Sensorless Salient-Pole PM Synchronous Motor Drives in All Speed Ranges

Abstract

This paper presents a position sensorless drive of salient-pole PM synchronous motors in all speed ranges including zero speed. Two kinds of position and speed estimation algorithm using the current differences between the actual and the estimated currents are proposed. One is based on the back emf estimation in the medium and high speed ranges. Another is based on the position-dependency of the winding inductances in the low speed ranges including zero speed. The effectiveness of the proposed algorithm has been verified by using a 6-pole, 1.5 kW, 1500 rpm test motor. The stable sensorless speed control from zero to 3000 rpm within ± 100% load torque range was achieved.