JPH09117127A - Gate driver for self-extinguishing element and gate driver for power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive gate driver in which a DC power supply dedicated for charging of capacitor is not employed. SOLUTION: An on/off capacitor C4 is operable at the time of turn on and turn off. The gate junction (G.K) of a self-extinguishing GTO, the on/off capacitor C4, a DC power supply VONH for turn on, a current limiting impedance IMP, and a turn on switch Tr3 being closed upon turn on constitute a closed circuit for forward current supply. The closed circuit supplies a forward current to the gate junction (G.K) and charges the on/off capacitor C4. The gate junction (G-K), the on/off capacitor C4 and a turn off switch Tr4 being closed upon turn off constitute a closed circuit for reverse current supply. The on/off capacitor C4 is discharged through the closed circuit which also supplies a reverse current to the gate junction (G.K). The power supply for charging the on/off capacitor C4 is not a power supply dedicated for charging but the DC power supply VONH for turn on which is essential to the closed circuit for forward current supply.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a gate turn-off (GTO) thyristor and a power transistor (PTr).
Etc. to a gate driving device for a self-extinguishing element such as.

[0002]

2. Description of the Related Art Self-extinguishing elements are widely used in power converters such as converters and inverters for converting power from alternating current to direct current or from direct current to alternating current, especially large-capacity power converters of tens of kW or more. Many gate drive devices that appropriately output an on-gate signal and an off-gate signal to a self-extinguishing element have been proposed. A preferable condition for the off-gate signal is that a high di / dt current having a high current rise rate (di / dt) for shortening the turn-off time of the self-extinguishing element and reducing switching loss and having a width of several to ten and several μS is used. Included, providing the required amount of turn-off gate charge, providing a gate reverse voltage that maintains the self-extinguishing device in a non-conducting state, etc.

As a device that satisfies such a condition, there is, for example, a gate driving device described in Japanese Patent Laid-Open No. 62-92765. This is because the DC power supply charges the off-dedicated capacitor to a high voltage in advance, and the charge is discharged through the off-switch that closes at turn-off, and the off-gate signal current (reverse current to the gate junction of the self-extinguishing element) is supplied. It is a method of forming.

[0004]

The above conventional method of precharging an off-only capacitor requires a dedicated DC power source to charge it. This complicates the structure. On the other hand, when the cut-off current becomes large as in the recent gate turn-off thyristor, it is necessary to set the initial charging voltage of the off-dedicated capacitor to be high in order to shorten the turn-off time as in the past. As a result, the current peak value of the off-gate signal becomes excessively large, and the off-switch for controlling the discharge of the off-dedicated capacitor is increased in capacity. still,
The prior application for this case is Japanese Patent Application No. 6-31626 by the same applicant.
There is one. This prior application consists of the same technical idea as the present invention.

An object of the present invention is to provide an inexpensive gate driving device which does not use a dedicated DC power source for charging a capacitor. A further object of the present invention is to effectively increase the charging voltage and increase the current rise rate (di / dt) of the off-gate signal. A further object of the present invention is to reduce the current peak value of the off-gate signal and relax the withstand capability of the off switch. Yet another object of the present invention is to provide another means for increasing the rate of rise of off-gate signal current.

[0006]

SUMMARY OF THE INVENTION The present invention uses an on / off capacitor that operates during turn-on and turn-off. Specifically, a forward current supply closed circuit including a gate junction of a self-extinguishing element, the on / off capacitor, an on DC power source, a current limiting impedance, and an on switch closed at turn-on is formed. This closed circuit supplies a forward current to the gate junction and charges the on / off capacitor. The present invention further includes a reverse current supply closed circuit including a gate junction, an on / off capacitor, and an off switch which is closed at turn-off. Through this closed circuit, the charge of the on / off capacitor is discharged and a reverse current is supplied to the gate junction. The power supply for charging the on / off capacitor is a direct current power supply originally required for the forward current supply closed circuit. Therefore, a power source dedicated to charging is unnecessary.

In the present invention, the current limiting impedance is a parallel circuit of a resistance and an inductance. When the ON switch is closed, a transient phenomenon occurs mainly with the inductance and ON / OFF capacitors, and the ON / OFF capacitor is overcharged (charging voltage> DC power supply voltage for ON).
Therefore, the level of the charging voltage that can be used in the reverse current supply closed circuit is increased, and the current increase rate of the reverse current (off-gate signal current) supplied to the gate junction is increased. The inductance acts to reduce the rate of current rise in the forward current supply closed circuit. The resistance in parallel with the inductance acts to mitigate this adverse effect.

Further, the present invention comprises the forward current supply closed circuit and the reverse current supply closed circuit. Further, including a gate junction and a switch for ON in the forward current supply closed circuit,
A second forward current supply closed circuit including a second ON DC power supply having a lower voltage than the ON DC power supply in the forward current supply closed circuit and a current limiting resistor is provided. The on-gate signal current is a combined value of the currents of the forward current supply closed circuit and the second forward current supply closed circuit.

Further, the present invention further comprises a second reverse current supply closed circuit including a gate junction, the OFF switch and an OFF DC power supply. The off-gate signal current is a combined value of the currents of the reverse current supply closed circuit and the second reverse current supply closed circuit. The main role of the reverse current supply closed circuit is the current rise rate (di / dt)
Is to raise. The main role of the second reverse current supply closed circuit is to supply the required turn-off gate charge amount and to provide the gate reverse voltage for maintaining the self-turn-off device in the non-conducting state. If the charging voltage of the on / off capacitor in the reverse current supply closed circuit is set high, the current increase rate of the reverse current increases. On the other hand, since the on / off capacitor does not share the role of supplying a required turn-off gate charge amount, the capacitor capacity can be set to an appropriately small value. For this reason, although the discharge current rises rapidly, it becomes possible to adopt an operation mode in which the electric charge is insufficient in the middle of the discharge current and the current peak value remains high.

Furthermore, in the practice of the invention, the problem of interference between closed circuits arises. This is a phenomenon in which current flows from one side to the other. This difficulty can be overcome by using conventional techniques with appropriate placement of anti-interference diodes.

Furthermore, the present invention integrates the reverse current supply closed circuit and the second reverse current supply closed circuit. The integrated shared reverse current supply closed circuit includes a gate junction, an off switch, and an off DC power supply, and further includes an on / off capacitor. The operation of the shared reverse current supply closed circuit is such that the charge of the on / off capacitor is accelerated by the off DC power supply and discharged. This has the same effect as setting the initial charging voltage of the on / off capacitor higher by the amount corresponding to the off DC power supply voltage, and the current increase rate (di /
dt) becomes high. In this case, a reverse charging prevention diode that blocks reverse charging of the on / off capacitor is connected in parallel to the on / off capacitor. Without the reverse charge prevention diode, it is necessary to increase the capacity of the on / off capacitor to supply the required turn-off gate charge amount via the on / off capacitor, and it becomes impossible to limit the current peak value during discharge.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to FIGS.
I will explain using. The present embodiment is a self-extinguishing element GTO.
Is a gate turn-off thyristor. The gate drive device according to the present embodiment is a gate junction (G / K) of the self-extinguishing element GTO, an ON / OFF capacitor C4, an ON DC power supply VONH, a current limiting impedance IMP, and a self-extinguishing element GTO that is closed at turn-on. Switch Tr3 for power supply, and a forward current supply closed circuit that supplies a forward current to the gate junction (G · K) and charges the on / off capacitor C4. In addition, gate junction (G
K), an on / off capacitor (for on / off high pulse) C4, and an off switch Tr3 which is closed when the self-extinguishing element GTO is turned off.
A reverse current supply closed circuit that discharges the electric charges of 1 to form a reverse current to the gate junction (G · K).

Further, it includes a gate junction (GK) and an ON switch Tr3, a second ON DC power supply VONL having a voltage lower than that of the ON DC power supply VONH, and a current limiting resistor R1. Second) to supply a forward current to
A forward current supply closed circuit is provided. In addition, gate junction (G
K), switch Tr3 for OFF, and DC power supply VOFF for OFF
And a second reverse current supply closed circuit for supplying a reverse current to the gate junction (G · K). The current limiting impedance IMP in the present embodiment is a parallel circuit of a resistor R4 and an inductance L1.

A more detailed description will be given below. The commercial frequency AC power supply E of FIG. 1 is rectified by the rectifier REC1 and supplied to the smoothing capacitor C1. The positive electrode of the smoothing capacitor C1 is connected to the center tap 10 of the primary winding with the center tap (10) of the transformer T. The positive electrodes of the transistors Tr1 and Tr2 are connected to both ends 11 and 12 of the primary winding with a center tap. The negative electrodes of the transistors Tr1 and Tr2 and the negative electrode of the smoothing capacitor C1 are connected. The above parts are the main parts of the constant voltage inverter. Transistor Tr1 ・ T
The constant voltage control circuit AVR performs on / off control of r2 at a high frequency so that the voltage target value VR and the voltage feedback value VF substantially match. The voltage feedback value VF is obtained via the rectifier REC2 from the voltage detection windings 41 to 42 (terminals or windings in the range from the taps 41 to 42; hereinafter referred to in the same manner) of the transformer T.

The output windings 21 to 24 with a center tap (20) of the transformer T are 21 to 22.22 to 20.20 to 2.
3, 23 to 24 are connected in series in the same polarity and in series, and the windings 21 to 20 and 20 to 24 are turned on DC power supply VO.
High voltage winding for NH. The output terminal 21 is connected to the anode of the rectifying diode D1, and the output terminal 24 is connected to the anode of the rectifying diode D4. The cathodes of the rectifying diodes D1 and D4 are connected to each other,
The positive electrode of the smoothing capacitor C2 is connected to the connection point. The smoothing capacitor C2 and the charging circuit in the preceding stage form an ON DC power supply VONH.

On the other hand, the windings 22 to 20 and 20 to 23 are the second
It is a low-voltage winding for the ON DC power supply VONL. The output terminal 22 is connected to the anode of the rectifying diode D2, and the output terminal 23 is connected to the anode of the rectifying diode D3. The cathodes of the rectifying diodes D2 and D3 are connected to each other, and the positive electrode of the smoothing capacitor C3 is connected to the connection point. The smoothing capacitor C3 and the charging circuit in the preceding stage form the second ON direct-current power supply VONL.

A high pulse current limiting impedance IMP is connected to the positive electrode side of the smoothing capacitor C2, and the anode of an interference prevention diode D6 is connected to the other end. The cathode of the interference prevention diode D6 is connected to the gate terminal G of the self-turn-off device GTO via the on / off capacitor C4.

A current limiting resistor R1 and an interference prevention diode D5 are connected in series to the positive electrode of the smoothing capacitor C3, and the cathode of the interference prevention diode D5 is connected to the gate terminal G of the self-extinguishing element GTO.

A field effect transistor Tr3 as an ON switch is connected between the cathode terminal K of the self-extinguishing element GTO and the negative electrodes of the smoothing capacitors C2 and C3. The field effect transistor Tr3 is controlled by the on / off control signal VG1 via the resistor R2.

On the other hand, the center tap (30) of the transformer T
The attached output windings 31 to 32 are connected in series in the order of 31 to 30 and 30 to 32 with the same polarity and are turned off.
It becomes a voltage winding for turning off. The output terminal 31 is connected to the cathode of the rectifying diode D8, and the output terminal 32 is connected to the cathode of the rectifying diode D9. The anodes of the rectifying diodes D8 and D9 are connected to each other, and the negative electrode of the smoothing capacitor C5 is connected to the connection point. The center tap 30 of the transformer T is connected to the positive electrode of the smoothing capacitor C5. The smoothing capacitor C5 and the charging circuit in the preceding stage form an off DC power supply VOFF.

An interference prevention diode D7 having an anode on the gate terminal G side is connected between the negative potential point of the OFF DC power supply VOFF and the gate terminal G of the self-extinguishing element GTO. A field effect transistor Tr4 as an OFF switch is connected between the high potential point of the OFF DC power supply VOFF and the cathode terminal K of the self-extinguishing element GTO. The field effect transistor Tr4 is controlled by the control voltage V via the resistor R3.
It is controlled by G1.

Next, the operation of the apparatus shown in FIGS. 1 and 2 will be described with reference to FIG. When turning on the self-extinguishing element GTO, the control voltage VG1 in FIG. 3 (1) is set to a negative voltage. When the control voltage VG1 becomes a negative voltage, the on-switch (field-effect transistor) Tr3 and the off-switch (field-effect transistor) Tr4 in FIG. 1 are turned on and off, respectively. Here, a high-voltage ON DC power supply VONH operates to supply a high-pulse forward current via the ON / OFF capacitor C4 to the gate junction (G · K) of the self-extinguishing element GTO. The positive half-wave of the C4 current in FIG. 3 (3) corresponds to this. Along with this, the on / off capacitor C
The voltage of 4 rises as shown in FIG. The voltage of the on / off capacitor C4 reaches a voltage level higher than that of the on DC power supply VONH due to the overcharge action of the inductance L1. On the other hand, the low-voltage second direct-current power supply VONL for ON also works, and a wide forward current is supplied to the gate junction (G · K) via the current limiting resistor R1. The forward current (on-gate signal current) flowing through the gate junction (G · K) has a value obtained by adding the above forward currents. Thus, the self-extinguishing element GTO turns on and maintains the on state.

In the above ON operation process, a higher voltage DC power source VONH for ON and a capacitor C4 for ON / OFF are provided.
Acts to form a high-current rise rate (di / dt) forward current useful for reducing switching loss at turn-on, and the on-off capacitor C4 is charged to a high voltage level to prepare for the next turn-off. Inductance L
1 acts to increase the voltage level of this charge. The resistor R4 acts so as to mitigate the effect of suppressing the high current increase rate by the inductance L1.

To turn off the self-extinguishing element GTO, the control voltage VG1 shown in FIG. 3A is set to a positive voltage.
As a result, the on switch Tr3 is turned off and the off switch Tr3 is turned on. At the same time, the charge of the on / off capacitor C4 is discharged to form a reverse current to the gate junction (G · K). The negative half-wave of the C4 current in FIG. 3 (3) corresponds to this. This discharge current is a high current rise rate (di /
It becomes the reverse current of dt). On / off capacitor C4
When the voltage drops to the voltage level of the DC power supply VOFF for OFF, the DC power supply VOFF for OFF operates and continues to supply a continuous reverse current through the diode D7 for interference prevention. The D7 current in FIG. 3 (4) corresponds to this. When the gate junction (G · K) recovers the non-conducting characteristic, the D7 current is extinguished, but the DC power supply VOFF for OFF continues to give the gate reverse voltage necessary for holding OFF.

During the above-described OFF operation, the ON / OFF capacitor C4 charged to a high voltage acts to form a forward current having a high current increase rate (di / dt) useful for reducing switching loss at turn-off. In addition, the on / off capacitor C4 drops to a low voltage level to prepare for the next turn-on operation. The total reverse current supplied to the gate junction (G · K) through the off switch Tr4 is shown in FIG.
Although the Tr4 current of (6) is obtained, most of the waveform area (turn-off gate charge amount) is covered by the D7 current (current from the OFF DC power supply VOFF). The contribution of the negative half-wave of the C4 current to the waveform area may be slight.

The on / off gate signal of FIG. 3 (7) has a current waveform obtained by integrating the above forward currents and reverse currents. The negative half wave (reverse current or off current) is t1.
It is divided into a high di / dt part in the <t <t2 period, an intermediate part in the t2 <t <t3 period, and an attenuating part in the t3 <t <t4 period.
Compared with a general triangular wave, it has a trapezoidal wave-like feature with a crushed top. The important parameters for this waveform formation are the charging voltage and the capacitance of the on / off capacitor C4.
This feature is obtained with a higher charging voltage and a lower capacitor capacity. If the charging voltage is higher and the capacitor capacity is higher, the current peak value ICP1 due to discharge of the on / off capacitor C4 becomes excessive. If the on-off capacitor C4 is released from the burden of supplying the turn-off gate charge amount and selected to have a low capacitance value such that its discharge is completed in a few microseconds, the negative half-wave of FIG. A corresponding off-gate signal current (reverse current) is obtained. Since the charging of the on / off capacitor C4 may be completed during the minimum on time, an appropriate impedance IM
By inserting P, the peak value ICP1 of the C4 current (forward current) can be limited.

In FIGS. 1 and 2, the drive target is the gate turn-off thyristor GTO, but the same applies to a power transistor (PTr). The gate junction in this case is the junction between the emitter and the base of the power transistor (PTr).

Another embodiment of the present invention is shown in FIGS.
I will explain using. The parts numbers in FIGS. 1 to 3 are used here as they are, and the duplicate description is omitted. 1 to 3
Embodiment uses a reverse current supply closed circuit and a second reverse current supply closed circuit. The embodiment of FIGS. 4 and 5 uses a shared reverse current supply closed circuit that integrates them together.
The shared reverse current supply closed circuit is a closed circuit that includes a gate junction (G / K), an off switch Tr4, an off DC power supply VOFF, and an on / off capacitor C4. The charge of the on / off capacitor C4 is accelerated and discharged by the off DC power supply VOFF, and a reverse current is supplied to the gate junction (G / K). The charging voltage of the on / off capacitor C4 and the off DC power supply VOFF are in a forward series relationship. D7 is a reverse charge prevention diode connected in parallel with the on / off capacitor C4. This prevents reverse charging of the on / off capacitor C4 (charge having a polarity opposite to that shown).

DC power supply VOFF for OFF shown in FIGS. 4 and 5.
The voltage is added to the charging voltage of the on / off capacitor C4. The sum voltage defines the current increase rate of the reverse current when the off switch Tr4 is closed. This is equivalent to the charging voltage of the on / off capacitor C4 being increased by the amount of the off DC power supply VOFF voltage, and the current rising rate of the reverse current can be increased. The role of the reverse charging prevention diode D7 is the same as that of the interference prevention diode D of FIGS.
A little different from 7. The interference prevention diode D7 of FIGS. 1 to 3 prevents the charge of the on / off capacitor C4 from being discharged against the on DC power supply VOFF (smoothing capacitor C5). This is different. However, FIG.
It is the same in that the D7 current shown in (4) is passed. Without the reverse charge prevention diode D7 of FIGS. 4 and 5, after the ON / OFF capacitor C4 having the illustrated polarity is discharged, the charge is reversely charged to the opposite polarity to that shown in the drawing, and the load for supplying the turn-off gate charge amount becomes heavy. Become. In this case, since a required turn-off gate charge amount has to be supplied through the on / off capacitor C4, a high capacitor voltage and a high capacitor capacity are adversely affected, and the current peak value due to discharge becomes excessive. When the reverse charge prevention diode D7 is provided, the on / off capacitor C4 does not have to bear the burden of supplying a predetermined turn-off gate charge amount, and the same effect as that of FIG. 1 is obtained.

[0030]

According to the present invention, a dedicated DC power source for charging a capacitor is not required, and the gate driving device becomes cheaper accordingly. Further, according to the present invention, since the on / off capacitor is overcharged, the current increase rate (di / dt) of the off gate signal current (reverse current) can be increased. Further, the present invention is useful for reducing the current peak value of the off-gate signal current and relaxing the withstand capability of the off-switch. The invention according to claim 4 accelerates the electric charge discharge of the on / off capacitor, and thus contributes to the improvement of the current increase rate (di / dt) of the off-gate signal current (reverse current).

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a schematic circuit diagram summarizing the circuit of FIG.

FIG. 3 is an operation waveform diagram of the above embodiment.

FIG. 4 is a circuit diagram showing another embodiment of the present invention.

FIG. 5 is a schematic circuit diagram summarizing the circuit of FIG.

[Explanation of symbols]

E Commercial frequency AC power supply REC1, REC2 Rectifier AVR Constant voltage control circuit VR Target voltage value VF Voltage feedback value C1, C2, C3, C5 Smoothing capacitor C4 On / off capacitor T Transformer Tr1, Tr2 Transistor Tr3 On switch Tr4 Off switch Switch D1, D2, D3, D4, D8, D9 Rectification diode D5, D6 Interference prevention diode D7 Interference prevention diode (reverse charging prevention diode) R1 Current limiting resistor R2, R3, R4 resistor IMP Current limiting impedance L1 inductance VONH DC power supply for ON VONL Second DC power supply for ON VOFF DC power supply for OFF GTO Self-extinguishing element G Gate terminal K Cathode terminal VG1 ON / OFF control signal

Claims (9)

[Claims] 1. A gate junction of a self-arc-extinguishing element, an on-off capacitor, a direct-current power source for on-state, a current limiting impedance, and an on-switch that is closed when the self-arc-extinguishing element is turned on, and a forward current is applied to the gate junction. A forward current supply closed circuit that supplies and charges the on / off capacitor is provided, including the gate junction, the on / off capacitor, and an off switch that is closed when the self-extinguishing element is turned off. A gate drive device for a self-extinguishing element, comprising a reverse current supply closed circuit for discharging and supplying a reverse current to the gate junction. 2. The gate drive device for a self-extinguishing element according to claim 1, wherein the current limiting impedance is a parallel circuit of a resistance and an inductance. 3. The forward current supply closed circuit according to claim 1, comprising the reverse current supply closed circuit according to claim 1, including a gate junction and an ON switch in the forward current supply closed circuit, and further including the forward switch. A second DC power supply for ON, which has a lower voltage than the DC power supply for ON in the closed current supply circuit, and a current limiting resistor, and which supplies a forward current to the gate junction.
A forward current supply closed circuit is provided, and a second reverse current supply closed circuit is provided, which includes an OFF switch and an OFF DC power supply in the gate junction and the reverse current supply closed circuit, and which supplies a reverse current to the gate junction. A gate driving device for a self-extinguishing element. 4. The gate drive device for a self-arc-extinguishing device according to claim 3, wherein the reverse junction of the reverse current supply and the second reverse current supply closed circuit are replaced by a gate junction, an off switch and an off switch. Forming a common reverse current supply closed circuit that includes a DC power supply for power supply, further includes an ON / OFF capacitor, accelerates and discharges the electric charge of the ON / OFF capacitor by the OFF DC power supply, and supplies a reverse current to the gate junction. And a gate drive device for a self-extinguishing element in which a reverse charging prevention diode that blocks reverse charging of the on / off capacitor is connected in parallel with the on / off capacitor. 5. The gate driving device for a self-turn-off device according to claim 1, wherein the self-turn-off device is a gate turn-off thyristor. 6. A gate drive device for a power converter, which outputs an on / off gate signal based on an on / off control signal, of a power converter configured by using a self-extinguishing element, wherein a rising portion having a high current rising rate is provided. In a gate drive device of a power converter in which a gate drive circuit is configured to output an off-gate signal composed of an intermediate part having a small current change rate, a current decay part after the self-extinguishing element is turned off, and a gate reverse voltage. The gate drive circuit includes three voltage sources, a high voltage source for an on-gate signal having a common reference potential, a low voltage source for an on-gate signal, and a voltage source for an off-gate signal having different reference potentials. The current limiting impedance, the first reverse current blocking diode, and the on / off capacitor are connected in series to the source, and the on / off capacitor The other end is connected to the gate terminal of the self-extinguishing element, the current limiting resistor and the second reverse current blocking diode are connected in series to the on-gate signal low voltage source,
The other end of the second backflow prevention diode is connected to the gate terminal of the self-turn-off device, and the common potential of the cathode terminal of the self-turn-off device, the high-voltage source for on-gate signal, and the low-voltage source for on-gate signal. A first semiconductor switch is connected between the point and a point, the connection point of the first reverse current blocking diode and the on-off capacitor is connected to the high potential end of the off-gate signal voltage source, and the off-gate signal voltage source. An interference prevention diode is connected between the reference potential end of the self-extinguishing element and the gate terminal of the self-extinguishing element, and a second diode is provided between the high-potential end of the off-gate signal voltage source and the cathode terminal of the self-extinguishing element. The semiconductor switch is connected, the first semiconductor switch is turned on when an on-pulse is generated, and the second semiconductor switch is turned on when an off-pulse is generated. Gate drive of the exchanger. 7. The gate drive device for a power converter according to claim 5, wherein the gate drive circuit is configured such that a high voltage source for an on-gate signal having a common reference potential, a low voltage source for an on-gate signal, and an off-gate signal having a different reference potential. A high-voltage source for on-gate signal, a current limiting impedance, a first reverse current blocking diode, and a parallel body of an on-off capacitor / interference prevention diode are connected in series to the high-voltage source for on-gate signal. The other end of the parallel body of the capacitor / interference prevention diode is connected to the gate terminal of the self-extinguishing element, and a current limiting resistor and a second reverse current blocking diode are connected in series to the on-gate signal low voltage source. Connecting the second backflow prevention diode to the gate terminal of the self-extinguishing element, the cathode terminal of the self-extinguishing element and the high-voltage for on-gate signal. A first semiconductor switch is connected between the voltage source and a common potential point of the on-gate signal low voltage source,
A connection point between the first reverse current blocking diode and the parallel body of the on / off capacitor / interference prevention diode is connected to the reference potential of the off-gate signal voltage source, and the other end of the off-gate signal voltage source is connected to the second Power that is connected to the cathode of the self-extinguishing element via a semiconductor switch, the first semiconductor switch is turned on when an on-pulse is generated, and the second semiconductor switch is turned on when an off-pulse is generated. Gate drive for converter. 8. The gate drive device for a power converter according to claim 6 or 7, wherein the current limiting impedance comprises a parallel body of a resistor and an inductance. 9. The gate drive device for a power converter according to claim 5, wherein the self-extinguishing element is a gate turn-off thyristor.