A speed sensorless induction motor (IM) drive with a sliding mode model-following speed controller is introduced. First, the speed estimation algorithm, based on the minmax control theory, and its stability analysis are described. An integral-proportional (IP) speed controller using the estimated speed signal is designed to obtain the desired control performance of command tracking. Moreover, to increase the robustness of the IM drive, a sliding mode model-following controller is added, where the state-space equation of the nominal designed IP speed control loop is selected as the reference model. To increase the accuracy of the estimator, the speed estimation algorithm is implemented using a digital signal processor.
