State observer with stator resistance and back-EMF constant estimation for sensorless PMSM

Recently, sensorless controls, which eliminate position and speed sensors in a permanent magnet synchronous motor drive, have been much studied. Most sensorless control algorithms are based on the back-EMF and speed estimations which are obtained from the voltage equations. Therefore, the sensorless control performance is largely affected by the parameter errors of a motor. This paper investigates an improved state observer with the parameter error compensation for the speed sensorless control of a permanent magnet synchronous motor. The proposed parameter estimation is obtained through the LMS algorithm minimizing the performance function of d- and q- axis current errors. The performance of the proposed algorithm is verified through the simulation and experimentation.