JPH0847260A - Low loss snubber circuit of power converter - Google Patents

Abstract

PURPOSE:To constitute a regenerating means simply and at a low cost by a method wherein the energy stored in a snubber circuit is stored in a regenerative energy storing capacitor to which a regenerated energy is supplied by the regenerating means through an energy transfer means. CONSTITUTION:The energy stored in a snubber capacitor CS2 is stored in a capacitor CT through a transfer means composed of a reactor LT, the capacitor CT and a diode DT when a GTO thyristor GTO2 is turned on. Then the energy is stored in a regenerative energy storing capacitor CR to which a regenerating means Rg composed of a self-extinguishing device is connected through a regenerative energy storing diode DR2 when a GTO thyristor GTO1 is turned on. Further, the energy stored in an anode reactor LA1 and a snubber capacitor CS1 is stored in the regenerative energy storing capacitor CR by the on-off control of the GTO thyristor GTO1 and collected into a DC power supply by the regenerating means Rg. As a result, the regenerating means can be constituted simply and at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-loss snubber circuit for a power converter which is constructed by using a plurality of self-turn-off devices.

[0002]

2. Description of the Related Art An apparatus for constructing a power converter using a plurality of self-extinguishing elements and converting power from direct current to direct current or from direct current to alternating current is used in many fields. In particular, voltage-type inverters using GTO thyristors are being put to practical use in the fields of electric railways, rolling mills, and electric power, and are becoming larger in capacity and higher in frequency. Resistance of the voltage snubber circuit (which is composed of a capacitor and is connected in parallel to the GTO) and the current snubber circuit (which is composed of a reactor and which is connected in series to the GTO) provided to reduce the Losses (conventionally, the energy stored in these circuits has been consumed by resistors) have increased, and their reduction has become a very important issue.

Therefore, various so-called low-loss snubber circuits (hereinafter referred to as low-loss snubber circuits) in which the resistance loss of these voltage / current snubber circuits is reduced are considered variously.

For example, FIG. 2 shows a conventional low-loss snubber circuit provided with a means for regenerating the stored energy of the voltage / current snubber circuit to a DC power source. An example of application to a three-phase voltage type inverter is shown in FIG. It is shown in a phase diagram.

In FIG. 2, GTO1 and GTO2 are GTO thyristors as an example of self-extinguishing elements. P and N are positive and negative terminals of the DC power supply, CF is a power supply filter capacitor, and UP and UN are U-phase positive and negative wirings, and V
P, VN and WP, WN respectively indicate positive and negative wirings of V phase and W phase. In the U phase showing the circuit for one phase,
LA1 and LA2 are the anode reactors (current snubber circuit) serially connected to GTO1 and GTO2, and CS1 and DS1 and CS2 and DS2 are GT.
Snubber capacitors and snubber diodes (which make up a voltage snubber circuit) connected in parallel to O1 and GTO2, DF1 and D
F2 is a freewheel diode connected in parallel with GTO1 and GTO2, DR1 and CR1, DR2 and C
R2 is the energy stored in the voltage / current snubber circuit
A diode and a capacitor for forming a circuit for temporarily storing electricity according to ON / OFF control of TO1 and GTO2. Rg1 and Rg2 are the storage capacitors CR1 and C
A means for regenerating the energy of R2 to a DC power supply. Here, the self-extinguishing element GTOg1 and the reactor Lg1 are provided.
And a diode Dg1, a self-extinguishing element GTOg2, a reactor Lg2 and a diode Dg2.

Here, the regenerative operation of the energy stored in the voltage / current snubber circuit will be briefly described by taking the upper arm as an example. The energy stored in the upper arm snubber capacitor CS1 is CS1-CR1-LA when GTO1 is turned on.
1-GTO1-CS1 closed circuit, and the stored energy of the upper arm anode reactor LA1 is LA1-DS1-DR1-CR1-LA1 when GTO1 is turned off.
The closed circuit is used to store electricity in the electricity storage capacitor CR1. The stored energy of the storage capacitor CR1 is used for the chopper operation by the on / off control of the self-extinguishing element GTOg1 of the regenerative means Rg1, that is, when the GTOg1 is turned on, the reactor L is turned on.
Energy is stored in g1, and when the GTOg1 is turned off, the energy of the reactor Lg1 is recovered in the power supply filter capacitor CF via the diode Dg1. The regenerative operation of the lower arm can be considered in the same way.

[0007]

As described above, in the conventional circuit of FIG. 2, since the energy stored in the voltage / current snubber circuit of the GTO can be regenerated to the DC power source, a power converter with low loss and very high conversion efficiency can be obtained. On the other hand, two sets of regenerative means are required, and in particular, two sets of self-extinguishing elements that require auxiliary devices such as a gate driver and a snubber are also required, which makes the regenerating means complicated and expensive. Therefore, the power converter also becomes expensive. Although the regenerative means of FIG. 2 is shown as a chopper circuit, for example, a DC-D using a transformer is used.
The C converter circuit also requires a plurality of self-extinguishing elements such as transistors, which inevitably becomes complicated and expensive.

The problem is that as the capacity and frequency of the power converter increase, the number of the above-mentioned regenerative means increases and the capacity increases, so that the power converter becomes more expensive.
For this reason, simplification of regenerative means and price reduction are very important issues.

In view of the above, an object of the present invention is to make the stored energy regenerating means of the voltage / current snubber circuit in the power converter constituted by a plurality of self-extinguishing elements unnecessarily complicated and expensive. It is to provide a low-loss snubber circuit that can be configured without any need.

[0010]

According to the present invention, in a power converter composed of a plurality of self-extinguishing elements, the stored energy regeneration of the above voltage / current snubber circuit is composed of self-extinguishing elements. To store the energy stored in another snubber circuit in a regenerative energy storage capacitor to which the regenerative means and the regenerative means composed of the self-extinguishing element are connected via the energy transfer means composed of a capacitor or a reactor. It is in.

[0011]

For this reason, the regenerative means constituted by the self-extinguishing element regenerates energy to the regenerative energy storage capacitor, and the energy stored in the other snubber circuit is passed through the energy transfer means constituted by the condenser and the reactor. Since the electricity can be stored, there is a feature that the stored energy of the voltage / current snubber circuit can be regenerated even if the number of regenerative means composed of complicated and expensive self-extinguishing elements is small.

[0012]

1 is an embodiment of a low-loss snubber circuit according to the present invention, showing an application example to a voltage type inverter corresponding to the conventional example of FIG. In FIG. 1, one set of regenerative means Rg composed of self-extinguishing elements (corresponding to Rg1 in FIG. 2)
Thus, the lower arm anode reactor LA2, the regeneration means Rg2, and the capacitor CR2 in the conventional example of FIG. 2 are eliminated. For this reason, the current snubber effect by the lower arm anode reactor LA2 is given by increasing the capacity of the upper arm anode reactor LA1.

In the embodiment of the present invention shown in FIG. 1, the energy stored in the snubber capacitor CS2 is first measured by the GTO thyristor G.
When the TO2 (or the freewheel diode DF2) is turned on, the energy is transferred to the capacitor CT by the energy transfer means including the reactor LT, the capacitor CT, and the diode DT. Next, when the GTO thyristor GTO1 is turned on, the regenerative energy storage capacitor C to which the regenerative means Rg composed of the self-extinguishing element is connected via the diode DR2 for the regenerative energy storage circuit.
Power is stored in R (corresponding to CR1 in the conventional example in FIG. 2). The other circuit configurations and reference numerals are the same as those in the conventional example of FIG.

The stored energy of the anode reactor LA1 and the snubber capacitor CS1 is based on the on / off control of the GTO1, and the regenerative energy storage capacitor CR.
That is, the power is stored in and is recovered by the regenerative means Rg in the DC power source, which is the same as the operation of the conventional example of FIG.

On the other hand, in the present invention, the snubber capacitor CS
The stored energy of 2 is once stored in the capacitor CT in the closed circuit of CS2-DT-LT-CT-GTO2-CS2 when the GTO2 (or freewheel diode DF2) is turned on, and the next GT is stored.
When the O thyristor GTO1 is turned on, the capacitor CT
Is stored in the regenerative energy storage capacitor CR in the closed circuit of CT-DR2-CR-LA1-GTO1-CT. As a result, the energy stored in the snubber capacitor CS2 can also be stored in the regenerative energy storage capacitor CR and then recovered in the DC power supply by the operation of the regenerating means Rg.

As described above, according to the embodiment of the present invention shown in FIG. 1, one set of regenerative means composed of self-extinguishing elements, which conventionally required two sets of stored energy regeneration of each voltage / current snubber circuit of the upper and lower arms. It is possible to reduce the cost of the regeneration means, that is, the power converter can be reduced.

FIG. 3 shows another embodiment of the low-loss snubber circuit of the present invention, which is an example applied to a structure in which each upper and lower arm of the above voltage type inverter has two self-extinguishing elements connected in series. is there. In the embodiment of FIG. 3, compared with the conventional embodiment of FIG. 2, the number of GTO thyristors, which are self-extinguishing elements, is increased by one in each of the upper and lower arms, and the upper arms are GTO1 and GTO.
The TO2 is connected in series, the lower arm is composed of GTO3 and GTO4 connected in series, and GTO1 is the GT of the conventional embodiment shown in FIG.
O1 and GTO4 correspond to GTO2 of the conventional embodiment shown in FIG. Therefore, the anode reactor LA1 and the snubber capacitor CS1 are controlled by the on / off control of the GTO1.
Stored energy regenerative operation and GTO4 on / off control for anode reactor LA2 and snubber capacitor C
The stored energy regeneration operation of S4 is performed by the regeneration means Rg1 and Rg2 as in the conventional example of FIG.

On the other hand, in the present invention, the GTO thyristor GT
The energy stored in the snubber capacitor CS3 of O3 is first stored in the capacitor CT2 by the energy transfer means ET2 including the reactor LT2 and the capacitor CT2 when the GTO3 is turned on, and then the capacitor CT2.
When the GTO1 and GTO2 are turned on, the stored energy of 2 is the diode DR for the regenerative energy storage circuit.
It is supplied via 3 to the regenerative energy storage capacitor CR1 to which the regenerative means Rg1 is connected. Further, the stored energy of the snubber capacitor CS3 of the GTO3 is supplied to the regenerative energy storage capacitor CR2 to which the regenerative means Rg2 is connected via the energy transfer means ET2 including the reactor LT2 and the capacitor CT2. The energy transfer means ET1 and ET2
Regenerative energy storage capacitors CR1 and CR
The operation of accumulating the energy stored in the snubber capacitor to the second snubber capacitor is the same as the operation in the embodiment of the present invention shown in FIG. 1, and therefore the description thereof will be omitted here, but according to the embodiment shown in FIG. The energy stored in the snubber capacitors of the two GTOs can be recovered to the power source without increasing the number of regenerative means composed of self-turn-off devices. In the present embodiment, the number of series-connected self-extinguishing elements forming the arm is set to two, but the present invention is not limited to this and is also applicable to the case of multiple series connection of two or more. .

As described above, according to the embodiment of the present invention shown in FIG. 3, even if the number of self-extinguishing elements forming the upper and lower arms is increased in series, the energy stored in each voltage / current snubber circuit is self-extinguished. The number of regenerative means composed of self-extinguishing elements is achieved by providing energy transfer means to store the stored energy of another voltage snubber circuit in the regenerative energy storage capacitor to which the regenerative means composed of arc elements are connected in parallel. Can be carried out without increasing the number, and the regeneration means can be made inexpensive, that is, the power converter can be made inexpensive.

FIG. 4 shows still another embodiment of the low-loss snubber circuit of the present invention, which is an example of application to a three-level voltage type inverter circuit. The operation of the three-level voltage type inverter is publicly known (for example, Japanese Patent Laid-Open No. 55-43996) and will not be described. In the embodiment of the present invention shown in FIG. 4, another voltage snubber circuit is provided for the regenerative means composed of the self-extinguishing elements of the upper and lower arms and the regenerative energy storage capacitor to which the regenerative means composed of the self-extinguishing elements are connected in parallel. The connection of the energy transfer means for storing the stored energy is stored in the same manner as in the embodiment of FIG. Then, the anode reactor LA1 and the snubber capacitor CS are controlled by the ON / OFF control of the GTO1.
The stored energy regeneration operation of No. 1 and the stored energy regeneration operation of the anode reactor LA2 and the snubber capacitor CS4 by the ON / OFF control of GTO4 are performed by the regeneration means Rg1 and Rg2 as in the embodiment of FIG.
Further, when the GTO2 or GTO3 is turned on, the snubber capacitors CS3, C of the GTO3 or GTO2 of the opposite arm are turned on.
The energy stored in S2 is transferred to the energy transfer means ET1, E
Regenerative energy storage capacitor C in which the regeneration means Rg1 and Rg2 are connected in parallel via T2.
The operation of supplying R1 and CR2 is performed in the same manner as in the embodiment of FIG.

As described above, according to the embodiment of the present invention shown in FIG.
Similar to the above embodiment, there is an effect that the power converter can be made inexpensive.

[0022]

According to the low-loss snubber circuit of the embodiment of the present invention described in detail above, in a power converter composed of a plurality of self-extinguishing elements, it is connected to a plurality of self-extinguishing elements. There is an effect that the stored energy regeneration means of the voltage / current snubber circuit can be configured without making it more complicated and expensive than necessary, and the power converter can be made inexpensive.

[Brief description of drawings]

FIG. 1 is a low-loss snubber circuit diagram of an embodiment of the present invention.

FIG. 2 is a conventional low-loss snubber circuit diagram.

FIG. 3 is a low-loss snubber circuit diagram of another embodiment of the present invention.

FIG. 4 is a low-loss snubber circuit diagram of another embodiment of the present invention.

[Explanation of symbols]

P ... Positive terminal of DC power supply, N ... Negative terminal of DC power supply, UP ...
U-phase positive wiring, UN ... U-phase negative wiring, VP ... V-phase positive wiring, VN ... V-phase negative wiring, WP ... W-phase positive wiring, WN ...
W-phase negative wiring, CF, CF1, CF2 ... Power supply filter capacitors, LA1, LA2 ... Anode reactor, GTO
1, GTO2, GTO3, GTO4 ... GOT thyristor, DF1, DF2, DF3, DF4 ... Free wheel diode, CS1, CS2, CS3, CS4 ... Snubber capacitor, DS1, DS2, DS3, DS4 ... Snubber diode, DR1, DR2, DR3 , DR4 ... Diode, CR, CR1, CR2 ... Capacitor, LT, LT
1, LT2 ... Reactor, CT, CT1, CT2 ... Capacitor, DT, DT1, DT2 ... Diode, Rg, R
g1, Rg2 ... Regeneration means, GTOg, GTOg1, GT
Og2 ... Self-extinguishing element, Lg, Lg1, Lg2 ... Reactor, Dg, Dg1, Dg2 ... Diode.

Claims (3)

[Claims] 1. A self-extinguishing element in which a DC power source and a current snubber composed of a reactor are connected in series, and a first voltage snubber composed of a series body of a capacitor and a diode is connected in parallel to form one arm in the structure. In the power converter in which the other arm is configured by the self-extinguishing element in which the second voltage snubber of is connected in parallel,
A stored energy regenerating means comprising an energy storage capacitor for storing the stored energy of the voltage snubber and a self-extinguishing element connected in parallel to the energy storage capacitor, the stored energy of the voltage snubber in the other arm, a reactor, a capacitor and a diode. A low-loss snubber circuit for a power converter, which stores electricity in the energy storage capacitor via an energy transfer means including the following. 2. A first self-extinguishing element in which a DC power supply and a current snubber composed of a reactor are connected in series, and a first voltage snubber composed of a series body of a capacitor and a diode is connected in parallel, and a first self-extinguishing element of the above construction. In a power converter in which two voltage snubbers are connected in parallel with a second self-extinguishing element in a series body to form upper and lower arms, a first self-extinguishing element for each of the upper and lower arms is provided. A stored energy regenerating means comprising an energy storage capacitor for storing and storing stored energy of a current / voltage snubber and a self-extinguishing element connected in parallel to the energy storage capacitor, and second upper and lower arms respectively. The energy stored in the voltage snubber in the self-extinguishing element is transferred through the energy transfer means including a reactor, a capacitor and a diode. Low-loss snubber circuit for a power converter wherein the power storage to electric capacitor. 3. The power conversion system according to claim 2, wherein the DC power supply is divided into two, and a diode is provided from the division point and the diode is connected to a connection point of the first and second self-extinguishing elements in the upper and lower arms. A low-loss snubber circuit for a power converter, comprising a power converter.