| 摘要 |
PURPOSE:To prevent the erroneous firing of a gate turn-OFF thyristor (GTO) by closing a switch of a reverse bias circuit having a DC power source and a series circuit of switches during the OFF period of the GTO. CONSTITUTION:Circuits 8, 9, 11 for supplying OFF gate currents to turn a gate turn-OFF thyristor (GTO) and reverse bias circuits 2, 3 for preventing the erroneous operation by reversely biasing the gate at the OFF time of the GTO are provided. When the switch 3 is closed during the OFF period of the GTO, the voltage of a DC power source 2 is applied directly to the GTO. The tail current of the GTO at the turning-OFF time of the GTO and the displacing current at the abruptly changing time of an anode volage flow through the power source 2, but since the impedance of passage is small, the variation in the gate voltage of the GTO is small. Accordingly, the GTO is not erroneously fired due to the application of the positive voltage. |
