PURPOSE: To speed up the turning-on of a GTO and to reduce the current duty of an FET for GTO trigger by connecting a capacitor between the gate of a gate turn-off thyristor (GTO) and a source of the FET connected in series with the GTO.
CONSTITUTION: In inverting a signal between control terminals (a, b) to L level, FETs 6, 7 are turned off, a current flowing to a GTO 5 and an FET 6 flows from a gate of the GTO 5 via a capacitor 4, the GTO 5 is turned off and the capacitor 4 is charged to a prescribed voltage. Conversely, in bringing the level of the signal fed between the terminals (a, b) to an H level, the FET 6 is turned off and the electric charge in the capacitor 4 is discharged from the gate of the GTO 5 via the FET 6 to accelerate the turning-on of the GTO 5. No on- current flows to the FET 7 until a level of the capacitor 4 is discharged to a prescribed level, then turned on to apply a gate current to the GTO 5, but the current duty of the FET 7 is reduced by providing the capacitor 4 and the turning-on of the GTO 5 is quickened.
TOKUNAGA KIICHI
AMANO HISAO
YABUNO KOHEI
