Position sensorless control for doubly salient electro‐magnetic motor based on the terminal voltage

Abstract

A sensorless control method based on the terminal voltage for doubly salient electro-magnetic motor (DSEM) is researched here. The negative-going zero-crossing point (NGZCP) of the fundamental component of terminal voltage is detected to obtain the rotor position. Firstly, a fourth Butterworth filter is introduced to extract the fundamental component of the terminal voltage. The ratio of signal frequency to cut-off frequency f/f c is optimised to acquire good filtering effect and good dynamic performance. Moreover, on this basis, the speed range is divided into several intervals to match the filters with different cut-off frequencies. Secondly, the coordinate transformation is adopted to compensate for the phase difference between the NGZCPs of the extracted voltages with the ideal commutation points. The transformation angle is obtained by offline simulation and test. An 18 kW DSEM prototype is tested to verify the feasibility of the proposed method.