Study of sensorless control algorithms for a permanent magnet synchronous motor vector control drive

In the recent past, the use of permanent magnet synchronous motors (PMSM) has increased considerably owing to their inherent advantages. The high performance speed and/or position control of a PMS motor requires an accurate knowledge of rotor shaft position and angular speed in order to synchronize the phase excitation pulses to the rotor position. The rotor position and speed information is specifically required for implementation of vector control scheme in a PMSM. In order to achieve the speed control various sensored methods are employed. Due to number of advantages recent trend is to implement the sensorless control drive for a PMSM. This paper presents and compares two main sensorless control algorithms viz, Sliding Mode observer(SMO) and Extended Kalman Filter (EKF) for sensorless estimation of rotor position and speed in a PMSM. The simulation results for both these methods on an identical PMSM are presented. The analysis of these results give some insights into the accuracy of estimations and subsequent working of the PMSM with them.