A novel speed-sensorless vector control technique of induction motor for Electrical vehicle propulsion

This paper presents an improved speed sensorless vector control method for induction motors used in the field of electrical vehicle propulsion. The proposed method is based on the d-q axis dynamic model of the induction motor and an improved closed-loop flux observer, which can achieve precise rotor and stator flux estimation over a wide speed range. And then, a rotor-speed-estimation method, based on the model reference adaptive systems (MRAS) theory, is discussed and deduced. The proposed algorithm has simpler control algorithms and little computational burden, both the flux observation and speed estimation can achieve perfect effect in both steady-state operating condition as well as in transient operation. An adaptive stator resistance compensation scheme is applied also to eliminate the stator resistance parameter sensitivity of speed estimator. Finally, a series of simulation and experimental research are conducted and the results verify the scheme above is valid and the estimated speed tracks the actual speed well in both rated speed region and field weakening region.