JPH0530757A - Power converter - Google Patents

Abstract

PURPOSE:To rapidly absorb current energy of an anode reactor (AL) and to suppress an overvoltage to a self-arc extinguishing type semiconductor element by turning ON a switching element when a voltage across the AL exceeds a predetermined value, and turning it OFF 7 when it is lowered. CONSTITUTION:It is assumed that, in a voltage suppressor 3, a voltage ER between input terminals P and N, i.e., a voltage across an AL (not shown) connected in parallel exceeds a predetermined value. After it is voltage-divided by voltage divides 31a, 31b, a voltage comparator 32 turns ON a self- extinguishing type semiconductor element (GTO) 36, and short-circuits between the terminals P and N by a resistor 35. The suppressor 3 turns OFF the element 36 when the voltage ER becomes lower than a predetermined value. Thus, the voltage ER can be suppressed to a predetermined value. In this manner, the current of the AL can be rapidly absorbed, and an overvoltage to the element 36 can be suppressed. Accordingly, even if a switching frequency is high and a cut-off current is large, the overvoltage can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter capable of keeping the voltage of an anode reactor within a certain range when a self-arc-extinguishing semiconductor element is turned off and suppressing an overvoltage when the self-arc-extinguishing semiconductor element is turned off.

[0002]

2. Description of the Related Art As a conventional technique related to the technique of the present invention, FIG. 5 shows an example of the configuration of a power converter which consumes energy of an anode reactor by a resistor. FIG. 5 is an example showing a configuration of two upper and lower arms connected to a DC voltage source of an inverter using a self-arc-extinguishing type semiconductor device (hereinafter, simply referred to as GTO).

A series circuit of a resistor 35 and a diode 2 is connected in parallel to an anode reactor (hereinafter simply referred to as AL) 1. One end of AL1 to which the resistor 35 is connected is connected to the positive side of the DC power supply 21. The other end of AL1 is connected to the anode of GTO 11a. GT
A diode 12a is connected in antiparallel to O11a. A snubber circuit 13a is further connected in parallel to the GTO 11a. The cathode of GTO11a is the output terminal 2
2 and the anode of GTO 11b. G
The TO12b also has a diode 12 as in the GTO11a.
b is connected in antiparallel, and the snubber circuit 13b is connected in parallel. The cathode of the GTO 11b is connected to the negative side of the DC power supply 21.

When the GTO 11a is turned off, the current flowing through the AL1 until then begins to decrease, and a voltage proportional to the current change rate is generated across the AL1a. This voltage turns on the diode 2, and a circulating current flows through the path of the diode 2, the resistor 35, and the AL1. Due to this circulating current, the energy stored in AL1 is
Consumed at 5. The resistance 35 suppresses the rise of the voltage across AL1 and prevents an overvoltage from being applied to the GTOs 11a and 11b and other main circuits.

FIG. 6 shows an example of the configuration of the snubber circuit 13. A snubber capacitor 51 and a snubber resistor 52 are connected in series, and a snubber diode 53 having the illustrated polarity is connected in parallel to the snubber resistor 52. The terminal A of the snubber circuit 13 is the anode of the GTO 11a, and the terminal B is the GTO 1
It is connected to the cathode of 1a.

[0006]

The conventional power conversion device as described above has the following drawbacks.

In FIG. 5, the current decay of AL1 is proportional to the time constant τ = L / R. In a circuit with a high switching frequency, the value of the resistor 35 must be increased in order to accelerate the attenuation of the current of AL1. On the other hand, the voltage generated across AL1 at the time of current interruption is the interruption current and the resistance 3
It is proportional to the size of 5.

Therefore, in a circuit having a high switching frequency and a large cutoff current, the voltage generated across AL1 becomes large, and the voltage when the GTO 11a is turned off becomes an overvoltage.

The present invention has been made in order to eliminate the above-mentioned drawbacks, and quickly absorbs the current energy of AL,
Another object of the present invention is to provide a power conversion device capable of suppressing an overvoltage transiently applied to a self-extinguishing semiconductor element.

[0010]

In order to achieve the above object, the present invention comprises an anodic reactor connected in series to a self-arc-extinguishing type semiconductor device connected to at least the positive electrode side of a DC power supply. In the power conversion device, a series circuit including a switching element and a resistor connected in parallel to the anodic reactor, a capacitor connected in parallel to the series circuit, and a voltage across the anodic reactor have a predetermined value. It is characterized by comprising a circuit which gives an ON command to the switching element when the voltage exceeds the predetermined value and gives an OFF command when the predetermined value decreases.

[0011]

As described above, according to the configuration, the voltage across the anode reactor is turned on when the voltage across the anode reactor exceeds a predetermined value and turned off when the voltage drops below the predetermined value. Can be kept within a desired range.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the block diagram of FIG.

One end of AL1 is connected to the positive side of the DC power source 21. Moreover, this terminal is connected to the voltage suppression circuit 3. The other end of AL1 is a self-extinguishing type semiconductor device 11a.
Connected to the node. Further, this terminal is connected to the node of the diode 2. The diode 2 is connected to a terminal different from the above of the voltage suppression circuit 3. Since the configuration other than the above is the same as that of FIG. 5, the description thereof will be omitted. FIG. 2 is a configuration example of the voltage suppression circuit 3 used in this embodiment.

The input terminal P has a voltage divider 31b and a resistor 3
5 and the capacitor 37 are connected. Voltage divider 31
The other end of b is connected to one terminal of the voltage comparator 32 and the voltage divider 31a. The voltage comparator 32 further includes a reference voltage 3
3 is connected. The output of the voltage comparator 32 is connected to the gate control circuit 34. Gate control circuit 34
Are connected to the gate of the self-extinguishing semiconductor device 36. The collector of the self-arc-extinguishing semiconductor element 36 is connected to the other end of the resistor 35. The input terminal N is the other end of the voltage divider 31a, the emitter of the self-extinguishing semiconductor element 36,
It is connected to the other end of the capacitor 37.

Next, the operation of the present invention will be described with reference to FIG. When the self-extinguishing semiconductor element 11a turns off,
Similar to FIG. 5, the current that has been flowing through AL1 begins to decrease, and a voltage is generated across AL1. When this voltage exceeds the voltage ER kept within a certain range by the voltage suppression circuit 3, the diode 2 turns on and a current flows through the voltage suppression circuit 3. Since the voltage across AL1 is kept within a fixed range by the voltage suppression circuit 3, the current flowing through AL1 decreases at a constant rate of change.

Next, the operation of the voltage suppression circuit 3 will be described with reference to FIG. In FIG. 2, the voltage ER between the input terminals P and N
Is divided by the voltage dividers 31a and 31b, and the voltage comparator 3
Entered in 2. In the voltage comparator 32, the input voltage is compared with the reference voltage 33, and when the input voltage is higher than the reference voltage, the self-extinguishing semiconductor element 36 is turned on and the input terminals P and N are short-circuited by the resistor 35. .. Input terminals P, N
When the voltage ER between them becomes lower than the reference voltage, the self-turn-off semiconductor element 36 is turned off. The voltage comparator 32 is
It may have hysteresis characteristics. With this device, the voltage ER between the input terminals P and N is suppressed to a predetermined voltage value.

Since the voltage ER is kept within a constant range by the voltage suppressing circuit 3, the current of AL1 decreases at a constant rate of change. As a result, the energy of AL1 is rapidly attenuated, and the current of AL1 can be reduced to zero during the off period of the self-arc-extinguishing semiconductor element 11a. Further, the overvoltage at turn-off of the self-extinguishing semiconductor element 11a (11b) can be suppressed to a substantially constant value regardless of the magnitude of the breaking current. FIG. 3 is a block diagram showing another embodiment of the present invention in which ALs are distributed and arranged.

The ALs 1a and 1b are connected to the positive side and the negative side of the DC power source 21, respectively. At the same time, they are connected to the voltage suppression circuits 3a and 3b, respectively. AL1a, A
The other end of L1b is connected to the anode of the self-extinguishing semiconductor element 11a.
11b cathode, diode 2a anode, 2
It is connected to each of the b cats. The self-extinguishing type semiconductor devices 11a and 11b include diodes 12a and 12
b is connected in antiparallel, and the snubber circuits 13a and 13b are connected in parallel. The cathode of the self-arc-extinguishing semiconductor element 11a is connected to the node of the self-arc-extinguishing semiconductor element 11b and is connected to the output 22.

The principle of operation is the same as that of FIG. 1, and the present invention shows that even if the ALs are centrally arranged in one place with respect to two arms as shown in FIG. 1, each arm is provided as shown in FIG. It can be applied even when distributed to.

FIG. 4 shows another embodiment of the present invention. AL1
The a is connected to the positive side of the DC power supply 21, the capacitor 4a, and the N terminal of the voltage suppression circuit 3. The other end of AL1a is connected to the anode of the self-extinguishing semiconductor element 11a and the anode of the diode 2a. The cathode of the diode 2a is connected to the other end of the capacitor 4a. Further, the cathode of the diode 2a is connected to the anode of the diode 5a. The cathode of the diode 5a is connected to the P terminal of the voltage suppression circuit 3. The other structure of the arm is the same as that shown in FIG.

In this embodiment, AL1b, diode 2
b, capacitor 4b, diode 5b, self-extinguishing semiconductor elements 11c and 11d, diodes 12c and 12d, and snubber circuits 13c and 13d, the other arm circuit is connected via diode 5b. Is connected to the voltage suppression circuit 3 which is common to the above-mentioned arm circuit.

In FIG. 4, the self-extinguishing semiconductor device 11
When a is turned off, the current flowing through AL1a starts decreasing and a voltage is generated across AL1a. If this voltage exceeds the voltage of the capacitor 4a, the diode 2
a turns on, and a current flows through the capacitor 4a. Due to the action of the capacitor 4a, the voltage across the AL1a has a substantially constant value, so that the current flowing through the AL1a decreases at a substantially constant rate of change.

In this embodiment, for a plurality of arm circuits,
This is an example in which the voltage suppression circuit 3 is common to AL1s connected to the same potential. The capacitors 4a and 4b are for suppressing a transient increase in the voltage of AL1. Capacitors 4a, 4b due to the stored energy of AL1
When the voltage rises, the diodes 2a and 2b turn on, the voltage suppression circuit 3 operates, and the capacitors 4a and 4b.
Voltage is kept below a certain value.

The operating principle of the voltage suppression circuit 3 is the same as that of FIG. In the present invention, a plurality of arms are connected to the same potential. Applicable to AL. Also, FIG.
The ALs distributed as described above can also be applied to the ALs connected to the same potential.

[0025]

As described above, according to the present invention, there is provided a power converter in which an anodic reactor is connected in series to a self-arc-extinguishing type semiconductor element connected at least to the positive electrode side of a DC power source. It is possible to provide a power conversion device capable of suppressing an overvoltage that occurs at turn-off of a self-arc-extinguishing semiconductor element within a predetermined value even when the switching frequency is high and the breaking current is large.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a power conversion device showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a specific example of a voltage suppression circuit which is a component of FIG.

FIG. 3 is a configuration diagram of a power conversion device showing another embodiment of the present invention.

FIG. 4 is a configuration diagram of a power conversion device showing still another embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional power conversion device.

FIG. 6 is a configuration diagram of a snubber circuit.

[Explanation of symbols]

 1, 1a to 1d ... Anode reactors 2, 2a to 2d ... Diodes 3, 3a to 3d ... Voltage suppression circuits 4a, 4b ... Capacitors 5a, 5b ... Diodes 11, 11a to 11d ... Self-extinguishing type semiconductor device 12, 12a to 12d ... Diode 13, 13a to 13d ... Snubber circuit 21 ... DC power source 22, 22a to 22b ... Output terminal 31a, 31b ... Voltage divider 32 ... Voltage comparator 33 ... Voltage reference 34 ... Gate control circuit 35 ... Resistor 36 ... Self-extinguishing type semiconductor element 37 ... Capacitor 51 ... Snubber capacitor 52 ... Snubber resistor 53 ... Snubber diode

Claims (1)

Claim: What is claimed is: 1. A power converter comprising a anodic reactor connected in series with a self-arc-extinguishing semiconductor element which is connected to at least the positive electrode side of a DC power source. A series circuit composed of a switching element and a resistor connected in parallel with each other, a capacitor connected in parallel with the series circuit, and an ON command to the switching element when the voltage across the anodic reactor exceeds a predetermined value. An electric power converter comprising a circuit for giving an OFF command when a given value is lowered.