JPS6096173A - Drive circuit of gate turn off thyristor - Google Patents

Abstract

PURPOSE:To enhance the performance of a gate turn OFF thyristor without increasing the size by inserting a transistor not only between the gate and the cathode of a GTO but also between the anode and the gate, thereby enabling to drive the GTO at a logical level. CONSTITUTION:The first and second transistors 3B, 3A are inserted between the anode and the base and between the gate and the cathode of a GTO1. When the GTO1 is turned ON, a base current is supplied to the transistor 3B to conduct the transistor. When the GTO1 is turned OFF, the transistor 3A is conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a drive circuit for a gate turn-off circuit.

[Prior art]

Figure 1 shows a conventional example of this type of drive circuit.
is a gate turn-off transistor (hereinafter abbreviated as GTO), 2 is a diode, and 3A is a transistor.

When this GTOl is turned off from an on state to an off state, a base current is supplied to the transistor 3A to make the transistor 3A conductive, and the accumulated carriers are drawn out from the gate of G'r01.

The diode 2 functions to increase the reverse bias voltage applied to the GTOl by the forward voltage drop thereof, and even if the diode 2 is removed, the function of turning off the GTO1 is exhibited.

Such a drive circuit can turn off the GTOI at a relatively high speed without using a reverse bias power supply, so a high-performance turn-off function can be obtained.
On the other hand, in order to improve the turn-on function, it is necessary to supply a sufficiently large on-gate current to the gate of G i"O at high speed, and as a result, the circuit for supplying the on-gate current becomes larger. There is a problem in that the advantage of miniaturization due to the high performance of the turn-off function is lost and the drive circuit becomes larger. This was noticeable when driving GTO.

[Summary of the invention]

This invention was made in view of the above-mentioned conventional problems, and includes inserting first and second transistors between the anode and gate and between the gate and cathode of the GTO, respectively.
GTO (7) - To provide high-performance turn-on and turn-off functions without increasing the size by driving the first transistor at turn-on and driving the second transistor at turn-off. This paper proposes a drive circuit for a gate turn-off circuit that can perform the following steps.

[Embodiments of the invention]

FIG. 2 is a circuit diagram showing an embodiment of the present invention. In the figure, 3B is an ignition transistor,
Its collector C and emitter E are respectively G'l"01
The transistor 3B1, the transistor 3A, and the diode DI are housed in the same bath cage (not shown) as the GTO1.

FIG. 2(b) shows the GTOI in the above circuit as an equivalent transistor circuit, and Sl is the equivalent PNPIN type transistor (equivalent NPN) run risk.

When turning on GTOl, transistor 3
A base current is supplied to B to make it conductive. When transistor 3B conducts, GTO1 etc.(il[1NPN
) Current flows into the base of run risk S2. equivalent PN
P l-run risk S1 and equivalent NPN) run risk S2
constitutes a positive feedback circuit, so the current increases rapidly, saturating both, and turning on the switch.

That is, GT01 is turned on.

The on-voltage drop after the turn-on is determined by the on-voltage drop of the GTO1, and no matter how high the saturation voltage of the transistor 3B is, it is sufficient to ensure the on-gate current of G"FOl. Therefore, as shown in FIG. As such, it is also possible to use a transistor with relatively high input/output impedance compared to a bipolar transistor such as a field effect type 1-run risk transistor, and it is possible to turn on the GTOl with a logic node signal. The control ability of GTol can be improved. In FIG. 3, S and D indicate the source and drain of the field effect transistor, respectively.

Turn-off of GTOl turns off transistor 3A
- This can be done by driving the run risk in the same way as in the conventional case described above.

FIG. 4 is a circuit diagram of another embodiment of the present invention, in which field-effect transistors are used for both transistors 3A and 3B, and the turn-on and turn-off of GTO1 can be performed using logic level signals. has, and furthermore,
A diode 4 is inserted in series with the transistor 3B to suppress the current flowing through the parasitic diode of the transistor 3B.

Note that although the transferers 3A and 3B in the above embodiment are N-type transistors, it is obvious that they may be P-type I/run-risk transistors.

As explained above, this invention has a structure in which a transistor is inserted not only between the gate and cathode of the GTO but also between the anode and gate, and the transistor between the anode and the gate is made conductive to supply on-day current to the GTO. As a result, the G"FO can be driven with a logic level signal, which has the advantage of providing high-performance turn-on and turn-off functions without increasing the size. It is extremely suitable for driving the GTO of a power converter such as an inverter that opens and closes.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional gate turn-off circuit drive circuit, Figure 2 (a) is a circuit diagram showing an embodiment of the present invention, and Figure 2 (b) is a circuit diagram of a conventional gate turn-off circuit.・A circuit diagram for explaining the operation of the above embodiment shown as a run risk circuit, and FIG. 3 and FIG. 4 are circuit diagrams of other embodiments of the present invention. 2.4-
Diode, 3 A, 3 B-1-run risk. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent Masuo Oiwa Figure 1 Figure 2 (cl) (b) /D S Figure/-1 2 Figure/-1 2

Claims (4)

[Claims] (1) A first transistor for ignition inserted between the anode and gate of the gate turn-off switch and a second transistor for extinction inserted between the gate and cathode of the gate turn-off switch. Gate turn-off thyristor drive circuit. (2) The gate turn-off transistor drive circuit according to claim 1, wherein at least the first transistor is a field effect transistor. (3) Cathode and second gate turn-off
3. A drive circuit for a gate turn-off circuit according to claim 1, wherein a diode is inserted between the transistor and the transistor. (4) A drive circuit for a gate turn-off transistor according to claims 1 to 3, characterized in that a diode is inserted between the gate of the gate turn-off transistor and the first transistor.