| 摘要 |
PURPOSE:To hold the prescribed gate current of a gate turn-off thyristor during ON period by providing an ON gate circuit in which a series unit of a phototrigger thyristor and a resistor is connected in parallel, between the anode and the gate of the thyristor. CONSTITUTION:An ON gate circuit 64 in which a series unit of a phototrigger thyristor 641 which flows a sufficient gate current at turning ON time and a resistor 642, and a series unit of a phototrigger thyristor 643 which supplies the prescribed gate current during ON and a resistor 644 are connected in parallel, is provided between the anode and the gate of a GTO 61. Lights S1, S2 are emitted to turn ON the GTO 61, and the prescribed gate current is supplied to the GTO 61 by the light S2 during ON period. Accordingly, the configuration is simplified by forming integrally the phototrigger thyristor 30b by the common use of the GTO 30a and a P type emitter layer 33, thereby supplying the gate current for preventing the abrupt rise of the ON voltage. |
