| 摘要 |
PURPOSE:To prevent AS-GTO from being turned on again and to reduce the unnecessary loss of an off-gate circuit by controlling an off-gate output time with a reimpressed anode voltage at the time of the turn-off operation of the AS-GTO even when the voltage varies. CONSTITUTION:The voltage Ed across a DC filter capacitor 3 is converted by an analog/digital converting circuit 4 into a digital signal, which is supplied to the selection control signal input of a selector 6. On the other hand, four single-shot pulse generating circuits MM1-MM4 output signals with time widths ta-td (ta<tb<tc<td) when inputting an off-gate trigger signal and they are supplied to the data input of the selector 6. The selector 6 selects one of the data inputs with the time widths ta-td according to a selection control signal and outputs it as an off-gate signal. This signal is inputted to the gate circuit 7 of the AS-GTO, which is supplied with off-gate electric power from the gate circuit 7. Consequently, an off-gate output time is controlled with a DC part voltage, thereby extending the off-gate output time as VD drops. |
