A modified sliding observer for robust estimation of rotor magnetizing current of AC IM drive

A modified sliding observer for robust estimation of rotor magnetizing current of a VSS controlled AC induction motor (IM) drive for an industrial robot is proposed. The switching control laws in the sliding observer are replaced by their continuous approximations. A quantitative analysis for evaluating the estimation error is described and guidelines on pole assignment for the observer with robustness against rotor time constant perturbation is given. The effectiveness of the proposed control scheme with this observer is confirmed by simulation results.<>