Back-EMF based sliding mode observer for vector control of induction machine

In this paper a high-order sliding mode observer (SMO) for back electromotive force (EMF) in induction machine (IM) is investigated to achieve speed estimation and vector orientation. The observer is derived from the mathematical mode of IM and a non-singular terminal sliding surface is adopted. With the observed EMF used as the reference, an adaptive observer is designed and the corresponding adaption mechanism for rotor speed is figured out. Considering the phase property of the observed EMF out of the rotor flux, the orientation of vector control is obtained with the designed observer. The outstanding advantages of the strategy are consist of its good robustness to rotor resistance mismatch and inhabitation of the chattering disturbances benefiting from the non-singular terminal sliding mode design.