JP2019146469A - Both-directional dc/dc converter - Google Patents

Abstract

To provide a both-directional DC/DC converter with an ARCP circuit having a further improved conversion efficiency.SOLUTION: The present invention includes: a first smoothing capacitor C1; a second smoothing capacitor C2; a high-side main switching element Q; a low-side main switching element Q; an output reactor Lout; and an ARCP circuit 10 having a commutation control circuit 11 and a rectification circuit 12. The present invention further includes: a resonance reactor Lr; a high-side commutation switching element Q; a low-side commutation switching element Q; a high-side transformer T1 including a high-side primary coil Nand a high-side secondary coil N; and a low-side transformer T2 including a low-side primary coil Nand a low-side secondary coil N. The high-side transformer T1 and the low-side transformer T2 are arranged separately without a magnetic coupling.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bidirectional DC / DC converter provided with an ARCP (Auxiliary Resonant Commutated Pole) circuit used in a power storage system or the like.

  A power storage system that stores low-price electric power in a battery at night and operates equipment by discharging from the battery during the day includes a bidirectional inverter connected to the system power supply, a bidirectional DC / DC converter, a battery, and the like. Configured. FIG. 11 is a circuit diagram showing a configuration of a conventional bidirectional DC / DC converter in a power storage system.

In FIG. 11, C1 is a first smoothing capacitor, C2 is a second smoothing capacitor, _Qm1 is a high-side main switching element, _Qm2 is a low-side main switching element, and _Dm1 and _Dm2 are diodes connected in antiparallel. (Parasitic diode), C _r1 , C _r2 are capacitors for resonance (parasitic capacitors), Lout is an output reactor, 10 is an ARCP circuit, 11 is a commutation control circuit, 12 is a rectifier circuit, Lr is a reactor for resonance , Q _t1 and Q _t2 are commutation switching elements, T0 is a charge / discharge transformer, N _L1 and N _H1 are primary windings, N _HL2 is a secondary winding, and D _H1 , D _H2 , D _L1 and D _L2 are rectified. Diodes D _G1 and D _G2 are diodes for preventing backflow.

  Next, the operation of the conventional bidirectional DC / DC converter configured as described above will be described. [A] The discharge mode and [B] the charge mode will be described separately.

[A] Discharge mode [A1] Discharge of reactor Lout for output (see FIG. 12A)
Both the high-side and low-side main switching elements Q _m1 and Q _m2 and the high-side and low-side commutation switching elements Q _t1 and Q _t2 are in the off state, and the output reactor Lout releases energy. parasitic diode D parallel-connected battery B → reverse parallel connection of the main switching element Q _m1 of the reactor Lout → the high side for the output 2 of the smoothing capacitor C2 _m1 → first smoothing capacitor C1 (bi-directional inverter) → battery A current flows through the path B. Here, the voltage applied between the first smoothing capacitor C1, i.e., the voltage between the terminals T _p1 and the terminal T _n1 is output to bi-directional inverter connected between the terminals, the terminal T _p1 via the bi-directional inverter Current flows from the terminal to the terminal T _n1 . This is a steady state before the commutation operation. Before the commutation, no current flows through the commutation control circuit 11 and no current flows through the rectifier circuit 12.

[A2] Commutation start (see FIG. 12B)
The low-side commutation switching element Q _{t2 in} the commutation control circuit 11 is turned on. Then, the current flowing through the anti-parallel parasitic diode D _m1 of the high-side main switching element Q _{m1 in} the above [A1] gradually commutates to the low-side commutation switching element Q _t2 side, and the battery B → output Current flows in the path of the reactor Lout for resonance, the reactor Lr for resonance, the primary winding N _L1 for low side, the diode D _G2 for preventing reverse current, the switching element Q _{t2 for} low side commutation, and the battery B.

In the rectifier circuit 12, the secondary winding N _HL2 → the rectifier diode D _H1 → the high side line L1 → the first smoothing capacitor C1 (by the electric power induced from the low side primary winding N _L1 to the secondary winding N _HL2 Bidirectional inverter) → Rectifier diode D _L1 → Secondary winding N _HL2 path and secondary winding N _HL2 → Rectifier diode D _{H2 →} High side line L1 → First smoothing capacitor C1 (bidirectional inverter) → Rectification A current flows through the path of the diode D _L2 → secondary winding N _HL2 , and the battery B discharges to charge the first smoothing capacitor C1.

A current flows through the low-side of the primary winding N _L1, induced current in the secondary winding N _HL2 via magnetic coupling, further high current flowing through the secondary winding N _HL2 is by electromagnetic induction by the magnetic coupling An upward counter electromotive force E (see a thick upward arrow) is generated in the primary winding N _H1 of the side. In order to avoid the occurrence of backflow in the commutation control circuit 11 due to this, a backflow prevention diode D _G1 is inserted in the high side portion of the commutation control circuit 11.

All four rectifier diodes D _H1 , D _H2 , D _L1 , and D _L2 are conductive in the rectifier circuit 12.

[A3] LC resonance (see FIG. 13A)
When the current flowing through the resonance reactor Lr exceeds the current flowing through the output reactor Lout in the state [A2], the resonance capacitors C _r1 and C _r2 start charging and discharging. That is, resonance capacitor C _r1 → resonance reactor Lr → low side primary winding N _L1 → backflow prevention diode D _G2 → low side commutation switching element Q _t2 → low side line L2 → first smoothing capacitor C1 (Bidirectional inverter) → high side line L1 → resonance capacitor C _r1 path and resonance capacitor C _r2 → resonance reactor Lr → primary winding N _L1 → backflow prevention diode D _G2 → low side A current flows through the path of the commutation switching element Q _t2 → the low side line L2 → the resonance capacitor C _r2 and the resonance operation is started.

Also in this case, an upward counter electromotive force E is generated in the high-side primary winding _NH1 as in the case of FIG.

The current flow in the rectifier circuit 12 is the same as [A2] (see FIG. 12B). Also in this case, all four rectifier diodes D _H1 , D _H2 , D _L1 , and D _L2 are conductive in the rectifier circuit 12.

[A4] Transition to steady state (see FIG. 13B)
Then, when the voltage across the resonance capacitor _Cr2 , that is, the voltage applied to the low-side main switching element _Qm2 becomes 0 level, the main switching element _Qm2 is turned on. The turn-on of the main switching element Q _m2 uses soft switching (zero voltage switching (ZVS)) due to a high frequency resonance phenomenon, and switching loss is reduced.

From the time when the low-side main switching element Q _m2 is turned on, the current flowing through the resonance reactor Lr gradually decreases. Until then, the battery B → the output reactor Lout → the resonance reactor Lr → the low-side primary winding N _L1 → Back-flow prevention diode D _G2 → Low-side commutation switching element Q _t2 → Current flowing through the path of battery B → Battery B → Output reactor Lout → Low-side main switching element Q _m2 → Battery B path Transition to the flow.

Also in this case, an upward counter electromotive force E is generated in the high-side primary winding N _H1 in the same manner as described above.

The current flow in the rectifier circuit 12 is the same as [A2] and [A3] described above (see FIGS. 12B and 13A). Also in this case, all four rectifier diodes D _H1 , D _H2 , D _L1 , and D _L2 are conductive in the rectifier circuit 12.

[A5] Steady state (see FIG. 14A)
The current in the resonance reactor Lr disappears, and the low-side commutation switching element Q _t2 is turned off. The turn-off of the commutation switching element Q _t2 uses soft switching (zero current switching (ZCS)), and switching loss is reduced. In this steady state, the current flows only through the path of battery B → output reactor Lout → low-side main switching element Q _m2 → battery B. Therefore, the reactor Lout for output accumulates energy.

Since no current flows through the low-side primary winding N _L1 , the current stops in the rectifier circuit 12.

[A6] Commutation start (see FIG. 14B)
The low-side main switching element Q _m2 is turned off. Its instantaneous current from the commutated to the capacitor C _r2 for resonance, charging is performed to the capacitor C _r2 for resonance. While the voltage across the main switching element Q _m2 rises slowly, the current is quickly transferred to the resonance capacitor C _r2 , so that almost no switching loss occurs.

  The reason why the ARCP circuit 10 is installed is as follows.

When the configuration of the step-up chopper is viewed globally by comparing the state of FIG. 12A and the state of FIG. 14A in the discharge mode, an output voltage is applied between both terminals of the second smoothing capacitor C2. A series circuit of the reactor Lout and the main switching element Q _m2 is connected, and a diode D _m1 (a parasitic diode connected in reverse parallel to the main switching element Q _{m1 on} the high side) is connected between both terminals of the main switching element Q _m2 . A series circuit with a smoothing capacitor C1 is connected, and this has the function of a step-up chopper.

The function of the step-up chopper is exhibited by switching of the low-side main switching element Q _m2 , and when the main switching element Q _m2 is turned on, the low-side commutation switching element Q _t2 is turned on in the previous stage. Thus, the low-side main switching element Q _m2 can be turned on by the soft switching method, and the conversion efficiency can be improved.

[B] Charging mode [B1] Storage of output reactor Lout (see FIG. 15A)
Both the high-side and low-side main switching elements Q _m1 and Q _m2 and the high-side and low-side commutation switching elements Q _t1 and Q _t2 are in the off state, and the output reactor Lout stores energy, and the battery A current flows in the path of B → low-side main switching element Q _m2 in antiparallel connection _Dm2 → output reactor Lout → battery B, and the battery B is charged. This is a steady state before the commutation operation. Before the commutation, no current flows through the commutation control circuit 11 and no current flows through the rectifier circuit 12.

[B2] Commutation start (see FIG. 15B)
The high-side commutation switching element Q _{t1 in} the commutation control circuit 11 is turned on. Then, in [B1], the parasitic diode D _m2 connected in reverse parallel to the low-side main switching element Q _m2 → the output reactor Lout → the current flowing through the path of the battery B is gradually commutated, and the first smoothing capacitor C1 (bidirectional inverter) → high-side commutation switching element Q _t1 → high-side primary winding N _H1 → resonance reactor Lr → output reactor Lout → battery B → first smoothing capacitor C1 Transition to the current. That is, the voltage output between the terminal T _p1 and the terminal T _n1 from the bidirectional inverter is applied between the first smoothing capacitor C1 and charged from the terminal T _p1 via the bidirectional DC / DC converter while charging the battery B. A current flows toward the terminal T _n1 . In the rectifier circuit 12, the secondary winding N _HL2 → the rectifier diode D _H1 → the first smoothing capacitor C 1 → the rectifier diode D _{L1 in the} rectifier circuit 12 by the power induced from the high side primary winding N _H1 to the secondary winding N _HL2. → a path of the secondary winding N _HL2, current flows in the path of the secondary winding N _HL2 → rectifier diode D _H2 → first smoothing capacitor C1 → the rectifier diode D _L2 → secondary winding N _HL2, battery The charging and discharging of the first smoothing capacitor C1 is performed along with the charging of B.

A current flows through the high side of the primary winding N _H1, induced current in the secondary winding N _HL2 via magnetic coupling, further current flowing through the secondary winding N _HL2 is by electromagnetic induction by the magnetic coupling An upward counter electromotive force E is generated in the low-side primary winding N _L1 . In order to avoid backflow from occurring in the commutation control circuit 11 due to this, a backflow prevention diode D _G2 is inserted in the low side portion of the commutation control circuit 11.

All four rectifier diodes D _H1 , D _H2 , D _L1 , and D _L2 are conductive in the rectifier circuit 12.

[B3] LC resonance (see FIG. 16A)
When the current flowing through the resonance reactor Lr exceeds the current flowing through the output reactor Lout in the state [B2], the resonance capacitors C _r1 and C _r2 start charging and discharging. That is, the resonance capacitor C _r1 → the high-side commutation switching element Q _t1 → the high-side primary winding NH ₁ → the resonance reactor Lr → the path of the resonance capacitor C _r1 and the resonance capacitor C _r2 → First smoothing capacitor C1 (bidirectional inverter) → High-side commutation switching element Q _t1 → High-side primary winding N _H1 → Resonance reactor Lr → Resonance capacitor C _r2 The resonance operation is started.

Also in this case, an upward counter electromotive force E is generated in the low-side primary winding N _L1 as in the case of FIG.

The current flow in the rectifier circuit 12 is the same as [B2] (see FIG. 15B). Also in this case, all four rectifier diodes D _H1 , D _H2 , D _L1 , and D _L2 are conductive in the rectifier circuit 12.

[B4] Transition to steady state (see FIG. 16B)
When the voltage across the resonance capacitor C _r1 , that is, the voltage applied to the high-side main switching element Q _m1 becomes 0 level, the main switching element Q _m1 is turned on. The turn-on of the main switching element Q _m1 uses soft switching (zero voltage switching (ZVS)) due to a high frequency resonance phenomenon, and switching loss is reduced.

From the time when the high-side main switching element Q _m1 is turned on, the current flowing through the resonance reactor Lr gradually decreases until the first smoothing capacitor C1 (bidirectional inverter) → the high-side commutation switching element Q _t1. → High-side primary winding N _H1 → Resonance reactor Lr → Output reactor Lout → Battery B → The current flowing in the path of the first smoothing capacitor C1 (bidirectional inverter) is the first smoothing capacitor A transition is made from the flow of C1 (bidirectional inverter) → high-side main switching element Q _m1 → output reactor Lout → battery B → first smoothing capacitor C1 (bidirectional inverter).

Also in this case, an upward counter electromotive force E is generated in the low-side primary winding N _L1 in the same manner as described above.

The current flow in the rectifier circuit 12 is the same as [B2] and [B3] described above (see FIGS. 15B and 16A). Also in this case, all four rectifier diodes D _H1 , D _H2 , D _L1 , and D _L2 are conductive in the rectifier circuit 12.

[B5] Steady state (see FIG. 17A)
The current in the resonance reactor Lr disappears, and the high-side commutation switching element Q _t1 is turned off. The turn-off of the commutation switching element Q _t1 uses soft switching (zero current switching (ZCS)), and switching loss is reduced. In this steady state, the current is as follows: first smoothing capacitor C1 (bidirectional inverter) → high-side main switching element Q _m1 → output reactor Lout → battery B → first smoothing capacitor C1 (bidirectional inverter) It will flow only on the route. Therefore, the output reactor Lout releases energy.

Since no current flows through the high-side primary winding N _H1 , the current stops in the rectifier circuit 12.

[B6] Commutation start (see FIG. 17B)
The high-side main switching element Q _m1 is turned off. Its instantaneous current from the commutated to the capacitor C _r1 for resonance, charging is performed to the capacitor C _r1 for resonance. While the voltage across the main switching element Q _m1 rises slowly, the current quickly transfers to the resonance capacitor C _r1 , so that almost no switching loss occurs. In this state, the current flows only through the path of the first smoothing capacitor C1 (bidirectional inverter) → resonance capacitor C _r1 → output reactor Lout → battery B → first smoothing capacitor C1 (bidirectional inverter). Will flow.

  In the transition operation as in [B1] to [B6] above, the state of electromagnetic induction by magnetic coupling from the commutation control circuit 11 to the rectifier circuit 12 is as follows.

When the configuration of the step-down chopper is viewed globally by matching the state of FIG. 15A and the state of FIG. 17A in the charging mode, the main switching element is connected between both terminals of the first smoothing capacitor C1. A series circuit of Q _m1 and a diode D _m2 (an antiparallel connection parasitic diode of the low-side main switching element Q _m2 ) is connected, and an output reactor Lout and a second smoothing capacitor are connected between both terminals of the diode D _m2. A series circuit with C2 is connected, which has the function of a step-down chopper.

The function of the step-down chopper is exhibited by switching of the high-side main switching element Q _m1 , but when the main switching element Q _m1 is turned on, the high-side commutation switching element Q _t1 is turned on in the previous stage. As a result, the high-side main switching element Q _m1 can be turned on by the soft switching method, and the conversion efficiency can be improved.

“High-efficiency, bi-directional insulated DC-DC converter”, [online], 2014, Pony Electric Co., Ltd. [searched on January 11, 2018], Internet <URL: http: //pony-e.jp/High_efficiency_bi -directional_insulated_DCDCconverter.pdf>

In the above conventional example, the transformer that magnetically couples the commutation control circuit 11 and the rectifier circuit 12 in the ARCP circuit 10 is used as a charge / discharge transformer. That is, the primary winding of the transformer is a center tap type winding in which the high-side primary winding N _H1 and the low-side primary winding N _L1 are directly connected. The secondary winding N _HL2 is a common winding for the pair of primary windings N _H1 and N _L1 of the center tap type. Since the iron core is shared by the three windings of the high side primary winding N _{H1, the} low side primary winding N _L1 and the secondary winding N _HL2 , as described above, in the discharge mode, the low side primary winding An upward counter electromotive force E is generated in the high-side primary winding N _H1 due to the current flowing in the winding N _L1 , and in the charging mode, current is supplied to the high-side primary winding N _H1. Due to the flow, an upward counter electromotive force E is generated in the low-side primary winding N _L1 . Therefore, in order to avoid the occurrence of backflow in the commutation control circuit 11, diodes D _G1 and D _G2 for backflow prevention are inserted.

However, the period during which current flows through these two backflow prevention diodes D _G1 and D _G2 is about half of the total period (FIGS. 12B, 13A, 13B, and 15B). 16) (see FIGS. 16A and 16B), a large loss was incurred.

  In recent power storage systems, the number of storage batteries in series tends to be reduced for cost reduction. However, since the battery voltage decreases when the number of storage batteries in series is reduced, the step-up / step-down ratio of the step-up / step-down chopper in the bidirectional DC / DC converter must be increased, which causes deterioration in conversion efficiency.

  Although the bidirectional DC / DC converter having the above-mentioned ARCP circuit is superior in conversion efficiency compared to the one not having the ARCP circuit, due to the loss caused by the above-described backflow prevention, From the viewpoint of compensating for the deterioration of the conversion efficiency accompanying the increase in the step-up / step-down ratio, there remains room for further improvement.

  The present invention was created in view of such circumstances, and an object of the present invention is to further improve the conversion efficiency of a bidirectional DC / DC converter.

  The present invention solves the above problems by taking the following measures.

The bidirectional DC / DC converter according to the present invention includes:
A first smoothing capacitor connected between a high-side input / output terminal on one end side and a low-side input / output terminal;
A second smoothing capacitor connected between the high-side input / output terminal on the other end side and the low-side input / output terminal;
A series circuit of a high-side main switching element and an output reactor inserted in a high-side line connecting the one-side high-side input / output terminal and the other-side high-side input / output terminal;
A low-side line connecting the low-side input / output terminal on the one end side and the low-side input / output terminal on the other end side, and a first connection node connecting the high-side main switching element and the output reactor. A low-side main switching element inserted between,
An ARCP circuit connected between the high side line and the low side line;
The ARCP circuit comprises a commutation control circuit and a rectifier circuit,
The commutation control circuit includes:
A resonance reactor having one end connected to the first connection node, a transformer connected to the other end of the resonance reactor, and a primary winding of the transformer and the high side line. A high-side commutation switching element, and a low-side commutation switching element connected between the primary winding of the transformer and the low-side line,
The rectifier circuit is connected between the high side line and the low side line in a state capable of receiving power induced in the secondary winding of the transformer, and is connected to the high side with respect to the first smoothing capacitor. It is configured to supply current only in one direction from the line side toward the low side line side,
The transformer is
A high-side transformer having a primary winding connected to the high-side commutation switching element; and a low-side transformer having a primary winding connected to the low-side commutation switching element. And the low-side transformer are separated from each other without being substantially magnetically coupled.

  When the features of the present invention are described in comparison with the above-described conventional example, the component for magnetic coupling between the commutation control circuit and the rectifier circuit has been conventionally used as a charge / discharge transformer. It is characterized by having a structure separated into a transformer and a charging transformer.

  As described above, the transformer for magnetic coupling between the commutation control circuit and the rectifier circuit is separated into the discharge transformer and the charge transformer instead of the conventional charge / discharge transformer. When the resonant operation is performed, the excitation for the low-side primary winding does not generate back electromotive force in the high-side primary winding, and the excitation for the high-side primary winding does not occur in the low-side primary winding. It does not generate power. As a result, it is not necessary to insert a backflow preventing diode in the high side portion and the low side portion of the ARCP circuit as in the conventional example, and the power consumed by the backflow preventing diode can be saved. Become.

  In addition, it is possible to simplify the circuit configuration of the rectifier diode provided for charging the first smoothing capacitor in the rectifier circuit, and to reduce the loss in the rectifier diode.

The bidirectional DC / DC converter of the present invention having the above configuration has the following preferred modes. That is,
The high side and low side secondary windings are both configured as center tap type windings,
The high-side center tap type secondary winding has one end and the other end connected to the high-side line via rectifier diodes, and the center tap is directly connected to the low-side line,
The low-side center tap type secondary winding has one end and the other end connected to the low-side line via rectifier diodes, and the center tap is directly connected to the high-side line. There is. With this configuration, it is not necessary to conduct all the rectifier diodes in both the discharge mode and the charge mode, and it is only necessary to wire in the state of the rectifier diode dedicated to each mode, thereby reducing the loss in the rectifier diode. Configuration is simplified.

Another bidirectional DC / DC converter according to the present invention is:
A first smoothing capacitor connected between a high-side input / output terminal on one end side and a low-side input / output terminal;
A second smoothing capacitor connected between the high-side input / output terminal on the other end side and the low-side input / output terminal;
A series circuit of a high-side main switching element and an output reactor inserted in a high-side line connecting the one-side high-side input / output terminal and the other-side high-side input / output terminal;
A low-side line connecting the low-side input / output terminal on the one end side and the low-side input / output terminal on the other end side, and a first connection node connecting the high-side main switching element and the output reactor. A low-side main switching element inserted between,
An ARCP circuit connected between the high side line and the low side line;
The ARCP circuit comprises a commutation control circuit and a rectifier circuit,
The commutation control circuit includes:
A resonance reactor having one end connected to the first connection node, a transformer connected to the other end of the resonance reactor, and a primary winding of the transformer and the high side line. A high-side commutation switching element, and a low-side commutation switching element connected between the primary winding of the transformer and the low-side line,
The rectifier circuit is connected between the high side line and the low side line in a state capable of receiving power induced in the secondary winding of the transformer, and is connected to the high side with respect to the first smoothing capacitor. It is configured to supply current only in one direction from the line side toward the low side line side,
The transformer is
The primary winding includes a high side primary winding portion and a low side primary winding portion with a center tap as a boundary, the center tap is connected to the resonance reactor, and the high side primary winding portion is the high side And the low-side primary winding portion is connected to the low-side commutation switching element, and the high-side primary winding portion and the low-side primary winding portion are opposite to each other. It is characterized by being wound.

  About the transformer which is a component for magnetic coupling of the commutation control circuit and the rectifier circuit, even if it is a type of transformer having a center tap type primary winding, the high side primary winding portion in the primary winding and By reversing the winding direction with the low-side primary winding portion, there is no route through which current flows due to the voltage generated in the winding on the unused side. Specifically, when the soft switching resonance operation is performed in the ARCP circuit, even when a voltage is generated in the high-side primary winding portion when the low-side commutation switching element is turned on, a current flows due to the generated voltage. There is no root. Further, even when a voltage is generated in the low-side primary winding portion when the high-side commutation switching element is turned on, there is no route through which current flows due to the generated voltage. As a result, it is not necessary to insert a backflow preventing diode in the high side portion and the low side portion of the ARCP circuit as in the conventional example, and the power consumed by the backflow preventing diode can be saved. Become.

  In addition, it is possible to simplify the circuit configuration of the rectifier diode provided for charging the first smoothing capacitor in the rectifier circuit, and to reduce the loss in the rectifier diode.

  The bidirectional DC / DC converter of the present invention that cancels the magnetic coupling has the following preferred modes. That is, the secondary winding is configured as a center tap type winding, and one end and the other end of the center tap type secondary winding are respectively connected to the high side line via a rectifier diode. There is a mode. If comprised in this way, it will become possible to simplify the circuit structure about the rectifier circuit which supplies an electric current only to one direction toward the low side line side from the high side line side with respect to the 1st smoothing capacitor. .

  According to the present invention, in the resonant operation of soft switching in the ARCP circuit, mutual interference of excitation between the low-side primary winding and the high-side primary winding is eliminated, or the high-side primary winding portion and the low-side primary winding are eliminated. Since the back electromotive force is prevented by substantially canceling the magnetic coupling through the secondary winding between the parts, the conventionally required reverse current prevention diode can be omitted, saving power consumption. Can be planned. In addition, the circuit configuration of the rectifier diode for charging the first smoothing capacitor can be simplified, and the diode loss can be reduced.

The circuit diagram which shows the structure of the bidirectional | two-way DC / DC converter in the Example of this invention. Operational explanatory diagram of bidirectional DC / DC converter of embodiment (part 1) Operational explanatory diagram of the bidirectional DC / DC converter of the embodiment (part 2) Operational explanatory diagram of the bidirectional DC / DC converter of the embodiment (part 3) Operational explanatory diagram of the bidirectional DC / DC converter of the embodiment (No. 4) Operational explanatory diagram of bidirectional DC / DC converter of embodiment (part 5) Operational explanatory diagram of the bidirectional DC / DC converter of the embodiment (No. 6) The circuit diagram which shows the structure of the bidirectional | two-way DC / DC converter in another Example of this invention. The circuit diagram which shows the structure of the bidirectional | two-way DC / DC converter in another Example of this invention. The circuit diagram which shows the structure of the bidirectional | two-way DC / DC converter in another Example of this invention. Circuit diagram showing the configuration of a conventional bidirectional DC / DC converter Operational explanatory diagram of a conventional bidirectional DC / DC converter (part 1) Operation explanatory diagram of a conventional bidirectional DC / DC converter (part 2) Operational explanatory diagram of a conventional bidirectional DC / DC converter (part 3) Operational explanatory diagram of a conventional bidirectional DC / DC converter (Part 4) Operational explanatory diagram of a conventional bidirectional DC / DC converter (part 5) Operational explanatory diagram of a conventional bidirectional DC / DC converter (Part 6)

  Hereinafter, the embodiment of the bidirectional DC / DC converter of the present invention having the above configuration will be described in detail at the level of specific examples.

〔Example〕
FIG. 1 is a circuit diagram showing a configuration of a bidirectional DC / DC converter in an embodiment of the present invention. In FIG. 1, T _p1 is a high-side input / output terminal on the inverter side (“one end side” of the present invention), T _n1 is a low-side input / output terminal on the inverter side, and T _p2 is a battery side (“other end side of the present invention”). )) High-side input / output terminal, T _n2 is a battery-side low-side input / output terminal, L1 is a high-side line connecting the high-side input / output terminal T _p1 and the high-side input / output terminal T _p2, and L2 is a low-side input / output A low-side line connecting the terminal T _n1 and the low-side input / output terminal T _n2 , C1 is a first smoothing capacitor connected between the high-side input / output terminal T _p1 and the low-side input / output terminal T _n1 on the inverter side, C2 second smoothing capacitor is connected between the high side input terminal T _p2 and low side output terminal T _n2 of the battery side, Q _m1 is the high-side main switching element (NMOS Transistor), Q _{m @ 2} is low-side main switching element (NMOS transistor), D _m1 is between both terminals of the high-side main switching element Q _m1 (reverse parallel connection of a diode between the drain and source) (parasitic diode), C _r1 Is a capacitor for resonance between the same terminals, D _m2 is a diode (parasitic diode) connected in reverse parallel between both terminals (between drain and source) of the main switching element Q _{m2 on} the low side, and _{Cr 2} is between the same terminals A resonance capacitor, Lout, is an output reactor.

A series circuit of the high-side main switching element Q _m1 and the output reactor Lout is inserted into the high-side line L1. The high-side main switching element Q _m1 has a drain connected to the inverter-side high-side input / output terminal T _p1 , a source connected to one end of the output reactor Lout, and the other end of the output reactor Lout connected to the battery. Side high-side input / output terminal _Tp2 . The low-side main switching element Q _m2 has a drain connected to the first connection node N1 that is a connection point between the high-side main switching element Q _m1 and the output reactor Lout, and a source connected to the low-side line L2. Has been.

  Reference numeral 10 denotes an ARCP (auxiliary resonant commutation pole) circuit connected between the high side line L1 and the low side line L2, and includes a commutation control circuit 11 and a rectifier circuit 12.

As constituent elements of the commutation control circuit 11, Lr is a resonance reactor, _Qt1 is a high-side commutation switching element (NMOS transistor), and _Qt2 is a low-side commutation switching element (NMOS transistor). One end of the resonance reactor Lr is connected to the first connection node N1, and the other end of the resonance reactor Lr is connected to a transformer (second connection node N2 described later). As components of the rectifier circuit 12, D _H1 , D _H2 , D _L1 , and D _L2 are rectifier diodes. The high-side commutation switching element Q _t1 is connected between the primary winding of the transformer and the high-side line L1, and the low-side commutation switching element Q _t2 is between the primary winding of the transformer and the low-side line L2. It is connected to the. The transformer includes a high-side transformer T1 that magnetically couples the commutation control circuit 11 and the rectifier circuit 12, and a low-side transformer T2 that similarly magnetically couples the commutation control circuit 11 and the rectifier circuit 12. T1 has a secondary winding N _H2 of the high-side of the connected high-side primary winding N _H1 and the center tap configuration commutation switching element Q _t1 of the high-side, transformer T2 of the low-side low-side commutation A low-side primary winding N _L1 connected to the switching element Q _t2 and a low-side secondary winding N _L2 having a center tap configuration are included.

Between the high side line L1 and the low-side line L2, commutating the high side switching element Q _t1 and the primary winding of the high side of the transformer T1 N _H1 and the low side of the primary winding N _L1 and low-commutation switching element Q A series circuit with _t2 is connected. The drain of the high-side commutation switching element Q _t1 is connected to the high-side line L1, and the source of the low-side commutation switching element Q _t2 is connected to the low-side line L2.

The series circuit of the resonance reactor Lr of the commutation control circuit 11 and the high-side commutation switching element Q _{t1 in} the ARCP circuit 10 is connected between the first connection node N1 and the high-side line L1. The resonance reactor Lr includes a first connection node N1 that commonly connects the high-side main switching element Q _m1 , the low-side main switching element Q _m2 and the output reactor Lout, and the high-side primary winding N _H1. And a second connection node N2 connecting the low-side primary winding N _L1 .

The high-side primary winding _NH1 is connected between the source of the high-side commutation switching element _Qt1 and the second connection node N2, and the drain of the low-side commutation switching element _Qt2 and the second connection node A low-side primary winding N _L1 is connected to N2. That is, as the primary winding of the transformer inserted between the high-side commutation switching element Q _t1 and the low-side commutation switching element Q _t2 , the second connection node N2 is sandwiched therebetween, The primary winding N _H1 and the low-side primary winding N _L1 are arranged in a separated state. The primary windings N _H1 and N _L1 are inserted in a line connecting the high-side commutation switching element Q _t1 and the low-side commutation switching element Q _t2 in series. In this manner, a series circuit of the high-side commutation switching element Q _t1 and the high-side primary winding N _H1 is connected between the high-side line L1 and the second connection node N2, and the low-side line L2 And a second connection node N2, a series circuit of a low-side commutation switching element Q _t2 and a low-side primary winding N _L1 is connected.

In the rectifier circuit 12, the rectifier diode D _H1 and the rectifier diode D _H2 whose cathodes are connected to the high side line L1 have their anodes connected to one end and the other end of the high side secondary winding N _H2. the center tap of the primary winding N _H2 is connected to the low side line L2. Further, the rectifier diode D _L1 and the rectifying diode D _L2 whose anode is connected to the low side line L2, each cathode connected to one end and the other end of the low-side of the secondary winding N _L2, the secondary winding N _L2 The center tap is connected to the high side line L1. The rectifier circuit 12 is connected between the high side line L1 and the low side line L2 in a state where it can receive power induced in the secondary windings N _H2 and N _L2 of the high side and low side transformers T1 and T2. Yes. All of the rectifier diodes D _H1 , D _H2 , D _L1 , and D _{L2 in} the rectifier circuit 12 supply current to the first smoothing capacitor C1 only in one direction from the high side line L1 side to the low side line L2 side. To do.

The high-side primary winding _NH1 is inserted between the high-side commutation switching element _Qt1 , the second connection node N2, and the high-side line L1. The low-side primary winding N _L1 is inserted between the low-side commutation switching element Q _t2 and the second connection node N2. The high-side secondary winding N _H2 is connected to the rectifier circuit 12 in a magnetically coupled state to the high-side primary winding N _H1 . The low-side secondary winding N _L2 is connected to the rectifier circuit 12 in a state of being magnetically coupled to the low-side primary winding N _L1 .

  Next, the operation of the bidirectional DC / DC converter of the embodiment configured as described above will be described.

(A) Discharge mode (A1) Discharge of the output reactor Lout (see FIG. 2A)
Both the high-side and low-side main switching elements Q _m1 and Q _m2 and the high-side and low-side commutation switching elements Q _t1 and Q _t2 are in the off state, and the output reactor Lout releases energy. parasitic diode D parallel-connected battery B → reverse parallel connection of the main switching element Q _m1 of the reactor Lout → the high side for the output 2 of the smoothing capacitor C2 _m1 → first smoothing capacitor C1 (bi-directional inverter) → battery A current flows through the path B. Here, the voltage applied between the first smoothing capacitor C1, i.e., the voltage between the terminals T _p1 and the terminal T _n1 is output to bi-directional inverter connected between the terminals, the terminal T _p1 via the bi-directional inverter Current flows from the terminal to the terminal T _n1 . This is a steady state before the commutation operation. Before the commutation, no current flows through the commutation control circuit 11 and no current flows through the rectifier circuit 12.

(A2) Commutation start (see FIG. 2B)
The low-side commutation switching element Q _{t2 in} the commutation control circuit 11 is turned on. Then, in (A1), the current flowing through the antiparallel-connected parasitic diode D _m1 of the high-side main switching element Q _m1 is gradually commutated to the low-side commutation switching element Q _t2 , and the battery B → output Current flows in the path of the reactor Lout for the resonance, the reactor Lr for the resonance, the primary winding N _{L1 for the} low side, the switching element Q _{t2 for the} low side commutation, and the battery B.

In the rectifier circuit 12, the upper half of the secondary winding N _L2 → the center tap → the high side line L1 → the first smoothing in the rectifier circuit 12 by the power induced from the low side primary winding N _L1 to the low side secondary winding N _L2 capacitor C1 (bi-directional inverter) → rectifier diode D _L1 → the path of the upper half of the secondary winding N _L2, the lower half of the secondary winding N _L2 → the center tap → the high side line L1 → the first smoothing capacitor C1 (Bidirectional inverter) → Rectifier diode D _L2 → Current flows through the lower half path of the secondary winding N _L2 , and the battery B discharges to charge the first smoothing capacitor C1 (bidirectional inverter). In this case, there are only two rectifier diodes D _L1 and D _L2 in the conductive state in the rectifier circuit 12, and no current flows through the two D _H1 and D _{H2 .}

(A3) LC resonance (see FIG. 3A)
When the current flowing through the resonance reactor Lr exceeds the current flowing through the output reactor Lout in the state (A2), the resonance capacitors C _r1 and C _r2 start charging and discharging. That is, resonance capacitor C _r1 → resonance reactor Lr → low side primary winding N _L1 → low side commutation switching element Q _t2 → low side line L2 → first smoothing capacitor C1 (bidirectional inverter) → high side Line L1 → Resonance capacitor C _r1 and resonance capacitor C _r2 → Resonance reactor Lr → Primary winding N _L1 → Low side commutation switching element Q _t2 → Low side line L2 → Resonance capacitor C _A current flows through the path _r2 , and resonance operation is started.

The current flow in the rectifier circuit 12 is the same as (A2) (see FIG. 2B). Also in this case, there are only two rectifier diodes D _L1 and D _L2 in the conductive state in the rectifier circuit 12, and no current flows through the two D _H1 and D _H2 .

(A4) Transition to steady state (see FIG. 3B)
Then, when the voltage across the resonance capacitor _Cr2 , that is, the voltage applied to the low-side main switching element _Qm2 becomes 0 level, the main switching element _Qm2 is turned on. The turn-on of the main switching element Q _m2 uses soft switching (zero voltage switching (ZVS)) due to a high frequency resonance phenomenon, and switching loss is reduced.

From the time when the low-side main switching element Q _m2 is turned on, the current flowing through the resonance reactor Lr gradually decreases. Until then, the battery B → the output reactor Lout → the resonance reactor Lr → the low-side primary winding N _L1 → Low-side commutation switching element Q _t2 → Current flowing in the path of battery B transitions from battery B → output reactor Lout → low-side main switching element Q _m2 → flow of battery B path.

The current flow in the rectifier circuit 12 is the same as (A2) and (A3) described above (see FIGS. 2B and 3A). Also in this case, there are only two rectifier diodes D _L1 and D _L2 in the conductive state in the rectifier circuit 12, and no current flows through the two D _H1 and D _H2 .

(A5) Steady state (see FIG. 4A)
The current in the resonance reactor Lr disappears, and the low-side commutation switching element Q _t2 is turned off. The turn-off of the commutation switching element Q _t2 uses soft switching (zero current switching (ZCS)), and switching loss is reduced. In this steady state, the current flows only through the path of battery B → output reactor Lout → low-side main switching element Q _m2 → battery B. Therefore, the reactor Lout for output accumulates energy.

Since no current flows through the low-side primary winding N _L1 , no current flows through the rectifier circuit 12.

(A6) Commutation start (see FIG. 4B)
The low-side main switching element Q _m2 is turned off. Its instantaneous current from the commutated to the capacitor C _r2 for resonance, charging is performed to the capacitor C _r2 for resonance. While the voltage across the main switching element Q _m2 rises slowly, the current is quickly transferred to the resonance capacitor C _r2 , so that almost no switching loss occurs.

  In the transition operation as described in (A1) to (A6) above, the state of electromagnetic induction by magnetic coupling from the commutation control circuit 11 to the rectifier circuit 12 is as follows.

  In the above, as a transformer for magnetically coupling between the commutation control circuit 11 and the rectifier circuit 12 in the ARCP circuit 10, the high-side charging transformer T1 and the low-side discharging transformer T2 are clearly separated from each other. One operation does not affect the other.

In the discharge mode, when a current is passed through the primary winding N _L1 of the low-side discharge transformer T2 by turning on the low-side commutation switching element Q _t2 , the center tap type secondary winding is performed by the rectifier circuit 12 by magnetic coupling. While current is induced in the lines N _L2, since the use of the high side of the transformer T1 and the low discharge transformer T2 are arranged separately from each other without substantially magnetically coupled to the secondary winding N _L2 It does not occur that the flowing current generates an upward counter electromotive force E in the high-side primary winding _NH1 as in the conventional example. That is, since the reverse flow to the commutation control circuit 11 does not occur, there is no need to insert a diode D _G1 for backflow prevention as in the prior art high-side portion of the commutation control circuit 11.

(B) Charging mode
(B1) Accumulation of output reactor Lout (see FIG. 5A)
Both the high-side and low-side main switching elements Q _m1 and Q _m2 and the high-side and low-side commutation switching elements Q _t1 and Q _t2 are in the off state, and the output reactor Lout stores energy, and the battery A current flows in the path of B → low-side main switching element Q _m2 in antiparallel connection _Dm2 → output reactor Lout → battery B, and the battery B is charged. This is a steady state before the commutation operation. Before the commutation, no current flows through the commutation control circuit 11 and no current flows through the rectifier circuit 12.

(B2) Commutation start (see FIG. 5B)
The high-side commutation switching element Q _{t1 in} the commutation control circuit 11 is turned on. Then, in (B1), the parasitic diode D _m2 connected in reverse parallel to the main switching element Q _{m2 on} the low side → the output reactor Lout → the current flowing through the path of the battery B is gradually commutated, and the first smoothing capacitor C1 (bidirectional inverter) → high-side commutation switching element Q _t1 → high-side primary winding _NH1 → resonance reactor Lr → output reactor Lout → battery B → first smoothing capacitor C1 (bidirectional) Transition to current in the inverter) path. That is, the voltage output between the terminal T _p1 and the terminal T _n1 from the bidirectional inverter is applied between the first smoothing capacitor C1 and charged from the terminal T _p1 via the bidirectional DC / DC converter while charging the battery B. A current flows toward the terminal T _n1 .

In the rectifier circuit 12, the upper half of the secondary winding N _H2 → the rectifier diode D _H1 → the first smoothing capacitor in the rectifier circuit 12 by the power induced from the high side primary winding N _H1 to the high side secondary winding N _H2 C1 → center tap → secondary winding _NH2 upper half path and secondary winding _NH2 lower half → rectifier diode _DH2 → first smoothing capacitor C1 → center tap → secondary winding _NH2 A current flows through the lower half path, and charging and discharging of the first smoothing capacitor C1 are performed along with charging of the battery B. In this case, there are only two rectifier diodes D _H1 and D _H2 in the conductive state in the rectifier circuit 12, and no current flows through the two D _L1 and D _L2 .

(B3) LC resonance (see FIG. 6A)
When the current flowing through the resonance reactor Lr exceeds the current flowing through the output reactor Lout in the state (B2), the resonance capacitors C _r1 and C _r2 start charging and discharging. That is, the resonance capacitor C _r1 → the high-side commutation switching element Q _t1 → the high-side primary winding NH ₁ → the resonance reactor Lr → the path of the resonance capacitor C _r1 and the resonance capacitor C _r2 → First smoothing capacitor C1 (bidirectional inverter) → High-side commutation switching element Q _t1 → High-side primary winding N _H1 → Resonance reactor Lr → Resonance capacitor C _r2 The resonance operation is started.

The current flow in the rectifier circuit 12 is the same as (B2) above (see FIG. 5B). Also in this case, there are only two rectifier diodes D _H1 and D _H2 in the conductive state in the rectifier circuit 12, and no current flows through the two D _L1 and D _L2 .

(B4) Transition to steady state (see FIG. 6B)
When the voltage across the resonance capacitor C _r1 , that is, the voltage applied to the high-side main switching element Q _m1 becomes 0 level, the main switching element Q _m1 is turned on. The turn-on of the main switching element Q _m1 uses soft switching (zero voltage switching (ZVS)) due to a high frequency resonance phenomenon, and switching loss is reduced.

From the time when the high-side main switching element Q _m1 is turned on, the current flowing through the resonance reactor Lr gradually decreases until the first smoothing capacitor C1 (bidirectional inverter) → the high-side commutation switching element Q _t1. → High-side primary winding N _H1 → Resonance reactor Lr → Output reactor Lout → Battery B → The current flowing in the path of the first smoothing capacitor C1 (bidirectional inverter) is the first smoothing capacitor A transition is made from the flow of C1 (bidirectional inverter) → high-side main switching element Q _m1 → output reactor Lout → battery B → first smoothing capacitor C1 (bidirectional inverter).

The current flow in the rectifier circuit 12 is the same as (B2) and (B3) described above (see FIGS. 5B and 6A). Also in this case, there are only two rectifier diodes D _H1 and D _H2 in the conductive state in the rectifier circuit 12, and no current flows through the two D _L1 and D _L2 .

(B5) Steady state (see FIG. 7A)
The current in the resonance reactor Lr disappears, and the high-side commutation switching element Q _t1 is turned off. The turn-off of the commutation switching element Q _t1 uses soft switching (zero current switching (ZCS)), and switching loss is reduced. In this steady state, the current is as follows: first smoothing capacitor C1 (bidirectional inverter) → high-side main switching element Q _m1 → output reactor Lout → battery B → first smoothing capacitor C1 (bidirectional inverter) It will flow only on the route. Therefore, the output reactor Lout releases energy.

Since no current flows through the high-side primary winding _NH1 , no current flows through the rectifier circuit 12.

(B6) Commutation start (see FIG. 7B)
The high-side main switching element Q _m1 is turned off. Its instantaneous current from the commutated to the capacitor C _r1 for resonance, charging is performed to the capacitor C _r1 for resonance. While the voltage across the main switching element Q _m1 rises slowly, the current quickly transfers to the resonance capacitor C _r1 , so that almost no switching loss occurs. In this state, the current flows only through the path of the first smoothing capacitor C1 (bidirectional inverter) → resonance capacitor C _r1 → output reactor Lout → battery B → first smoothing capacitor C1 (bidirectional inverter). Will flow.

  In the transition operation as described in (B1) to (B6) above, the state of electromagnetic induction by magnetic coupling from the commutation control circuit 11 to the rectifier circuit 12 is as follows.

In charge mode, when current flows in the primary winding N _H1 of the high-side charging transformer T1 in turning on the commutation switching element Q _t1 of the high side, the center tap type by the rectifying circuit 12 by the magnetic coupling two A current is induced in the secondary winding N _H2 , but since the high-side charging transformer T1 and the low-side transformer T2 are separated from each other without substantially magnetic coupling, the secondary winding N It does not occur that the current flowing through _H2 generates an upward counter electromotive force E in the low-side primary winding N _L1 unlike the conventional example. That is, since the reverse flow to the commutation control circuit 11 does not occur, there is no need to insert a diode D _G2 for backflow prevention as in the prior art low-side portion of the commutation control circuit 11.

Furthermore, the diode loss in the rectifier circuit 12 can also be reduced. In the discharge mode, the number of diodes that pass when the current induced in the low-side secondary winding N _L2 flows into the first smoothing capacitor C1 (bidirectional inverter) is determined by the rectifier diodes D _L1 and D _L2. (See FIG. 2B, FIG. 3A, and FIG. 3B). In the charging mode, the number of diodes that pass when the current induced in the high-side secondary winding N _H2 flows into the first smoothing capacitor C1 (bidirectional inverter) is the rectifier diode D _H1. , D _H2 (see FIGS. 5B, 6A, and 6B).

In the case of the conventional example, the number of diodes through which the induced current passes is all four of the rectifier diodes D _H1 , D _H2 , D _L1 , and D _L2 in both the discharge mode and the charge mode. Therefore, in the embodiment of the present invention, the diode loss in the rectifier circuit 12 can be halved.

  The configuration of the rectifier circuit 12 in the ARCP circuit 10 may be configured as shown in the circuit diagram of FIG. 8 as another embodiment of the present invention.

In FIG. 8, D1 and D2 are cathode common type rectifier diodes each including two elements in one package. That is, in the first rectifier diode D1 containing two elements, two diode elements d ₁₁ and d ₁₂ are built in one package, and the respective cathodes are connected in the package. Similarly, in the second rectifier diode D2, two diode elements d ₂₁ and d ₂₂ are built in one package, and the respective cathodes are connected in the package.

The first rectifier diode D1 is associated with both the secondary winding N _H2 of the first transformer T1 and the secondary winding N _L2 of the second transformer T2, and the second rectifier diode D2 is also the first rectifier diode D2. Associated with both the secondary winding N _H2 of the transformer T1 and the secondary winding N _L2 of the second transformer T2.

That is, one of the diode element d ₁₁ of the first rectifier diode D1 has its anode connected to one end of the secondary winding N _H2 of the first transformer T1 (upper end), the other diode element d ₁₂ is The anode is connected to the other end (lower end) of the secondary winding N _L2 of the second transformer T2. Also, one of the diode elements d ₂₁ of the second rectifier diode D2 has its anode connected to the other end of the secondary winding N _H2 of the first transformer T1 (lower end), the other diode elements d The anode ₂₂ is connected to one end (upper end) of the secondary winding N _L2 of the second transformer T2.

At the operation timing corresponding to FIGS. 2B, 3A, and 3B, the low-side secondary winding N _L2 is excited, but the diode element involved in charging the first smoothing capacitor C1 is: and a diode element d ₁₂ of the first rectifier diode D1 met diode d ₂₂ of the second rectifier diode D2, the diode elements involved in charging the first rectifier diode D1 and a second rectifier diode D2 Since it is divided, the heat generated by energization is dispersed.

Further, the high-side secondary winding _NH2 is excited at the operation timing corresponding to FIGS. 5B, 6A, and 6B, but the diode involved in charging the first smoothing capacitor C1. element is a diode element d ₁₁ of the first rectifier diode D1 and meet our second diode element d ₂₁ of the rectifier diode D2, also in this case, diode elements involved in charging the first rectifier diode D1 first Since it is divided into two rectifier diodes D2, heat generated by energization is dispersed.

  FIG. 9 shows the configuration of a bidirectional DC / DC converter in still another embodiment. In this embodiment, each of the two rectifier diodes D1 and D2 is configured to include two elements of an anode common type package.

At the operation timing corresponding to FIGS. 2B, 3A, and 3B, the low-side secondary winding N _L2 is excited, but the diode element involved in charging the first smoothing capacitor C1 is: and a diode element d ₁₁ of the first rectifier diode D1 met diode element d ₂₁ of the second rectifier diode D2, the diode elements involved in charging the first rectifier diode D1 and a second rectifier diode D2 Since it is divided, the heat generated by energization is dispersed.

Further, the high-side secondary winding _NH2 is excited at the operation timing corresponding to FIGS. 5B, 6A, and 6B, but the diode involved in charging the first smoothing capacitor C1. element is a diode element d ₁₂ of the first rectifier diode D1 met diode d ₂₂ of the second rectifier diode D2, also in this case, diode elements involved in charging the first rectifier diode D1 first Since it is divided into two rectifier diodes D2, heat generated by energization is dispersed.

  Further, as another countermeasure against heat dispersion, an embodiment in which the first transformer T1 and the second transformer T2 are mechanically connected with a heat conducting member denoted by reference numeral 20 in FIGS. Is also preferable. For example, the first transformer T1 and the second transformer T2 may be arranged side by side, and the cores of the transformers may be connected to each other with a heat conductive sheet. The advantages of this measure are as follows.

  In the above-described embodiment of the present invention, when the second transformer T2 is operating, the first transformer T1 is not operating. Conversely, when the first transformer T1 is operating, the second transformer T2 is not operating. Is inoperative. That is, when one of the transformers T1 and T2 is operating, the other is not operating. An operating transformer generates heat, but a non-operating transformer does not generate heat. Therefore, heat generated in the operating transformer can be released to the other non-operating transformer having a low temperature through the heat conducting member 20, and overheating of the operating transformer can be prevented. In other words, it is possible to effectively use the other transformer as a heat sink against the heat generated by one transformer. In addition, although the sheet-like thing is preferable as the heat conductive member 20, another form may be sufficient.

  FIG. 10 shows the configuration of a bidirectional DC / DC converter in still another embodiment. 10, the same reference numerals as those used in FIG. 1 indicate the same components, and detailed descriptions thereof are omitted.

In this embodiment, as the transformer, instead of the two transformers T1 and T2 separated into the high side and the low side in the embodiment of FIG. 1, the primary winding has a center tap as a boundary and the high side portion and the low side side A transformer T0 'consisting of a part is used. In other words, the charge / discharge transformer T0 ′ in which the high-side primary winding portion N _H1 ′ and the low-side primary winding portion N _L1 ′ are connected by a center tap is used. In this charge / discharge transformer T0 ', as the secondary winding, a high-side secondary winding portion N _H2 ' and a low-side secondary winding portion N _L2 'are connected by a center tap. .

The center tap that connects the high-side primary winding portion N _H1 ′ and the low-side primary winding portion N _L1 ′ is connected to one end of the resonance reactor Lr, and the high-side primary winding portion N _H1 ′ is for high-side commutation. The low-side primary winding portion N _L1 ′ is connected to the switching element Q _t1 and the low-side commutation switching element Q _t2 .

The center tap connecting the high-side secondary winding portion N _H2 ′ and the low-side secondary winding portion N _L2 ′ is connected to the low-side line L2, and the high-side secondary winding portion N _H2 ′ is connected to the rectifier circuit 12. The rectifier diode D _H1 is connected to the high side line L1, and the low side secondary winding portion N _L2 ′ is connected to the high side line L1 via the rectifier diode D _L1 .

The high side primary winding portion N _H1 ′ and the low side primary winding portion N _L1 ′ are wound in opposite directions. The reverse polarity of the primary winding is indicated by the position of the black circle symbol “●” indicating the “winding start” of the winding described beside the winding portion. The symbol “●” is added to the lower end of the high-side primary winding portion N _H1 ′, whereas the symbol “●” is added to the upper end of the low-side primary winding portion N _L1 ′. It is noted that the polarities are opposite to each other.

When the low-side commutation switching element Q _t2 is turned on (conductive) and the other switching elements are turned off (non-conductive) when the battery is discharged, a voltage (center tap side has a high potential) is applied to the low-side primary winding portion N _L1 ′. Simultaneously, a reverse voltage (high potential on the center tap side) is generated in the high side primary winding portion N _H1 '. Here, since the high-side commutation switching element Q _t1 is off, there is no route through which current flows due to the voltage generated in the high-side primary winding portion N _H1 ′ (since the high-side commutation switching element Q _t1 is off). The current does not flow in the route of the high-side primary winding portion N _H1 ′ → resonance reactor Lr → high-side main switching element Q _m1 → high-side commutation switching element Q _t1 ). Looking at a potential level, since the (high side line L1 side of the terminal of the high side of the commutation switching element Q _t1) side drain of the high side of the commutation switching element Q _t1 becomes positive potential (high potential), Figure 11 Unlike the conventional bidirectional DC-DC converter shown in the _figure , it is not necessary to insert the back-flow prevention diode D _G1 into the line of the high-side commutation switching element Q _t1 .

Further, when the high-side commutation switching element Q _t1 is turned on (conductive) and the other switching elements are turned off (non-conductive) when the battery is charged, the voltage (center tap side is connected to the high-side primary winding portion N _H1 ′). At the same time, a reverse voltage (high potential on the center tap side) is generated in the low-side primary winding portion N _L1 ′. Here, since the low-side commutation switching element Q _t2 is OFF, there is no route through which current flows due to the voltage generated in the low-side primary winding portion N _L1 ′. Looking at a potential level, since the (low-side primary winding portion N _L1 'side of the terminal of the low side commutation switching element Q _t2) side drain of the low side of the commutation switching element Q _t2 is positive potential, conventionally shown in FIG. 11 Unlike the bidirectional DC-DC converter, it is not necessary to insert the back-flow preventing diode _DG2 into the line of the low-side commutation switching element _Qt2 .

  The present invention is useful as a technique for improving the conversion efficiency of a bidirectional DC / DC converter including an ARCP circuit.

DESCRIPTION OF SYMBOLS 10 ARCP circuit 11 Commutation control circuit 12 Rectifier circuit B Battery C1 1st smoothing capacitor C2 2nd smoothing capacitor L1 High side line L2 Low side line Lout Output reactor Lr Resonant reactor N1 1st connection node N2 1st 2 connection nodes N _H1 high side primary winding N _L1 low side primary winding N _H2 high side secondary winding N _L2 low side secondary winding N _H1 'high side primary winding part N _L1 ' low side primary Winding part Q _m1 High-side main switching element Q _m2 Low-side main switching element Q _t1 High-side commutation switching element Q _t2 Low-side commutation switching element T _p1 Inverter-side high-side input / output terminal T _n1 Inverter-side the low-side input-output terminal T _p2 the battery side of the high-side input and output terminals T _n2 trans D of the battery side of the low-side output terminal T1 the high side of the transformer T2 low _{H1, D H2, D L1,} D L2 rectifier diode

Claims (5)

A first smoothing capacitor connected between a high-side input / output terminal on one end side and a low-side input / output terminal;
A second smoothing capacitor connected between the high-side input / output terminal on the other end side and the low-side input / output terminal;
A series circuit of a high-side main switching element and an output reactor inserted in a high-side line connecting the one-side high-side input / output terminal and the other-side high-side input / output terminal;
A low-side line connecting the low-side input / output terminal on the one end side and the low-side input / output terminal on the other end side, and a first connection node connecting the high-side main switching element and the output reactor. A low-side main switching element inserted between,
An ARCP circuit connected between the high side line and the low side line;
The ARCP circuit comprises a commutation control circuit and a rectifier circuit,
The commutation control circuit includes:
A resonance reactor having one end connected to the first connection node, a transformer connected to the other end of the resonance reactor, and a primary winding of the transformer and the high side line. A high-side commutation switching element, and a low-side commutation switching element connected between the primary winding of the transformer and the low-side line,
The rectifier circuit is connected between the high side line and the low side line in a state capable of receiving power induced in the secondary winding of the transformer, and is connected to the high side with respect to the first smoothing capacitor. It is configured to supply current only in one direction from the line side toward the low side line side,
The transformer is
A high-side transformer having a primary winding connected to the high-side commutation switching element; and a low-side transformer having a primary winding connected to the low-side commutation switching element. The bidirectional DC / DC converter is characterized in that the low-side transformer and the low-side transformer are separated from each other without substantially magnetic coupling. A second connection node connecting the high-side primary winding and the low-side primary winding is connected to the other end of the resonance reactor;
A series circuit of the high-side commutation switching element and the high-side primary winding is connected between the high-side line and the second connection node, and a high-side primary winding is connected to the high-side primary winding. While the side secondary winding is magnetically coupled to the rectifier circuit,
A series circuit of the low-side commutation switching element and the low-side primary winding is connected between the low-side line and the second connection node, and a low-side secondary winding is connected to the low-side primary winding. The bidirectional DC / DC converter according to claim 1, wherein the line is magnetically coupled to the rectifier circuit. The high side and low side secondary windings are both configured as center tap type windings,
The high-side center tap type secondary winding has one end and the other end connected to the high-side line via rectifier diodes, and the center tap is directly connected to the low-side line,
The low-side center tap type secondary winding has one end and the other end connected to the low-side line via rectifier diodes, and the center tap is directly connected to the high-side line. The bidirectional DC / DC converter described in 1. A first smoothing capacitor connected between a high-side input / output terminal on one end side and a low-side input / output terminal;
A second smoothing capacitor connected between the high-side input / output terminal on the other end side and the low-side input / output terminal;
A series circuit of a high-side main switching element and an output reactor inserted in a high-side line connecting the one-side high-side input / output terminal and the other-side high-side input / output terminal;
A low-side line connecting the low-side input / output terminal on the one end side and the low-side input / output terminal on the other end side, and a first connection node connecting the high-side main switching element and the output reactor. A low-side main switching element inserted between,
An ARCP circuit connected between the high side line and the low side line;
The ARCP circuit comprises a commutation control circuit and a rectifier circuit,
The commutation control circuit includes:
A resonance reactor having one end connected to the first connection node, a transformer connected to the other end of the resonance reactor, and a primary winding of the transformer and the high side line. A high-side commutation switching element, and a low-side commutation switching element connected between the primary winding of the transformer and the low-side line,
The rectifier circuit is connected between the high side line and the low side line in a state capable of receiving power induced in the secondary winding of the transformer, and is connected to the high side with respect to the first smoothing capacitor. It is configured to supply current only in one direction from the line side toward the low side line side,
The transformer is
The primary winding includes a high side primary winding portion and a low side primary winding portion with a center tap as a boundary, the center tap is connected to the resonance reactor, and the high side primary winding portion is the high side And the low-side primary winding portion is connected to the low-side commutation switching element, and the high-side primary winding portion and the low-side primary winding portion are opposite to each other. A bidirectional DC / DC converter characterized by being wound.   The secondary winding is configured as a center tap type winding, and one end and the other end of the secondary winding of the center tap type are respectively connected to the high side line via a rectifier diode. The bidirectional DC / DC converter described in 1.

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