Sensorless Control of PM Synchronous Motors in the Whole Speed Range Including Standstill Using a Combined INFORM/EMF Model

The paper presents the combination of a lowspeed model ("INFORM method") and a specially adapted high speed model ("Voltage model or EMF model") for covering the full speed range of sensorless permanent magnet (PM-) synchronous motor drives. Both models generate "measuring information" for a linear observer, modelling the mechanical structure of the motor. A special feedback loop is introcuded, coupling back the observer information to the integrating voltage model. Thus, a stable operation with high robustness against parameter uncertainties and low frequency disturbances is achieved.