PWM AC chopper control of single-phase induction motor for variable-speed fan application

This work presents a variable speed control method for fan applications. A pulse-width-modulated (PWM) AC chopper changes the effective value of the supply voltage applied to a single-phase induction motor. This variable supply voltage gives the ability to control the speed of the motor. Harmonics generated by the speed control unit are filtered by an input filter according to EN 61000-3-2 limits for harmonic current emissions standards. Experimental results on a 230 V, 210 W in-line centrifugal fan for exhaust ventilation application shows that PWM AC chopper is simple and cost effective control method compared to other methods in terms of simplicity and input harmonic content.