Position Estimation of AC Machines Over a Wide Frequency Range Based on Space Vector PWM Excitation

This paper presents a new method for position estimation in shaft-sensorless ac motor drives over the entire speed range, including zero frequency. The method is based on the standard fundamental wave space vector pulsewidth-modulation (PWM) excitation sequence and requires neither an observer-based model nor a signal injection test signal. Experimental results confirm the effectiveness of the new technique, and a comparison with other PWM-excitation-based methods for estimating the rotor position of ac machines is made.