JPS6253516A - Control circuit for semiconductor control rectifier - Google Patents

Abstract

PURPOSE:To recover the forward dielectric strength characteristic of a gate turn-off thyristor (GTO) section by flowing a reverse current to the GTO section so as to sweep out the carrier of the GTO section. CONSTITUTION:A current flowing to the GTO section 11 is detected by a detection circuit 26, a signal is sent to a flip-flop (FF) 27, the FF output is sent by the trailing of the signal and a transistor 33 is driven via a base circuit 29. When the transistor 33 is driven in a gate reverse current circuit 30 of the GTO section, the residual carrier of the GTO section 11 is swept out by flowing the reverse current to the gate of the GTO section 11 to be transited in the off-state. Further, the output signal width of the FF 27 is proper by a reset signal generating circuit 28. Thus, the forward dielectric strength characteristic of the GTO section is recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a gate turn-off thyristor (GTO) section;
This relates to a control circuit for a semiconductor-controlled rectifier equipped with a reverse conduction rod GTO that has a diode part connected in antiparallel with this in the same pellet, and is particularly used in an inverter device (DC-AC converter). It is something.

[Technical background of the invention and its problems]

Conventionally, for example, in an inverter device using a flat GTO,
A diode section is installed in antiparallel with the GTO section and operated as one arm.By using a reverse conduction type GTO having the same pellet KGTO section and the upper part of the diode, the elements in the inverter device shown in Fig. 3 are Only six pieces were required, making the entire device more compact and lower in cost. In Figure 3, 11 is the U-arm GTO
12 is the diode section of the U arm, 13 is the GTO section of the X arm, 14 is the diode section of the X arm, and 15 is the load (in this case, the interaction motor).

In addition, the reverse conduction type GTO has two GTO parts in the same pellet.
3 and a diode part 25, in order to separate them, a separating part 24 with high resistance as shown in FIG. , hole carriers are in the GTO section 23
The current in the diode section 25 stops flowing, the GTO section 23 recovers its forward breakdown voltage characteristics, and the GTO section 23 recovers its forward breakdown voltage characteristics.
This allows the TO section 23 to turn off smoothly. In Figure 4, 16 is the gate, 17 is the cathode, 18
19 is an N-type layer, 20 is a P-type layer, 21 is an anode, and 22 is an N-type layer.

However, in case the load progresses, G T
Natural commutation may occur from the O section 23 to the diode section 25. As a result, the carrier in the GTO section 23 remains, and the GTO
This prevents the transition to recovery of the forward breakdown voltage characteristics of the parts. In this case, the recovery of the forward voltage characteristics of the U-arm GTO in FIG. 3 is incomplete, and when an on signal is input to the X-arm GTO,
, and the X arm, resulting in an arm short circuit, resulting in destruction of the element and further damage and stoppage of the device.

[Purpose of the invention]

In the present invention, in a reverse conduction type GTO, after the GTO section is energized, the current is commutated to the diode section, and when the diode section is turned off,
The purpose is to allow the GTO section to smoothly recover its forward breakdown voltage characteristics.

[Summary of the invention]

In the present invention, in a reverse conduction type GTO, when natural commutation occurs from the GTO section to the diode section, by flowing a reverse current to the gate of the GTO section and expelling carriers from the GTO section,
This is designed to restore the forward breakdown voltage characteristics of the GTO section.

[Examples of practical inventions]

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a circuit diagram of the same embodiment, and FIG. 2 is a signal waveform diagram showing the operation of the same circuit. In FIG. 1, 26 is a GTO current detection circuit, 27 is a flip-flop, 28 is a reset signal generation circuit for the flip-flop 27, 29 is a base circuit of the transistor of the reverse current circuit 30 of the GTO gate, and 31 is a normal forced commutation. The drive signal of the transistor 33 in the case of (
32 is a reverse conduction type GTO.

Figure yX2 (shows the current waveform of the reverse conduction type GTO 32).

The current detection circuit 26 of the GTO receives the input from the current detector 34 through a transistor 35, a resistor 36, a diode 37,
A circuit consisting of an inverter 38 converts it to an integrated circuit level, and sends out the GTO section current detection output shown in FIG. 2(b). The reset signal generation circuit 28 of the flip-flop 27 is
When the voltage due to R exceeds the null threshold voltage of the normal rotation amplifier 39, the flip 70 in FIG. 2(C) provides a positive signal. When the flip-flop 27 receives this reset signal, it returns the output signal to 0 level and sends out the flip-flop output shown in FIG. 2(d).

In the control circuit shown in FIG. 1, the detection circuit 26 detects the current flowing through the GTO section, and sends the signal shown in FIG. 2(b) to the flip-flop 22.
The 7-lip flop output of d) is sent out, and the base circuit 2
In the gate reverse current circuit 3Q of the oGTO in which the transistor 33 is driven through the gate 9, when the transistor 33 is driven, a reverse current flows through the gate of the GTO section 1. As a result, residual carriers in the QTO section 11 are expelled and the QTO section 11 is shifted to the off state. Further, the output signal width of the flip-flop 27 can be set to an appropriate width by the reset signal generation circuit 28.

In this way, when the current in the GTO section naturally flows through the diode section, a reverse current flows through the gate of the GTO section, thereby recovering the forward breakdown voltage characteristics of the GTO section. In addition, in the case of normal forced commutation operation, the reverse current circuit 29
It is operated by the signal 31 to.

〔Effect of the invention〕

As explained above, according to the present invention, even when a reverse conduction type GTO needs to recover its forward breakdown voltage characteristics through natural commutation, a reverse undercurrent is caused to flow through the gate of the GTO section to quickly restore the forward breakdown voltage characteristics. Recover. As a result, reliable operation of the reverse conduction f51 GTO used in inverter equipment, etc. can be achieved, and the use of the reverse conduction 7JI GTO can take advantage of the compactness and cost reduction of the entire device. reliability can be improved.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of an embodiment of the present invention, Figure 2 is a timing chart showing the operation of the circuit, Figure 3 is a circuit diagram of an inverter using a GTO, and Figure 4 is a reverse conduction type GTO. 11...GTO section, 12... diode section, 26...
...GTO current detection circuit, 22...Flip-flop, 28...Reset signal generation circuit, 29...GT
Base circuit of transistor of O gate reverse current circuit, 3
0... Reverse current circuit of GTO gate, 32... Reverse conduction type GTO0 Applicant's agent Patent attorney Suzue Nihiko
YZFigure 3Figure 4

Claims (1)

[Claims] Gate turn-off thyristor (
A reverse conduction type GTO is composed of a GTO section and a diode section that is antiparallel to the GTO section, and when the current flowing through the GTO section naturally commutates from the GTO section to the diode section, By applying a reverse current to the gate, the GTO
1. A control circuit for a semiconductor-controlled rectifier, characterized in that the control circuit includes means for shifting the section to an OFF state.