In this work, a hybrid control strategy derived from the control literature for induction machines is proposed, where a sliding-mode controller paired with an estimator from the same function is incorporated to provide fast, robust speed regulation while minimizing chattering. The controller operates using a fast integral terminal sliding surface that accelerates the convergence rate of tracking error after entering the sliding surface. A new super-twisting reaching law is provided which incorporates an integral term designed to suppress highfrequency switching actions associated with chattering. The estimator that accompanies the controller also implements the same sliding surface coupled with the reaching law to estimate load torque and send the estimate to the controller to improve performance during sudden changes in load or when models are uncertain. Experimental results demonstrate the proposed method successfully (i) reduced convergence time (ii) reduced quaternion-like oscillations (chattering) (iii) improved performance robustness to time-varying load time, and where models were uncertain. From the results, it can be seen that the proposed approach improves chattering substantially (around 7% lower chattering), and convergence times are reduced to approximately 0.15 - 0.25 sec, as opposed to the 0.8 - 0.9 sec convergence times found with the reference. Speed tracking is better, on average, by around 9%, and transient torque errors went down to about 1 - 2 rpm. Overall, it can be said that performance is better when compared to the reference.
Donghai Liu (Mon,) studied this question.