Sensor-based and Sensorless Vector Control of PM Synchronous Motor Drives: A Comparative Study

Speed and rotor position estimation is mandatory for vector control scheme of Permanent Magnet Synchronous Motor (PMSM). The estimation accuracy of Non-adaptive (Open loop) methods degrades as mechanical speed reduces. At lower speed, discrepancy in resistance and estimated stator flux values leads to significant impact on the steady state and transient performance of the drive system. The system becomes more robust against parameter mismatch and signal noises by employing adaptive observers for estimation of speed and flux. In this paper, a comprehensive analysis of sensor-based and sensorless based on sliding mode observer (SMO) techniques for vector control of PMSM is presented with regards to the steady- state and dynamic performance robustness against parameter sensitivity, stability and computational complexity. The synopsis of pros and cons of both observers are also discussed.