Extended EMF- and parameter observer for sensorless controlled PMSM-machines at low speed

The paper describes an extended EMF- and parameter observer for sensorless controlled PMSM-machines. Therefore a combination of INFORM-method and EMF-model is used. At low speed, the reference position of the permanent magnet flux is calculated by INFORM-method and compared with the permanent magnet flux provided by EMF-model. By transformation of the voltage equation into a current-oriented reference frame, a 4th order state model is presented which provides the observed stator resistance and stator inductance of the PMSM. A stability analysis results in a stable operation. Measurement results of the extended EMF-and parameter observer at stationary operation point and in dynamical operation are given.