A comparative study of sensorless speed control

Abstract

In this paper, a sensorless control scheme using back-EMF observer for permanent magnet synchronous motor drive (PMSM) is presented. Based on a general relationship between back-EMF and rotor position, observed rotor position is calculated and corrected with position estimation error. To obtain the velocity information from the observed rotor position, the velocity observer method and state of the art direct difference method are implemented and compared with each other.