JPH02302125A - Snubber circuit for self-arc quenching element in power converter - Google Patents

Abstract

PURPOSE:To reduce a resistance loss of a snubber circuit considerably by utilizing a charge stored in a capacitor of the snubber circuit connected in parallel with a self-arc quenching element for the recovery energy of a flywheel diode or the like. CONSTITUTION:A series circuit comprising a discharge diode 12 and a discharge reactor 11 connects between a connecting point of a snubber diode 7 and a snubber capacitor 8 in a snubber circuit of a self-arc quenching element 6 and a snubber circuit comprising a flywheel diode 9. Thus, most of the recovery current to the flywheel diode 9 is supplied by a discharge current from the snubber capacitor 8 and after the recovery of the flywheel diode 9, the energy stored in the discharge reactor 13 is discharged to charge the snubber capacitor 11. Thus, the loss consumed in the resistor in the conventional technology is eliminated.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a snubber circuit for a self-arc-extinguishing element in a power converter, and particularly to a snubber circuit for a self-arc-extinguishing element constituting a power converter such as a chopper or an inverter. The present invention relates to a snubber circuit for a self-extinguishing element in a power conversion device suitable for use in reducing resistance loss in the snubber circuit.

[Prior Art] - G. A snubber circuit is provided in parallel with a switching element in order to prevent the switching element from being destroyed by a spike voltage generated when the switching element is turned off. It is composed of a resistor and a capacitor. The capacitor of this snubber circuit is charged to the power supply voltage when the switching element is off, and then discharges the charge through the resistor when the switching element is turned on. Therefore, the resistance of the snubber circuit causes considerable power loss.

As a conventional technique for reducing resistance loss in such a snubber circuit, particularly in a snubber circuit of a self-extinguishing element, a technique described in, for example, Japanese Patent Laid-Open No. 59-222073 is known.

This conventional technology temporarily transfers the charged charge of a snubber capacitor, which had been consumed by a discharge resistor, to a separately provided auxiliary capacitor via a first diode and an inductance when a self-extinguishing element turns on. By supplying the charged charge of this auxiliary capacitor to the load via the second diode when the self-extinguishing element is turned off, the aforementioned resistance loss in the snubber circuit can be reduced.

[Problem to be solved by the invention]

However, the above-mentioned conventional technology has the problem that the device becomes large and expensive because it is necessary to separately provide an auxiliary capacitor. It is necessary to set the capacitance ratio of the auxiliary capacitor and the auxiliary capacitor to appropriate values.
The problem is that this setting is difficult.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above, and to provide a snubber circuit for a self-extinguishing element in a power conversion device that does not require an auxiliary capacitor and has low resistance loss.

[Means for Solving the Problems] According to the present invention, the object is to cause a freewheel diode in a chopper control device and a snubber capacitor of a snubber circuit connected in parallel to the diode to play the role of the auxiliary capacitor described above, Alternatively, the freewheeling diode and the snubber capacitor of the snubber circuit connected in parallel to the self-extinguishing element of the paired arm in the inverter device can be used to discharge the charging charge of the self-snubber capacitor. This is achieved by discharging through the freewheeling diode or the self-extinguishing element of the counter arm via the circuit.

[Function] When the self-extinguishing element is turned on, the charge in the snubber capacitor of the own arm is discharged through the series circuit of the discharge diode and the handle, and then through the diode circuit of the opposite arm in freewheel mode. Ru. This discharge current cancels the current in the diode of the opposite arm in the freewheel mode to recover the diode, and also functions to store the charge in the snubber capacitor of the own arm as energy in the reactor.

Therefore, it is possible to eliminate the need to limit the capacitance ratio between the snubber capacitor of the diode circuit of the paired arm and the snubber capacitor of the own arm.

Moreover, when the diode circuit of the paired arm is no longer in freewheel mode, the energy stored in the reactor is
The snubber capacitor in the diode circuit for the arm is charged. Then, when the self-extinguishing element is turned off, this charged charge is supplied to the load via the diode of the diode circuit of the paired arm. The present invention can thereby eliminate the need to separately provide an auxiliary capacitor.

[Example] Hereinafter, an example of a snubber circuit system for a self-extinguishing element in a power converter according to the present invention will be described in detail with reference to the drawings.

Figure 1 shows a first example of the present invention in which the present invention is applied to a chopper circuit.
FIG. 2 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing current waveforms to explain its operation. In Fig. 1, 1 is a filter capacitor, 2.3 is a wiring inductance, 4.5 is an armature and field coil of a DC motor, 6 is a self-extinguishing element,
7 is a snubber diode, 8.11 is a snubber capacitor,
9 is a freewheel diode, 10 is a snubber resistor, 1
2 is a discharge diode, and 13 is a discharge reactor.

In one embodiment of the present invention shown in FIG. 1, a filter capacitor 1 is connected between a positive terminal and a negative terminal of a DC power source (not shown) to remove ripples contained in the DC power source. The wiring inductance 2.3 also serves as an anode reactor, and is preferably provided as concentrated on the positive electrode side of the DC power source as shown in the figure. Also,
The series circuit of the snubber diode 7 and the snubber capacitor 8 is connected in parallel to the self-extinguishing element 6 and functions as a snubber circuit for the self-extinguishing element 6. It functions as a snubber circuit for the freewheel diode 9.

The chopper control operation in the first embodiment of the present invention configured as described above will be briefly described below.

In FIG. 1, when the self-arc extinguishing element 6 is turned on, current flows from the DC power supply to the motor circuit consisting of the armature 4 and the field coil 5, and when the self-arc extinguishing element 6 is turned off, the electric current flows to the motor circuit. The current that was flowing flows back through the freewheel diode 9. The current value of the motor circuit is controlled by repeating such ON/OFF operations of the self-arc extinguishing element 6 and changing the current flow time ratio of the self-arc extinguishing element 6.

In the above-described operation, when the self-extinguishing element 6 turns off, the wiring inductance 2, which also serves as an anode reactor, generates a spike voltage. In order to prevent the self-extinguishing element 6 from being destroyed by this spike voltage, the first embodiment of the present invention shown in FIG. , are connected in parallel to the self-extinguishing element 6. The snubber capacitor 8 is charged to the power supply voltage during the period when the self-extinguishing element 6 is turned off, and conventionally, when the self-extinguishing element 6 is turned off, this charged charge is transferred to a snubber resistor (not shown). However, in the embodiment of FIG. 1, it was discharged through the snubber diode 7 (which was connected in parallel to the snubber diode 7).

For this reason, in the prior art, all of the charging energy of the snubber capacitor 8 is consumed by this resistor, and heat treatment such as cooling must be performed on the resistor, resulting in a problem that the power efficiency also decreases. A conventional technique that solves this problem and makes it possible to reduce power loss due to resistance is the technique described in the above-mentioned Japanese Patent Application Laid-Open No. 59-222073.
As already mentioned, there are still problems with this prior art.

In order to solve this problem, the first embodiment of the present invention shown in FIG. A series circuit of a discharge diode 12 and a discharge reactor 11 is connected to the snubber circuit.

The operation of the first embodiment of the present invention will be explained below using the operation waveforms shown in FIG.

Now, it is assumed that the self-extinguishing element 6 is turned on at time t shown in FIG. In this case, at the above-mentioned time, the electric charge that had been charged in the snubber capacitor 8 during the period in which the self-extinguishing element 6 was in the OFF state earlier is transferred to the discharging reactor 13 connected to this snubber capacitor 8. It is discharged via the discharge diode 12 and the freewheel diode 9 in freewheel mode. During this discharge, most of the DC power supply voltage (2) is applied to the wiring inductance 2.3, which also serves as an anode reactor. The discharge current IC flowing along the path shown by the dotted line in FIG.
It becomes a resonant current between c and the snubber capacitor capacitance C8,
Therefore, when this current reaches its maximum value, all the energy of the charge in the snubber capacitor 8 is transferred to the inductance L of the discharging reactor 13. This means that the energy is converted into stored energy and stored in the discharge reactor 13.

At this time, the first
The current that cancels the load current shown by the dashed line in the figure and recovers the freewheel diode 9 is the discharge current shown in the figure. When the self-extinguishing element 6 turns on, the voltage of the DC power supply becomes ■.

The current ICM shown by the solid line in FIG.
It is given as a composite current of

This composite current■. Earthworks. 2. In this example, a current is applied to the self-embedding element 6. a. After canceling out the load current flowing through the freewheel diode 9 at time t, a required recovery current flows through the freewheel diode 9 to recover the freewheel diode 9 at time t1. Due to the recovery of the freewheel diode 9, the load current I+ flows to the motor circuit which is the load, and the recovery current I+, which was flowing to the freewheel diode 9, is freed by the snubber resistor 10 and the snubber capacitor 11. It flows into the snubber circuit of the wheel diode 9 and charges the snubber capacitor 11 to the voltage of the DC power supply.

The first embodiment of the invention, operating as described above, supplies most of the recovery current to the freewheeling diode 9 by
The snubber capacitor 11 is supplied with a discharge current from the snubber capacitor 8, and after the freewheel diode 9 recovers, the energy stored in the discharge reactor 13 (that is, the discharge energy from the snubber capacitor 8) is released. Charging is in progress. Therefore, in the first embodiment of the present invention, almost all of the energy stored in the snubber capacitor 8 can be used as recovery energy for the freewheeling diode 9 and charging energy for the snubber capacitor 11 of the freewheeling diode 9. It is possible to eliminate the loss consumed by resistance in the conventional technology.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention. In FIG. 3, 14 is a snubber diode, and other symbols are the same as in FIG. 1.

This second embodiment of the present invention is an application of the present invention to a chopper circuit similar to that shown in FIG. In the embodiment of the present invention shown in FIG. 1, the energy stored in the discharge reactor 13 charges the snubber capacitor 11, and
Snubber capacitor 1 due to turn-off of self-extinguishing element 6
Since the energy of 1 is discharged to the load via the snubber resistor 10, a resistance loss occurs due to the snubber resistor 10.

In a second embodiment of the present invention shown in FIG. 3, a snubber diode 14 is connected in parallel to the snubber resistor 10 in order to reduce the loss caused by the snubber resistor 1o. That is, in this embodiment, the snubber diode 14 is
By connecting as shown by the solid line, the loss when charging the snubber capacitor 11 can be reduced, and by connecting as shown by the dotted line in parentheses, the loss when discharging the snubber capacitor 11 can be reduced. .

FIG. 4 is a circuit diagram showing a third embodiment of the present invention. In FIG. 4, 15 is a snubber resistor, and the other symbols are the same as in FIG. 1.

This embodiment also applies the present invention to a chopper circuit. The embodiment of the present invention illustrated in FIGS. 1 and 3 is as follows:
When the load current of the motor circuit caused by the armature 4 and the field coil 5, which are loads, is extremely small, that is, when the current flowing through the freewheel diode 9 is small, a snubber capacitor is used to recover the freewheel diode 9. 8, the discharge current is so small that the charge in the snubber capacitor 8 may not be fully discharged.

A third embodiment of the present invention shown in FIG. 4 solves the above-mentioned problems, and is constructed by connecting a snubber resistor 15 in parallel to the snubber diode 7 in the embodiment explained in FIG. Ru. In this case, the discharge time constant due to the resistance value of the snubber resistor 15 and the capacitance value of the snubber capacitor 8 is made larger than the oscillation period due to the capacitance value of the snubber capacitor 8 and the inductance value of the discharge reactor 13.
Select the resistance value of the snubber resistor 15. As a result, when the load current is large, most of the charge in the snubber capacitor 8 can be discharged through the discharge reactor 13, and when the load current is small, it can be discharged through the circuit of the discharge reactor 13. The unused charge in the snubber capacitor 8 can be discharged via the snubber resistor 15.

According to the third embodiment of the present invention described above, the charge in the snubber capacitor 8 can be discharged more reliably, and the loss caused by the snubber resistor 15 can be reduced.

It should be noted that it is also possible to use the method of the second embodiment of the present invention explained in FIG. I can do it.

FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention. In FIG. 5, 16 is an anode reactor, 17 is a diode, 18 is a resistor, and other symbols are the same as in FIG. 1.

The fourth embodiment shown in FIG. 5 also applies the present invention to a chopper circuit, like the other embodiments described above. This embodiment is an embodiment in which the wiring inductance 2.3 cannot also be used as an anode reactor in the embodiments of the present invention explained in FIGS. 1 to 4, and is configured with a separate anode reactor 16. There is. A diode 17 connected in parallel to this anode reactor 16
The series circuit of the resistor 8 and the resistor 8 circulates the stored energy of the anode reactor 16 when the self-arc-extinguishing element 6 is turned off, so that the energy applied to the self-arc-extinguishing element 6 is This has the effect of reducing the spike voltage that occurs.

In the fourth embodiment of the present invention shown in FIG. 5, the anode reactor 16 is provided separately and is not used as a wiring reactor, so the inductance ratio between the anode reactor 16 and the discharge reactor 13 is set within a certain range. It is now possible to select within the input current ICH from the DC power supply.
By suppressing this, it becomes possible to use the charge in the snubber capacitor 8 more effectively as recovery energy for the freewheeling diode 9.

In addition, it is also possible to use the methods of the second and third embodiments of the present invention explained in FIGS. 3 and 4 in conjunction with the fourth embodiment of the present invention, and in this case, these methods The effects of the embodiments can be brought out together.

FIG. 6 is a circuit diagram showing a fifth embodiment of the present invention. In FIG. 6, 19 is a self-extinguishing element, 20.23 is a snubber diode, 21.24 is a snubber resistor, 22.25 is a snubber capacitor, and other symbols are the same as in FIG. 5.

The fifth embodiment of the present invention shown in FIG. 6, like the other embodiments already described, applies the present invention to a chotsuba circuit and includes a plurality of self-extinguishing elements in order to control high voltage. This is an example in which two self-extinguishing elements are connected in series, and FIG. 6 shows an example in which two self-extinguishing elements are connected in series.

In the fifth embodiment of the present invention, the self-extinguishing elements 6 and 19 connected in series each include a diode 22.
．． 23, a resistor 21.24, and a capacitor 22.25, and a snubber circuit composed of a diode 7 and a capacitor 8 is connected in parallel to the series-connected self-extinguishing elements 6 and 19. It is connected to the.

From the connection point between the diode 7 and the capacitor 8, a discharge circuit consisting of a series circuit of a discharge diode 12 and a discharge reactor 13 is connected to a freewheeling circuit, similar to the embodiments described in FIGS. 1 to 5. It is connected to the diode 9 circuit.

In the fifth embodiment of the present invention shown in FIG. 6, the snubber capacitors 22 and 25 of the snubber circuit connected in parallel to each of the self-extinguishing elements 6 and 19 have a small capacity.
The capacitance of the snubber capacitor 8, which is connected in parallel to the series-connected self-arc-extinguishing elements 6 and 19, is In order to suppress the voltage sharing of the self-arc-extinguishing element to a predetermined value, and to suppress the spike voltage applied to the self-arc-extinguishing element to a predetermined value by wiring inductance 2.3 etc. when the self-arc-extinguishing element is turned off, the comparison is made. It is configured with a large target.

For example, when connecting 4.5KV, 2KA GTO elements in series as self-extinguishing elements, the snubber capacitor 22
．． It was optimal to set the capacitance of the capacitor 25 to 0.5 μF and the capacitance of the snubber capacitor 8 to 8 μF.

In the circuit of this embodiment, the charges charged in the snubber capacitors 22, 25, each having a small capacitance, are transferred to the snubber resistors 21, 21, 25, and 25, respectively.
24, and the charged charge of the snubber capacitor 8 having a large capacity is discharged through a discharge circuit including a discharge diode 12 and a discharge reactor 13, as in the embodiments shown in FIGS. 1 to 5 described above. The energy is discharged through the freewheeling diode 9 and used as recovery energy for the freewheeling diode 9.

According to the fifth embodiment of the present invention as described above, even when a plurality of self-extinguishing elements are connected, most of the charge charged in the snubber capacitor can be used as freewheeling diode coverage energy. , resistance loss in the snubber circuit can be reduced.

Although the embodiment in which the present invention is applied to a chopper concave path has been described above with reference to FIGS. 1 to 6, the present invention can also be applied to an inverter circuit. Embodiments in which the present invention is applied to an inverter circuit will be described below with reference to the drawings.

FIG. 7 is a diagram showing a sixth embodiment of the present invention. In Fig. 7, 26.3o is a self-extinguishing element, 27.31
is a freewheel diode, 28.32 is a snubber capacitor, 29.33 is a snubber diode, 34 is a discharge resistor of the snubber capacitor 28.32, 3S, 37 is a discharge diode, 36.38 is a discharge reactor,
Other symbols are the same as in FIG. 6.

In the sixth embodiment of the present invention, the present invention is applied to an inverter circuit, and only one phase of the inverter circuit is illustrated.

In the illustrated embodiment, a freewheeling diode 27 and a snubber circuit including a snubber capacitor 28 and a snubber diode 29 are connected in parallel to the self-extinguishing element 26 of the upper arm, and a freewheeling diode 31 is connected to the self-extinguishing element 30 of the lower arm. , a snubber circuit consisting of a snubber capacitor 33 and a snubber diode 33 are connected in parallel, and a discharging circuit is connected between the freewheel diode 27 of the upper arm and the connection point between the snubber capacitor 32 and the snubber diode 33 of the snubber circuit of the lower arm. A discharge circuit of the snubber capacitor 32 is connected to the diode 35 and the discharge reactor 36, and the freewheel diode 3 of the lower arm is connected.
A discharge circuit of the snubber capacitor 28 including a discharge diode 37 and a discharge reactor 38 is connected between the snubber capacitor 28 and the snubber diode 29 of the snubber circuit of the upper arm.

A resistor 34 is connected between the connection points between the snubber capacitor and the snubber diode of both snubber circuits.
is a discharge resistance for the snubber capacitor 28, 32, which becomes effective when the load current is small, as in the embodiment described with reference to FIG.

In the sixth embodiment of the present invention configured in this way,
The operation will now be described assuming that the self-extinguishing element 26 of the upper arm is in an off mode.

In this case, the snubber capacitor 28 is charged to almost the same voltage as the power supply voltage, and the load current is circulated through the freewheel diode 31 in the lower arm. In this state, when the self-arc extinguishing element 26 of the upper arm is turned on, the charge in the snubber capacitor 28 is transferred from the self-arc extinguishing element 26 #freewheel diode 31 to the discharge reactor 38 to the discharge diode 37, which causes the momentary snubber capacitor 28 to close. discharged through the circuit. At this time, a composite current obtained by adding the current from the power source to this discharge current flows through the lower arm freewheeling diode 31, and the freewheeling diode 31 is recovered by this composite current. In this state, almost all of the charge in the upper arm snubber capacitor 28 is transferred to the discharge reactor 38.
Then, the energy stored in this discharge reactor 38 flows through the closed circuit of the discharge reactor 38 from the discharge diode 37 to the snubber diode 29.33 and then to the snubber capacitor 32, and is transferred to the lower arm snubber capacitor 32. will be charged.

In the above, the operation has been explained assuming that the self-arc extinguishing element 26 of the upper arm is in the off mode, but it is possible to similarly operate when the self-arc extinguishing element 30 of the lower arm is in the off mode. Needless to say.

According to the sixth embodiment of the present invention shown in FIG. 7 which performs such an operation, the electric charge of the snubber capacitor 28 of the upper arm is can be used as recovery energy for the lower arm freewheel diode 31 and charge energy for the lower arm snubber capacitor 32, and losses due to discharge resistance in the case of the prior art can be significantly reduced.

FIG. 8 is a circuit diagram showing a seventh embodiment of the present invention, and the reference numerals in the figure are the same as those in FIG. 7.

In this embodiment, the discharging resistor 34 of the snubber capacitor, which is necessary when the load current is small, is connected to the connection point between the discharging diode 37 and the discharging reactor 38 that discharge the charge of the snubber capacitor 28 on the upper arm, and the discharging reactor 38 on the lower arm. Discharge diode 35 that discharges the charge of the snubber capacitor 32
and the connection point of the discharge reactor 36.

According to the seventh embodiment of the present invention shown in FIG. reactor (or 3
Since the discharge current is not shunted to the discharge resistor 34 due to the voltage drop in 6), the loss due to the discharge resistor 34 can be made smaller than in the case of the embodiment described with reference to FIG.

FIG. 9 is a circuit diagram showing an eighth embodiment of the present invention. In Figure 9, 39.44.47.52 is a snubber capacitor, 40.45.48.53 is a snubber diode, 4
1.46.49.54 is a snubber resistor, 42.50 is a self-extinguishing element, 43, Sl is a freewheeling diode, - other symbols are the same as in FIG.

The embodiment of the present invention shown in FIG. 9 is the same as the embodiment shown in FIG. 7, in which a plurality of self-extinguishing elements for each of the upper and lower arms are connected in series. The arc element 26.42 also has a self-extinguishing element 30 on the lower arm.
．． 5o are connected in series. Each self-extinguishing element is connected in parallel with a freewheel diode and a snubber circuit, although a detailed explanation thereof will be omitted. Furthermore, as in the case of the embodiment described with reference to FIG. 6, a diode 29 and a capacitor 2
8 are connected in series, and a snubber circuit is connected in parallel to the self-extinguishing elements 30 and 50 of the lower arm.
A snubber circuit in which the capacitor 32 and the capacitor 32 are connected in series is connected in parallel. Also, each diode 29 (3
3) and the capacitor 28 (32), a discharge circuit formed by a series circuit of a diode 37 (35) and an axle 38 (36) is connected to the freewheeling diode circuit of the paired arm.

The eighth embodiment of the present invention shown in FIG. 9 operates in the same way as the embodiments shown in FIGS. Most of the charge in the snubber capacitor of the snubber circuit connected in parallel to the arc-extinguishing element can be used as energy for covering the freewheeling diode of the paired arm.
Resistance loss in the snubber circuit can be reduced. In addition,
In this embodiment as well, as in the embodiment explained in FIG. On the other hand, the resistance loss in the snubber circuit which is smaller than the capacitance of the snubber capacitor of the snubber circuit connected in parallel and connected to each self-extinguishing element is extremely small and does not pose a problem.

As explained above, according to the present invention, the charge accumulated in the capacitor of the snubber circuit connected in parallel to the self-extinguishing element of the power converter is used for freewheeling diode glue coverage energy, etc. Therefore, the resistance loss of the snubber circuit can be significantly reduced.

[Brief explanation of the drawing]

Figure 1 shows a first example of the present invention in which the present invention is applied to a chopper circuit.
FIG. 2 is a diagram showing current waveforms to explain its operation, FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8, and FIG. 9. FIG. 2 is a circuit diagram showing second to eighth embodiments of the present invention. 1...Filter capacitor, 2.3...
・Wiring inductance, 4.5... Armature and field coil of DC motor, 6.19.26.3o・Old・
・Self-extinguishing element, 7.14... Snubber diode, 8.11... Snubber capacitor, 9.27
．． 31...Freewheel diode, 10.
15. Old... Snubber resistance, 12.35.37...
- Discharge diode, 13.36.38... Discharge reactor, 16... Anode reactor, 34... Discharge resistor. Figure 1 Figure 1 Figure 3 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1. An anode reactor, an inductive load, and a freewheeling diode circuit connected in parallel to the inductive load;
In a power converter including a snubber circuit and a self-extinguishing element connected in parallel, the snubber circuit is composed of a series circuit of a snubber diode and a snubber capacitor, and when the self-extinguishing element is turned off, the snubber capacitor is connected to the snubber circuit. Self-extinguishing in a power converter, characterized in that accumulated charge is discharged to the freewheeling diode circuit through a series circuit of a discharging diode and a discharging reactor when the self-extinguishing element is turned on. Element snubber circuit. 2. An anode reactor, an inductive load, self-extinguishing elements in the upper and lower arms that constitute the inverter, a freewheel diode circuit connected in parallel to the self-extinguishing element, and a freewheel diode circuit connected in parallel to the self-extinguishing element. In a power conversion device configured with a snubber circuit connected to the snubber circuit, the snubber circuit is configured of a series circuit of a snubber diode and a snubber capacitor, and discharges the charge accumulated in the snubber capacitor when the self-extinguishing element is turned off. , a power conversion device characterized in that, when the self-arc extinguishing element is turned on, a freewheeling diode circuit connected to the self-arc extinguishing element of the opposite arm is discharged through a series circuit of a discharging diode and a discharging reactor. Snubber circuit for self-extinguishing element. 3. A resistor is separately provided to discharge the charge of the snubber capacitor when the self-arc extinguishing element is turned on, and the discharge time constant of the resistor and the snubber capacitor is an oscillation determined by the snubber capacitor and the discharging reactor. 3. A snubber circuit for a self-extinguishing element in a power conversion device according to claim 1 or 2, wherein the snubber circuit is set to be longer than a period. 4. A plurality of the self-extinguishing elements are connected in series,
A snubber circuit having a small capacitor is connected in parallel to each self-extinguishing element, and a snubber circuit having a large-capacity snubber capacitor is connected in parallel to all the self-extinguishing elements connected in series. In the power conversion device according to claim 1, 2, or 3, the electric charge of the large-capacity snubber capacitor is discharged to the freewheel diode circuit. Snubber circuit for arc-extinguishing element. 5. The freewheeling diode circuit according to claim 1, wherein the freewheeling diode circuit includes at least a freewheeling diode and a snubber circuit connected in parallel to the diode. A snubber circuit for a self-extinguishing element in a power converter.