| 摘要 |
PURPOSE:To prevent a thyrister from commutation failure, by providing a commutation ciruit by a capacitor and backwardly biassing a thyrister gate by a gate turn-off circuit. CONSTITUTION:When a thyrister 4 is turned ON, a load 2 is supplied with DC power, and at the same time, a commutation capacitor 8 is charged through a resistor 3 as depicted in the sketch. When a thyrister 5 is turned ON, an oscillation circuit 14 which operates at several KHz is activated to operate a transistor 10, and the electric charge which has already been charged to a capacitor 11 through a resistor 9 is discharged through the transistor 10, a cathode of the thyrister 4, a gate and a diode 13. And, the gate and the cathode of the thyrister 4 are backwardly biassed by highfrequency to allow turn-off to occur easily, and therefore, with a help of function of the commutation capacitor 8, commutation failure can be prevented. |
