JPH0645901A - Gate turn-off thyristor gate circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] While the GTO is in the ON operation, it is detected that the gate potential becomes negative due to some external factor, and the turn-on pulse current is applied again to prevent the GTO from being damaged. As means for charging the first and second on-pulse current generating circuits, a means for connecting one end of a capacitor to a negative potential through a switch at the time of off operation, and a means for charging the second on-pulse current generating circuit at the time of on-operation. The on-pulse generation circuit is a gate circuit equipped with a switch that detects that the gate potential has become negative even during the on-operation and sends an on-pulse again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate circuit for controlling on / off of a gate turn-off thyristor.

[0002]

2. Description of the Related Art FIG. 4 shows a main part of a conventional gate circuit disclosed in, for example, Japanese Patent Application Laid-Open No. 1-109912, in which 1 is a gate turn-off thyristor (hereinafter referred to as GTO), and G is a gate electrode. , K are cathode electrodes. 2 is a chopper circuit, which is an on-gate power supply 3
It is composed of a chopper switch 14 for switching the current, a current detecting means 16 for detecting the output current of the chopper circuit 2, and a free wheeling diode 15. Reference numeral 11 denotes a coupling reactor, which includes a primary winding 11a and a secondary winding 11b. Reference numeral 8 is a first capacitor, 9 is a second capacitor, 10 is a current limiting resistor, and 5 and 36 are discharging diodes. An on-gate switch 12 supplies the output currents of the chopper circuit 2, the first capacitor, and the second capacitor to the GTO 1 as an on-gate current.
Reference numeral 7 is a diode for charging the first capacitor 8. Reference numeral 18 is a second switch, which is a switch for charging the first and second capacitors. An off-gate switch 13 supplies an off-gate current to the GTO 1. Reference numeral 20 is an interface circuit for ON / OFF signals, and 19 is an inverter for polarity reversal.

Next, the operation will be described. In FIG. 5, the chopper circuit 2 that constitutes the on-gate power supply 3 in combination with the on-gate power supply 3 has a function of constant current control, and detects the gate current Ig by the current detection circuit 16,
The value of the on-gate current is made constant by adjusting the conduction ratio of the chopper switch 14. The free wheeling diode 15 conducts when the chopper switch 14 is off, and functions to make the gate current continuous via the reactor 11. When the signal sent from the interface circuit 20 is off by the on / off command, the off-gate current is supplied to the GTO 1 from the off-gate switch 13.

A case where the on-gate switch 12 is turned on and off will be described with reference to operation waveforms shown in FIG. Before time t ₁ , the on-gate switch 12 and the first turn-on pulse generating switch 17 are off, the second charging switch 18 and the off-gate switch 13 are on.
Is on and the chopper switch 14 is on and off, and the first and second capacitors 8 and 9 are charged to the polarities shown in the figure. When the on-gate switch 12 and the first turn-on pulse generation switch 17 are turned on at time t ₁ , the gate current Ig is the discharge current Ic of the first capacitor 8, the second capacitor 9 and the secondary winding 11b of the reactor 11. _Flow with the sum of the oscillating current I _cc .

At time t ₂ , the voltage Ecq of the second capacitor 9 decreases and the primary winding 11 of the reactor 11 is reduced.
Voltage generated at a (generated at the reverse polarity of the power supply at a ratio of 1: n)
Becomes lower than the voltage of the on-gate power supply 3, the current of the secondary winding 11b of the reactor 11 commutates (transfers) to the primary winding 11a. Assuming that the winding ratio of the primary winding 11a and the secondary winding 11b of the reactor 11 is 8: 1, for example, the output current I _CH of the chopper circuit 2 is I at time t ₂ .
_CH = I _cc / 8 and the flow begins. In practice, it is desirable to determine the winding ratio of the reactor 11 so that the initial value of the primary winding 11a of the reactor 11 matches the constant current value of the chopper circuit 2.

After the time t ₂ , the gate current Ig flows as a substantially constant current due to the constant current control function of the chopper circuit 2. At time t ₃ , the on-gate switch 12 and the first turn-on pulse generation switch 17
Is turned off and the off-gate switch 13 and the second charging switch 18 are turned on, the common portion X of the first and second capacitors 8 and 9 becomes a negative potential, and the first charging diode 7 Through the second charging diode 6, the first and second capacitors are instantaneously charged to the off-gate power supply voltage. After time t _4, I _CH does not flow.
That is, the first capacitor 8 and the second capacitor 9
Is instantly highly charged when the off-gate current is supplied.

[0007]

Since the gate circuit of the conventional gate turn-off thyristor is configured as described above, the second charging switch is required, and the GT
When the gate potential is biased in the reverse direction due to an external factor during the ON operation of O, that is, when the positive gate forward current is flowing, the ON pulse current cannot flow even though the re-strike signal is required, and the GTO does not flow. There was a problem that was damaged.

The present invention has been made in order to solve the above problems. The second charging switch is also used as an off-gate switch, and a resistor or a reactor is inserted as a current limiting element. The turn-on pulse generator circuit is designed to allow the turn-on pulse current to flow to the GTO again when the gate potential becomes negative in the ON state.

[0009]

In the gate circuit according to the present invention, a series body of a diode and a current limiting element is connected to an off-gate switch from the common part of the first and second capacitors, and the charging circuit is commonly used. , The gate of the second on-pulse generation circuit is the sum of the oscillation current of the third capacitor and the reactor and the discharge current of the fourth capacitor and the resistor when the gate signal is on and the gate potential becomes negative. In addition to being generated as a re-ignition current, the charging voltage of the third and fourth capacitors is charged in a resonance state by using a resistor or a reactor as a current limiting element.

[0010]

The charging for the on-pulse current according to the present invention is performed when the off-gate switch is on.
By using a resistor or a negative potential in the resonance state with the reactor, one end of the capacitor is charged from the 0 potential through the charging diode, and the forward gate current is applied, and this current becomes 0 due to an external factor. If so, the on-pulse current is forced to flow again.

[0011]

EXAMPLES Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. It should be noted that the same components as those of the related art are denoted by the same reference numerals, and duplicate description thereof will be omitted. In FIG. 1, 25 is a third capacitor, 26 is a fourth capacitor, 21 is a reactor, 23 is a current limiting resistor, 22,
Reference numeral 24 is a discharging diode. 28 is a third charging diode, and 37 is a fourth charging diode. The diode 29 is for charging and is connected to the common portion Y of the capacitors 25 and 26, and the charging diode 27 is connected to the output terminal from the common portion X of the first capacitor 8 and the second capacitor 9 of the conventional circuit. However, this common portion is connected to the off-gate switch (= on-gate switch = G terminal of GTO) through the current limiting element (resistor) 30.

Further, a second turn-on pulse generating switch 33 is connected between 0 voltage (= K terminal of GTO) from the common portion Y of the third and fourth capacitors 25 and 26. , Gate voltage detection comparator 35
Is connected to a gate output terminal G (= common point of the turn-on switch 12 and the turn-off switch 13), and the inverting input terminal of the bias power supply 34 has a 0 potential (= gate output terminal K) as a positive potential. Are connected. An AND circuit of the output of the comparator 35 and the output of the interface circuit is 31, and a one-shot multi 32 is connected to this output to serve as a drive signal for the switch 33.

Next, the operation will be described. The operation from time t ₁ to t ₃ is the same as the conventional one, and therefore will be omitted.
However, conventionally, the second charge switch 18 is omitted in the present invention (the off-gate switch 13 is shared).
For the operation after the time t _3, the on-gate switch 1
2 and the first turn-on pulse generation switch 17 are turned off (the second turn-on pulse generation switch 33 is turned off after the one-shot operation), and the off-gate switch 13 is turned on (= off operation is started). ) First,
The common portion X of the second capacitor is the charging diode 6,
Through the diode 7, the diode 27, and the current limiting element (resistor) 30, the potential becomes negative and the first capacitor and the second capacitor are charged to the off-gate voltage. Further, in this mode, the third capacitor 25 and the fourth capacitor 26 do not discharge because the second turn-on pulse generating switch 33 does not operate at the time of the on command after the time t ₁ and the charging action is not performed.

Next, when an ON command is subsequently input and the gate current Ig continues to flow a constant current after the same operation as that after the above-mentioned trail t ₁ (described as t ₁ ′ in FIG. 3), an external factor, for example, , GTO1 is connected in parallel in ON mode when the flywheel diode is reversely recovered or when the arm is connected in series, the oscillating current flows between the gate and cathode of GTO1 and the gate and cathode are reverse biased (=
Gate forward current stops flowing). After that, if the ON high gate current is not applied as the gate forward current, the GTO
Gate current becomes insufficient and GTO1 is damaged. Therefore,
The voltage at time t ₆ when the gate terminal G of the GTO 1 becomes a negative potential than the gate terminal K at an arbitrary point is compared with the bias voltage 34 by the comparator 35, and becomes larger than the specified voltage, and the ON operation is in progress. One shot multi 3 with AND condition with
2 is operated to turn on the second turn-on pulse generation switch 33 for a certain period. As a result, the on-pulse current I is obtained as the sum of the vibration waveform of the third capacitor 25 and the reactor 21 and the discharge current of the fourth capacitor and the resistor 23.
g flows to GTO1 again.

After that, when the OFF command is input, since the first, second, third and fourth capacitors are discharged from the time of t ₈ , the first and second capacitors are connected from the common portion X to the diode 27 and the second capacitor. The third and fourth capacitors are charged by the off-gate switch 13 through the current limiting element (resistor) 30 through the diode 29 from the common portion Y and are brought to the state of t ₉ .

Example 2. Although 30 is expressed as a current limiting element (resistor) in the above embodiment, the current limiting element 30 may be a reactor as shown in FIG. 2, and in this case, the first, second, third and fourth elements are used. Will be charged up to twice the off-gate voltage 4 due to the resonance action with the reactor. When the off-gate voltage 4 is low and the first and second turn-on pulse currents are small, more turn-on current flows. Is an effective means when necessary.

[0017]

As described above, according to the present invention, (1) the first on-pulse generating first and second capacitor charging switches are also used as the off-gate switches, so that the circuit is simplified. (Usually, on-pulses flow several tens of amperes, so a switch that can withstand this was required, but since the off-gate switch originally flows several hundred amps, there is no problem in sharing power.) (2) When the GTO is on Since the second turn-on pulse generation switch for detecting that the gate potential becomes negative and generating the on-pulse again and the peripheral circuit are added, the GTO is not damaged. (3) First, second, and first for generating first and second on-pulses
By using a reactor as a means for charging the capacitors 3 and 4 and resonating, it is possible to charge up to twice the power supply voltage, a large pulse current can be generated, and the loss is reduced compared to the limitation by the resistance.

[Brief description of drawings]

FIG. 1 shows a first embodiment of the present invention.

FIG. 2 shows a second embodiment of the present invention.

FIG. 3 shows operation waveforms of Examples 1 and 2.

FIG. 4 shows a conventional example.

FIG. 5 shows a conventional operation waveform.

[Explanation of symbols]

 1 GTO (gate turn-off thyristor) 2 chopper circuit 3 on-gate power supply 4 off-gate power supply 5, 22, 24, 36 discharging diode 6, 7, 27, 28, 29, 37 charging diode 8 first capacitor 9 second capacitor 10, 23 Current limiting resistor 11 Coupling reactor 12 On-gate switch 13 Off-gate switch 14 Chopper switch 15 Chopper reflux diode 16 Current detection circuit 17 First turn-on pulse generation switch 18 Second charging switch 19 Inverter 20 Interface Circuit 21 Reactor 25 Third Capacitor 26 Fourth Capacitor 30 Current Limiting Element 31 AND Circuit 32 OSM (One Shot Multi) 33 Second Turn-On Pulse Generation Switch 34 Via Power supply 35 comparator 38 Reactor

[Procedure amendment]

[Submission date] November 10, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art FIG. 4 shows a main part of a conventional gate circuit disclosed in, for example, Japanese Patent Application Laid-Open No. 1-109912, in which 1 is a gate turn-off thyristor (hereinafter referred to as GTO), and G is a gate electrode. , K are cathode electrodes. 2 is a chopper circuit, which is an on-gate power supply 3
It is composed of a chopper switch 14 for switching the current, a current detecting means 16 for detecting the output current of the chopper circuit 2, and a free wheeling diode 15. Reference numeral 11 denotes a coupling reactor, which includes a primary winding 11a and a secondary winding 11b. Reference numeral 8 is a first capacitor, 9 is a second capacitor, 10 is a current limiting resistor, and 5 and 36 are discharging diodes. An on-gate switch 12 supplies the output currents of the chopper circuit 2, the first capacitor, and the second capacitor to the GTO 1 as an on-gate current.
Reference numeral 7 is a diode for charging the first capacitor 8, and 6 is a diode for charging the second capacitor 9. Reference numeral 18 is a second switch, which is a switch for charging the first and second capacitors. An off-gate switch 13 supplies an off-gate current to the GTO 1. Reference numeral 20 is an interface circuit for ON / OFF signals, and 19 is an inverter for polarity reversal.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (4)

[Claims] 1. A primary winding and a secondary winding, wherein:
The output terminals of the secondary and secondary windings are connected to each other,
Further, it has a reactor configured to cause a coupling action between the primary winding and the secondary winding, and has a function of constant current control, and the first DC output terminal is the input terminal of the primary winding of the reactor. The connected on-gate power supply, the second direct current output terminal of the on-gate power supply, and the primary and the secondary of the reactor.
A first switch including a first switch, a first capacitor, a resistor, and a diode connected to the common output terminal of the next winding.
A series connection body, a second capacitor connected between one end of the secondary winding of the reactor and the first switch, a second series connection body including a diode, the first capacitor, and a resistor. The first and second charging diodes connected to the second output end of the on-gate power supply from the middle point and the second capacitor and the second output end of the on-gate power supply from the middle point of the diode; and the first and second charging diodes. Of a gate turn-off thyristor for supplying an on-gate current to the gate turn-off thyristor, which includes a diode connected to a common point of the off-gate switch and the common point of the on-gate switch from the common point of the capacitor and the first switch, and a series body of current limiting elements. Gate circuit. 2. A series body composed of a second switch, a third capacitor, a diode, and a reactor, which is connected between the on-gate switch input terminal and the second DC output terminal of the on-gate power supply, and the second body. From the midpoint between the fourth capacitor, the diode, and the resistor connected between the switch and the input terminal for the on-gate switch, and the second output terminal of the on-gate power supply from the midpoint between the third capacitor and the diode. , The fourth capacitor and the diode, and the third and fourth charging diodes connected to the second output terminal of the on-gate power source from the middle point, and the one end of the second switch, and the common part is the diode. , Connected in series to the common body of the current limiting element, the off-gate switch and the on-gate switch, and the driving condition of the second switch is G
The gate circuit of the gate turn-off thyristor according to claim 1, further comprising a circuit driven under an AND condition in which a signal to the gate of TO is ON and the gate potential changes from positive to negative. 3. The gate circuit of a gate turn-off thyristor according to claim 1, further comprising a one-shot multi circuit that generates an ON state for a certain period of time after the circuit driven under the AND condition. 4. The gate circuit of a gate turn-off thyristor according to claim 1, wherein the current limiting element is a reactor.