A Fast Self Adjusting PLD-based Three-phase Firing Circuit for Phase Angle Control Applications

The paper presents a fast, simple and configurable scheme to automatically provide the correct firing pulses for the working thyristors irrespective of any mistake that might happen during connections, in the application of four-wire three-phase AC voltage controller system. The proposed scheme can readjust itself in case of a missed connection or sequence alteration and it is built around a single chip programmable logic device with self generated firing pulses and capable of readjusting the firing circuit against any phase or sequence alteration in 8.4 seconds. The system has additional advantages like the ability of detecting the faulty thyristors, if any, and built in self test routine. Experimental results verify the principle of operation. Keywords:: Phase angle, Firing angle, Self-correcting, PL