Review and evaluation of some position and speed estimation methods for PMSM sensorless drives

The paper describes the comparison between four different high-performance techniques used for the sensorless estimation of the motor shaft position in permanent magnet synchronous motor sensorless drives. Rotor position and speed are estimated from either electrical measurement or Hal effect pulses, and are used as feedback in a sensorless vector control scheme, achieving almost the same high performance of a sensored drive. The paper point out the differences, by using experimental implementation, between the four methods: open-loop flux estimator, flux algebraic estimator, reduced flux observer and Hall effect pulses based estimator.