JP6466121B2 - Snubber circuit - Google Patents

Description

  The present invention relates to a snubber circuit.

  2. Description of the Related Art Conventionally, in a semiconductor bridge circuit, a soft switching operation using a snubber circuit is performed in order to prevent the semiconductor switching element from being destroyed due to a sudden rise in input voltage or current (Patent Document 1 and Patent Document 2). ).

  FIG. 5 is a diagram showing a snubber circuit described in Patent Document 1. As shown in FIG. As shown in FIG. 5, the snubber circuit described in Patent Document 1 includes reactors 3a and 3b, capacitors 14a and 14b, a capacitor 6, diodes 7a and 7b, and chopper circuits 18a and 18b. The semiconductor bridge circuit 20 has GTO (Gate Turn-Off thyristor) 1a, 1b and diodes 2a, 2b.

  In the turn-on operation of the GTO 1a or GTO 1b, the reactor 3a and the reactor 3b suppress a steep current change (di / dt) at the output terminal C of the semiconductor bridge circuit 20. As a result, the semiconductor bridge circuit 20 performs a ZCS (Zero Current Switching) operation. Further, when the GTO 1a or GTO 1b is turned off, the capacitor 14a, the capacitor 14b, and the capacitor 6 suppress a steep voltage change (dv / dt) at the output terminal C of the semiconductor bridge circuit 20. As a result, the semiconductor bridge circuit 20 performs a ZVS (Zero Voltage Switching) operation.

  In the series of ZCS and ZVS operations, the energy absorbed by the capacitor 14a and the capacitor 14b is converted into a DC power supply 12a and a DC power supply 12b using the chopper circuit 18a and the chopper circuit 18b including the auxiliary switch 15a and the auxiliary switch 15b. It is regenerated.

  FIG. 6 is a diagram showing a snubber circuit described in Patent Document 2. As shown in FIG. As shown in FIG. 6, the snubber circuit described in Patent Document 2 includes reactors 210 a and 210 b, capacitors 240 a and 240 b, a capacitor 30, diodes 230 a and 230 b, and a resistor 220. The semiconductor bridge circuit 40 includes IGBTs (Insulated Gate Bipolar Transistors) 410a and 410b and diodes 420a and 420b.

  In the turn-on operation of the IGBT 410a or the IGBT 410b, the reactor 210a and the reactor 210b suppress a steep current change (di / dt) of the AC output terminal 40e of the semiconductor bridge circuit 40. Thereby, the semiconductor bridge circuit 40 becomes a ZCS operation. Further, when the IGBT 410a or the IGBT 410b is turned off, the capacitor 240a, the capacitor 240b, and the capacitor 30 suppress a steep voltage change (dv / dt) at the AC output terminal 40e of the semiconductor bridge circuit 40. As a result, the semiconductor bridge circuit 40 performs a ZVS operation.

  In the series of ZCS and ZVS operations, energy absorbed by the capacitors 240a and 240b is regenerated to the DC power source 110 via the resistor 220.

JP-A-5-103481 JP 2004-80880 A

  However, the snubber circuit described in Patent Document 1 requires an auxiliary switch that is controlled by an external control command in order to regenerate energy stored in the capacitor of the snubber circuit to the DC power source. Therefore, there is a problem that the circuit configuration and system configuration of the snubber circuit are complicated and expensive. Further, in the snubber circuit described in Patent Document 2, since a resistor is used to regenerate the energy stored in the capacitor of the snubber circuit to the DC power source, there is a problem that loss occurs due to the resistor. .

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a snubber circuit that has a simple circuit configuration and can reduce loss compared to the prior art.

  One aspect of the present invention is a semiconductor bridge circuit connected in parallel between a positive electrode and a negative electrode of a DC power supply, and is connected between the semiconductor bridge circuit and the DC power supply, and constitutes the semiconductor bridge circuit. Di / dt suppression means for suppressing a steep current change di / dt at the time of turn-on of the semiconductor element and each of the semiconductor elements are provided in parallel, and a steep voltage change dv / dt at the time of turn-off of each semiconductor element is suppressed. A dv / dt suppression means for performing recovery, a recovery means for temporarily recovering energy stored in the di / dt suppression means when the semiconductor element is turned on to the dv / dt suppression means when the semiconductor element is turned off, and a turn-off of the semiconductor element. Sometimes the energy stored in the dv / dt suppression means is exchanged by the semiconductor bridge circuit when the semiconductor element is turned on. And release means for releasing the side, a snubber circuit which is characterized in that it comprises a.

  One aspect of the present invention is the above-described snubber circuit, wherein the di / dt suppression means includes a first reactor connected between a positive electrode of a DC power supply and a positive electrode of a semiconductor bridge circuit, The dv / dt suppressing means includes a first capacitor having one end connected to the positive electrode of the semiconductor bridge circuit, a second capacitor having one end connected to the negative electrode of the semiconductor bridge circuit, and the semiconductor bridge circuit. A third capacitor having one end connected to the AC output terminal, and the recovery means is connected between the other end of the first capacitor and the other end of the second capacitor. A diode series circuit including a first diode and a second diode, wherein the other end of the third capacitor is connected to a series connection point of the first diode and the second diode, Release The means includes: a first LD series circuit having a third diode and a third reactor connected between a connection point between the first capacitor and the diode series circuit and a negative electrode of the semiconductor bridge circuit; A fourth diode connected between a connection point between the second capacitor and the diode series circuit and a positive electrode of the semiconductor bridge circuit, and a second LD series circuit having a fourth reactor. .

  One embodiment of the present invention is the above-described snubber circuit, wherein the di / dt suppressing means includes a first reactor connected between a positive electrode of a DC power supply and a positive electrode of the semiconductor bridge circuit; A second reactor connected between the negative electrode of the power source and the negative electrode of the semiconductor bridge circuit, and the dv / dt suppression means has a first end connected to the positive electrode of the semiconductor bridge circuit. And a second capacitor having one end connected to the negative electrode of the semiconductor bridge circuit, and a third capacitor having one end connected to the AC output terminal of the semiconductor bridge circuit, and the recovery means Comprises a first diode and a second diode connected between the other end of the first capacitor and the other end of the second capacitor, and the first diode and the second diode Dio A diode series circuit in which the other end of the third capacitor is connected to a series connection point with the power supply circuit, and the discharge means includes a connection point between the first capacitor and the diode series circuit, and the DC power supply. A first LD series circuit having a third diode and a third reactor connected between the negative electrodes, a connection point between the second capacitor and the diode series circuit, and a positive electrode of the DC power supply And a second LD series circuit having a fourth reactor.

  One embodiment of the present invention is the above-described snubber circuit, wherein the third reactor and the fourth reactor are configured by a two-winding reactor including two windings on one iron core.

  One embodiment of the present invention is the above-described snubber circuit, in which the first reactor and the second reactor are inductance components by a distribution line from the DC power supply.

  As described above, according to the present invention, it is possible to provide a snubber circuit having a simple circuit configuration and capable of reducing loss.

It is a figure which shows the structural example of the snubber circuit 2 in the 1st Embodiment of this invention. It is a figure which shows the structural example of 2 A of snubber circuits in the 2nd Embodiment of this invention. It is a figure which shows the structural example of the snubber circuit 2B in the 3rd Embodiment of this invention. It is a figure which shows the structural example of the snubber circuit 2C in the 4th Embodiment of this invention. It is a figure which shows the 1st structural example of the conventional snubber circuit. It is a figure which shows the 2nd structural example of the conventional snubber circuit.

Below, the snubber circuit in embodiment is demonstrated using drawing.
(First embodiment)
Hereinafter, the snubber circuit 2 in the first embodiment will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of the snubber circuit 2 according to the first embodiment of the present invention.

  As shown in FIG. 1, the snubber circuit 2 is connected in parallel between the DC power supply 11 and the semiconductor bridge circuit 4. The snubber circuit 2 realizes a soft switching operation of the semiconductor bridge circuit 4 by preventing the voltage and current of the semiconductor bridge circuit 4 from rising sharply.

  The semiconductor bridge circuit 4 includes a semiconductor switch 4a and a semiconductor switch 4b. The semiconductor switch 4a is connected in series with the semiconductor switch 4b. An AC output terminal 4c that is an output terminal of the semiconductor bridge circuit 4 is connected to a series connection point between the semiconductor switch 4a and the semiconductor switch 4b. A load such as a motor is connected to the AC output terminal 4c. The semiconductor bridge circuit 4 switches between the on state and the off state of the semiconductor switch 4a and the semiconductor switch 4b by turning off or turning on the semiconductor switch 4a or the semiconductor switch 4b. Thereby, the semiconductor bridge circuit 4 supplies and drives the power of the DC power supply 11 to an inductive load such as a motor connected to the AC output terminal 4c. The DC power supply 11 is a capacitor, for example. At this time, in the turn-on operation, the semiconductor bridge circuit 4 is subjected to zero current switching (ZCS) by a reactor 21a (described later) of the snubber circuit 2. On the other hand, during the turn-off operation, the semiconductor bridge circuit 4 is subjected to zero voltage switching (ZVS) by a capacitor 26 (described later) of the snubber circuit 2.

  The semiconductor switch 4a has a switch element 42a and a diode 41a. The switch element 42a is, for example, a bipolar transistor, a MOSFET (metal-oxide-semiconductor field-effect transistor), an IGBT (Insulated Gate Bipolar Transistor), or the like. The switch element 42a is connected in parallel to the diode 41a. The semiconductor switch 4b has a switch element 42b and a diode 41b. The switch element 42b is, for example, a bipolar transistor, a MOSFET, or an IGBT. The switch element 42b is connected in parallel to the diode 41b. The positive terminal 4d of the semiconductor bridge circuit 4 is connected to the cathode of the diode 41a. The negative terminal 4e of the semiconductor bridge circuit 4 is connected to the anode of the diode 41b.

The snubber circuit 2 includes a reactor 21a, a capacitor 22a, a capacitor 22b, a diode series connection circuit 23, a capacitor 26, an LD series circuit 10, and an LD series circuit 20.
The reactor 21 a is connected between the DC power supply positive terminal 1 a and the positive terminal 4 d of the semiconductor bridge circuit 4. That is, the reactor 21a has one end connected to the DC power source positive terminal 1a and the other end connected to the positive terminal 4d.

  One end of the capacitor 22 a is connected to the positive terminal 4 d of the semiconductor bridge circuit 4 and the other end of the reactor 21 a, and the other end is connected to one end of the diode series connection circuit 23.

  One end of the capacitor 22 b is connected to the negative terminal 4 e of the semiconductor bridge circuit 4. The other end of the capacitor 22 b is connected to the other end of the diode series connection circuit 23.

  The diode series connection circuit 23 includes a diode 23a and a diode 23b. The diode 23a is connected in series with the diode 23b. That is, the cathode of the diode 23a is connected to the anode of the diode 23b. The anode of the diode 23a is connected to the other end of the capacitor 22a. The diode 23b has a cathode connected to the other end of the capacitor 22b.

  The capacitor 26 is connected between the series connection point of the diode 23 a and the diode 23 b and the AC output terminal 4 c of the semiconductor bridge circuit 4. The capacitor 26 suppresses a steep voltage change dv / dt of the output voltage at the AC output terminal 4c by discharging the electric charge stored therein.

The LD series circuit 10 includes a diode 24a and a reactor 25a. The diode 24a is connected in series with the reactor 25a. The diode 24a has an anode connected to the cathode of the diode 23b and a cathode connected to one end of the reactor 25a. Reactor 25a has the other end connected to the other end of reactor 21a.
When the reactor 25a regenerates the electric charge stored in the capacitor 22b to the AC output terminal 4c via the LD series circuit 10, the reactor 25a suppresses a steep current change di / dt of the current during the regeneration.

The LD series circuit 20 includes a diode 24b and a reactor 25b. The diode 24b is connected in series with the reactor 25b. The diode 24b has a cathode connected to the anode of the diode 23a. The diode 24a has an anode connected to one end of the reactor 25b. The other end of the reactor 25b is connected to the negative electrode terminal 4e.
When reactor 25b regenerates the electric charge stored in capacitor 22a to AC output terminal 4c via LD series circuit 20, reactor 25b suppresses a steep current change di / dt of the current during the regeneration.

Next, the operation of the snubber circuit 2 of this embodiment will be described.
First, an operation of turning off the semiconductor switch 4a from the semiconductor switch 4a in the snubber circuit 2 of the present embodiment when the semiconductor switch 4a is in the ON state and the semiconductor switch 4b is in the OFF state will be described.
When the semiconductor switch 4a is in the ON state and the semiconductor switch 4b is in the OFF state, the current from the DC power source 11 (hereinafter referred to as “output current”) is DC power source 11 → DC power source positive terminal 1a → reactor 21a → semiconductor. It flows through the path of the switch 4a → the AC output terminal 4c. The output current is output from the AC output terminal 4c to a load such as a motor. At this time, since an output current flows through the reactor 21a, energy is accumulated in the reactor 21a. At this time, since the semiconductor switch 4a is in the ON state, the capacitor 26 is charged with electric power.

  The semiconductor switch 4a is turned off when the semiconductor switch 4a is in the ON state and the semiconductor switch 4b is in the OFF state. The output current commutates in the turn-off transition period in the path of DC power supply 11 → DC power supply positive terminal 1a → reactor 21a → capacitor 22a → diode 23a → capacitor 26 → AC output terminal 4c. Thereby, the energy stored in the reactor 21a is stored in the capacitors 22a and 22b. Therefore, the voltage of the capacitor 22a and the capacitor 22b rises due to the stored energy.

  The voltage of the AC output terminal 4c is lowered by turning off the semiconductor switch 4a. At that time, the electric power stored in the capacitor 26 is released. Therefore, the potential of the AC output terminal 4c is lowered from the positive potential of the semiconductor bridge circuit 4 to the negative potential while the voltage change dv / dt is suppressed by the discharge of the capacitor 26. That is, in the turn-off operation of the semiconductor switch 4a, soft switching by ZVS that suppresses a steep voltage change dv / dt of the potential of the AC output terminal 4c with the discharge of the capacitor 26 is realized.

  Further, the output current flowing from the capacitor 26 to the AC output terminal 4c until the potential of the AC output terminal 4c drops from the positive side potential to the negative side potential of the semiconductor bridge circuit 4 is further reduced to the diode 23b → the capacitor 22b → the semiconductor switch. 4b → commutates to AC output terminal 4c. Finally, the output current flows through the path of DC power supply 11 → DC power supply negative terminal 1b → semiconductor switch 4b → AC output terminal 4c, and the commutation operation accompanying the turn-off operation of the semiconductor switch 4a is completed.

Next, the operation in which the semiconductor switch 4a is turned on from the OFF state of the semiconductor switch 4a and the semiconductor switch 4b in the snubber circuit 2 of the present embodiment will be described.
Next, when the semiconductor switch 4a is turned on again from the OFF state, the output current from the AC output terminal 4c is not only the path of the DC power supply 11 → DC power supply negative terminal 1b → semiconductor switch 4b → AC output terminal 4c described above, It also flows through the following three routes. The first is a first path of reactor 25b → diode 24b → capacitor 22a → semiconductor switch 4a. The second is a second path of capacitor 22b → diode 24a → reactor 25a → semiconductor switch 4a. The third is a path of DC power supply 11 → DC power supply positive terminal 1a → reactor 21a → semiconductor switch 4a.

  The first path is a path for regenerating the energy stored in the capacitor 22a to the AC output terminal 4c side during the turn-off operation of the semiconductor switch 4a. The second path is a path for regenerating energy stored in the capacitor 22b toward the AC output terminal 4c when the semiconductor switch 4a is turned off.

  At this time, the turn-on current of the semiconductor switch 4a passes through any one of the reactor 21a, the reactor 25a, and the reactor 25b. Therefore, the turn-on current of the semiconductor switch 4a rises slowly while suppressing a steep change in the current change di / dt. On the other hand, the output current flowing through the semiconductor switch 4b decreases.

  After the current of the semiconductor switch 4b becomes 0 and is turned off, the capacitor 26 is charged by the current flowing through the semiconductor switch 4a. Therefore, the potential of the AC output terminal 4c rises while suppressing a steep voltage change dv / dt from the negative side potential to the positive side potential of the semiconductor bridge circuit 4. That is, in the turn-on operation of the semiconductor switch 4a, soft switching by ZCS that suppresses a change in the current change dv / dt of the steep turn-on current in the turn-on operation of the semiconductor switch 4a is realized.

  Finally, all output current flows through the path of the DC power supply 11 → the reactor 21a → the semiconductor switch 4a → the AC output terminal 4c, and the commutation operation accompanying the turn-on operation of the semiconductor switch 4a is completed.

Thus, the current energy of the reactor 21 that has been stored in the capacitors 22a and 22b at the time of the previous turn-off and has increased the capacitor voltage is transferred to the output side along with the commutation of the output current in the process of the current turn-on operation. Released. For this reason, the current energy of the reactor 21 can be regenerated to the output side without causing loss of electric energy in the snubber circuit 2. Further, in the reverse recovery operation at the diode 41b of the semiconductor switch 4b caused by the turn-on of the semiconductor switch 4a, soft switching is realized because the current change di / dt and the voltage change dv / dt are suppressed. Yes.
Note that the same effect can be obtained from the symmetry of the circuit even in the turn-on and turn-off operations of the semiconductor switch 4b in the reverse direction of the output current, and detailed description thereof will be omitted.

  As described above, the snubber circuit 2 according to the present embodiment includes the reactor 21 a that is a current change di / dt suppression unit between the semiconductor bridge circuit 4 and the DC power supply 11. Further, capacitors 22a, 22b and 26, which are steep voltage change dv / dt suppression means, are provided in parallel with the semiconductor switch. As a result, the energy stored in the current change di / dt suppressing means can be temporarily recovered by the steep voltage change dv / dt suppressing means when the semiconductor bridge circuit 4 is turned off. Further, the energy stored in the steep voltage change dv / dt suppressing means can be released to the AC side of the semiconductor bridge circuit 4 without using a resistance element or a controllable semiconductor element (switch) when the semiconductor bridge circuit 4 is turned on. . Therefore, the loss of electrical energy and / or the number of parts in the snubber circuit 2 can be reduced as compared with the conventional method, which contributes to the downsizing, cost reduction, and loss reduction of the device. Furthermore, since the EMI noise emitted from the snubber circuit 2 is reduced in principle by the soft switching operation, the countermeasure against EMI becomes easier as compared with the general method of the hard switching method.

(Second Embodiment)
Hereinafter, the snubber circuit 2A in the second embodiment will be described with reference to the drawings. FIG. 2 is a diagram illustrating a configuration example of the snubber circuit 2A according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.
The snubber circuit 2A of the present embodiment further includes a reactor 21B in the configuration of the first embodiment. Further, the snubber circuit 2A of the present embodiment has a configuration in which the connection positions of the reactor 25a and the reactor 25b of the configuration of the first embodiment are changed to the DC power supply positive terminal 1a and the DC power supply negative terminal 1b of the DC power supply 11.

  As shown in FIG. 2, the snubber circuit 2 </ b> A is connected in parallel between the DC power supply 11 and the semiconductor bridge circuit 4. The snubber circuit 2 </ b> A realizes a soft switching operation of the semiconductor bridge circuit 4 by preventing the voltage and current of the semiconductor bridge circuit 4 from rising sharply.

The snubber circuit 2A includes a reactor 21A, a reactor 21B, a capacitor 22a, a capacitor 22b, a diode series connection circuit 23, a capacitor 26, an LD series circuit 10, and an LD series circuit 20.
The reactor 21 </ b> A is connected between the DC power supply positive terminal 1 a and the positive terminal 4 d of the semiconductor bridge circuit 4. Further, the reactor 21 </ b> A is connected between one end of the capacitor 22 a and the LD series circuit 10.

  The reactor 21 </ b> B is connected between the DC power supply negative terminal 1 b and the negative terminal 4 e of the semiconductor bridge circuit 4. That is, one end of the reactor 21 </ b> B is connected to the LD series circuit 20. Reactor 21B has the other end connected to one end of capacitor 22b.

  The LD series circuit 10 includes a diode 24a and a reactor 25a. The diode 24a is connected in series with the reactor 25a. The anode of the diode 24a is connected to the cathode of the diode 23b. The diode 24a has a cathode connected to one end of the reactor 25a. Reactor 25a has the other end connected to one end of reactor 21A.

  The LD series circuit 20 includes a diode 24b and a reactor 25b. The diode 24b is connected in series with the reactor 25b. The diode 24b has a cathode connected to the anode of the diode 23a. The diode 24a has an anode connected to one end of the reactor 25b. Reactor 25a has the other end connected to one end of reactor 21B.

Next, the operation of the snubber circuit 2A of this embodiment will be described.
First, in the snubber circuit 2A of this embodiment, an operation in which the semiconductor switch 4a is turned off from the semiconductor switch 4a being turned on and the semiconductor switch 4b being turned off will be described.
When the semiconductor switch 4a is in the ON state and the semiconductor switch 4b is in the OFF state, the output current flows through the path of the DC power supply 11 → DC power supply positive terminal 1a → reactor 21A → semiconductor switch 4a → AC output terminal 4c. The output current is output from the AC output terminal 4c to a load such as a motor. At this time, since an output current flows through the reactor 21A, energy is accumulated in the reactor 21A. At this time, since the semiconductor switch 4a is in the ON state, the capacitor 26 is charged with electric power.

  The semiconductor switch 4a is turned off when the semiconductor switch 4a is in the ON state and the semiconductor switch 4b is in the OFF state. The output current commutates in the turn-off transition period in the path of DC power supply 11 → DC power supply positive terminal 1a → reactor 21A → capacitor 22a → diode 23a → capacitor 26 → AC output terminal 4c. Thereby, the energy stored in the reactor 21A is stored in the capacitor 22a and the capacitor 22b. Therefore, the voltage of the capacitor 22a and the capacitor 22b rises due to the stored energy.

  The voltage of the AC output terminal 4c is lowered by turning off the semiconductor switch 4a. At that time, the electric power stored in the capacitor 26 is released. Therefore, the potential of the AC output terminal 4c is lowered from the positive potential of the semiconductor bridge circuit 4 to the negative potential while the steep voltage change dv / dt is suppressed by the discharge of the capacitor 26. That is, in the turn-off operation of the semiconductor switch 4a, soft switching by ZVS that suppresses a steep voltage change dv / dt of the potential of the AC output terminal 4c with the discharge of the capacitor 26 is realized.

  Further, the output current flowing from the capacitor 26 to the AC output terminal 4c until the potential of the AC output terminal 4c drops from the positive side potential to the negative side potential of the semiconductor bridge circuit 4 is further reduced to the diode 23b → the capacitor 22b → the semiconductor switch. 4b → commutates to AC output terminal 4c. Finally, the output current flows through the path of DC power supply 11 → DC power supply negative terminal 1b → reactor 21B → semiconductor switch 4b → AC output terminal 4c, and the commutation operation accompanying the turn-off operation of the semiconductor switch 4a is completed. To do.

Next, an operation of turning on the semiconductor switch 4a from the semiconductor switch 4a and the semiconductor switch 4b in the snubber circuit 2A of the present embodiment from the OFF state will be described.
Next, when the semiconductor switch 4a and the semiconductor switch 4b are turned off again from the OFF state, when the semiconductor switch 4a is turned on again, the output current is the DC power supply 11 → DC power supply negative terminal 1b → reactor 21B → semiconductor switch 4b → AC output terminal 4c. In addition to this route, it also flows through the following three routes. The first is a first path of reactor 25b → diode 24b → capacitor 22a → semiconductor switch 4a. The second is a second path of capacitor 22b → diode 24a → reactor 25a → semiconductor switch 4a. The third is a path of DC power supply 11 → DC power supply positive terminal 1a → reactor 21A → semiconductor switch 4a.

  The first path is a path for regenerating the energy stored in the capacitor 22a to the AC output terminal 4c side during the turn-off operation of the semiconductor switch 4a. The second path is a path for regenerating energy stored in the capacitor 22b toward the AC output terminal 4c when the semiconductor switch 4a is turned off.

  At this time, the turn-on current of the semiconductor switch 4a passes through any one of the reactor 21A, the reactor 21B, the reactor 25a, and the reactor 25b. Therefore, the turn-on current of the semiconductor switch 4a rises while suppressing the steep current change di / dt. On the other hand, the output current flowing through the semiconductor switch 4b decreases.

  After the current of the semiconductor switch 4b becomes 0 and becomes the OFF state, the capacitor 26 is charged by the current flowing through the semiconductor switch 4a. Therefore, the potential of the AC output terminal 4c rises while suppressing a steep voltage change dv / dt from the negative side potential to the positive side potential of the semiconductor bridge circuit 4. That is, in the turn-on operation of the semiconductor switch 4a, soft switching by ZCS that suppresses the current change dv / dt of the turn-on current in the turn-on operation of the semiconductor switch 4a is realized.

  Finally, all output current flows through the path of the DC power source 11 → the reactor 21A → the semiconductor switch 4a → the AC output terminal 4c, and the commutation operation accompanying the turn-on operation of the semiconductor switch 4a is completed.

Thus, the current energy of the reactor 21 that has been stored in the capacitors 22a and 22b at the time of the previous turn-off and has increased the capacitor voltage is transferred to the output side along with the commutation of the output current in the process of the current turn-on operation. Released. For this reason, the current energy of the reactor 21 can be regenerated to the output side without causing the loss of the snubber circuit 2A. Further, in the reverse recovery operation at the diode 41b of the semiconductor switch 4b caused by the turn-on of the semiconductor switch 4a, soft switching is realized because the current change di / dt and the voltage change dv / dt are suppressed. Yes.
Note that the same effect can be obtained from the symmetry of the circuit even in the turn-on and turn-off operations of the semiconductor switch 4b in the reverse direction of the output current, and detailed description thereof will be omitted.

  As described above, the snubber circuit 2 </ b> A of the present embodiment includes the reactor 21 </ b> A and the reactor 21 </ b> B that are current change di / dt suppression means between the semiconductor bridge circuit 4 and the DC power supply 11. Further, capacitors 22a, 22b and 26, which are steep voltage change dv / dt suppression means, are provided in parallel with the semiconductor switch. This has the same effect as the first embodiment.

(Third embodiment)
Hereinafter, the snubber circuit 2B in the third embodiment will be described with reference to the drawings. FIG. 3 is a diagram illustrating a configuration example of the snubber circuit 2B according to the third embodiment. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.
The snubber circuit 2B of the present embodiment has a configuration in which the reactor 25a and the reactor 25b are changed to a single reactor 27 including two windings (reactor 27-1 and reactor 27-2) in the configuration of the first embodiment. is there. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 3, the snubber circuit 2 </ b> B is connected in parallel between the DC power supply 11 and the semiconductor bridge circuit 4. The snubber circuit 2B realizes a soft switching operation of the semiconductor bridge circuit 4 by preventing the voltage and current of the semiconductor bridge circuit 4 from rising sharply.

  The snubber circuit 2B includes a reactor 21a, a capacitor 22a, a capacitor 22b, a diode series connection circuit 23, a capacitor 26, a reactor 27, a diode 24a, and a diode 24b.

  The reactor 27 includes a reactor 27-1 and a reactor 27-2. The reactor 27 is a reactor in which the cores of the reactor 27-1 and the reactor 27-2 are made common.

The diode 24a is connected in series with the reactor 25a. The anode of the diode 24a is connected to the cathode of the diode 23b. The diode 24a has a cathode connected to one end of the reactor 27-1. Reactor 27-1 has the other end connected to the other end of reactor 21a.
When reactor 27-1 regenerates the electric charge stored in capacitor 22b to AC output terminal 4c via diode 24a and reactor 27-1, it suppresses a steep current change di / dt of the current during the regeneration. .

The diode 24b is connected in series with the reactor 27-2. The diode 24b has a node connected to the anode of the diode 23a. The anode of the diode 24a is connected to one end of the reactor 27-2. The other end of the reactor 27-2 is connected to the negative electrode terminal 4e.
When reactor 27-2 regenerates the electric charge stored in capacitor 22a to AC output terminal 4c via diode 24b and reactor 27-2, reactor 27-2 suppresses a steep current change di / dt of the current during the regeneration. .
Note that the operation of the snubber circuit 2B of the present embodiment is the same as that of the first embodiment, and thus the description thereof is omitted.

  As described above, the snubber circuit 2 </ b> B of the present embodiment includes the reactor 21 a that is a current change di / dt suppression unit between the semiconductor bridge circuit 4 and the DC power supply 11. Further, capacitors 22a, 22b and 26, which are steep voltage change dv / dt suppression means, are provided in parallel with the semiconductor switch. This has the same effect as the first embodiment. Moreover, the snubber circuit 2B of this embodiment changed the reactor 25a and the reactor 25b into one reactor 27 provided with two windings (reactor 27-1 and reactor 27-2) in the structure of 1st Embodiment. It is a configuration. Therefore, the snubber circuit 2B of the present embodiment can be made smaller and less expensive than the first embodiment.

(Fourth embodiment)
Hereinafter, the snubber circuit 2C in the fourth embodiment will be described with reference to the drawings. FIG. 4 is a diagram illustrating a configuration example of the snubber circuit 2C according to the fourth embodiment. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.
The snubber circuit 2C of the present embodiment has a configuration in which the reactor 21a of the configuration of the first embodiment is omitted. However, the snubber circuit 2C of the present embodiment takes in the stray inductance components 28a and 28b existing in the wiring (distribution line) as components when manufacturing an actual snubber circuit. In order to adjust the stray inductance components 28a and 28b, the semiconductor bridge circuit 4 and the snubber circuit 2C are arranged closest to each other. In addition, the snubber circuit 2C and the DC power supply 11 are wired long.

  The snubber circuit 2C includes a stray inductance component 28a, a stray inductance component 28b, a capacitor 22a, a capacitor 22b, a diode series connection circuit 23, a capacitor 26, an LD series circuit 10, and an LD series circuit 20.

  The stray inductance component 28 a is connected between the DC power source positive terminal 1 a and the positive terminal 4 d of the semiconductor bridge circuit 4. That is, one end of the stray inductance component 28a is connected to the DC power source positive terminal 1a. The other end of the stray inductance component 28a is connected to the positive terminal 4d.

  The stray inductance component 28 b is connected between the DC power source negative terminal 1 b and the negative terminal 4 e of the semiconductor bridge circuit 4. That is, one end of the stray inductance component 28b is connected to the DC power source negative terminal 1b. The other end of the stray inductance component 28b is connected to the negative electrode terminal 4e.

  One end of the capacitor 22a is connected to the positive terminal 4d of the semiconductor bridge circuit 4 and the other end of the stray inductance component 28a. The other end of the capacitor 22 a is connected to one end of the diode series connection circuit 23.

  One end of the capacitor 22b is connected to the negative terminal 4e of the semiconductor bridge circuit 4 and the other end of the stray inductance component 28b. The other end of the capacitor 22 b is connected to the other end of the diode series connection circuit 23.

The other end of the reactor 25a is connected to the other end of the stray inductance component 28a. The other end of the reactor 25b is connected to the other end of the stray inductance component 28b.
Note that the operation of the snubber circuit 2C of this embodiment is the same as that of the first embodiment, and a description thereof will be omitted.

  As described above, the snubber circuit 2C of the present embodiment incorporates the stray inductance components 28a and 28b existing in the wiring as current change di / dt suppressing means. Further, capacitors 22a, 22b and 26, which are steep voltage change dv / dt suppression means, are provided in parallel with the semiconductor switch. This has the same effect as the first embodiment.

  The above-described embodiments are all illustrative of the embodiments of the present invention and are not limited to the embodiments, and the present invention can be implemented in various other modifications and changes.

  2 ... Snubber circuit, 4, 20 ... Semiconductor bridge circuit, 4a, 4b ... Semiconductor switch, 10, 20 ... LD series circuit, 11 ... DC power supply, 21a ... Reactor, 22a, 22b, 26 ... Capacitor, 23 ... Diode series connection circuit

Claims (4)

In the semiconductor bridge circuit connected in parallel between the positive electrode and the negative electrode of the DC power supply,
Di / dt suppressing means connected between the semiconductor bridge circuit and the direct current power source for suppressing a steep current change di / dt at turn-on of each semiconductor element constituting the semiconductor bridge circuit;
Dv / dt suppressing means that is provided in parallel with each of the semiconductor elements, and suppresses a steep voltage change dv / dt when the semiconductor elements are turned off;
Recovery means for temporarily recovering energy stored in the di / dt suppression means when the semiconductor element is turned on to the dv / dt suppression means when the semiconductor element is turned off;
An emission means for releasing energy stored in the dv / dt suppressing means when the semiconductor element is turned off to the alternating current side of the semiconductor bridge circuit when the semiconductor element is turned on;
Bei to give a,
The di / dt suppression means has a first reactor connected between the positive electrode of the DC power supply and the positive electrode of the semiconductor bridge circuit,
The dv / dt suppressing means includes a first capacitor having one end connected to the positive electrode of the semiconductor bridge circuit, a second capacitor having one end connected to the negative electrode of the semiconductor bridge circuit, and the semiconductor bridge circuit. A third capacitor having one end connected to the AC output terminal of
The recovery means includes a first diode and a second diode connected between the other end of the first capacitor and the other end of the second capacitor, and the first diode and the second diode A diode series circuit in which the other end of the third capacitor is connected to a series connection point with the second diode;
The discharge means is
A first LD series circuit having a third diode and a third reactor connected between a connection point between the first capacitor and the diode series circuit and a negative electrode of the semiconductor bridge circuit; A second LD series circuit having a fourth diode and a fourth reactor connected between a connection point of two capacitors and the diode series circuit and a positive electrode of the semiconductor bridge circuit;
Snubber circuit and having a. In the semiconductor bridge circuit connected in parallel between the positive electrode and the negative electrode of the DC power supply,
Di / dt suppressing means connected between the semiconductor bridge circuit and the direct current power source for suppressing a steep current change di / dt at turn-on of each semiconductor element constituting the semiconductor bridge circuit;
Dv / dt suppressing means that is provided in parallel with each of the semiconductor elements, and suppresses a steep voltage change dv / dt when the semiconductor elements are turned off;
Recovery means for temporarily recovering energy stored in the di / dt suppression means when the semiconductor element is turned on to the dv / dt suppression means when the semiconductor element is turned off;
An emission means for releasing energy stored in the dv / dt suppressing means when the semiconductor element is turned off to the alternating current side of the semiconductor bridge circuit when the semiconductor element is turned on;
With
The di / dt suppression means is connected between the first reactor connected between the positive electrode of the DC power supply and the positive electrode of the semiconductor bridge circuit, and between the negative electrode of the DC power supply and the negative electrode of the semiconductor bridge circuit. A second reactor,
The dv / dt suppressing means includes a first capacitor having one end connected to the positive electrode of the semiconductor bridge circuit, a second capacitor having one end connected to the negative electrode of the semiconductor bridge circuit, and the semiconductor bridge circuit. A third capacitor having one end connected to the AC output terminal of
The recovery means includes a first diode and a second diode connected between the other end of the first capacitor and the other end of the second capacitor, and the first diode and the second diode A diode series circuit in which the other end of the third capacitor is connected to a series connection point with the second diode;
The discharge means is
A first LD series circuit having a third diode and a third reactor connected between a connection point of the first capacitor and the diode series circuit and a negative electrode of the DC power supply;
A second LD series circuit having a fourth diode and a fourth reactor connected between a connection point of the second capacitor and the diode series circuit and a positive electrode of the DC power supply;
Features and be away snubber circuit to have a. The third reactor and the fourth reactor, the snubber circuit according to claim 1 or claim 2, characterized in that it is composed of two winding-reactor having two windings on a single core. 3. The snubber circuit according to claim 2 , wherein the first reactor and the second reactor are inductance components due to a distribution line from the DC power supply.

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