JPH1094249A - Chopper circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regenerate snubber energy collectively into a main circuit in a chopper circuit which uses a plurality of self-arc-extinguishing devices by a method wherein a snubber circuit constituted of a snubber diode, of a snubber capacitor and of an auxiliary switch which is composed of a self-arc- extinguishing device is installed in common to respective phases. SOLUTION: A snubber circuit which is constituted of a snubber diode 29, of a snubber capacitor 31 which is connected in series with the diode and of an auxiliary switch 33 which is connected in parallel with the diode 29 and the capacitor 31 and which is composed of a self-arc-extinguishing device is installed in common to respective phases. When the auxiliary switch 33 is turned on simultaneously with the turn-on operation of chopping parts 1G1 to 1Gn, an electric charge in a capacitor 9 is discharged in respective circuits of the capacitor 9- reactors 1L1 (1L2, 1Ln) - the chopping devices 1G1 (1G2, 1Gn) the capacitor 9, energy is accumulated in the main circuit reactors 1L1 to 1Ln. Thereby, snubber energy can be regenerated in a main circuit, and a power loss can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chopper circuit having a circuit for regenerating snubber energy.

[0002]

2. Description of the Related Art As a direct current converter such as a chopper circuit constructed by using a self-extinguishing type semiconductor device such as a GTO (gate turn-off thyristor), FIG.
Conventionally, a step-down chopper circuit shown in FIG. 0 and a step-up chopper circuit shown in FIG. 31 are known.

In the step-down chopper circuit shown in FIG. 30, a main circuit is constituted by a DC power supply 60, a chop unit 1 composed of a GTO, a main circuit reactor 1L, and a load 90. Diode 2 for main circuit reactor 1L and load 90
1 are connected in anti-parallel. A snubber circuit including a snubber diode 2, a snubber capacitor 3 connected in series with the snubber diode 2, and a snubber resistor 4 </ b> R connected in parallel to the snubber diode 2 is connected to the chop unit 1 in parallel.

The step-down chopper circuit shown in FIG. 30 is configured such that the main circuit reactor 1 is turned on while the chop unit 1 is turned on.
A current flows to the load 90 via L, and energy is stored in the main circuit reactor 1L during this period. When the chop unit 1 is turned off, the energy stored in the main circuit reactor 1L returns to the load via the diode 21. The time width of the ON period Ton can be controlled to function as a step-down chopper that converts a high DC voltage into a low DC voltage.

In the step-up chopper circuit shown in FIG. 31, a DC power supply 60, a main circuit reactor 1L, a diode 21 and a load 90 constitute a main circuit, and a chop unit 1 made of GTO is provided for the diode 21 and the load 90.
Are connected in parallel. A snubber diode 2 and a snubber capacitor 3 similar to those in FIG.
And a snubber circuit composed of a snubber resistor 4R is connected in parallel.

The boost chopper circuit shown in FIG. 31 turns on the chop unit 1 to accumulate energy in the main circuit reactor 1L, turns off the chop unit 1 for the next predetermined period, and restores the main circuit to a voltage from the DC power supply 60. A low DC voltage is converted into a high DC voltage by superimposing a voltage based on the energy stored in the reactor 1L and supplying the voltage to the load 90 via the diode 21.

The above is an example of a conventional DC direct conversion device. On the other hand, in a conventional orthogonal conversion device such as an inverter 50, a DC circuit includes a power supply 60, a reactor 15, and an inverter 50 as shown in FIG. It is known that a main circuit is configured, and a surge absorbing circuit having the same configuration as the snubber circuit, which includes a diode 7, a capacitor 6, and a resistor 4R, is connected in parallel to the inverter 50. The AC circuit of the inverter 50 is connected to the AC circuit via the transformer 51.

In these DC direct converters and quadrature converters, the capacity of self-extinguishing devices has been increased in recent years, and it has become possible to manufacture devices with higher capacity and higher pressure. FIG. 33 shows an example of a conventional step-up chopper circuit which is multi-phased for such a large capacity.

The device shown in FIG. 33 is a multi-phase (n-phase) version of the boost chopper circuit shown in FIG. 31. A main circuit capacitor 9 is connected to a DC input terminal, and a main output capacitor is connected in parallel to a load at a DC output terminal. The circuit capacitor 6 is connected. Here, n
.., N unit chopper circuits. Each unit chopper circuit, as a main circuit component,
Main circuit reactor 1L and main circuit diode 7D connected in series to a DC power supply and a load (not shown)
And a chop 1G made of GTO connected in parallel to the main circuit diode 7D and the load. A snubber circuit including a snubber capacitor 3C, a snubber diode 2D and a snubber resistor 4R is connected in parallel to the chop unit 1G. Components specific to any of the first to nth unit circuits are illustrated by adding one of 1 to n to the end of each element code. For example, the n-th chop portion is indicated by a code “1Gn” by adding a code “n” to a code “1G”. In the n-phase chopper circuit configured as described above, for example, the loss Ps of the snubber resistor 4R1 included in the snubber circuit of the first unit circuit is a sum of the loss at the time of turning on and the time of turning off of the chop unit 1G1, and is generally expressed by the following equation. Is shown. Ps = (１ ／) ・ C ・ E ²・ f + (１ ／) ・ kＣC ・ E ²・ f (1) where C: capacitance of snubber capacitor 3C1 E: DC voltage f: switching frequency k: Proportional constant depending on wiring inductance From equation (1), it can be seen that the loss Ps of the snubber circuit is determined by the DC voltage, frequency and snubber capacitor capacitance. Generally, in order to increase the capacity of the device and to achieve high performance such as PWM control, it is necessary to increase the operating frequency and increase the capacity of the GTO.
In this case, a self-extinguishing device such as that described above is used, but this requires not only a large-capacity snubber capacitor to ensure the withstand voltage during turn-off, but also an increase in operating frequency and DC voltage. According to equation (1), the snubber loss is greatly increased.

A trial calculation of the case of five phases (n = 5) in equation (1) shows that, for example, a GT of 6000 V / 3000 A
For O, C = 6 μF, E = 2.33 kV, k = 1.2,
f = 180 Hz, and when, in per phase, Ps = (1/2) · 6 × 10 -6 · 2.33 2 × 10 6 · 180 · 2.2 = 6.45 is [kW], 5 For the phase component, 6.45 × 5 = 32.2 [kW]
Also reach.

[0011]

As will be understood from the above calculation, the problems in the conventional chopper circuit are extracted as follows. (1) Due to the increase in the capacity of the semiconductor device, a large-capacity snubber capacitor is required in order to secure the blocking resistance at the time of turn-off, and the snubber loss increases. (2) As the operating frequency increases due to the higher frequency of the device,
A large power loss occurs in the snubber circuit. (3) With the increase in the pressure and the capacity of the device, it becomes necessary to connect a plurality of semiconductor devices in parallel or in series, and the loss of the snubber circuit also increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In a direct current direct-current converter such as a polyphase chopper device using a plurality of self-extinguishing devices such as a GTO, a snubber energy is mainly used. It is an object of the present invention to provide a chopper circuit that can regenerate a circuit and greatly reduce power loss.

[0013]

In order to achieve the above object, the present invention is configured as follows. Claim 1
The invention of the present invention relates to a first main circuit capacitor connected between a positive DC input terminal and a negative DC input terminal, and a first main circuit capacitor connected between a positive DC output terminal and a negative DC output terminal common to the negative DC input terminal. A main circuit capacitor, a main circuit reactor arranged on the input side, and a series main circuit composed of a main circuit diode arranged in series with the main circuit current and having a forward polarity with respect to the main circuit current on the output side. A plurality of series main circuit groups connected in parallel between the positive DC output terminals, and a self-discharge circuit connected between the connection point of each main circuit reactor and main circuit diode of the series main circuit group and the negative DC input terminal. A chop group consisting of an arc-shaped device, a first snubber capacitor arranged on the positive side and a first snubber diode arranged in series with the first snubber diode on the negative side for each chop section, and are parallel to the chop section. Connected to A first snubber circuit group, a reactor connected between the DC input terminals via a first diode having a polarity opposite to the main circuit voltage, and an anode connected to a connection point between the reactor and the first diode. A second snubber circuit comprising a second snubber diode and a second snubber capacitor connected in series thereto, and an auxiliary switch connected in parallel to the second snubber diode and the second snubber capacitor; The anode is connected to the cathode of the second snubber diode between the connection point of the second snubber diode and the second snubber capacitor in the second snubber circuit and the anode of the first chop section in the chop section group. A second diode, a connection point between the auxiliary switch and the second snubber capacitor, and a first snubber capacitor in the first snubber circuit group. Between each of the connection points of the support and the first snubber diode, a chopper circuit that includes a third diode group connected with its anode to the switch side.

According to a second aspect of the present invention, in the chopper circuit according to the first aspect, a third snubber diode connected in series to an anode of the second diode, and a third snubber capacitor connected in series to the third snubber diode. A third snubber circuit including a second auxiliary switch connected in parallel to the third snubber diode and the third snubber capacitor; a connection point between the second auxiliary switch and the second snubber capacitor; And a third diode having a cathode connected to the anode of the third snubber diode between the snubber diode and the connection point of the third snubber capacitor.

According to a third aspect of the present invention, there is provided a chop section comprising a self-arc-extinguishing device disposed on the input side and a main circuit reactor connected in series to the output side thereof. A main circuit connected in reverse polarity with respect to the main circuit voltage between a series main circuit connected between the terminals, and a connection point between the chop portion and the main circuit reactor and a negative DC output terminal common to the negative DC input terminal. A first snubber capacitor arranged on the input side and a first snubber diode arranged on the output side in series with the diode;
A first snubber circuit connected in parallel to the chop unit, a reactor and a first diode connected in series with the first diode in reverse polarity to the main circuit voltage, and connected in parallel between the positive and negative DC input terminals. An auxiliary circuit, a second snubber diode having a cathode connected to the cathode of the first diode and a second snubber capacitor connected in series thereto, and a second snubber diode connected in parallel to the second snubber diode and the second snubber capacitor. A second snubber circuit comprising a first auxiliary switch connected to a third snubber diode having an anode connected to a connection point of a chop portion and a main circuit reactor, and an anode of a second snubber diode connected in series with the third snubber diode. And a third snubber capacitor connected in parallel with the third snubber diode and the third snubber capacitor. Third of a second auxiliary switches
Between the connection point of the third snubber diode and the third snubber capacitor and the connection point of the second snubber capacitor and the first auxiliary switch.
And a second diode connected to the cathode of the snubber diode.

According to a fourth aspect of the present invention, there is provided a first main circuit capacitor connected between positive and negative DC input terminals, a first main circuit reactor connected between a positive DC input terminal and a positive DC output terminal, A first power supply having a positive electrode disposed between the positive DC output terminal and the negative DC output terminal common to the negative DC input terminal, with the anode disposed between the positive DC output terminal and the negative DC output terminal.
A second main circuit capacitor connected in series to the second diode via a diode, a second diode having an anode connected to the cathode of the first diode, and a second diode connected in series to the cathode of the second diode. A chop circuit including a chop unit including a self-arc-extinguishing device, a second main circuit reactor connected between a cathode of the chop unit and a positive DC output terminal, and a chop unit including a chop unit and a second main circuit reactor. A third diode connected between the connection point and the negative DC input terminal with the anode being the negative DC input terminal side, a first snubber diode having a cathode connected to the cathode of the chop section, and a series connected thereto; A first snubber circuit comprising a first snubber capacitor connected between the anode of the chop portion, a second snubber diode having the anode connected to the positive DC output terminal, and a series connected thereto; The first of the snubber capacitor and the first
A second snubber circuit including a second snubber capacitor connected between the second snubber diode and a connection point between the second snubber diode and the second snubber capacitor, and a cathode of the second diode. And a fourth diode connected between the anode and the fourth diode with the anode facing the cathode of the second snubber diode. According to a fifth aspect of the present invention, the first main circuit capacitor is connected between the positive DC input terminal and the negative DC input terminal, and is connected between the positive DC output terminal and the negative DC input terminal and the common negative DC output terminal. A series main circuit comprising a second main circuit capacitor, a main circuit reactor arranged on the input side, and a main circuit diode arranged in series with the main circuit current and having a forward polarity with respect to the main circuit current on the output side has a positive DC input terminal. And a plurality of series main circuit groups connected in parallel between the positive DC output terminals, and each main circuit reactor and the main circuit diode of the series main circuit group are connected in series between a connection point of the main circuit diode and a negative DC input terminal. A first and a second chopping unit group comprising a self-extinguishing device, a first snubber capacitor disposed on the positive side, and a first snubber diode disposed in series with the first snubber diode on the negative side. Chop section A first snubber circuit group connected in parallel to the first chop unit, a second snubber capacitor arranged on the positive side, and a second snubber diode arranged in series with the second snubber diode on the negative side, A second snubber circuit group connected in parallel to the second chop section in each chop section, a first diode arranged on the positive side with a polarity opposite to the main circuit voltage, and arranged in series with the first diode on the negative side Reactor connected between the positive and negative DC input terminals, and a third snubber diode having an anode connected to the connection point of the first diode and the reactor in the series auxiliary circuit, connected in series with the reactor A third snubber capacitor, and a third snubber circuit including a third snubber diode and a first auxiliary switch connected in parallel to the third snubber capacitor. A fourth snubber diode having a cathode connected to a connection point of the first and second self-extinguishing devices of the first chop unit in the chop unit group, and a third snubber circuit in series with the third snubber circuit. A fourth snubber capacitor connected between the third snubber diode and the third snubber capacitor, and a second auxiliary switch connected in parallel with the fourth snubber diode and the fourth snubber capacitor. A fourth snubber circuit, and a second snubber circuit having an anode connected to a third snubber capacitor side between a free end of the third snubber capacitor and a connection point of the fourth snubber diode and the fourth snubber capacitor. A connection point between the diode, the fourth snubber capacitor and the second diode, and a first snubber circuit of each first snubber circuit in the first snubber circuit group; A third diode group having the anode connected to the fourth snubber capacitor side between the capacitor and the first snubber capacitor connection point; and a connection point between the fourth snubber capacitor and the second diode and the first diode group. A fourth snubber capacitor connected between the second snubber capacitor and the second snubber capacitor connection point of each second snubber circuit in the snubber circuit group with the anode connected to the fourth snubber capacitor side; This is a chopper circuit.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. This embodiment relates to a step-up chopper circuit and employs a known multi-phase (n
While removing the snubber resistors 4R1, 4R2,..., 4Rn from the snubber circuit in the phase) type boost chopper circuit,
A new snubber circuit is added. In other words, here, since the snubber energy is collectively regenerated to the main circuit, as a simple single snubber energy regeneration circuit unit,
A second auxiliary switch 33 composed of a snubber diode 29 and a snubber capacitor 31 connected in series with the snubber diode 29 and a self-extinguishing device connected in parallel to the snubber diode 29 and the snubber capacitor 31; A snubber circuit is provided commonly for each phase. Further, if necessary, a transformer 30 is provided, one end of the primary winding is connected to the negative DC input terminal via the reactor 12, and the secondary winding is connected to a diode having a polarity opposite to the voltage between the two DC input terminals. 22 is connected in parallel to the capacitor 9. The other end of the primary winding of the transformer 30 is connected to the anode of a snubber diode 32 and the anode of an auxiliary switch 33 composed of a self-extinguishing device. A connection point between the snubber diode 29 and the snubber capacitor 31 is connected via a diode 32 to the anode of the chop portion 1G1 of the first phase unit circuit. The cathode of the auxiliary switch 33 is connected to the snubber diode 2D via the diode 4D1.
1 and the anode of the snubber diode 2D2 via the diode 4D2, and the anode of the snubber diode 2Dn via the diode 4Dn.

Hereinafter, referring to the operation waveform diagrams of the respective parts of the circuit of FIG. 1 shown in FIG. 2 and the operation mode diagrams of FIGS.
The operation of the circuit of FIG. FIG. 2A shows the chop 1G.
2 (b) shows the voltage V33 across the auxiliary switch 33, FIG. 2 (c) shows the voltages V3C1 to V3Cn of the snubber capacitors 3C1 to 3Cn,
FIG. 2D shows the voltage V31 of the snubber capacitor 31 and FIG.
(E) shows currents I1L1 to I1L of reactors 1L1 to 1Ln.
2 (f) shows each waveform of the current I12 of the reactor 12. FIG. 3 shows the operation mode 1, FIG. 4 shows the operation mode 2, FIG. 5 shows the operation mode 3, and FIG.
7 shows the operation mode 5 and FIG. 8 shows the operation mode 6.

In FIG. 2, chops 1G1 to 1Gn
Is turned on at time t0. It is assumed that the initial voltage exists with the polarity shown in FIG. 3 due to the periodic phenomenon before the time point t0. Here, the voltages V3C1 to V3C1 to V3 of the snubber capacitors 3C1 to 3Cn charged up to the voltage of the capacitor 6 on the output side.
3Cn is higher than the snubber capacitor voltage V31 charged up to the voltage of the main circuit capacitor 9 on the input side.
When the auxiliary switch 33 is turned on almost at the same time as the time point t0 as shown in FIG. 2B, as shown in FIG. 3, the electric charge of the capacitor 9 is transferred to the circuit of the capacitor 9-reactor 1L1-chop unit 1G1-capacitor 9. Capacitor 9-reactor 1L2-chop unit 1G2-capacitor 9, and capacitor 9-reactor 1Ln-chop unit 1
Discharge occurs in the circuit of the Gn-capacitor 9, whereby energy is stored in the main circuit reactors 1L1 to 1Ln. At this time, the charges of the snubber capacitors 3C1 to 3Cn are simultaneously transferred to the capacitor 3C1, the chop unit 1G1, the reactor 12, the transformer 30, the auxiliary switch 33, the diode 4D1, the circuit of the capacitor 3C1, and the capacitor 3C2.
Chop part 1G2-reactor 12-transformer 30-auxiliary switch 33-diode 4D2-capacitor 3C2,
Further, discharging is performed by the circuit of the capacitor 3Cn, the chop unit 1Gn, the reactor 12, the transformer 30, the auxiliary switch 33, the diode 4Dn, and the capacitor 3Cn. In mode 1, since the initial voltage V31 of the snubber capacitor 31 is lower than the voltages V3C1 to V3Cn of the snubber capacitors 3C1 to 3Cn, the diode 32 is in the reverse blocking state and does not discharge as shown in FIG. As shown in FIGS. 2C and 2D, the voltages V3C1 to V3C of the snubber capacitors 3C1 to 3Cn are changed.
At time t1 when n and the voltage V31 of the snubber capacitor 31 become equal, the next mode 2 is set as shown in FIG.

In the mode 2 shown in FIG. 4, the discharge circuit 3C1-1G1-12-30-33-4D1-3C of the mode 1 is used.
1,3C2-1G2-12-30-33-4D2-3C
2, and 3Cn-1Gn-12-30-33-4Dn
In addition to the -3Cn circuit, the diode 32, which was in the reverse blocking state in mode 1, is turned on, so that the electric charge of the snubber capacitor 31 is also reduced by the capacitor 31-diode 32-chop unit 1G1-reactor 12-transformer 30-auxiliary switch 33- Discharge occurs in the circuit of the capacitor 31. FIG.
As shown in (c) and (d), the snubber capacitor 3
C1-3Cn and the voltage V3C1-V of the snubber capacitor 31
At time t2 when 3Cn and V31 are almost completely discharged to zero, mode 3 in FIG. 5 is set.

In mode 3 of FIG. 5, the snubber energy transferred to reactor 12 is converted to reactor 12-transformer 3
It is circulated in the circuit of 0-auxiliary switch 33-diode 4D1-snubber diode 2D1-reactor 12 and regenerated to capacitor 9 via transformer 30. FIG. 2 (a),
When snubber energy has been regenerated to the capacitor 9 via the reactor 12 and the transformer 30 at a time t3 after a predetermined time as shown in (b), the exciting current of the transformer 30 is reduced as shown in FIG. Reactor 12-Transformer 30-
The mode becomes the mode 4 in which the circuit is circulated by the circuit of the auxiliary switch 33-diode 4D1-snubber diode 2D1-reactor 12.

When the chopping units 1G1 to 1Gn and the auxiliary switch 33 are simultaneously turned off at a time t4 after a predetermined time, as shown in FIG. 7, the exciting current of the transformer 30 is reduced to the reactor 12-transformer 30-. Snubber diode 2
9-snubber capacitor 31-diode 4D1-snubber diode 2D1-reactor 12 charges snubber capacitor 31 at the same time as snubber capacitor 3C
1-3Cn are reactor 1L1-snubber capacitor 3
C1-Snubber diode 2D1 circuit, reactor 1L
2-snubber capacitor 3C2-snubber diode 2D2
Circuit, reactor 1Ln-snubber capacitor 3Cn-
It is charged by the circuit of the snubber diode 2Dn. At time t5 when the snubber capacitors 3C1 to 3Cn are charged to the voltage of the output-side capacitor 6, the mode 6 in FIG. 8 is set.

In mode 6 of FIG. 8, the main circuit reactor 1
The stored energy of L1 to 1Ln is supplied to the main circuit capacitor 6 on the output side via diodes 7D1 to 7Dn,
At the same time, the exciting current of the transformer 30 is absorbed by the snubber capacitor 31, and as shown in FIG. 2F, the mode 6 is completed at time t6 when the exciting current of the transformer 30 attenuates to zero. After a further predetermined time, at time t7, FIGS. 2 (a) and 2 (b)
As shown in (5), at time t7 when the chop units 1G1 to 1Gn and the auxiliary switch 33 are turned on, the operation is exactly one cycle.

FIG. 9 shows the present invention in which the same operation as described above is achieved without using the transformer 30 (FIG. 1), and a more favorable regenerative operation is performed by providing a third snubber circuit. This shows a second embodiment of the present invention.

In FIG. 9, the same or corresponding parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In the figure, a third snubber circuit comprising a snubber capacitor 35, a snubber diode 36 and a second auxiliary switch 37 is additionally provided in series on the anode side of the diode 32.
The cathode side of the auxiliary switch 33 is connected via a diode 34 to the anode side of a snubber diode 36. A connection point between the snubber diode 29 and the reactor 12 is connected to the anode of the diode 22. Others are the same as the circuit of FIG.

The operation of the second embodiment of the present invention will be described below with reference to the operation waveform diagrams of the respective parts of the circuit of FIG. 9 shown in FIG. 10 and the operation mode diagrams of FIGS.

FIG. 10A shows the chop portions 1G1 to 1Gn.
10 (b) shows the voltages V33 and V37 of the auxiliary switches 33 and 37, and FIG.
Are the voltages V3C1 to V3C of the snubber capacitors 3C1 to 3Cn.
10 (d) shows the voltage V31 of the snubber capacitor 31.
10 (e) shows the current I of the reactors 1L1 to 1Ln.
1L1 to I1Ln, and FIG. 10F shows respective waveforms of the current I12 of the reactor 12. 11 shows operation mode 1, FIG. 12 shows operation mode 2, and FIG. 13 shows operation mode 3.
14 shows operation mode 4 and FIG. 15 shows operation mode 5.

In FIG. 10, chop portions 1G1 to 1G
The time when n turns on is defined as t0. The snubber capacitor 3 with the polarity shown in FIG.
C1 to 3Cn and 31 have initial voltages V3C1 to V3Cn,
It is assumed that V31 exists. Here, the snubber capacitor 3C charged up to the voltage of the capacitor 6 on the output side.
The voltages V3C1 to V3Cn of 1 to 3Cn are applied to the snubber capacitor 3 charged up to the voltage of the capacitor 9 on the input side.
It is assumed that the voltages V1 and V35 are higher than the voltages V31 and V35. Time t
When the auxiliary switches 32 and 33 are turned on almost simultaneously with 0 as shown in FIG. 10B, as shown in FIG. 11, the electric charge of the capacitor 9 is transferred to the capacitor 9-reactor 1L1-
Chop section 1G1-Circuit 9 circuit, capacitor 9
-Reactor 1L2-chop unit 1G2-capacitor 9
And the capacitor 9-reactor 1Ln-chop unit 1Gn-capacitor 9 discharges and accumulates energy in the reactors 1L1 to 1Ln. At the same time, the charges of the snubber capacitors 3C1 to 3Cn are transferred to the snubber capacitor 3C1, the chop unit 1G1, the reactor 12, the auxiliary switch 33, the diode 4D1, and the snubber capacitor 3C.
1 circuit, snubber capacitor 3C2-chop section 1G2
-Reactor 12-auxiliary switch 33-diode 4D
Discharge is performed by the circuit of 2-snubber capacitor 3C2 and the circuit of snubber capacitor 3Cn-chop unit 1Gn-reactor 12-auxiliary switch 33-diode 4Dn-snubber capacitor 3Cn. In this mode 1, since the initial voltages V31 and V35 of the snubber capacitors 31 and 35 are lower than the voltages V3C1 to V3Cn of the snubber capacitors 3C1 to 3Cn, the diode 37 is in the reverse blocking state and does not discharge as shown in FIG. As shown in FIGS. 10C and 10D, voltages V3C1 to V3C1 of snubber capacitors 3C1 to 3Cn are output.
V3Cn and the voltages V31, V35 of the snubber capacitors 31, 35
At the time point t1 when is equal, the next mode 2 is set as shown in FIG.

In the mode 2 of FIG. 12, the discharge circuit 3C1-1G1-12-33-4D1-3C1, 3C of the mode 1 is used.
2-1G2-12-33-4D2-3C2, and 3C
In addition to the circuit of n-1Gn-12-33-4Dn-3Cn, in mode 1, the diode 37 in the reverse blocking state is turned on, and the electric charge of the snubber capacitor 31 is also changed to the snubber capacitor 31-auxiliary switch 37-diode 32-chop portion. 1G1-reactor 12-auxiliary switch 33-snubber capacitor 31 discharges. At the same time, the electric charge of the snubber capacitor 35 is discharged in the circuit of the snubber capacitor 35, the auxiliary switch 37, the diode 32, the chop unit 1G1, the reactor 12, the auxiliary switch 33, the diode 34, and the snubber capacitor 35. As shown in FIGS. 10C and 10D, voltages V3C1 to V3Cn of snubber capacitors 3C1 to 3Cn and voltage V31 of snubber capacitor 31
At the time point t2 when the discharge is completed to almost zero, FIG.
Mode 3.

In mode 3 of FIG. 13, the snubber energy transferred to the reactor 12 flows back in the circuit of the reactor 12, the auxiliary switch 33, the diode 4D1, the diode 2D1, and the reactor 12. FIG. 10 (a), (b)
As shown in FIG. 14, when the auxiliary switches 32 and 37 are turned off at time t3 after a short period of time, the accumulated energy of the reactor 12 causes the reactor 12-snubber diode 29-snubber capacitor 31 to turn on as shown in FIG. Charging the snubber capacitor 31 with the circuit of the diode 4D1-snubber diode 2D1-reactor 12,
At the same time, the mode of charging the snubber capacitor 35 in the circuit of the reactor 12, the snubber diode 29, the snubber capacitor 35, the diode 33, the diode 32, the chop unit 1G1, and the reactor 12 is set.

The time t when the snubber capacitors 31 and 35 are charged to a value substantially equal to the voltage of the capacitor 9 on the input side.
After 4, the mode becomes 5, and as shown in FIG. 15, the diode 22 is turned on, and the energy stored in the reactor 12 is regenerated to the capacitor 9. Mode 5 is completed at time t5 when the stored energy of the reactor 12 decreases to zero. After a predetermined time, at time t6, as shown in FIG.
As shown in FIG. 10B, the chop units 1G1 to 1Gn are turned off, and after a predetermined time, the chop units 1G1 to 1Gn are turned off.
As shown in (b), one cycle of the operation is completed at time t7 when the chop units 1G1 to 1Gn turn on.

FIG. 16 shows an embodiment in which the present invention is applied to a step-down chopper circuit. In the circuit of FIG. 16, the main circuit is the same as that of FIG. 30, and the same or corresponding parts have the same reference characters allotted, and description thereof will not be repeated. Again, no snubber resistor is provided in the snubber circuit.
In this embodiment, in addition to a first snubber circuit including a snubber diode 2 and a snubber capacitor 3, a reactor 12 and a reverse-polarity diode 22 are connected in series between an output terminal of a DC power supply 6, that is, an input terminal of a chopper circuit. It is connected. The anode of the snubber diode 29 is connected to the cathode of the diode 22, a snubber capacitor 31 is connected to the anode side of the diode 29, and an auxiliary switch 33 made of GTO is connected in parallel with the snubber capacitor 31 and the snubber diode 29. . A second snubber circuit is configured by the snubber capacitor 31, the snubber diode 29, and the auxiliary switch 33. The connection point between snubber capacitor 31 and snubber diode 29 is connected to the connection point between snubber diode 2 and snubber capacitor 3.

Chop part 1 and main circuit reactor 1L
Is connected to the anode of the snubber diode 36, and the snubber capacitor 35 is connected between the cathode and the connection point of the snubber capacitor 31 and the snubber diode 29. Further, a second auxiliary switch 37 is connected in parallel with the snubber diode 36 and the snubber capacitor 35. The snubber diode 36, snubber capacitor 35 and auxiliary switch 37 constitute a third snubber circuit.

Hereinafter, the operation of the third embodiment of the present invention will be described with reference to the operation waveform diagrams of each part of the circuit of FIG. 16 and the operation mode diagrams of FIGS.

FIG. 17A shows the voltage V across the chop unit 1.
17 (b) shows the voltages V32 and V37 across the auxiliary switches 32 and 37, FIG. 17 (c) shows the voltage V3 of the snubber capacitor 3, and FIG. 17 (d) shows the snubber capacitors 31 and 3.
FIG. 17 (e) shows the voltage of V1 and V35 of FIG.
17 (f) shows the current waveform of the reactor 12, and FIG. 18 shows operation mode 1, FIG. 19 shows operation mode 2, FIG. 20 shows operation mode 3, and FIG.
Reference numeral 1 denotes an operation mode 4. In FIG. 17, the time when the chop unit 1 is turned on is defined as t0. It is assumed that the initial voltage exists in the snubber capacitors 3, 31, and 35 with the polarity shown in FIG. 18 due to the periodic phenomenon before the time point t0. In the mode 1, almost at the same time as the time point t0, FIG.
When the auxiliary switches 32 and 33 are turned on as shown in (b), the snubber capacitors 3 and 3 are turned on as shown in FIG.
The electric charges of 1 and 35 are stored in the snubber capacitor 3-auxiliary switch 33-reactor 12-chop unit 1-snubber capacitor 3 circuit, snubber capacitor 31-auxiliary switch 33
-Reactor 12-Chop unit 1-Auxiliary switch GTO
Discharge occurs in the circuit of 32-snubber capacitor 31 and the circuit of snubber capacitor 35-diode 34-auxiliary switch 33-reactor 12-chop unit 1-auxiliary switch 32-snubber capacitor 35. In this mode 1,
At the same time, power is supplied from the DC power supply 6 to the load 9 via the chop unit 1 and the reactor 1L. At time t1 when the voltages of the snubber capacitors 3, 31, and 35 become substantially zero, the next mode 2 is set as shown in FIG.

In the mode 2 of FIG. 19, the snubber energy transferred to the reactor 12 circulates in the circuit of the reactor 12, the snubber diode 2, the auxiliary switch 33, and the reactor 12. As shown in FIG. 17B, when the auxiliary switches 32 and 33 are turned off at a time t2 after a short time, as shown in FIG. 20, the energy stored in the reactor 12 is reduced to the reactor 12-snubber diode 2-.
Diode 31-snubber diode 29-reactor 1
In the circuit of No. 2, the snubber capacitor 31 is charged, and at the same time, the reactor 12-chop unit 1-snubber diode 36-
In the circuit of the snubber capacitor 35, the snubber diode 29, and the reactor 12, a mode 3 in which the snubber capacitor 35 is charged is set.

The time t3 when the snubber capacitors 31, 35 are charged to a value substantially equal to the voltage of the DC power supply 6 on the input side.
, The diode 2 as shown in the mode 4 in FIG.
2 is turned on, and the energy stored in the reactor 12 is regenerated to the DC power supply 6. The mode 4 is completed at a time point t4 when the stored energy of the reactor 12 is attenuated. After a predetermined time, at time t5, the chop unit 1 is turned off as shown in FIG.
As shown in (a), at time t6 when the chop unit 1 turns on, one cycle of operation is completed.

FIG. 22 shows, as a fourth embodiment of the present invention, a step-down chopper circuit which regenerates energy of a surge absorbing circuit composed of a diode 7 and a capacitor 6 to an input side capacitor 9 of a DC main circuit. is there. In the figure, the same or corresponding parts as those in FIG. 16 are denoted by the same reference numerals, and description thereof will be omitted. In this circuit, a main circuit capacitor 9 is connected to the input side and a main circuit capacitor 6 is connected to the output side via a diode 7, and a reactor 15 is connected in series to a main current circuit between the capacitors 9 and 6. I have. Between the connection point of the diode 7 and the capacitor 6 and the negative DC terminal, a diode 21 having a forward polarity and the chop unit 1 are connected.
In addition, diodes 22 of opposite polarity are connected in series. The reactor 12 is connected between a connection point between the chop unit 1 and the diode 22 and a positive DC terminal. A first snubber circuit including a snubber capacitor 3 and a snubber diode 2 is connected to the chop unit 1. A second snubber circuit including a snubber diode 29, a snubber capacitor 31, and an auxiliary switch 33 including a GTO is connected between the DC input terminal and a connection point between the snubber capacitor 3 and the snubber diode 2. . Further, a diode 32 is connected between the connection point of the snubber diode 29 and the snubber capacitor 31 and the connection point of the diode 21 and the chop unit 1 with the anode facing the cathode of the snubber diode 29.

The operation of the fourth embodiment of the present invention will be described below with reference to the operation waveform diagrams of the respective parts of the circuit of FIG. 22 shown in FIG. 23 and the operation mode diagrams of FIGS.

FIG. 23A shows the voltage V across the chop unit 1.
23 (b) shows the voltage V33 across the auxiliary switch 33.
FIG. 23C shows the voltage V of the snubber capacitors 3 and 31.
3 and V31, and FIG.
FIG. 23E shows waveforms of the current I12 of the reactor 12. 24 shows the operation mode 1, FIG. 25 shows the operation mode 2, FIG. 26 shows the operation mode 3, FIG. 27 shows the operation mode 4, and FIG. 28 shows the operation mode 5.

In FIG. 23, the time when the chop unit 1 is turned on is defined as t0. Due to the periodic phenomenon before time t0,
Assume that initial voltages V3 and V31 exist in the snubber capacitors 3 and 31 with the polarities shown in FIG. When the auxiliary switch 33 is turned on as shown in FIG. 24 almost at the same time as the time point t0, the electric charge of the snubber capacitors 3 and 31 is reduced to the circuit of the snubber capacitor 3-chop unit 1-reactor 12-auxiliary switch 33-snubber capacitor 3 Snubber capacitor 31-diode 32-chop unit 1-reactor 12-auxiliary switch 33-snubber capacitor 31
Discharge in the circuit. Voltage V of snubber capacitors 3 and 31
When the sum of V31 and the voltage V9 of the capacitor 9 is slightly lower than the voltage V6 of the capacitor 6 for the surge absorbing circuit and reaches a time point t1 when the discharge is performed, the next mode 2 is established as shown in FIG.

In the mode 2 of FIG. 25, the diode 21 is turned on, and the electric charge stored in the capacitor 6 is also discharged through the chop unit 1 and the reactor 12. As shown in FIG. 23C, at time t2 when the voltages V3 and V31 of the snubber capacitors 3 and 31 become substantially zero, the mode becomes the mode 3 in FIG.

In mode 3 of FIG. 26, the snubber energy transferred to the reactor 12 flows back through the circuit of the reactor 12, the auxiliary switch 33, the snubber diode 2, and the reactor 12. When the chop unit 1 and the auxiliary switch 33 are turned off at a time t3 after a predetermined time as shown in FIGS. 23 (a) and 23 (b), the current due to the energy stored in the reactor 12 is reduced as in mode 4 in FIG. Reactor 12-snubber diode 29-snubber capacitor 31
In the circuit of the snubber diode 2-the reactor 12, the snubber capacitor 31 is charged, and at the same time, in the circuit of the reactor 12-the snubber diode 29-the diode 32-the snubber capacitor 3-the snubber diode 2-the reactor 12,
The snubber capacitor 3 is charged. Snubber capacitor 3,
At the time t4 when the battery 31 is charged to a value substantially equal to the DC circuit voltage and the voltage V9 of the capacitor 9, at the time t4, FIG.
As in Mode 5, the diode 22 is turned on, and the energy stored in the reactor 12 is regenerated to the capacitor 9 of the DC power supply circuit.

Mode 5 is completed at time t5 when the current of reactor 12 attenuates to zero. After a predetermined period of time t
As shown in FIG. 23 (d), it is assumed that the capacitor 6 of the surge absorbing circuit absorbs the overvoltage by the switching operation of the converter (not shown) and reaches the above-mentioned initial voltage value by time t7. After a further predetermined time, FIG.
As shown in (a) and (b), at time t8 when the chop unit 1 and the auxiliary switches 31 and 33 are turned on, one cycle of operation is completed.

FIG. 29 shows a fifth embodiment of the present invention in the case of an n-phase step-up chopper circuit in which a plurality of GTO chops connected in series are multi-phased. FIG. 29 is based on the step-up chopper circuit of FIG. 9, and the chop sections connected to the main circuit in the shunt are provided for each phase by the chop sections 1G1m, 1G11;
G2m, 1G21;... Are composed of two sets of chop sections connected in series with 1Gnm and 1Gn1.

A snubber circuit including a snubber capacitor 3C1m and a snubber diode 2D1m is connected to the chop 1G1m. Similarly, a snubber capacitor 3C11 and a snubber diode 2 are connected to the chop 1G11.
A snubber circuit composed of a snubber capacitor 3C2m and a snubber diode 2D
A 2 m snubber circuit includes a snubber capacitor 3C21 and a snubber diode 2D2 in the chop 1G21.
The snubber circuit consisting of a snubber capacitor 3Cnm and a snubber diode 2Dnm
And a snubber circuit including a snubber capacitor 3Cn1 and a snubber diode 2Dn1 is connected to the chop unit 1Gn1.

The energy absorbing circuit 60 including the reactor 12 is the same as that of FIG. Energy absorption circuit 6
The cathode of the zero snubber diode 36 is connected to the connection point between the chop portions 1G1m and 1G11 of the first phase. A connection point between the snubber capacitor 31 and the diode 36 is connected to a connection point between the snubber capacitor 3C1m and the snubber diode 2D1m via the diode 5D11.
Similarly, the connection point between the snubber capacitor 3C11 and the snubber diode 2D11 via the diode 4D11 is connected to the snubber capacitor 3C via the diode 5D21.
A diode 5D is connected to a connection point of the snubber capacitor 3C21 and the snubber diode 2D21 via a diode 4D21 to a connection point of the snubber diode 2D2m and the snubber diode 2D2m.
It is connected to the connection point of snubber capacitor 3Cnm and snubber diode 2Dnm via Dn1, and to the connection point of snubber capacitor 3Cn1 and snubber diode 2Dn1 via diode 4Dn1, respectively.

This embodiment is configured to regenerate the snubber energy of a plurality of chop sections connected in series. With this circuit configuration, the same operation as that shown in FIG. 9 can be satisfactorily achieved. it can.

The invention has been described with reference to specific embodiments. In each of the above embodiments, for example, as a self-extinguishing device used as a chop portion or an auxiliary switch, in addition to the GTO, for example, a GTR (high power transistor), an IGBT (gate insulating bipolar transistor), or the like is used. It can also be used.

Further, for example, the reactor 12 may be constituted by using a transformer as shown in FIG. Also,
The transformer may be either a transformer or a current transformer.

[0051]

According to the present invention described above, a plurality of parallel multi-phase chopper circuits can be formed under a single-stage simple circuit configuration using a common snubber energy regenerating circuit. The snubber energy of the auxiliary switch used in the regenerative circuit itself can be satisfactorily regenerated.

[Brief description of the drawings]

FIG. 1 is a connection diagram of a boost chopper circuit according to a first embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of the circuit in FIG. 1;

FIG. 3 is an operation mode 1 in the boost chopper circuit of FIG.
FIG.

FIG. 4 is an operation mode 2 in the boost chopper circuit of FIG.
FIG.

FIG. 5 is an operation mode 3 in the boost chopper circuit of FIG. 1;
FIG.

6 is an operation mode 4 in the boost chopper circuit of FIG.
FIG.

FIG. 7 is an operation mode 5 in the boost chopper circuit of FIG. 1;
FIG.

8 is an operation mode 6 in the boost chopper circuit of FIG.
FIG.

FIG. 9 is a connection diagram of a boost chopper circuit according to a second embodiment of the present invention.

FIG. 10 is a timing chart for explaining the operation of the circuit in FIG. 9;

11 is an equivalent circuit diagram of an operation mode 1 in the boost chopper circuit of FIG.

FIG. 12 is an equivalent circuit diagram of an operation mode 2 in the boost chopper circuit of FIG. 9;

13 is an equivalent circuit diagram of an operation mode 3 in the boost chopper circuit of FIG.

FIG. 14 is an equivalent circuit diagram of an operation mode 4 in the boost chopper circuit of FIG. 9;

FIG. 15 is an equivalent circuit diagram of an operation mode 5 in the boost chopper circuit of FIG. 9;

FIG. 16 is a connection diagram of a step-down chopper circuit according to a third embodiment of the present invention.

FIG. 17 is a time chart for explaining the operation of the circuit in FIG. 16;

18 is an equivalent circuit diagram of an operation mode 1 in the step-down chopper circuit of FIG.

19 is an equivalent circuit diagram of an operation mode 2 in the step-down chopper circuit of FIG.

FIG. 20 is an equivalent circuit diagram of an operation mode 3 in the step-down chopper circuit of FIG. 16;

21 is an equivalent circuit diagram of an operation mode 4 in the step-down chopper circuit of FIG.

FIG. 22 is a connection diagram of a step-down chopper circuit according to a fourth embodiment of the present invention.

FIG. 23 is a time chart for explaining the operation of the circuit in FIG. 22;

FIG. 24 is an equivalent circuit diagram of an operation mode 1 in the step-down chopper circuit of FIG. 22;

FIG. 25 is an equivalent circuit diagram of an operation mode 2 in the step-down chopper circuit of FIG. 22;

FIG. 26 is an equivalent circuit diagram of an operation mode 3 in the step-down chopper circuit of FIG. 22;

FIG. 27 is an equivalent circuit diagram of an operation mode 4 in the step-down chopper circuit of FIG. 22;

FIG. 28 is an equivalent circuit diagram of an operation mode 5 in the step-down chopper circuit of FIG. 22;

FIG. 29 is a connection diagram of a boost chopper circuit according to a fifth embodiment of the present invention.

FIG. 30 is a connection diagram of a conventional step-down chopper circuit.

FIG. 31 is a connection diagram of a conventional boost chopper circuit.

FIG. 32 is a connection diagram of a conventional surge absorbing circuit.

FIG. 33 is a connection diagram of a conventional multi-phase boost chopper circuit.

[Explanation of symbols]

1, 1a1 to 1an Chop unit 33, 37 Auxiliary switch 31, 35, 3C1 to 3Cn Snubber capacitor 29, 36, 2D1 to 2Dn Snubber diode 12, 1L1 to 1Ln Reactor 30 Transformer 6, 9 Capacitor 22, 32, 4D1 to 4Dn , 7D1-7Dn, 34,
21 Diode

Claims (5)

[Claims] A first main circuit capacitor connected between a positive DC input terminal and a negative DC input terminal; and a first main circuit capacitor connected between a positive DC output terminal and a negative DC output terminal common to the negative DC input terminal. A series main circuit comprising a second main circuit capacitor, a main circuit reactor arranged on the input side, and a main circuit diode arranged in series with the main circuit current and having a forward polarity with respect to the main circuit current on the output side. A plurality of series main circuit groups connected in parallel between an input terminal and the positive DC output terminal; and between a connection point of each main circuit reactor and main circuit diode of the series main circuit group and the negative DC input terminal. Group consisting of a self-arc-extinguishing device connected to a first snubber capacitor arranged on the positive side and a first snubber diode arranged on the negative side in series with each other for each of the chop sections From A first snubber circuit group connected in parallel to the chop section, a reactor connected between the DC input terminals via a first diode having a polarity opposite to the main circuit voltage, and the reactor and the reactor A second snubber diode having an anode connected to a connection point of the first diode, a second snubber capacitor connected in series thereto, and a second snubber diode and a second snubber capacitor connected in parallel to the second snubber capacitor. A second snubber circuit including an auxiliary switch, and a connection point between a connection point of a second snubber diode and a second snubber capacitor in the second snubber circuit and an anode of a first chop section in the chop section group. A second diode having an anode connected to the cathode of the second snubber diode, and the auxiliary switch and the second snubber. A third anode connected to the auxiliary switch side between a connection point of the capacitor and each of the connection points of the first snubber capacitor and the first snubber diode in the first snubber circuit group. A chopper circuit including a diode group. 2. The chopper circuit according to claim 1, wherein a third snubber diode connected in series to an anode of said second diode, a third snubber capacitor connected in series to said third snubber diode, and said third snubber capacitor. A third snubber circuit composed of a second auxiliary switch connected in parallel with the snubber diode and the third snubber capacitor of the third embodiment, and a connection point between the second auxiliary switch and the second snubber capacitor and the third snubber capacitor. A third cathode having a cathode connected to the anode of the third snubber diode between the snubber diode and the connection point of the third snubber capacitor.
Chopper circuit further provided with a diode. 3. A chopping section comprising a self-extinguishing device arranged on the input side and a main circuit reactor connected in series to the output side and connected between a positive DC input terminal and a positive DC output terminal. A main circuit diode connected in reverse polarity to the main circuit voltage between a connection point of the chop section and the main circuit reactor and a negative DC output terminal common to the negative DC input terminal; A first snubber circuit disposed on the input side and a first snubber diode disposed in series with the output side on the output side, and a first snubber circuit connected in parallel to the chop section; A first auxiliary diode connected in series with a polarity opposite to the main circuit voltage, a parallel auxiliary circuit connected between the positive and negative DC input terminals, and a cathode connected to the cathode of the first diode A second snubber diode, a second snubber capacitor connected in series with the second snubber diode, and a first auxiliary switch connected in parallel to the second snubber diode and the second snubber capacitor. A third snubber diode having an anode connected to a connection point between the chop portion and the main circuit reactor, and a third snubber connected in series with the third snubber diode to an anode of the second snubber diode. A capacitor, a third snubber circuit including a second auxiliary switch connected in parallel to the third snubber diode and the third snubber capacitor, and a connection between the third snubber diode and the third snubber capacitor. An anode is connected between a point and a connection point of the second snubber capacitor and the first auxiliary switch. Second connected toward the cathode of the snubber diode
Chopper circuit including the diode of FIG. 4. A first main circuit capacitor connected between positive and negative DC input terminals, a first main circuit reactor connected between a positive DC input terminal and a positive DC output terminal, and the positive DC output terminal. A second main circuit capacitor connected in series to the negative DC input terminal via a first diode disposed with the anode facing the positive DC output terminal, and a negative DC output terminal common to the negative DC input terminal; A second diode having an anode connected to the cathode of the first diode, a chop section comprising a self-extinguishing device connected in series to the cathode side of the second diode, and A chop circuit including a second main circuit reactor connected to a positive DC output terminal; and an anode between a connection point of the chop section and the second main circuit reactor and the negative DC input terminal. The negative DC input A third diode connected on the end side, a first snubber diode having a cathode connected to the cathode of the chop section, and a first snubber connected in series with the first snubber diode to the anode of the chop section. The first consisting of a capacitor
And a second snubber diode having an anode connected to the positive DC output terminal and a second snubber diode connected in series with the second snubber capacitor and a connection point of the first snubber diode and the first snubber diode. A second snubber circuit comprising a second snubber capacitor; and a second snubber diode between the second snubber diode and a connection point between the second snubber capacitor and a cathode of the second diode. And a fourth diode connected to the cathode of the chopper. 5. A first main circuit capacitor connected between a positive DC input terminal and a negative DC input terminal, and a first main circuit capacitor connected between a positive DC output terminal and a negative DC output terminal common to the negative DC input terminal. A main circuit capacitor, a main circuit reactor arranged on the input side, and a main circuit diode connected in series with the main circuit diode on the output side with a forward polarity to the main circuit current. A plurality of series main circuit groups connected in parallel between the positive DC output terminals; and a series connection between the connection point of each main circuit reactor and main circuit diode of the series main circuit group and the negative DC input terminal. A first and a second group of chop sections each composed of a self-arc-extinguishing device connected to a first snubber capacitor arranged on the positive side and a first snubber diode arranged on the negative side in series therewith. What A first snubber circuit group connected in parallel to the first chop unit in each chop unit, a second snubber capacitor arranged on the positive side, and a second snubber capacitor arranged in series with the second snubber capacitor on the negative side. A second snubber circuit group connected in parallel to the second chop section of each chop section, a first diode disposed on the positive side with a polarity opposite to the main circuit voltage, and A reactor circuit connected in series between the positive and negative DC input terminals; and an anode connected to a connection point of the first diode and the reactor in the series auxiliary circuit. A third snubber diode, a third snubber capacitor connected in series thereto, and a third snubber diode connected in parallel to the third snubber diode and the third snubber capacitor. A third snubber circuit comprising a first auxiliary switch, which is the first of the first chopped portion of the chopped portion group
And a fourth snubber diode having a cathode connected to a connection point of the second self-extinguishing device, and a series connection of the third snubber diode and the third snubber capacitor in the third snubber circuit. A fourth snubber capacitor connected between the second snubber capacitor and a fourth auxiliary switch connected in parallel to the fourth snubber diode and the fourth snubber capacitor; A second diode having an anode connected to the third snubber capacitor side between a free end of the third snubber capacitor and a connection point of the fourth snubber diode and the fourth snubber capacitor; 4 and a connection point of the second diode and the first snubber of each first snubber circuit in the first snubber circuit group. A third diode group connected between the capacitor and the first snubber capacitor connection point with the anode being on the fourth snubber capacitor side; a connection point between the fourth snubber capacitor and the second diode; A fourth diode group connected between the second snubber capacitor and the second snubber capacitor connection point of each second snubber circuit in the first snubber circuit group, with the anode having the fourth snubber capacitor side. And a chopper circuit comprising: