Filter design of PWM AC chopper on soft starting application 3 phase induction motors

The use of PWM AC Chopper for soft starter applications to feed 3 phase induction motors causes current and voltage ripple. Higher ripple means higher harmonic distortion in the system. To minimize the ripple, a filter consisting of an inductor and a capacitor, connected in series to the load was designed and analyzed. A prototype of AC chopper soft starter was also built to feed 3 phase 1 hp induction motor for experimental verifications. The analysis includes varying the switching frequency from 1 kHz to 5 kHz, the inductor from 0.01 to 0.05 H, and the capacitor from 2.2 to 10 micro Farad. The best ripple voltage was obtained as 0.16 V of 220 V normal voltage.