| 摘要 |
PURPOSE:To obtain a gate current having a high peak level and a large time width required to ignition of a thyristor by providing 1st and 2nd capacitor charging circuits supplying a high peak gate current and a gate current with a large time width respectively separately to the ignition circuit. CONSTITUTION:The capacitor of capacitors C1, C2 is selected to be C2>C1 and a charging time constant has a relation of C2XRC2>C1XRC1. Thus, the capacitor C1 is charged up to nearly a peak of an AC power supply voltage as a charging voltage EC1. Since a discharge current IG1 of the capacitor C1 is expressed as IG1=EC1/RD, the current is matched with a required peak current of the gate current of a main thyristor MTH. Since the capacitor C2 is selected to be larger in its capacitance than that of the C1, a discharge time constant is selected large and a discharge current IG2 with a larger time width is obtained. Thus, the gate current IG of the main thyristor MTH is given as a sum IG=IG1+IG2 and the gate current having a required peak level and a time width is obtained. |
