JPH06189444A - Low loss snubber circuit of power converter - Google Patents

Abstract

PURPOSE:To simplify an energy regenerative apparatus and reduce the cost of the apparatus, by dividing and using anode reactors inserted for controlling a current increase rate in GTOs as means for temporarily storing the energy stored in a snubber capacitor in an energy regenerative circuit when the GTOs are turned on. CONSTITUTION:When unit series bodies of upper arms GTO1 and GTO2 are turned on, snubber capacitors CS1 and CS2 are respectively discharged through a closed circuit comprising a capacitor CS1-diode DP1-capacitor CP1-divided anode reactor LA1-GTO1-capacitor CS1 and a capacitor CS2-GTO2-anode reactor LA2-capacitor CP2-diode DP2-capacitor CS2, the charge from the snubber capacitors CS1, CS2 is almost stored in the capacitors CP1 and CP2 with the help of the reactors LA1 and LA2. Next, when the upper arms GTO1 and GTO2 are turned off, the stored energy in the reactors LA1 and LA2 is respectively discharged through a closed circuit comprising an LA1-DS1-DP1-CP1-LA1 and an LA2-DS2-DP2-CP2-LA2, and are stored in the capacitors CP1 and CP2.

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 composed of an arm in which a large number of power semiconductor devices are connected in series.

[0002]

2. Description of the Related Art An apparatus for constructing a power converter using a power semiconductor device 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 that use GTO thyristors are being put to practical use in the fields of electric railways, rolling mills, and electric power, and are being made larger in capacity and higher in frequency. The snubber circuit and the anode reactor circuit provided for reducing the resistance loss increase, and the reduction thereof is a very important problem.

Therefore, various types of so-called low-loss snubbers (hereinafter referred to as low-loss snubbers) in which the resistance loss of these snubber circuits and anode reactor circuits are reduced have been considered, for example, Japanese Patent Application No. 3- No. 118723 "Snubber circuit" describes a low-loss snubber circuit in a power converter that is configured by an arm in which a large number of GTO thyristors are connected in series in order to increase the capacity of the power converter.

That is, in each of the GTOs connected in series, a snubber circuit composed of a series body of a snubber diode and a snubber capacitor is connected in parallel. And a capacitor)
After that, it is regenerated to a power source by a DC-DC converter or the like, and has a feature that the resistance loss of the snubber circuit can be reduced. Further, the energy stored in the anode reactor is also DC-DC via a regenerative circuit provided separately from the regenerative circuit.
It is regenerated to a power source by a converter or the like.

[0005]

However, in this low-loss snubber circuit, a separate reactor for temporarily storing the stored energy of each snubber capacitor in the regenerative circuit is additionally provided, and the stored energy of the anode reactor is Since a regenerative circuit is separately provided to store electricity, the energy regenerative device including these may be complicated and expensive.

In view of the above, an object of the present invention is to provide a power converter including an arm in which a large number of power semiconductor devices are connected in series, without making the energy regenerating device described above unnecessarily complicated and expensive. An object of the present invention is to provide a low-loss snubber circuit that can significantly reduce the resistance loss of the circuit and the anode reactor circuit.

[0007]

According to the present invention, in a power converter comprising an arm in which a large number of power semiconductor devices are connected in series, each snubber capacitor in a snubber circuit of the above construction connected in parallel to the power semiconductor device. As a means for temporarily storing the stored energy in the energy regenerating circuit at the time of turn-on, the anode reactor originally inserted for the purpose of suppressing the current increase rate of the power semiconductor device is divided and used. Further, the stored energy of the anode reactor itself has a circuit means for storing the energy in the energy regeneration circuit.

[0008]

In the power converter having the arm circuit structure as described above, when the power semiconductor devices connected in series are turned on and turned off, not only the stored energy of the anode reactor itself but also each snubber capacitor in the snubber circuit. The stored energy can also be stored in the energy regeneration circuit, and after that DC-D
It is possible to reduce the resistance loss of the snubber circuit and the anode reactor circuit described above by regenerating the power source by the C converter or the like.

[0009]

1 is a block diagram of a main circuit showing an embodiment of the present invention, showing one phase when applied to a three-phase voltage type GTO inverter. Since the configurations of the upper and lower arms are the same, FIG. 1 shows the upper arm circuit when the number of GTO series units is two per arm.

In FIG. 1, P and N are positive and negative terminals of a DC power source, and CF _P is a divided upper arm power source filter capacitor. LA ₁ and LA ₂ are obtained by dividing the anode reactor LA that is originally inserted to suppress the rate of increase of the current flowing in the GTO, and are connected to each GTO as shown in the figure.

GTO ₁ and GTO ₂ are upper arm series-connected gate turn-off thyristors, and DF ₁ and DF ₂ are upper arm series-connected freewheel diodes.
TO and DF are connected in an antiparallel relationship. GT
RP ₁ and RP ₂ connected in parallel to O ₁ and GTO ₂ are voltage dividing resistors.

CS ₁ and DS ₁ and CS ₂ and DS ₂ are capacitors and diodes that compose the snubber circuit of the GTO ₁ and GTO ₂ , and are connected to each GTO as shown in the figure. It Further, DP ₁ and CP ₁ and DP ₂ and CP ₂ are diodes and capacitors for the regenerative circuit, respectively, and are shown via snubber diodes DS ₁ and DS _{2 respectively} to the anode reactors LA ₁ and LA _2. Is connected like.
DC-DC converters CON ₁ and CON ₂ are connected to the regenerative circuit capacitors CP ₁ and CP ₂ , respectively, and the DC-DC converters CON ₁ and CON ₂ are divided filter capacitors on the power supply side. It is connected in parallel to CF _P. This DC-DC converter is, for example, a well-known type such as the full bridge type shown in FIG. 3 or the push-pull type shown in FIG. 4, and the detailed description of its circuit and operation will be omitted.

The operation of the low-loss snubber circuit according to the embodiment of the present invention shown in FIG. 1 will be described based on the turn-on / turn-off operation of the upper arm.

[0014] First, the unit series body of the upper arm GTO ₁ and GTO ₂ is in the off state, of the GTO ₁ and GTO ₂ in parallel connected snubber capacitor CS ₁ and CS ₂ to the power supply voltage 1
The voltage of / 2 is charged. Upper arm GTO ₁ and GT
Wherein the unit series of O ₂ is turned on the electric charge of the snubber capacitor CS ₁ and CS ₂ are each Re Re each _{CS 1 -DP 1 -CP 1 -LA 1} -GTO 1 -CS 1 CS 2 -GTO 2 -LA ₂ -CP ₂ -DP ₂ discharged at -CS ₂ closed circuit, that the largely anode reactor L
Regenerative circuit capacitor CP with the help of A ₁ and LA ₂
It is stored in ₁ and CP ₂ .

Next, the unit series body of the upper arm GTO ₁ and GTO ₂ is turned off from the on state, the stored energy of the anode reactor LA ₁ and LA ₂ are each Re Re each LA ₁ -DS ₁ -DP ₁ -CP _{1 -LA 1 LA 2 -DS 2 -DP} 2 -CP 2 discharged at -LA ₂ closed circuit, that most of them are stored in the capacitor CP ₁ and CP ₂ for regeneration circuit. The energy of the regenerative circuit capacitors CP ₁ and CP ₂ thus stored is regenerated to the divided filter capacitors on the power source side via the well-known DC-DC converters CON ₁ and CON ₂ , respectively. . In the present embodiment, the case of regenerating into the divided filter capacitors has been shown, but it is not limited to this, and it goes without saying that the power may be regenerated directly into the power supply. When two or more GTOs are connected in series, a plurality of pairs of arm configurations of the embodiment of FIG. 1 may be connected in series.

As described above, according to the embodiment of the present invention shown in FIG. 1, the energy regenerator is complicated by dividing and utilizing the anode reactor LA which is originally inserted to suppress the increase rate of the current flowing in the GTO. -There is an effect that the resistance loss of the snubber circuit and the anode reactor circuit can be significantly reduced without increasing the cost.

FIG. 2 is a block diagram of a main circuit showing another embodiment of the present invention. FIG. 2 simplifies the energy regeneration device when the number of GTO series is two or more, and shows an upper arm circuit when four GTOs are provided per arm.

In FIG. 2, the anode reactor LA is divided into three into LA ₁ , LA ₂ and LA ₃ , and the GTOs are connected in series by _two GTO ₁ and GTO ₂ and GTO ₃ and GTO.
Two of TO ₄ series-connected and are divided into two parts. And GT
Anode reactors LA ₁ and LA ₂ for two series connection bodies of O ₁ and GTO ₂ and snubber circuits CS _{1 to} DS ₁ and CS ₂
-DS _{2 and} regenerative circuits DP ₁ -CP ₁ and DP ₂ -CP
_{The two} are connected almost the same as in FIG. On the other hand, GTO ₃ and G
The two series connection of TO _4, wherein the upper end thereof an anode reactor LA _2, also the arrangement of Figure 2 where the anode reactor LA ₃ is connected at its lower end. GTO ₃ and GT
O ₄ snubber circuit in CS ₃ to DS ₃ and CS ₄ to DS ₄ is also in the anode reactor LA ₃ regenerative circuit CP ₃ to DP ₃
Are connected in parallel as shown. The regenerative circuit capacitor CP ₃ has a DC-DC converter CO
N ₃ is connected, and the DC-DC converter CON ₃ is connected to the divided filter capacitor CF _P on the power source side.

[0019] Each GTO is turned on from the off state, the energy stored in the snubber capacitor CS _1, CS _2, CS _3, the husband Re Re each _{CS 1 -DP 1 -CP 1 -LA 1} -GTO 1 -CS 1 _{CS 2 -GTO 2 -LA 2 -DS 3} -CP 2 -DP 2 -CS 2 CS 3 -CP 2 -DP 2 -DS 2 -LA 2 -GTO 3 -CS 3 CS 4 -GTO 4 -LA 3 -CP _3- DP ₃ -CS ₄ closed circuit discharges, most of which is anode reactor L
Electricity is stored in the regeneration circuit capacitors CP ₁ and CP ₂ and CP ₃ with the help of A ₁ , LA ₂ and LA ₃ .

Further, when the GTO is turned off from the on state, the stored energy of the anode reactor LA _1, LA _2, LA ₃ is each Re Re each _{LA 1 -DS 1 -DP 1 -CP 1} -LA 1 LA _{2 -DS 3 -CP 2 -DP 2 -DS} 2 -LA 2 LA 3 -CP 3 -DP 3 -DS 4 was discharged at closed circuit -LA _3, the most of them regenerative circuit capacitors CP _1, CP ₂ , stored in CP ₃ . The regenerative circuit capacitors CP ₁ , CP ₂ and CP ₃ thus stored.
The stored energy is regenerated by the divided filter capacitors on the power source side via the DC-DC converters CON ₁ and CON ₂ and CON ₃ described above.

As described above, the embodiment of the present invention shown in FIG. 2 has the series body of the two GTOs and the two anode reactors of the embodiment shown in FIG.
Of the four GTOs and four anode reactors in series obtained by connecting two sets in series, two anode reactors in the central portion can be considered to be combined into one. By doing so, in the embodiment of FIG.
For each, anode reactor, regenerative circuit and DC-D
Two sets of C converters were required, but three sets of anode reactors, regenerative circuits, and DC-DC converters are required for four GTOs, which complicates and replenishes the energy regenerating device. Without this, the resistance loss of the snubber circuit and the anode reactor circuit can be significantly reduced.

[0022]

The circuit configuration of the present invention described above is a GTO.
As the number of series of the GTO increases, it is possible to reduce the energy regenerative device configured by the anode reactor, the regenerative circuit, the DC-DC converter, and the like. Since n / 2) +1, a low-loss snubber circuit, which is the object of the present invention, can be obtained without making the energy regeneration device complicated and expensive.

The DC-DC converter in the above embodiment may be a chopper, and the main circuit power source for energy recovery may be an auxiliary power source. Furthermore, it goes without saying that the power converter may be configured by connecting a plurality of sets of the arms as a unit and connecting them in series.

[Brief description of drawings]

FIG. 1 is a main circuit configuration diagram showing an embodiment of a low-loss snubber system according to the present invention.

FIG. 2 is a main circuit configuration diagram showing another embodiment of the low-loss snubber system according to the present invention.

FIG. 3 is a circuit example of a DC-DC converter applicable to the circuit of the present invention.

FIG. 4 is another circuit example of a DC-DC converter applicable to the circuit of the present invention.

[Explanation of symbols]

P ... DC power source positive side terminal, N ... DC power source negative side terminal, C
F _P ... divided upper arm filter capacitor, LA
₁ , LA ₂ , LA ₃ ... Divided upper arm anode reactor, GTO ₁ , GTO ₂ , GTO ₃ , GTO ₄ ... Upper arm gate turn-off thyristor, DF ₁ , DF ₂ , D
F ₃ , DF ₄ ... upper wheel free wheel diode, R
_{P 1, RP 2, RP 3} , RP 4 ... voltage dividing resistors of the upper arm,
CS ₁ , CS ₂ , CS ₃ , CS ₄ ... upper arm snubber capacitors, DS ₁ , DS ₂ , DS ₃ , DS ₄ ... upper arm snubber diodes, DP ₁ , DP ₂ , DP ₃ ... upper arm regenerative circuit use _{diodes, CP 1, CP 2, CP} 3 ... regeneration circuit capacitor of the upper _{arm, CON 1, CON 2, CON} 3 ... regenerative DC-DC converter of the upper arm.

Claims (3)

[Claims] 1. A power converter comprising an arm in which a large number of power semiconductor devices are connected in series, wherein the arm has two arms.
A unit series body in which power semiconductor devices are connected in series,
A first snubber circuit composed of a series body of a diode and a capacitor connected in parallel to one power semiconductor device of the unit series body, and a series body of a capacitor and a diode connected in parallel to the other power semiconductor device. A second snubber circuit, a reactor connected to the upper and lower ends of the unit series body, and a first body composed of a series body of a diode and a capacitor connected in parallel to the reactor of the upper end via a diode of the first snubber circuit. Energy storage circuit,
Further, the second energy storage circuit consisting of a series body of a diode and a capacitor connected in parallel to the reactor at the lower end via a diode of a second snubber circuit,
A low-loss snubber circuit for a power converter, wherein the stored energy of the first and second energy storage circuit capacitors is regenerated to a main circuit power source or an auxiliary power source using a DC-DC converter. 2. A low-loss snubber circuit for a power converter, wherein a plurality of sets of the arm structure according to claim 1 are connected in series to form an arm. 3. The set according to claim 2, wherein two sets of reactors that are directly connected in series without a power semiconductor device, an energy storage circuit and a DC-DC converter that are connected in parallel to the reactor are shared. A low-loss snubber circuit of a power converter characterized by the above.