Binary observer for speed sensorless vector control of induction motors

Field oriented control methods have been used for design techniques in variable speed induction motor drives. This paper describes a binary observer which includes the rotor flux and speed estimations for induction motor drives. Sliding observers, based on the variable structure control theory, have been known to be applied for optimal pole assignment to maintain insensitivity to parameter variations and ensure the stability of the identifier. Sliding observers, however, possess high frequency chattering which deteriorates the state estimation performance. To reduce the chattering on the sliding surface in an adaptive sliding observer and improve the estimation performance, a binary control scheme which has main advantages of the absence of high-frequency chattering and finite gains is applied in this paper. Experimental results show the effectiveness of the proposed binary observer for the sensorless speed control of induction motor drives