A speed estimator for high performance sensorless control ofinduction motors in the field weakening region

摘要

The paper proposes a modified version of the model referencenadaptive system (MRAS) based speed estimator, whose outputs of thenreference and the adjustable model are rotor flux space vectors. Thenestimator is modified in such a way that the variation in theninstantaneous level of the main flux saturation during operation in thenfield weakening is recognized and properly compensated at all times. Thenspeed estimation scheme is equally applicable to both vector controllednand direct torque controlled induction machines, since it operates innthe stationary reference frame and requires measurement of only statornvoltages and currents. Verification of the proposed scheme is providednby simulation and by experimentation on an indirect feedforward rotornflux oriented induction machine for speed references of up to twice thenbase speed