Kalman filter and redundant observer comparison for sensorless PMSM velocity control

This paper presents a comparison made on two observers for permanent magnet synchronous machine control without mechanical sensor. The well known Kalman filter is presented, the structure estimating currents, velocity and position for PMSM is exposed. A redundant observer structure is described. This completely different structure allows building back-emf, velocity and position estimation. The two structures are compared and the synthesis of correction coefficients is discussed as well as results obtained for variable speed control of a PMSM drive. Critics and difficulties are listed and robustness of the two structures is analyzed to conclude on performances of the two observer structures and facility to be implemented.