Improved angular velocity estimation for high performance sensorless PMSM

The permanent magnet synchronous motor (PMSIM) is increasingly playing an important role in electric propulsion systems due to its many advantages over competing technologies such as induction, reluctance, and DC motors. An encoder or resolver attached to the shaft of the motor typically supplies the feedback required for PMSM torque and velocity control. Many propulsion applications, however, cannot tolerate the use of these feedback devices because of reliability concerns in a harsh operating environment, space and weight limitations, and packaging issues. A model-based sensorless PMSM drive strategy is presented with emphasis on an improved rotor angular velocity estimator. Through experimental results, the sensorless drive is shown to be robust to mechanical parameters and disturbances while providing the highly accurate rotor angle and velocity feedback that allows sensorless PMSM operation in high-performance vehicle propulsion systems.