Sensorless Position Control for Surface Permanent Magnet Synchronous Motors at Zero Speed and Acceleration

Abstract

This paper proposes a position, speed and load torque observation technique for position control of a non-salient Permanent Magnet Synchronous Motor (PMSM). Unlike the speed control, the position control implies that the motor is often in low speed and standstill conditions. Observability analyze is done to show that the motor is not observable in standstill condition. A high-frequency signal injection is introduced to get round this unobservability. An Extended Kalman Filter is then used to observe the rotor position, speed and load torque by taking into account the injected signal into the observation model. Position tracking and load torque influence are studied on a test bench. Experimental results are provided to confirm the performance and efficiency of the proposed solution.