Robust speed identification for speed sensorless vector control of induction motors

An approach to estimating induction motor speed from measured terminal voltages and currents for speed-sensorless vector control is described. The proposed technique is very simple and robust to variations of motor parameters. This approach is not dependent upon the knowledge of the value of the stator resistance, nor is it affected by stator-resistance thermal variations. Pure integration of sensed variables, in principle, is not required. Therefore, this method can achieve much wider bandwidth speed control than previous tacholess drives. The effectiveness of the technique is verified by simulation and experiment