Novel speed sensorless vector control with adaptive rotor flux identification of induction motors

This paper compares three voltage model observer structures for rotor flux orientation of induction motors, and presents a novel method of speed sensorless vector control at very low speed, which is based on the finite compensating voltage model and the model-reference adaptive system (MRAS) for the estimation of voltage drop across the stator resistance. The accurate rotor flux can be estimated by this novel method in very low speed range, thus the performance of an induction motor is improved when the speed is decreased to very low range. This method is simple and effective, and it needs not any signal injection. The digital simulation results have validated the effectiveness of the proposed algorithm.