JP3333614B2 - Gate turn-off thyristor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A gate turn-off thyristor (hereinafter simply referred to as GTO) is a current-driven semiconductor switch element. A positive gate voltage (a voltage at which the gate side becomes positive) is applied between its gate and cathode. When a gate current equal to or higher than a predetermined trigger level flows from the gate to the cathode side, the transistor is turned on (conducted), and the gate current is maintained at a predetermined holding current value to maintain the ON state. It is desirable that the gate current that flows when the GTO is turned on be as fast as possible, and its peak value usually reaches 100 [A] to 300 [A].
The gate current that needs to flow to maintain the GTO in the ON state is about several amperes to several tens of amperes.

The GTO is turned off (turns off) when a negative gate voltage (a voltage at which the cathode becomes positive) is applied between its gate and cathode.
In order to keep the GTO in the off state, it is desirable to apply a negative voltage of several volts between its gate and cathode.

As a control device for a gate turn-off thyristor, a flyback voltage generated by using a transformer and an excitation control circuit for controlling the primary current of the transformer to turn on and off is used.
There is known a device in which TO is controlled to be turned on and off. In this type of control device, since a plurality of secondary coils are provided in the transformer, a plurality of GTOs can be controlled simultaneously, so that the configuration of the control device can be simplified.

For example, when a plurality of GTOs are connected in series to provide a predetermined withstand voltage, when a plurality of GTOs are connected in parallel to obtain a predetermined current capacity, In some cases, GTOs are connected in series / parallel to be used. In this case, by providing one transformer having a secondary coil equal to the number of GTOs and one excitation control circuit for controlling the primary current to be on / off. , A plurality of GTOs can be simultaneously turned on and off.

FIG. 6 shows a flyback voltage generated by a transformer and an excitation control circuit for controlling the primary current of the transformer.
FIG. 1 shows an example of the configuration of a gate turn-off thyristor control device for controlling TO. In FIG. 1, reference numeral 1 denotes a GT having an anode 1a, a cathode 1k, and a gate 1g.
O, 2 is a gate signal supply transformer, 3 is a transformer 1
An excitation control circuit 4 for controlling an excitation current flowing through the next coil is a gate circuit.

In this example, a plurality of GTOs 1, 1,... Are connected in series, and a transformer 2 includes one primary coil 2p.
, And the same number of secondary coils 2s, 2s,... As the GTO are wound around the iron core 2c.

The excitation control circuit 3 is a so-called modified half-bridge type inverter circuit, and is connected to the first and second DC power supply units E1 and E2 from the first DC power supply unit to the primary coil 2p of the transformer when conducting. A first switch S1 for supplying an exciting current of one polarity to the first switch S2 and a second switch S2 for supplying an exciting current of the other polarity to the primary coil of the transformer 2 from the second DC power supply unit E2 when conducting. Have. In this example, the first switches S1 and S2 are composed of IGBTs (insulated gate bipolar transistors).
The emitter of the IGBT constituting the switch S1 is connected to the negative output terminal of the first DC power supply E1, and the collector is connected to one end of the primary coil 2p of the transformer. The collector of the IGBT constituting the second switch S2 is connected through a resistor R1 to the positive output terminal of a second DC power supply E2, and the emitter is connected through a diode D1 to one end of a primary coil 2p of a transformer. .

A capacitor C1 is connected between the output terminals of the second DC power supply E2, and the positive output terminal of the first DC power supply E1 and the negative output terminal of the second DC power supply E2 are shared. To the other end of the primary coil 2p of the transformer.

The output of each secondary coil 2s of the transformer 2 is supplied through the gate circuit 4 between the gate and cathode of the corresponding GTO 1. In the illustrated example, each secondary coil 2s
Is connected directly to the gate 1g of the corresponding GTO1, and the other end of each secondary coil 2s is connected to the cathode 1k of the corresponding GTO1 through the capacitor C2. A Zener diode ZD having an anode facing the transformer and a diode D2 are connected in parallel to both ends of the capacitor C2.
The output voltage of the third DC power supply E3 is applied to both ends of the capacitor C2 through the choke coil L and the diode D3. Capacitor C2 and Zener diode ZD
, Diodes D2 and D3, a choke coil L, and a third DC power supply section E3 constitute a gate circuit 4.

Although only one gate circuit 4 is shown in the drawing, in practice, each secondary coil 2s and GTO
One gate circuit is provided for each, and the output of each secondary coil is supplied through the gate circuit 4 between the gate and cathode of the corresponding GTO.

In the gate turn-off thyristor control device shown in FIG. 6, a reverse bias voltage Vo having a constant value limited by the Zener voltage of the Zener diode ZD is generated across the capacitor C2 of the gate circuit 4.
o is applied between the gate and cathode of GTO1. The reverse bias voltage Vo is necessary to keep the GTO 1 in the off state, and is set to several volts.
In the excitation control circuit 3, the second DC power supply E2
The capacitor C1 is charged to the polarity shown in FIG.

IGB constituting first and second switches
T receives a command signal from a command signal generator (not shown). That is, the IGB constituting the first switch S1
The gate of T is supplied with a charge command signal Vch as shown in FIG. 7 (A). At the same time as this charge command signal disappears (or after a short dead time), the second switch S
The ON command signal Von as shown in FIG. 7 (B) is given to the gate of the IGBT constituting 2. On command signal V
At the same time as on disappears (or after a short dead time), an off command signal Voff as shown in FIG. 7A is applied to the gate of the IGBT constituting the first switch S1.

As shown in FIG. 7A, when the charge command signal Vch is given to the first switch S1 at time t1,
The first switch S1 is turned on, the output of the first DC power supply E1 is applied to the primary coil 2p of the transformer, and a primary current flows through the primary coil 2p. With the increase in the primary current, a voltage having a polarity for holding the GTO 1 in the off state is generated in the secondary coil 2s of the transformer. The first DC power supply unit E
When a current flows from 1 to the primary coil 2p of the transformer, magnetic energy is accumulated in the transformer 2.
The period during which the charge command signal Vch is generated is the charging period of the transformer.

At time t2, when the charge command signal Vch disappears and the ON command signal Von rises, the first switch S1 is turned off, and simultaneously the second switch S2 is turned on and the voltage across the capacitor C1 is turned on. Is applied to the primary coil 2p of the transformer 2. At this time, the electric charge of the capacitor C1 is discharged through the primary coil of the transformer, and the magnetic energy stored in the transformer is released. Therefore, the voltage and magnetic energy generated by the discharge of the capacitor C1 are applied to the secondary coil 2s of the transformer. A fast-rising positive voltage corresponding to a superimposition of the flyback voltage generated by the emission is induced, and this voltage is applied between the gate and cathode of the GTO1. Therefore, a positive-polarity gate voltage Vg having a fast rise as shown in FIG. 7C is applied between the gate and the cathode of the GTO, and a gate current Ig having a fast rise flows between the gate and the cathode of the GTO1 by this voltage, and the GTO1 is turned on. I do. The gate current reaches a peak immediately after the ON command signal is given, and then attenuates. However, while the ON command signal is given, the gate current holds a level necessary to hold the GTO 1 in the ON state.

At time t3, when the on-command signal Von disappears and the off-command signal Voff rises at the same time, the second switch S2 is turned off and the first switch S1 conducts at the same time. A negative voltage is induced in 2s, and a voltage of opposite polarity is applied between the gate and cathode of GTO1 as shown in FIG. 7 (C). This turns off GTO1.

Although the period during which the off command signal Voff is applied is extremely short, magnetic energy is also stored in the transformer 2 during this period.
When f disappears and the first switch S1 is turned off,
A flyback voltage is induced in the secondary coil 2s of the transformer 2, and a positive gate voltage is applied between the gate and cathode of the GTO 1 as shown in FIG. When a gate voltage is applied at time t4, a gate current Ig flows as shown in FIG. 7D. If the gate voltage and the gate current exceed a predetermined trigger level, GTO1 is erroneously triggered, and again. Turn on.

[0018]

As described above, in the control device in which the GTO is controlled by the flyback voltage generated by using the transformer and the exciting circuit for controlling the primary current of the transformer, the transformer has By providing a plurality of secondary coils, a plurality of GTOs can be controlled at the same time, so that the configuration of the control device can be simplified when controlling a large number of GTOs.

However, in this type of conventional control device as shown in FIG. 6, when the off command signal Voff is extinguished at time t4 in FIG. Since the GTO cannot be reliably turned off while the signal is being generated, there is a problem that the turn-off timing cannot be accurately controlled. In the case of the conventional control device, GT
When it is necessary to arbitrarily set the period in which O is in the ON state, to change or shorten the period in which the O is in the ON state, there is a problem that it is not possible to meet the demand.

For example, in an electric precipitator, a high voltage (for example, 30 [KV]) is applied to both ends of a large number (for example, 8) of GTOs connected in series, and each GTO is turned on and off, thereby making 60 GTOs per second. It is necessary to generate a high voltage pulse of such a degree, but in this case, if the conventional control device shown in FIG. 6 is used, the GTO may fail to turn off.

An object of the present invention is to provide a gate turn-off thyristor control device for controlling on / off of a GTO using a transformer and an excitation control circuit for controlling a primary exciting current of the transformer, thereby ensuring that the GTO is turned off and the turn-off timing. Is to be able to control accurately.

[0022]

According to the present invention, there are provided a transformer for generating a gate signal, a charge command signal for commanding to store energy in the transformer, and an off command signal for commanding to turn off a gate turn-off thyristor. Excitation current of one polarity is supplied to the primary coil of the transformer for a period during which the ON command signal for instructing to turn on the gate turn-off thyristor is supplied to the primary coil of the transformer for the other polarity. And a command signal generator for sequentially supplying a charge command signal, an ON command signal, and an OFF command signal to the excitation control circuit, and outputs the output of the secondary coil of the transformer to the gate circuit of the gate turn-off thyristor. Gate turn-off thyristor control for turning on and off the thyristor by giving It is those related to the location.

In the present invention, the command signal generating section may further generate a bypass command signal which rises before the off command signal disappears and disappears after the off command signal disappears. A bypass circuit that has a bypass switch that conducts while the bypass command signal is being provided and forms a low-impedance current path when the bypass switch conducts is parallel to at least a part of the primary coil of the transformer. And when at least a portion of the primary coil of the transformer is substantially short-circuited through a bypass circuit before the off signal disappears, the magnetic energy stored in the transformer is removed when the off command signal disappears. To prevent a voltage of a polarity that turns on the GTO from being induced in the secondary coil of the transformer.

Here, the "low impedance current path" means that a bypass current required to suppress the voltage induced in the secondary coil of the transformer to less than the GTO trigger level when the OFF command signal is extinguished can flow. This means that the current path has a sufficiently low impedance.

When the bypass command signal is generated after the off command signal disappears, a voltage having a polarity for turning on the GTO is induced at the moment when the off command signal disappears. Preferably, it is generated before the signal disappears.

The bypass circuit does not necessarily need to be connected in parallel to the primary coil. Instead, a tertiary coil is provided in the transformer, and a bypass circuit is connected in parallel to at least a part of the tertiary coil. It may be.

The excitation control circuit is electrically connected to the first and second DC power supply units for a period during which the charge command signal and the OFF command signal are supplied, and is connected to the primary coil of the transformer by the first DC power supply unit. And a second switch for conducting an exciting current of the other polarity from the second DC power supply to the primary coil of the transformer while conducting during a period in which the ON command signal is supplied. And can be configured.

The bypass circuit may be constituted by only a bypass switch, or a small resistor (a resistor having a small resistance value) may be connected in series to the bypass switch.

When a small resistor is connected to the bypass switch, it is preferable to connect a capacitor in parallel with the small resistor.

[0030]

With the above arrangement, the magnetic energy stored in the transformer while the off command signal is being generated is:
After the OFF command signal disappears, it is consumed through the bypass circuit. Therefore, it is possible to prevent the voltage of the polarity that turns on the GTO from being induced in the secondary coil of the transformer, and it is possible to reliably turn off the GTO. Further, when the current path of the bypass circuit is established, the primary coil or the tertiary coil of the transformer is substantially short-circuited, so that the inductance component when the transformer is viewed from the secondary side is reduced. Therefore, it is possible to suppress voltage and current oscillations caused by the capacitance existing in the secondary circuit of the transformer and the inductance component of the transformer. Therefore, it is possible to prevent the voltage of the polarity that turns on the GTO from being slightly induced in the secondary coil of the transformer after the OFF command signal disappears, and it is possible to reliably turn off the GTO.

[0031]

FIG. 1 shows an embodiment of the present invention.
The control device of this embodiment includes a transformer 2 for generating a gate signal and an excitation control circuit 3 similar to the control device shown in FIG.
And a gate circuit 4, and the configuration and operation thereof are the same as those shown in FIG. In this embodiment,
A bypass circuit 5 is connected in parallel with the primary coil 2p of the transformer 2. This bypass circuit is an IGBT
And a diode D4.
, A small resistor R2, and a capacitor C3. More specifically, the bypass switch S3
Is connected to one end of the primary coil 2p of the transformer 2 through a diode D4, and the emitter is connected to the other end of the primary coil 2p through a resistor R2. The capacitor C3 is connected in parallel to both ends of the resistor R2.

A command signal generator 6 is provided for supplying command signals to the first and second switches S1 and S2 of the excitation control circuit 3 and the bypass switch S3. This command signal generating section 6 is provided with a switch I1 which constitutes the first switch S1.
The charge command signal Vch and the off command signal Vof are applied to the gate of the GBT.
f, and an ON command signal Von is applied to the gate of the IGBT constituting the second switch S2. The timings of generation of the charge command signal Vch, the ON command signal Von, and the OFF command signal Voff are the same as those of the related art.

The command signal generator 6 also supplies a bypass command signal Vbp to the gate of the IGBT constituting the switch S3 for bypass. The bypass command signal Vbp rises just before the off command signal Voff disappears, and the off command signal Vbp rises.
A signal that disappears after off disappears.

The command signal generator 6 is configured, for example, as shown in FIG. The command signal generator shown in FIG. 2 includes a trigger signal generator 601 and a trigger signal generator 601.
602 generates a rectangular waveform charge command signal Vch having a constant time width Tch when a trigger signal is generated, and a zero cross detection which is set at the fall of the charge command signal Vch and detects a zero point of the anode current of the GTO. A flip-flop circuit 604 which is reset by an output of the circuit 603 and outputs an ON command signal Von;
Is triggered by the fall of the ON command signal Von
A timer 605 for outputting a pulse signal Voff 'having a time width Toff' necessary for turning off the TO;
The falling time of the pulse signal Voff 'is set to a small time Δt (<< Tof
f), a falling delay circuit 606 that outputs an off command signal Voff with a delay of a given time, and a fixed time width T triggered by the falling of a pulse signal Voff ′ output by a timer 605.
Timer circuit 607 that outputs bp bypass command signal Vbp
It is composed of Timers 602, 605 and 6
07 can be composed of, for example, a monostable multivibrator.

FIG. 3 shows the voltage and current waveforms at various points in the embodiment of FIG.
(A) to (G). FIG. 3 (A) to (C)
Indicates a command signal generated by the command signal generator 6. In this example, the set of the flip-flop circuit 604 is delayed by a minute time Δt ′ from the fall of the charge command signal Vch, and the charge command signal Vch disappears. After that, the ON command signal Von rises after a dead time of Δt ′ has elapsed. Further, by delaying the trigger of the timer 605 by the time Δt ”, the off command signal Voff rises after a dead time of Δt” elapses after the ON command signal Von disappears. In the embodiment, the signal width Tch of the charge command signal Vch is 160 [μsec], the signal width Ton of the ON command signal Von is 50 [μsec], the signal width Toff ′ of the OFF command signal is 20 [μsec], and the bypass command signal Vbp. Is 6 [msec]. Δt = Δt ′ = Δt ″ = 2 [μsec]

In this embodiment, one of the transformers 2
The ratio n1 / n2 of the number of turns n1 of the secondary coil 2p to the number of turns n2 of the secondary coil 2s was 10/1.

In the embodiment of FIG. 1, when the charge command signal Vch is given to the first switch S1 at time t1, the first switch S1 is turned off.
Is turned on, the output of the first DC power supply E1 is applied to the primary coil 2p of the transformer, and a negative primary current I11 flows through the primary coil 2p as shown in FIG. 3 (E). . The negative primary current I11 increases linearly. Since the temporal change rate of the primary current I11 is constant,
As the primary current I11 increases, the secondary coil 2 of the transformer
At s, a substantially constant voltage V21 of a polarity (negative polarity) for holding the GTO1 in the off state is generated. At this time, a reverse voltage Vg1 obtained by adding the voltage V21 to the reverse bias voltage Vo obtained between both ends of the capacitor C2 is applied between the gate and the cathode of the GTO1.

Further, when the current I11 flows from the first DC power supply section E1 to the primary coil 2p of the transformer, magnetic energy is accumulated in the transformer 2. Charge command signal V
The period Tch during which the channel is generated is the charging period of the transformer.

When the charge command signal Vch is extinguished at time t2, the first switch S1 is turned off, and when the ON command signal Von rises at time t2 'after a short dead time .DELTA.t' has elapsed from time t2, the second switch S1 is turned off. Switch S2 is turned on. When the second switch S2 conducts, the capacitor C1
3 and the flyback voltage induced by the discharge of the magnetic energy accumulated in the transformer during the charging period Tch are applied to the primary coil 2p of the transformer 2 almost simultaneously. As shown in FIG.
A positive primary current I12, which rises quickly and has a large peak value, flows through the secondary coil 2p. At this time, the voltage V22 induced in each of the secondary coils 2s is induced by a voltage induced by a change in the primary current due to the discharge of the capacitor C1 and by a discharge of magnetic energy accumulated in the transformer during the charging period Tch. And the flyback voltage is superimposed, and as shown in FIG. 3D, the voltage rises quickly and has a high peak value. This fast rising voltage V22 is GT
Since the voltage is applied between the gate and the cathode of O1, as shown in FIG.
O is applied between the gate and cathode of O.
The gate current Ig having a fast rise flows between the gate cathode of O1 and GTO1 is turned on. The gate current reaches a peak immediately after the ON command signal is given, and then attenuates. However, while the ON command signal is given, the gate current maintains a level necessary to hold the GTO1 in the ON state. .

When the ON command signal Von disappears at time t3 ', the second switch S2 is turned off. When the off command signal Voff is generated at time t3 when a slight dead time Δt "has elapsed at time t3 ', the first switch S1 is turned on, so that a negative voltage V21' is induced in the secondary coil 2s of the transformer 2. 3 (F), a voltage Vg1 'of opposite polarity is applied between the gate and the cathode of the GTO 1. This turns off the GTO 1. At time t4, the time T4 is longer than the time when the turn-off command signal Voff disappears by Δt. When the bypass command signal Vbp is generated at the previous time t4 ', the bypass switch S3 is turned on and the primary coil 2 of the transformer is turned on.
A low-impedance current path is formed in parallel with p, and the primary coil 2p is substantially short-circuited.
Therefore, the magnetic energy stored in the transformer during the period in which the off command signal Voff is given flows into the bypass circuit 5 immediately when the off command signal Voff disappears at time t4 and is consumed. Therefore, when the OFF command signal disappears at time t4, a positive voltage is hardly induced in the secondary coil 2s, and erroneous triggering of the GTO is prevented.

As described above, according to the present invention, it is possible to suppress the positive voltage induced in the secondary coil of the transformer when the off command signal is extinguished. Not only can the GTO be turned off reliably, but also the period during which the GTO is on can be set arbitrarily, and the period during which the GTO is on can be set to a very short time.

In the embodiment, a voltage of 30 [KV] is applied to both ends of a series circuit of eight GTOs to turn on / off each GTO, thereby generating 60 high voltage pulses per second. No false triggers occurred.

In the above embodiment, the off command signal Voff
The effect of suppressing the positive voltage induced at the time of disappearance of the resistor is that the resistor R2 connected in series with the bypass switch S3
Becomes smaller as the resistance value of the resistor R2 decreases, but as the resistance value of the resistor R2 decreases, the bypass period Tbp needs to be lengthened. If the bypass period can be long,
The bypass switch S3 may be directly connected to both ends of the primary coil 2p by removing the resistor R2.

As in the above embodiment, the bypass switch S
When the resistor R2 is connected in series with the resistor R3, connecting the capacitor C2 in parallel with the resistor R2 has a high effect of suppressing the positive voltage induced in the secondary coil when the OFF command signal disappears. However, the capacitor C2 may be omitted.

In the above embodiment, the bypass circuit 5 is connected in parallel to both ends of the primary coil 2p of the transformer. However, as shown in FIG.
p may be drawn out and the bypass circuit 5 may be connected between the tap and the end of the primary coil 2p. Further, as shown in FIG. 5, a tertiary coil 2t may be provided in the transformer 2, and the bypass circuit 5 may be connected in parallel to the tertiary coil 2t.

Also in the configuration shown in FIG. 4 or FIG. 5, since the magnetic energy stored in the transformer is consumed when the bypass switch S3 is turned on, the transformer is turned off when the off command signal Voff disappears. The positive voltage induced in the secondary coil can be suppressed. FIG. 4
In the configuration shown in FIG. 5, the voltage applied to the bypass switch can be reduced by setting the position of tap extraction from the primary coil 2p appropriately, and a sufficient voltage suppression effect can be obtained. And an inexpensive switch having a low withstand voltage can be used as the switch. Similarly, in the case of the configuration shown in FIG. 5, the voltage applied to the bypass switch S3 is reduced by appropriately setting the number of turns of the tertiary coil 2t (less than the number of turns of the primary coil 2p). be able to.

In the above embodiment, IGBTs are used as the switches S1 to S3. However, these switches need only be switches that conduct only while a trigger signal is being applied. It can also be used.

In the above-described embodiment, a half-bridge type inverter circuit is used as the excitation control circuit 3. However, the excitation control circuit 3 determines when the current of one polarity flows to the primary coil of the transformer and the other time. Any circuit can be used as long as it can control the timing of current flow, and a full-bridge inverter circuit or a push-pull inverter circuit can be used.

In the above description, the first to third DC power supply units E1 to E3 are represented by batteries, but these DC power supply units only need to generate a DC voltage of a predetermined magnitude. Of course, these power supply units may be configured by a power supply circuit that rectifies the power supply and obtains a DC voltage.

[0050]

As described above, according to the present invention, the bypass circuit is connected in parallel to at least a part of the primary coil of the transformer or in parallel to at least a part of the tertiary coil of the transformer. Then, by turning on the switch of the bypass circuit before the OFF command signal disappears, the magnetic energy accumulated in the transformer during the period when the OFF command signal is given is consumed by the bypass circuit. There is an advantage that the voltage induced in the secondary coil of the transformer when the off command signal disappears can be suppressed to prevent erroneous triggering of the GTO, and the GTO can be surely turned off.

Furthermore, according to the present invention, the GTO is turned on.
The gate current that flows when
In addition to the above, the period during which the GTO is on can be arbitrarily set without considering the reset operation of the transformer, and the period during which the GTO is on can be set to a very short period. There are advantages.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration example of a command signal generator used in the embodiment of FIG.

FIG. 3 is a waveform diagram of voltage and current of each part in the embodiment of FIG.

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

FIG. 5 is a circuit diagram showing a main part of still another embodiment of the present invention.

FIG. 6 is a circuit diagram showing a configuration of a conventional control device.

FIG. 7 is a waveform diagram showing voltage and current waveforms of respective parts in FIG.

[Explanation of symbols]

 Reference Signs List 1 GTO (gate turn-off thyristor) 2 Transformer for gate signal generation 2p Primary coil 2s Secondary coil 2t Tertiary coil 3 Excitation control circuit 4 Gate circuit 5 Bypass circuit S1 First switch S2 Second switch S3 Bypass switch R2 Low resistance C3 capacitor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-74083 (JP, A) JP-A-57-85573 (JP, A) JP-A-55-63570 (JP, A) 80382 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02M 1/06

Claims (5)

(57) [Claims] 1. A gate signal generating transformer, a charge command signal for commanding to store energy in the transformer, and an off command signal for commanding to turn off a gate turn-off thyristor, respectively, during a period in which the transformer is provided. An excitation control circuit that supplies an exciting current of one polarity to the primary coil and supplies an exciting current of the other polarity to the primary coil of the transformer while an ON command signal for instructing to turn on the gate turn-off thyristor is given. The charging command signal to the excitation control circuit,
A command signal generator for sequentially supplying an ON command signal and an OFF command signal, wherein a gate turn-off thyristor control device that controls the thyristor to turn on and off by providing an output of a secondary coil of the transformer to a gate circuit of the gate turn-off thyristor; The command signal generator is configured to further generate a bypass command signal that rises before the off command signal disappears and disappears after the off command signal disappears, and the bypass command signal is generated. A bypass circuit having a bypass switch that conducts between the first and second coils and a bypass circuit that forms a low-impedance current path when the bypass switch is conductive is connected in parallel to at least a part of the primary coil of the transformer. Gate turn-off thyristor control device. 2. A gate signal generating transformer, a charge command signal for commanding to store energy in the transformer, and an OFF command signal for commanding to turn off a gate turn-off thyristor, respectively, during the period when the transformer is provided. An excitation control circuit that supplies an exciting current of one polarity to the primary coil and supplies an exciting current of the other polarity to the primary coil of the transformer while an ON command signal for instructing to turn on the gate turn-off thyristor is given. The charging command signal to the excitation control circuit,
A command signal generator for sequentially supplying an ON command signal and an OFF command signal, wherein a gate turn-off thyristor control device that controls the thyristor to turn on and off by providing an output of a secondary coil of the transformer to a gate circuit of the gate turn-off thyristor; The transformer has a tertiary coil magnetically coupled to a primary coil and a secondary coil, and the command signal generator rises before the off command signal disappears and disappears after the off command signal disappears. A bypass circuit that is configured to further generate a bypass command signal that conducts while the bypass command signal is generated, and that forms a low-impedance current path when the bypass switch is conductive. A gate connected to at least a part of the tertiary coil in parallel; Down off thyristor controller. 3. The excitation control circuit conducts with the first and second DC power supply units during a period in which the charge command signal and the OFF command signal are supplied, and the first DC power supply unit supplies the first and second DC power supply units with each other. A first switch for supplying an exciting current of one polarity to the secondary coil, and conducting for a period during which the ON command signal is supplied, and exciting the other polarity to the primary coil of the transformer from the second DC power supply. The gate turn-off thyristor control device according to claim 1, further comprising a second switch for flowing a current. 4. The gate turn-off thyristor control device according to claim 1, wherein said bypass circuit includes a small resistor connected in series to said bypass switch. 5. The gate turn-off thyristor control device according to claim 4, wherein said bypass circuit includes a capacitor connected in parallel to said small resistor.