 include a first series circuit connected in series. Both ends of the first series circuit are connected to both ends of the first bridge circuit 1 and both ends of the high-voltage DC power supply V1.

  The auxiliary resonance reactor Lr, the secondary winding S2 of the auxiliary resonance transformer T2, and the second auxiliary resonance switch Q9 are composed of a second series circuit connected in series. Both ends of the second series circuit are connected to both ends of the second bridge circuit 2. The auxiliary resonant transformer T2 induces a voltage necessary for resonance on the primary side and the secondary side.

  The switch elements Q1 to Q8, the first auxiliary resonance switch Q10, and the second auxiliary resonance switch Q9 are made of MOSFETs. Diodes D1-D8 may be parasitic diodes of switch elements Q1-Q8. Capacitors C1 to C8 may be parasitic capacitances of switch elements Q1 to Q8.

  The control circuit 10 turns on / off the switch elements Q1 to Q10 by the gate drive signals Q1g to Q10g of the switch elements Q1 to Q10 as shown in FIG.

  When converting from high voltage to low voltage (during step-down), the control circuit 10 simultaneously turns on and off the switch element Q1 and switch element Q4, and simultaneously turns on and off the switch element Q2 and switch element Q3, as shown in FIG. The switch elements Q1 and Q2 and the switch elements Q3 and Q4 are alternately turned on and off. When converting from a high voltage to a low voltage, the control circuit 10 applies a voltage required for resonance to the auxiliary resonance transformer T2 by turning on the first auxiliary resonance switch Q10 as shown in FIG.

  At the time of step-down, the control circuit 10 simultaneously turns on and off the switch element Q5 and the switch element Q8, simultaneously turns on and off the switch element Q6 and the switch element Q7, and switches the switch element Q5, the switch element Q6, and the switch element as shown in FIG. Q7 and switch element Q8 are alternately turned on and off. When converting from low voltage to high voltage, the control circuit 10 turns on the second auxiliary resonance switch Q9 to apply a voltage necessary for resonance to the auxiliary resonance transformer T2.

  The control circuit 10 operates the conversion-side first bridge circuit 1 as a bridge converter, operates the second bridge circuit 2 as a synchronous rectification circuit, and converts the voltage of the high-voltage side DC power supply V1 input to the first bridge circuit 1. When the DC voltage is taken out from the second bridge circuit 2 by performing step-down conversion, the first auxiliary resonance switch Q10 is turned on, and the first and second voltages that are not turned on by the voltage induced in the secondary winding S2 of the auxiliary resonance transformer T2 are turned on. The capacitor of the two-bridge circuit and the resonance reactor are resonated, and the capacitor of the switch elements Q1 to Q4 is charged and discharged with the current. And the switch element which makes the diagonal of the 1st bridge circuit 1 is turned ON simultaneously.

  The control circuit 10 operates the second bridge circuit 2 as a bridge converter, operates the first bridge circuit 1 as a synchronous rectifier circuit, and boosts and converts the DC voltage input to the second bridge circuit 2. When the DC voltage is taken out from 1, the second auxiliary resonance switch Q9 is turned on, and the voltage of the switch elements Q5 to Q8 of the second bridge circuit 2 is made to resonate by flowing the current of the second bridge circuit 2 to the resonance reactor Lr. The switch elements forming the diagonal of the second bridge circuit 2 are simultaneously turned on.

  In Example 1, the turn ratio of the primary winding P1 and the secondary winding S1 of the insulating transformer T1 is 1: 1. The turns ratio of the primary winding P2 and the secondary winding S2 of the auxiliary resonant transformer T2 is 2: 1.

  In this case, the number of turns of the secondary winding S2 of the auxiliary resonant transformer T2 connected to the low-voltage side DC power source V2 via the smoothing reactor L and the resonant reactor Lr is “1”, and the auxiliary voltage is connected to the high-voltage side DC power source V1. The number of turns of the primary winding P2 of the resonant transformer T2 is “2”.

  In this case, a high voltage V1 / 2 is induced in the secondary winding S2 of the auxiliary resonant transformer T2 during resonance. Due to the induced voltage, a resonant operation occurs between the resonant reactor Lr and the capacitor connected in parallel to each switch element, thereby realizing ZVS. The induced voltage resonates even if it is not the high voltage / 2, but the most stable resonance occurs when the voltage is high / 2.

  Next, the operation at the time of step-down of the resonant bidirectional DC / DC converter according to the first embodiment configured as described above will be described in detail with reference to FIGS. 3, 4, and 5. FIG. FIG. 3 is a diagram illustrating a step-down conversion simulation waveform of the resonant bidirectional DC / DC converter according to the first embodiment.

  In FIG. 3, the transformer primary current is a current flowing through the primary winding P2 of the auxiliary resonant transformer T2. The resonance current is a current flowing through the resonance reactor Lr. Q5 and Q8 gates are gate drive signals applied to the gates of the switch elements Q5 and Q8.

  First, in the reflux mode shown in FIG. 4A, the switch elements Q5 to Q8 are turned on, and a current flows through a path of Q8 → Q7 (and Q6 → Q5) → L → V2 → Q8. At this time, the switch elements Q1 to Q4 are turned off.

  Note that the switch elements Q5 to Q8 may be turned off. In this case, the diodes D5 to D8 connected in parallel to the switch elements Q5 to Q8 are turned on, and a current flows through the above path.

  Next, in the reflux mode shown in FIG. 4B, the switch elements Q5 and Q8 are turned on by the gate drive signal shown in FIG. The switch elements Q6 and Q7 are turned off so that the switch elements Q2 and Q3 are the targets of ZVS. At this time, a current flows through a path of Q8 → D7 (and D6 → Q5) → L → V2 → Q8.

  Next, in the reflux mode shown in FIG. 4C, the auxiliary resonance switch Q10 is turned on while the switch elements Q5 and Q8 are turned on and the switch elements Q6 and Q7 are turned off. At this time, the high-voltage side DC power source V1 is applied to the primary winding P2 of the auxiliary resonant transformer T2, and a transformer primary current flows through the primary winding P2 of the auxiliary resonant transformer T2 as shown in FIG.

  Further, when the auxiliary resonance switch Q10 is turned on, the current rises from 0 A by the action of the reactor, so that zero current switching (ZCS) is performed. At the same time, the secondary side current of the auxiliary resonant transformer T2 also rises with a current gradient caused by the resonant reactor Lr, and the secondary side diode recovers during resonance, resulting in ZCS.

  Further, V1 / 2 is induced in the secondary winding S2 of the auxiliary resonant transformer T2 by the turn ratio. Due to the voltage induced in the secondary winding S2 of the auxiliary resonant transformer T2, the current of the switch elements Q5 to Q8 is commutated to the resonant reactor Lr.

  Next, in the resonance mode shown in FIG. 5 (a), the resonant reactor Lr and each switch in a state where the switch elements Q5 and Q8 are turned on, the switch elements Q6 and Q7 are turned off, and the auxiliary resonant switch Q10 is turned on. Resonant operation is started by the snubber capacitors C6 and C7 and the capacitors of the first bridge circuit 1 connected in parallel to the elements Q6 and Q7. For this reason, a sinusoidal resonance current as shown in FIG. 3 flows in the resonance reactor Lr. At this time, a current flows through a route of S2, Lr, Q5, S1, Q8, D9, and S2. For this reason, a current flows through a path of P1 → C3 → C1 → P1 and a path of P1 → C4 → C2 → P1. At this time, the capacitors C2 and C3 are discharged, and the capacitors C1 and C4 are charged.

  Next, in the resonance mode shown in FIG. 5 (b), the voltages of the capacitors C6 and C7 in the state where the switch elements Q5 and Q8 are turned on, the switch elements Q6 and Q7 are turned off, and the auxiliary resonant switch Q10 is turned on. Becomes a high voltage V1, a voltage of V1 / 2 to -V1 / 2 before resonance is applied to the resonance reactor Lr.

  For this reason, as shown in FIG. 3, the resonance current decreases. At this time, as shown in FIG. 3, when the switch elements Q2 and Q3 are turned on, zero volt switching (ZVS) can be realized.

  Next, in the power supply mode shown in FIG. 5C, the switch elements Q5 and Q8 are turned on, the switch elements Q6 and Q7 are turned off, the auxiliary resonance switch Q10 is turned off, and the switch elements Q2 and Q3 are turned on. That is, the auxiliary resonance switch Q10 is turned off and the power supply mode is changed. At this time, a current flows through a route of V1 → Q3 → P1 → Q2 → V1. In addition, a current flows through a route of S1, Q5, L, V2, Q8, and S1, and is stepped down from high pressure to low pressure.

  Next, in the reflux mode shown in FIG. 5D, the switch elements Q5 to Q8 are turned on and the switch elements Q2 and Q3 are turned off. When the switch elements Q6 and Q7 are turned on, the exciting current of the insulating transformer T1 returns to the secondary side, and when the switch elements Q2 and Q3 are turned off, ZVS is turned off.

  Next, the case where the switch elements Q1 and Q4 are ZVS will be briefly described.

  First, in the reflux mode, the switch elements Q6 and Q7 are turned on. The switch elements Q5 and Q8 are turned off, and the switch elements Q1 and Q4 are targeted for ZVS. In this state, the auxiliary resonance switch Q10 is turned on. At this time, the high-voltage side DC power source V1 is applied to the primary winding P2 of the auxiliary resonant transformer T2, and the transformer primary current flows through the primary winding P2 of the auxiliary resonant transformer T2.

  Further, V1 / 2 is induced in the secondary winding S2 of the auxiliary resonant transformer T2 by the turn ratio. Due to the voltage induced in the secondary winding S2 of the auxiliary resonant transformer T2, the current of the switch elements Q5 to Q8 is commutated to the resonant reactor Lr.

  Next, in a state where the switch elements Q6 and Q7 are turned on, the switch elements Q5 and Q8 are turned off, and the auxiliary resonant switch Q10 is turned on, the resonance reactor Lr and each switch element Q5 and Q8 connected in parallel are connected. Resonant operation is started by the snubber capacitors C5 and C8 and by the capacitor of the first bridge circuit 1. For this reason, a sinusoidal resonance current as shown in FIG. 3 flows in the resonance reactor Lr. At this time, a current flows through a route of S2, Lr, Q7, S1, Q6, D9, and S2. For this reason, a current flows through a path of P1 → C2 → C4 → P1 and a path of P1 → C1 → C3 → P1. At this time, the capacitors C1 and C4 are discharged, and the capacitors C2 and C3 are charged.

  Next, in the state where the switch elements Q6 and Q7 are turned on, the switch elements Q5 and Q8 are turned off, and the auxiliary resonant switch Q10 is turned on, when the voltage of the capacitors C5 and C8 becomes the high voltage V1, the resonant reactor Lr is set. The voltage of V1 / 2 to -V1 / 2 before resonance is applied. For this reason, as shown in FIG. 3, the resonance current decreases. At this time, as shown in FIG. 3, ZVS can be realized by turning on the switching elements Q1 and Q4.

  Next, in the power supply mode, the switch elements Q6 and Q7 are turned on, the switch elements Q5 and Q8 are turned off, the auxiliary resonance switch Q10 is turned off, and the switch elements Q1 and Q4 are turned on. That is, the auxiliary resonance switch Q10 is turned off and the power supply mode is changed. At this time, a current flows through a route of V1 → Q1 → P1 → Q4 → V1. Further, a current flows through a route of S1, Q7, L, V2, Q6, and S1, and the voltage is stepped down from a high voltage to a low voltage.

  Next, the switch elements Q5 to Q8 are turned on, and the switch elements Q1 and Q4 are turned off. When the switch elements Q5 and Q8 are turned on, the exciting current of the insulating transformer T1 returns to the secondary side, and when the switch elements Q1 and Q4 are turned off, ZVS is turned off.

  Next, the operation at the time of step-up of the resonant bidirectional DC / DC converter according to the first embodiment will be described in detail with reference to FIGS. 6, 7, and 8. FIG. FIG. 6 is a diagram illustrating boost conversion simulation waveforms of the resonant bidirectional DC / DC converter according to the first embodiment. In this step-up conversion, the energy of the smoothing reactor L is transmitted from the low pressure side to the high pressure side by switching of the switch elements Q5 to Q8.

  First, in the transmission mode shown in FIG. 7A, the switch elements Q5 and Q8 are turned on and the switch elements Q6 and Q7 are turned off. At this time, a current flows through a route of V2, L, Q5, S1, Q8, and V2. Further, a current flows through a path of P1, D3, V1, D2, and P1. That is, the low-voltage DC power supply V2 and the voltage induced in the smoothing reactor L are transmitted to the secondary side of the insulating transformer T1.

  Next, in the resonance mode shown in FIG. 7B, the switch elements Q5 and Q8 are turned on. The switch elements Q6 and Q7 are turned off, and the auxiliary resonance switch Q9 is turned on. Then, the voltage applied to the resonant reactor Lr becomes V1 / 2−V1 = −V1 / 2. For this reason, a current flowing through the smoothing reactor L is drawn into a resonance circuit including the resonance reactor Lr, the secondary winding S2 of the auxiliary resonance transformer T2, and the second auxiliary resonance switch Q9.

  Next, in the resonance mode shown in FIG. 7C, the switch elements Q5 and Q8 are turned on, and the auxiliary resonance switch Q9 is turned on. Then, all of the current that has flowed through the switching elements Q5 and Q8 flows through the resonant reactor Lr. For this reason, a current flows through a route of V2-> L-> Lr-> S2-> Q9-> V2.

  Next, in the resonance mode shown in FIG. 8A, the resonance reactor Lr and the capacitors C6 and C7 of the switch elements Q6 and Q7 are switched with the switch elements Q5 and Q8 turned on and the auxiliary resonance switch Q9 is turned on. Due to resonance. Due to this resonance, the charges of the switch elements Q6 and Q7 are extracted, so that a current flows through the parasitic diodes of the switch elements Q6 and Q7. At this time, as shown in FIG. 6, when the switch elements Q6 and Q7 are turned on, ZVS of the switch elements Q6 and Q7 can be realized. The voltage applied to the resonant reactor Lr becomes V1 / 2−0 = V1 / 2, and the current of the resonant reactor Lr gradually decreases.

  Next, in the energy storage mode shown in FIG. 8B, the switch elements Q5 to Q8 are turned on and the auxiliary resonance switch Q9 is turned off. At this time, a current flows through the path V2 → L → Q5 → Q6 → V2 and the path V2 → L → Q7 → Q8 → V2. For this reason, energy can be stored in the smoothing reactor L from the low-voltage DC power supply V2.

  Next, in the energy release mode shown in FIG. 8C, the switch elements Q5 and Q8 are turned off, the switch elements Q6 and Q7 are turned on, and the auxiliary resonance switch Q9 is turned off. At this time, a current flows through a path of V2-> L-> Q7-> S1-> Q6-> V2. In addition, a current flows through a path of P1, D1, V1, D4, and P1. For this reason, the energy of the smoothing reactor L is released to the secondary side of the insulating transformer T1.

  Next, the case where the switch elements Q5 and Q8 are ZVS will be briefly described.

  First, in the transmission mode, the switch elements Q6 and Q7 are turned on and the switch elements Q5 and Q8 are turned off. At this time, a current flows through a path of V2-> L-> Q7-> S1-> Q6-> V2. Further, a current flows through a path of P1, D1, V1, D4, and P1. That is, the low-voltage DC power supply V2 and the voltage induced in the smoothing reactor L are transmitted to the secondary side of the insulating transformer T1.

  Next, in the resonance mode, the switch elements Q6 and Q7 are turned on, the switch elements Q5 and Q8 are turned off, and the auxiliary resonance switch Q9 is turned on. Then, the voltage applied to the resonant reactor Lr becomes V1 / 2−V1 = −V1 / 2. For this reason, a current flowing through the smoothing reactor L is drawn into a resonance circuit including the resonance reactor Lr, the secondary winding S2 of the auxiliary resonance transformer T2, and the second auxiliary resonance switch Q9.

  Next, the switch elements Q6 and Q7 are turned on, and the auxiliary resonance switch Q9 is turned on. Then, all of the current that has flowed through the switch elements Q6 and Q7 flows through the resonant reactor Lr. For this reason, a current flows through a route of V2-> L-> Lr-> S2-> Q9-> V2.

  Next, the resonance reactor Lr and the capacitors C5 and C8 resonate in a state where the switch elements Q6 and Q7 are turned on and the auxiliary resonance switch Q9 is turned on. Due to this resonance, the electric charges of the capacitors C5 and C8 are extracted, so that a current flows through the parasitic diodes of the switch elements Q6 and Q7. At this time, when the switch elements Q5 and Q8 are turned on, ZVS of the switch elements Q5 and Q8 can be realized as shown in FIG. The voltage applied to the resonant reactor Lr becomes V1 / 2−0 = V1 / 2, and the current of the resonant reactor Lr gradually decreases.

  Next, in the energy storage mode, the switch elements Q5 to Q8 are turned on and the auxiliary resonance switch Q9 is turned off. At this time, a current flows through the path V2 → L → Q5 → Q6 → V2 and the path V2 → L → Q7 → Q8 → V2. For this reason, energy can be stored in the smoothing reactor L from the low-voltage DC power supply V2.

  Next, in the energy release mode, the switch elements Q6 and Q7 are turned off, the switch elements Q5 and Q8 are turned on, and the auxiliary resonance switch Q9 is turned off. At this time, a current flows through a route of V2, L, Q5, S1, Q8, and V2. In addition, a current flows through a path of P1, D3, V1, D2, and P1. For this reason, the energy of the smoothing reactor L is released to the secondary side of the insulating transformer T1.

  Thus, according to the resonant bidirectional DC / DC converter of Example 1, the control circuit 10 operates the first bridge circuit 1 as a bridge converter and operates the second bridge circuit 2 as a synchronous rectifier circuit. When the DC voltage input to the first bridge circuit 1 is stepped down to extract the DC voltage from the second bridge circuit 2, the first auxiliary resonance switch 10 is turned on and induced in the secondary winding S2 of the auxiliary resonance transformer T2. The voltage of the switch element of the first bridge circuit 1 is caused to resonate by the applied voltage, and the switch elements forming the diagonal of the first bridge circuit 1 are simultaneously turned on.

  Therefore, the DC voltage can be stepped down and the switch element forming the diagonal of the first bridge circuit 1 can be ZVSed.

  Further, during the step-down operation, the primary side ripple current is reduced by the smoothing reactor L, which is suitable for wide input. Further, since a return current for the primary side ZVS is not required, conduction loss can be reduced. Further, the secondary side ZCS can be realized simultaneously with the primary side ZVS by the resonance operation.

  Furthermore, ZVS and ZCS can be realized in all regions from a light load to a rated load. Further, since the auxiliary resonance switches Q9 and Q10 can be turned off when the current is near zero, the loss is reduced.

  Further, the control circuit 10 operates the second bridge circuit 2 as a bridge converter, operates the first bridge circuit 1 as a synchronous rectifier circuit, boosts and converts the DC voltage input to the second bridge circuit 2 to the first. When taking out a DC voltage from the bridge circuit 1, the second auxiliary resonance switch Q9 is turned on, and the current of the second bridge circuit 2 is caused to flow through the resonance reactor Lr, thereby resonating the voltage of the switch element of the second bridge circuit 2. The switch elements forming the diagonal of the two-bridge circuit 2 are simultaneously turned on.

  Therefore, the DC voltage can be boosted and converted, and the switch element forming the diagonal of the second bridge circuit 2 can be ZVSed. That is, the resonant bidirectional DC / DC converter can perform bidirectional voltage conversion.

  Further, during the step-up operation, the ZVS turn-on can be performed by using the resonance circuit during the step-down operation, and the efficiency can be improved. Further, since the auxiliary resonance switches Q9 and Q10 can be turned off in the vicinity of the current, the loss can be reduced.

DESCRIPTION OF SYMBOLS 1 1st bridge circuit 2 2nd bridge circuit 10 Control circuit V1 High voltage side DC power supply V2 Low voltage side DC power supply L Smoothing reactor Q1-Q8 Switch element Q9 1st auxiliary resonance switch Q10 2nd auxiliary resonance switch T1 Insulation transformer T2 Auxiliary resonance transformer P1, P2 Primary winding S1, S2 Secondary winding D1-D10 Diode C1-C8 Capacitor

Claims (5)

A first bridge circuit configured by a bridge including a plurality of first switch elements in which a first diode and a first capacitor are connected in parallel;
A second bridge circuit comprising a plurality of second switch elements in which a second diode and a second capacitor are connected in parallel and configured as a bridge;
A smoothing reactor having one end connected in series to the second bridge circuit;
An isolation transformer having a primary winding connected to the first bridge circuit and a secondary winding connected to the second bridge circuit;
A first series circuit in which a primary winding of an auxiliary resonant transformer and a first auxiliary resonant switch are connected in series to both ends of the first bridge circuit;
A second series circuit in which an auxiliary resonance reactor, a secondary winding of the auxiliary resonance transformer, and a second auxiliary resonance switch are connected in series to both ends of the second bridge circuit;
A resonance type bidirectional DC / DC converter comprising:   The first bridge circuit is operated as a bridge converter, the second bridge circuit is operated as a synchronous rectifier circuit, and a direct current voltage input to the first bridge circuit is stepped down to obtain a direct current voltage from the second bridge circuit. When taking out, the first auxiliary resonance switch is turned on, the voltage of the switch element of the first bridge circuit is resonated by the voltage induced in the secondary winding of the auxiliary resonance transformer, and the diagonal of the first bridge circuit is obtained. 2. The resonant bidirectional DC / DC converter according to claim 1, further comprising a control circuit for simultaneously turning on the switching elements forming the above.   The second bridge circuit is operated as a bridge converter, the first bridge circuit is operated as a synchronous rectifier circuit, and the DC voltage input to the second bridge circuit is boosted to convert the DC voltage from the first bridge circuit. When taking out, the second auxiliary resonance switch is turned on, and the voltage of the switch element of the second bridge circuit is caused to resonate by causing the current of the second bridge circuit to flow through the resonance reactor. 2. The resonant bidirectional DC / DC converter according to claim 1, further comprising a control circuit for simultaneously turning on the switching elements forming the above.   The ratio of the primary winding and the secondary winding of the auxiliary resonant transformer is twice the ratio of the primary winding and the secondary winding of the insulating transformer. A resonant bidirectional DC / DC converter according to claim 1.   The first auxiliary resonance switch or the second auxiliary resonance switch is turned on before the switch element operating as the bridge converter is turned on, and is turned off after the switch element operating as the bridge converter is turned on. The resonant bidirectional DC / DC converter according to any one of claims 1 to 4.

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