Electrical power converter thyristor firing circuit having noise immunity

摘要

A power control circuit has a thyristor bridge interposed between a.c. buses connected to an a.c. power supply and a load. The firing circuit for the thyristors of the bridge includes a light actuated controlled rectifier for generating firing pulses. Two series connected resistor-capacitor pairs are connected in series across the a.c. buses. Taps intermediate the resistors and capacitors provide an energizing anode voltage to the controlled rectifier reduced with respect to the a.c. voltage in the buses. The voltage reducing and capacitive properties of the pairs render operation of the controlled rectifier immune to transient voltage spikes in the a.c. buses.