JPS6035904B2 - thyristor commutation circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thyristor commutation circuit, and particularly to a circuit that controls commutation of a thyristor by using a gate turn-off thyristor (hereinafter abbreviated as GTO).

Generally, a thyristor is used to control the load current.To turn off the thyristor, the anode of the thyristor applies a reverse voltage to the cathode, or the gate current is removed and the forward current is maintained. There is a method of lowering the voltage below the current, but a method of applying a reverse voltage between the anode and cathode of the thyristor is more advantageous for turning off the thyristor in a short time.

Because of the aforementioned reverse voltage application, when the load current is small, it is suitable to use the GTO, and it is possible to obtain a very simple control effect. Conventionally, the circuit shown in FIG. 1 has been used as a circuit for controlling the commutation of a syringe using a GTO. In FIG. 1, a forward voltage is applied between the anode and cathode of the thyristor 10 from a power source (not shown). Kosiris Evening 10'Koha GT
A series circuit of O1 2 and a DC power supply 114 is connected in antiparallel to form a turn-off circuit for the thyristor 10. DC power supply 2 is connected between the gate and cathode of GTO12.
A series circuit consisting of 0, a resistor 28, and a transistor 6, and a series circuit consisting of a DC power supply 24 and a transistor 22 are connected in parallel to form a gate on/off circuit for the GTO 12. A controller 26 is connected to the gate of the thyristor 10 and the bases of the transistor 6 and the transistor 22.
A base control signal is supplied. The operation of FIG. 1 will be explained below with reference to the time chart of FIG. 2.

In FIG. 2, waveform 10 is a gate control signal supplied from controller 26 to the gate of thyristor 10, waveform 20.
0 represents the base control signal applied to the base of transistor 16, waveform 300 represents the base control signal applied to the base of transistor 22, and waveform 400 represents the base control signal applied to the base of thyristor 1.
0 and waveform 50 indicate the off state of GTO12.

First, when the gate control signal 100 is applied from the controller 26 to the gate of the thyristor 10, the thyristor becomes conductive, a current flows in the opposite direction, and the thyristor enters a self-holding state. Next, in order to turn off the thyristor 10, the base control signal 200 is applied from the controller 26 to the base of the transistor 16 at time t2, and the transistor 16 becomes conductive between its collector and emitter. Due to this, G
Since the DC power supply 20 is inserted between the cathode and the gate of the TO 12, a positive gate control signal from the DC power supply 2 is applied to the gate of the GTO 12, and the GTO 12 becomes conductive and self-maintained. When the GTO 12 is in the conductive state, since the DC power supply 14 is connected in series with the GTO 12, a directional current flows through the GTO 1 2.
A reverse voltage is applied to the thyristor 10 connected in parallel to the DC power supply 14 and the GTO 12. As a result, the thyristor 10 is turned off by the reverse voltage of the DC power supply 14. Then, when the base control signal 300 is applied from the controller 26 to the base of the transistor 22, the transistor 22 becomes conductive between its collector and emitter. Therefore, the DC power supply 24 is inserted between the cathode and the gate of GTO12, and a negative gate control signal is applied from the DC power supply 24 to the gate of GTO12.
is turned off. Then, at time t3, when the base control signal 300 is applied from the controller 26 to the base of the transistor 22, the transistor 22 becomes conductive between its collector and emitter. Therefore, the DC power supply 24 is inserted between the cathode and the gate of the GTO 12, and a negative gate control signal is applied from the DC power supply 24 to the gate of the GTO 12, thereby turning off the GTO 12. GT like this
When O12 turns off, this means that the state returns to the state before the initial time t, and by repeating the above operation, it becomes possible to control the on/off operation of the thyristor 10. The conventional thyristor commutation circuit described above has three DC power supplies, so it has the disadvantage that the device is expensive.

The present invention has been made in view of the above-mentioned conventional problems, and it is an object of the present invention to provide a thyristor commutation circuit that is less expensive by reducing the number of DC power supplies.

In order to achieve the above object, the present invention provides a siris
A gate turn-off thyristor switch circuit having a series circuit of a DC power supply that applies a reverse voltage between an anode and a cathode of a thyristor and a gate turn-off thyristor, and a DC power supply and switch that provide a gate-on signal and a gate-off signal to the gate turn-off thyristor. A thyristor commutation circuit including a gate turn-off thyristor gate signal circuit with a gate turn-off thyristor gate signal circuit, and a control device that provides a control signal to the gate of the thyristor and each switch of the gate turn-off thyristor gate signal circuit. and a DC power supply that provides a gate-on signal to the gate of the gate turn-off thyristor.

Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 3 shows a circuit diagram of a preferred embodiment of the thyristor commutation circuit according to the present invention. The same members as in FIG. In the thyristor commutation circuit, the DC power supply for the GTO switch circuit and the DC power supply for providing a turn-on signal to the gate of the GTO are shared.

In the embodiment, the common power supply that is used as the DC power supply for the GTO switch circuit and the DC power supply that provides a turn-off signal to the gate of the GTO is connected to the cathode of the transistor and the collector of the transistor that controls the turn-on signal to the gate of the GTO. The anode is connected to the point, and the cathode is connected to the connection point of the anode of the DC power supply that gives the turn-off signal to the GTO gate and the cathode of the GTO.The DC power supply that gives the turn-on signal only to the gate of the GTO is Omitted. Other members that are the same as those shown in FIG. 1 are designated by the same reference numerals and their explanations will be omitted. The operation of the embodiment shown in FIG. 3 will be described below with reference to the waveforms of the conventional and same machine shown in FIG. 2.

First, when the gate control signal 100 is applied from the controller 26 to the gate of the thyristor 10 at the L time, the thyristor 10 becomes conductive, a controlled current flows in the forward direction, and the thyristor 10 enters the holding state.

Next, when the base control signal 200 is applied to the base of the controller 26 or the transistor 16 at time t2, the transistor 1
6 is in a conductive state between its collector and emitter. This means that the DC power supply 14 is connected between the cathode and the gate of the GTO 1 2, and a positive gate control signal is applied to the gate of the GTO 1 2, so that the GTO 12 becomes conductive. When GTO12 becomes suitable state, GTO
A current flows through a series circuit consisting of the DC power supply 12 and the DC power source 14, and since the thyristor 10 is connected in parallel to this series circuit, a reverse voltage is applied to the thyristor 01. The thyristor 10 is turned off by this reverse voltage, and the holding state is released. When the base control signal 300 is applied from the controller 26 to the base of the transistor 22 at time t3, the transistor 22 becomes conductive between its emitter and collector. This means that the DC power supply 24 is inserted between the cathode and the gate of the GTO 12, and a negative gate control signal is applied to the gate of the GTO 12 by the DC power supply 24, thereby turning off the GTO 12. When the GTO 12 is finally turned off in this way, this state returns to the state before the first time t, and the above-mentioned operations are repeated to turn the thyristor 10 on and off using the GTO 12. It becomes possible to control. According to the present invention described above, the number of DC power supplies can be reduced by sharing the DC power supply of the GTO switch circuit and the DC power supply that provides a turn-off signal to the gate of the GTO in the thyristor commutation circuit. It is possible to provide a thyristor commutation circuit which is possible and cheaper.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional thyristor commutation circuit, FIG. 2 is a waveform diagram of each part of FIG. 1, and FIG. 3 is a circuit diagram of a preferred embodiment of the present invention. The same members in each figure are given the same reference numerals, 10 is a thyristor, 12 is a gate turn-off thyristor, 14 and 24 are DC power supplies, 16 is a GTO gate turn-on switch transistor, 22 is a GTO gate turn-off switch transistor, 26 is a control device, a gate signal given from the control device to the gate of the 100 G thyristor, a base control signal given from the control device to the base of the 20 G transistor, 300 is a base control signal given from the control device to the base of the transistor, 40 is a waveform showing the state of the load current of the thyristor, and 500 is a waveform showing the state of the load current of the GTO. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 A gate turn-off thyristor switch circuit having a series circuit of a thyristor, a DC power supply for applying a reverse voltage to turn off the thyristor and a gate turn-off thyristor between the anode and cathode of the thyristor, and a gate turn-off thyristor switch circuit for applying a reverse voltage to turn off the thyristor between the anode and cathode of the thyristor; A thyristor commutation circuit comprising: a gate turn thyristor gate signal circuit equipped with a DC power supply and a switch that provides a signal and a gate off signal; and a control device that provides a control signal to each switch of the thyristor gate and gate turn off thyristor gate signal circuit. The gate turn-off thyristor switch circuit includes a gate turn-off thyristor having an anode connected to the anode of the thyristor, a DC power supply having a cathode connected to the cathode of the gate turn-off thyristor, and an anode connected to the cathode of the thyristor; The turn-off thyristor gate signal circuit includes a turn-on transistor whose emitter is connected to the gate of the gate turn-off thyristor and whose collector is connected to the anode of the DC power source, a turn-off transistor whose collector is connected to the gate of the gate turn-off thyristor, and a turn-off transistor whose collector is connected to the gate of the gate turn-off thyristor. The gate turn-off thyristor switch circuit includes another DC power supply having a cathode connected to the emitter of the transistor and an anode connected to the cathode of the gate turn-off thyristor, and the DC power supply provided in the gate turn-off thyristor switch circuit is used for turning on the gate of the gate turn-off thyristor and for turning off the thyristor. A thyristor commutation circuit characterized in that it is used as a power source.