Voltage control of single-phase induction motors using asymmetrical PWM and fuzzy logic

A microcontroller-based AC voltage regulator for single-phase induction motors, using asymmetrical pulse width modulation (PWM) and fuzzy logic is proposed. The optimal switching angles are computed in real-time, using a nine-rule fuzzy system, with the objective to correct the phase difference between the output voltage and current. The voltage controller achieves an almost linear response and the motor speed is smoothly regulated within the full dynamic range of the control input. The proposed fuzzy switching regulator is verified both in simulation and with a circuit prototype. The performance of the asymmetrical PWM fuzzy controller is compared against other methods.