| 摘要 |
PURPOSE:To prevent a gate turn-off thyristor (GTO) from damage, by such means that an auxiliary thyristor be used for turning off the GTO with the commutation operated to part of the way, and a negative pulse be given at the time of decreasing point of a current flowing in the GTO. CONSTITUTION:With a gate turn-off thyristor GTO being off, a current is supplied to a commutation condenser Cmc through an auxiliary thyristor ACRF. If given a positive pulse to a gate of the GTO, a current flows in a DC motor M. Subsequently, if given a pulse to a gate of the auxiliary thyristor ACRF, an electric charge of the commutation condenser Cmc is discharged through the GTO. At the time when the current in the GTO is attenuated to a certain degree, with a negative pulse, at a level corresponding to the current value, given to the gate of the GTO, the GTO is made turn-off. |
