| 摘要 |
PURPOSE:To maintain the turn-off gain of a GTO thyristor constantly by controlling the reverse voltage applied between the gate and the cathode of the thyristor to a value proportional to the main current of the thyristor and supplying the turn-off current. CONSTITUTION:When a turn-off controlling pulse is given, a base current controlling circuit 17 serves to control a transistor 15 in response to the detected current of a current detector 16. The transistor 15 is controlled at its base current to operate as a variable resistor, the current flowed from a DC power source 14 to the gate of a GTO thyristor 1 is limited by the transistor 15, and thus becomes a gate current corresponding to the main current of the thyristor 11, thereby maintaining the turn- off gain of the thyristor constantly. |
