JPS59158127A - Gate driving circuit of gate turn-off thyristor - Google Patents

Abstract

PURPOSE:To allow a simple circuit to perform overdriving and wide-width gating with a narrow-width signal and to eliminate interference between circuits by providing a wide-width on gate circuit, and turning a control thyristor for it on by an on gate transformer and off by an off gate transformer. CONSTITUTION:An on control signal turns on a TRTON at time t1 and the on gate transformer PTON turns on a thyristor SON for prevention against on/off interference to turn on a gate turn-off thyristor GTO. At this time, even the control thyristor SW is turned on to flow a current through a loop including the SW and GTO from a DC power source E, obtaining a wide-width on gate current (figure (b)). The on control signal is ceased at time t2 and the thyristor SON turns off, but the thyristor SW turns on to flow the wide-width on gate current continuously (figure (b)). An off control signal turns off an off TRTOFF at time t3 as shown in a figure (c) to apply a voltage to the off gate transformer PTOFF, and the current of a route shown by a solid line turns off the GTO (figure (d)) to turn on a TRSOFF for turning off the SW. Therefore, the current of the power source E, SOFF, and PTOFF power source E turns off the thyristor SW.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gate drive circuit for a gate turn-off thyristor that is turned on and off by a gate current.
has a self-extinguishing ability and is a functionally superior power semiconductor element. However, the turn-on gain is lower than that of a thyristor, and overdrive is required when turning on. In addition, the holding current is large, and during the on period, a considerably larger gate current must flow than in a thyristor. Furthermore, at turn-off, a very large off-state current must flow through the gate, and in order to cut off the main current of 100A, the off-state current is more than 200A.For this reason, the gate circuit tends to be complex and quite expensive. 0 This becomes noticeable in applications such as inverters for trains, where the main circuit voltage is high and the number of semiconductor elements is large, due to the problem of insulation from the gate control circuit. 0 Figure 1 shows the gate drive of a conventional GTO. This is a diagram showing an example of the circuit. Figure 2 is a diagram explaining its operation. In Figure 1, P is the positive terminal of the DC power supply, N is the negative terminal of the DC power supply, TON is the ON transistor, and 8ON is for preventing ON/OFF interference. Thyristor s R1# R2 is a resistor, p'roN is an on-insulation pulse transformer (hereinafter referred to as an on-gate gate transformer), and constitutes a narrow on-gate circuit.

TOFF is a transistor for turning off, DP is a diode that prevents on-gate current from flowing into the off-circuit, and FTOFF
is an OFF insulating pulse transformer (hereinafter referred to as an OFF gate transformer), which constitutes an OFF circuit.

TWI p TW2 is a wide gate pulse generation transistor that turns on and off alternately at high frequency, PTW is a wide insulating pulse transformer (hereinafter referred to as wide gate transformer), and Dwl and Dw2 are wide gate transformers PTW.
A diode for full-wave rectification of the secondary voltage, R3 is a resistor, and constitutes a wide on-gate circuit.

The control signals for each transistor are shown in Figure 2 (,1) to (C
), and the gate current of the GTO is as shown in Fig. 2(d). At time ti, the overdrive current starts to flow, and at time t2, the overdrive current disappears, and the gate current becomes wide as shown in the figure. The current is a full-wave rectified high-frequency wave. Further, at time t3, an off-gate current flows to turn off the GTO, and at time t4, the off-gate current becomes zero.

In this conventional example, three types of control signals are required, making the circuit extremely complex. What is even worse is that as shown in Figure 1, off-circuit current flows from the cathode of the GTO to the gate, as shown by the solid line. In addition to the current, it is also shunted to a wide on-gate circuit as shown by the dotted line. In particular, when the main current of the GTO is cut off and a voltage is maintained between the cathode and the gate, the current only appears as shown by the dotted line in FIG. This current is
If the resistor R3 is a thyristor, the resistance is quite low compared to lζ (
(2 to 3 A or more is normally required as a wide on-current), so this current is a non-negligible value.0 This current not only reduces the utilization rate of off-current, but also when the off-gate pulse disappears, The current flowing in the wide on-gate circuit also tries to disappear, but the wide gate transformer PT
The current indicated by the dotted line in Figure 1 is attempted to flow continuously due to the inductance of the winding w and the wiring inductance of the circuit.

On the other hand, the OFF gate transformer FTOFF generates a reverse induced voltage due to the interruption of the OFF transistor TOFF, and 2
Therefore, the current in the wide on-gate circuit described above flows to the gate and cathode of the GTO at time t4 in the gate current waveform of FIG. 2(d), as shown by the dotted line. There is a risk of turning off the GTO. Therefore, a switch element is always required in a wide on-gate circuit, and if a circuit for generating an isolated control signal to control this switch element is also considered, the circuit becomes extremely complicated.

Furthermore, as shown in the gate current in Figure 2(d), as a wide on-gate signal, discontinuity in the gate current due to the full high frequency is always generated, which has an extremely detrimental effect on the operation of the GTO. 0 The present invention was developed in view of the above-mentioned drawbacks of the conventional technology, and the present invention will be explained below based on the drawings of an embodiment. ◎Figure 3 is a gate drive circuit diagram of a GTO showing an embodiment of the present invention. , OE is a wide on-gate power supply, and any insulated DC power supply may be used (hereinafter referred to as DC power supply B). ). 8
w is the control thyristor that turns on and off the wide on-gate current, and R4 is the resistance % that limits the control thyristor Sw.
801F is 8w for turning off the control thyristor 8w
The off transistor, R5, is this switch element (8OF
F) is a resistor that limits the current that turns on and off.

In FIG. 3, the configurations of the narrow ON gate circuit to which the ON control signal is applied and the OFF circuit to which the OFF control signal is applied are the same as in FIG. , resistor R3 and control thyristor 8
The wide on-gate circuit is connected to the gate and cathode of the GTO through a series circuit of W, and the thyristor 8w for controlling this wide on-gate circuit is fired by the secondary voltage of the on gate transformer FTON, and the off gate transformer is activated by the secondary voltage of the on gate transformer FTON. P
The control thyristor Sw is connected to the 8W off transistor 5OFF via the diode D connected to the secondary winding of TOFF, and this 8W off transistor 801F is connected to the 8W off transistor 5OFF to connect the control thyristor Sw to the 8W off transistor 5OFF.
The control thyristor Sw is configured to conduct at the next voltage and extinguish the arc of the control thyristor Sw.

Next, the operation of the embodiment circuit of FIG. 3 according to the present invention will be explained in the fourth section.
This will be explained using figures. At time tl, the on control signal shown in Fig. 4(a) is applied to the on transistor TON, turning on the on transistor TON.◎This applies voltage to the on gate transformer PTON, and the thyristor for preventing on/off interference When SON turns on, FTON secondary winding → resistor 2 → GTO gate →
GTO cathode → Son → p'r (, N current flows through the path of the secondary winding, turning on the GTO.

At this time, current also flows through the path of the resistor 4→8w cathode, which is a parallel circuit of the resistor 2, turning on the control thyristor Sw. Therefore, the resistance R)1-) from the DC power supply B is also
Current flows through the Sy-+GTO gate → GTO cathode → DC power supply path, resulting in a wide on-gate current (Figure 4 (b)
).

As shown in FIG. 4(,), at time t2, the on control signal disappears and the on/off interference prevention thyristor 8ON turns off, but the control thyristor Sw remains on and a wide on-gate current flows from the DC power supply E. Continue (Figure 4 (b)
)).

At time t3, the off control signal is applied to the off transistor TOFF as shown in FIG. The off-state current flows through the path shown by the solid line, turning off the GTO (
Figure 4(d)). When GTO is cut off, current flows through the 8W off transistor 8OFF through the path shown by the dotted line in FIG. 3 due to the secondary voltage of the off gate transformer PTOFF, turning on the 8W off transistor 8OFF. When the 8w off transistor 5OFF turns on, the current flowing through the control thyristor 8w is commutated to the 8w off transistor 5OFF, DC power supply E → Low resistance 3 → 8OFF-+PTOFF Secondary winding → DC power supply B
Current begins to flow through the path. This operation turns off the control thyristor SW, and the wide on-gate current no longer flows (FIG. 4(b)). At time t4, the off-state current becomes zero.

As described above, according to the present invention, with a relatively simple circuit configuration, two narrow signals for ON and OFF can be used to overdrive the GTO and provide a wide ON gate.

This not only makes it possible to turn off the gate, but also completely eliminates interference between each circuit, making it possible to turn the wide on-gate current into a complete direct current, making it possible to operate the GTO reliably.

[Brief explanation of drawings]

FIG. 1 is a gate drive circuit diagram of a conventional gate turn-off thyristor, FIG. 2 is an explanatory diagram of the operation of the circuit shown in FIG. 1, and FIG. 3 is a gate drive circuit diagram of a gate turn-off thyristor showing an embodiment of the present invention. FIG. 4 is an explanatory diagram of the operation of the circuit shown in FIG. TON・・・・・・Transistor for ON % TOFF・
...Transistor for off, Twl, Twz/mountain/wide gate pulse generation transistor, FTON...
Isolation pulse transformer for ON, PTOFF...Isolation pulse transformer for OFF, PTw...Isolation pulse transformer for wide width, DWI s DW2 tD,...
...Diode, SoN...Thyristor for preventing on/off interference, Sw...Control thyristor, 8OFF...8W off transistor, G
TO...-gate turn-off thyristor, R1'=R5
·····resistance. Patent applicant Toyo Denki Manufacturing Co., Ltd. Representative Atsushi Doi 1 Figure 1.尤z Z3 Power 4 NF43 Figure 41st child (OA talent J″iki 74 people 81 Power! t4

Claims (1)

[Claims] The gate and cathode of the gate turn-off thyristor are connected to the secondary winding through a limiting resistor, and the gate transformer for turning on overdrives when turned on.The cathode and gate of the gate turn-off thyristor are connected to the secondary winding through a diode. In the gate circuit of a gate turn-off thyristor, the gate turn-off thyristor is equipped with a wide on-gate circuit in which a DC power source is connected to the gate and cathode of the gate turn-off thyristor through a series circuit of a limiting resistor and a control thyristor. The control thyristor of the circuit is ignited by the secondary voltage of the ON gate transformer, and the transistor is used for the control via the diode connected to the secondary winding of the OFF gate transformer. A gate drive circuit for a gate turn-off thyristor, which is characterized by extinguishing the arc of a thyristor.