JPS5899263A - Thyristor gate drive circuit - Google Patents

Abstract

PURPOSE:To reduce consumption power of gate device circuit, by a method wherein when average voltage becomes a prescribed value pulse signal with duty control having constant peak value is supplied as SCR ignition signal to SCR gate. CONSTITUTION:SCR ignition command signal (a) is entered to a duty control circuit 1, a transistor TR drive circuit 2 is connected to the duty control circuit 1, and base of TR 3A, 3B is connected to the drive circuit 2. Primary winding of a pulse transformer 4 is connected to collector of TR 3A, 3B, and DC power source 6 is connected to the neutral of the primary winding and also to emitter of TR 3A, 3B. A rectifier 5 is connected to secondary winding of the transformer 4, and gate of SCR 7 is connected to the rectifier 5 through a current control resistor 8. In this constitution, consumed power of the gate device circuit can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wide gate drive circuit for a thyristor, and more particularly to a thyristor gate drive circuit that varies and supplies pulse width control at turn-on and after turn-on.

Conventionally, the method of generating a wide gate voltage for a thyristor by rectifying a high frequency voltage is to output a pulse signal of a constant width, and at turn-on, generate a high voltage accumulated in a capacitor, which turns on the thyristor. After that, the voltage is lowered using a resistor, and this lowered voltage is applied to the gate of the thyristor. That is, in the conventional method, the peak value of the low voltage applied to the gate of the thyristor is changed. However, such conventional methods have the disadvantages that the loss due to the resistance used to change the peak value is large, and the gate current is small when the thyristor is re-ignited, so the switching loss of the thyristor increases. .

An object of the present invention is to provide a thyristor gate drive circuit that can reduce power consumption of the gate drive circuit.

The present invention aims to reduce the power consumption of a gate drive circuit by supplying a pulse signal with a constant peak value, which is Denity-controlled so that the average voltage becomes a predetermined voltage, to the thyristor gate as a thyristor firing signal. .

Examples of the present invention will be described below.

FIG. 4 shows an embodiment of the invention.

In the figure, a transistor drive circuit 2 is connected to a duty control circuit 1 to which a thyristor firing command signal is input. The transistor drive circuit 2 is connected to the bases of transistors 3A and 3B. A pulse transformer 4 is connected to the collectors of these transistors 3A and 3B.
0 primary winding is connected, and this pulse transformer 40
A DC power supply 6 is connected to the middle point of the primary winding. Further, a DC power supply 6 is connected to the emitters of the transistors 3A and 3B.

Further, a rectifier circuit 5 is connected to the secondary winding of the pulse transformer 4, and this rectifier circuit 111i! +5 is connected to the gate of the thyristor 7 via a current limiting resistor 8.

It has the configuration as shown. That is, the SIRISK ignition command is input to the start/stop circuit 10.

A comparison circuit 11 and a sawtooth wave oscillation circuit 12 are connected to the start/stop circuit 10, respectively.

A comparison circuit 11 and a flip-flop circuit 13 are connected to this sawtooth wave oscillation circuit 12. This comparison circuit 11 compares the signal output from the start/stop circuit with the signal output from the sawtooth wave oscillation circuit 12 and outputs a pulse signal. Further, the flip-flop circuit 13 is used to alternately output signals to the AND circuits 14 and 15. The outputs from the comparator circuit 11 are input to AND circuits 14 and 15, respectively, and the flip-flop circuit 13 is configured to drive both transistors 3A and 3B shown in FIG.

With this configuration, when a thyristor firing command as shown in FIG. 3 is input to the AC power source as shown in FIG. The output will be as shown in FIG. 30. A sawtooth wave as shown in FIG. 3(G) is output by the signal output from the start-stop circuit 10, and this sawtooth wave and the start-stop circuit output signal as shown in FIG. The comparison is made and a pulse signal as shown in FIG. 3 is output. The pulse signal as shown in FIG. A pulse voltage as shown in FIG. 3 [F] is induced.The pulse signal induced in the secondary winding of the pulse transformer 4 is as follows.
The rectifier circuit 5 converts the signal into a signal as shown in FIG. 3 and applies it to the gate of the thyristor 7. The average output voltage of the rectifier circuit 5 is as shown in FIG. 30. By applying a voltage as shown in FIG. 30 to the thyristor 7, a voltage as shown in FIG. 3 (D) is applied to the AC power upstream load via the thyristor 7.

Therefore, according to this embodiment, it is possible to prevent power loss in the gate drive circuit as in the conventional example.

Further, since the voltage is not lowered using a resistor as in the conventional example, according to this embodiment, heat generation is reduced, and no other heat dissipation treatment is required, resulting in miniaturization.

As described above, according to the present invention, the power consumption of the gate drive circuit can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, and Fig. 2 is a circuit diagram showing an embodiment of the present invention.
FIG. 3, which is a detailed diagram of the illustrated duty control circuit, is a time chart of FIG. 1 and FIG. 2.

Claims (1)

[Claims] 1. Converting the thyristor firing command pulse into a high frequency pulse signal having a constant peak value and turning on/off the high frequency pulse signal.
A duty control circuit that changes the duty, a transformer that drives a transistor with a signal from the duty control circuit to generate positive and negative primary pulse voltages, and a rectifier circuit that rectifies the secondary pulse voltage of the transformer. Thyristor gate drive circuit with 2. In the invention as set forth in claim 1, the duty control pulse outputted by the duty control circuit is a pulse signal having a large duty when the thyristor is turned on, and a small duty after turning on the thyristor. Thyristor gate drive circuit.