Back EMF Estimation-Based Sensorless Salient-Pole Brushless DC Motor Drives

Abstract

This paper presents a position sensorless drive of a salient-pole brushless dc motor with a sinusoidal flux distribution. The algorithm is based on the estimation of back emf which is identified by the errors between the actual and estimated currents. Since the direction and amplitude of the estimated emf correspond to the rotor position and speed respectively, the position and speed can be estimated. The stability of the estimation and the design of the estimation gains are examined. The proposed algorithm were verified by using a 6-pole, 200 W, 3000 rpm test motor. In the results, thesensorless speed control range from 50 rpm to 4000 rpm under 0~100% load was obtained. The estimation algorithm is stable for any position error and any emf error. © 1997, The Institute of Electrical Engineers of Japan. All rights reserved.