| 摘要 |
PURPOSE:To prevent damage of a photocoupler, and also to prevent erroneous ignition of a GTO, by constituting so that reverse induced voltage in case of turn-off is not applied to a photocoupler element. CONSTITUTION:A switching electric power source 2 supplies gate electric power to an on-gate circuit 17 for supplying a turn-on gate current to a GTO16, and a negative biasing circuit 21 for biasing negative a control electrode in an off- period of the GTO16, through a pulse transformer 1. The on-gate circuit 17 has a photocoupler 11 for setting a transistor 12 to an on-state by an on-command. Subsequently, the photocoupler 11 is connected to an electric circuit to which reverse spike voltage of the GTO6 is not applied. By constituting in this way, damage of a photocoupler and erroneous ignition of the GTO are prevented. |
