JPS62147952A - Drive circuit for thyristor - Google Patents

Abstract

PURPOSE:To drive a thyristor only by using one power supply by driving the thyristor by a switching element through a resistor and a capacitor. CONSTITUTION:Three resistors 1-3 are connected in series, another terminal of the resistor 1 is connected to the positive side of a DC power supply E, and another terminal of the resistor 3 is grounded. A capacitor C is connected in parallel with both terminals of the resistor 2. A gate for a self-arc- extinguishing type thyristor S is connected at a node between the resistor 2 and the resistor 3, and a switching element S1 is connected between a node between the resistor 1 and the resistor 2 and the ground. The thyristor S is driven by turning the switching element S1 ON-OFF.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a drive circuit for a self-extinguishing semi-four-body element such as a gate turn-off thyristor (GTO thyristor) or a static induction thyristor (SI nyristor). be.

[Background technology]

Conventionally, a circuit as shown in FIG. 1 has been used as a drive circuit for a thyristor. In this circuit, 81 and S2 are switch elements consisting of MOSFETs connected in series, E1 and E
2 is a DC power supply connected in series to the switch elements SI and S2, and P is an input pulse whose one end is grounded via the DC power supply E+ and 62, and whose other end is connected to the gates of the switch elements S, , and S2. be.

The connection point of the switching elements S, , S2 is connected to the gate of the thyristor S. Thyristor S does not require a large amount of energy when it is on, but when it is off, it is necessary to draw a large current from the gate, so as in this example, the gate is connected to the negative side via switching element S2 and input It is common to use a method in which it is turned off by a pulse P signal. For this reason, as in this example, the circuit required SL, L switching elements S, , S2, etc. became complicated, and the power supply required a dual positive and negative source. Therefore, it has been difficult to downsize and reduce costs.

[Purpose of the invention]

The present invention was made in view of such prior art, and its purpose is to be able to drive using only one power source,
Another object of the present invention is to provide a low-cost thyristor drive circuit.

[Disclosure of the invention]

The gist of the present invention is to connect three resistors 1, 2.3 in series, and connect the other end of resistor 1 to the positive side of a DC power supply.
The other end of resistor 3 is grounded, a capacitor is connected in parallel to both ends of resistor 2, the gate of the self-extinguishing thyristor S to be driven is connected to the connection point of resistor 2 and resistor 3, and resistor 1 and resistor 2 are connected. This is a thyristor drive circuit that connects a switch element between a point and ground, and drives the thyristor by turning the switch element on and off.

The present invention will be explained below based on illustrated examples.

FIG. 2 shows one embodiment of the present invention.

E is a DC power supply, 1, 2, and 3 are resistors, C is a capacitor, and Sl is a switch element consisting of a MOS FET. P is a driving pulse source. Resistor 1.2.3 is the voltage r
The capacitor C is connected in series between the positive terminal and the negative terminal of XE, and the capacitor C is connected in parallel to both ends of the resistor 2. A connection point B between the resistor 2, the capacitor C, and the resistor 3 is connected to the gate of the thyristor S to be driven. On the other hand, resistor 1 and resistor 2
A switch element S1 is connected between the connection point and ground (the negative side of the DC power source E), and a drive pulse source P is connected to the gate of this switch element S1.

Next, the thyristor drive circuit of this embodiment will be explained using the timing chart shown in FIG.

P shown in FIG. 3 is the input of the driving pulse source.

Since the switch element S1 is turned on and off by this input signal, the input waveform at the connection point +8) between the resistors 1 and 2 in FIG. 2 becomes the waveform shown in FIG. 3, P(a).

On the other hand, the capacitor C is normally charged to approximately the voltage of the DC power supply E. This is because there is a diode between the gate and cathode of the thyristor, and the forward voltage drop is 0.
This is because the voltage is about 6 V to 0.7 V, which is sufficiently small compared to the voltage of the DC power supply E. When the switch element S1 is turned on, the potential at the connection point (a) is forcibly grounded and O
Therefore, the potential at the connection point (b) becomes -Vc, where Vc is the charging voltage of the capacitor. Therefore, current can be drawn down from the gate of the thyristor S.

FIG. 3P(b) shows this state. Thereafter, the capacitor C is discharged through the resistor 3, and when the signal from the drive pulse source P becomes LO level, the switch element S1 is turned off, and the capacitor C is charged from the power source E through the resistor 1.

This circuit is particularly effective for driving when an SI thyristor is used as the thyristor S. Due to its characteristics, an SI thyristor improves its switching characteristics by applying a positive bias when it is turned on, and by swinging the gate negative to initially draw out holes from the gate when turning it off. Furthermore, since the St thyristor can be turned off with less energy than the GTO thyristor, the capacitance of this circuit can be reduced and it is more effective as a drive circuit.

〔Effect of the invention〕

As mentioned above, the present invention provides a circuit that can drive a self-extinguishing thyristor with a small number of circuit components and only one positive power supply, so it is easy to integrate the circuit and integrate it with a control circuit. This has the effect of greatly contributing to cost reduction, and the effect is further enhanced especially when applied to an s■ thyristor.

[Brief explanation of drawings]

FIG. 1 shows a conventional drive circuit, FIG. 2 shows an embodiment of the present invention,
FIG. 3 is a waveform diagram showing the operation timing of the embodiment shown in FIG. ■...2...3 resistor, C...capacitor, s1 switch element, E...power supply, S...thyristor, P...
...Drive pulse source.

Claims (1)

[Claims] (1) Three resistors 1, 2, and 3 are connected in series, the other end of resistor 1 is connected to the positive side of the DC power supply, the other end of resistor 3 is grounded, and a capacitor is connected in parallel to both ends of resistor 2. Then, the gate of the self-extinguishing thyristor S to be driven is connected to the connection point between resistors 2 and 3, and a switch element is connected between the connection point between resistors 1 and 2 and ground, and this switch element is turned on and off. A thyristor drive circuit for driving the thyristor.