Electrical parameter observation for induction machine sensorless drive using a sensitivity and observability based EKF

This paper focuses on an effective method for both stator and rotor resistance on-line observation of induction machine driven without mechanical speed sensor. These resistances change over a large range with both the temperature and the flux frequency, making on-line adaptation of these parameters necessary to reach a precise speed observer. To do so, the sensitivity of the speed observation with respect to each resistance and the observability of the resistances are analysed in order to define an observation strategy for the stator and rotor resistances for which the resistances are updated only when necessary. HIL experimentations show that the observation precision on the resistances is good and that the speed observation remains precise and stable despite electrical parameter variation.