Discussion on “A Differential Algebraic Estimator for Sensorless Permanent-Magnet Synchronous Machine Drive”

Diao et al. are to be commended for proposing a new approach for permanent magnet synchronous machine (PMSM) position estimation, using the differential algebraic theory. In the following comments, we would like to highlight some points concerning the machine observability under the applied approach. In paper by Diao et al., it is claimed that the rotor position observability of the nonsalient PMSM is ensured regardless the speed, based on the relationship.