Robust and Stable Speed Control Design Using the Variable Gains Backstepping Technique for High-Efficiency Three-Phase Induction Motor Drives

For high-performance industrial applications based on AC electrical machines, it is necessary to develop a robust variable speed drive capable of ensuring the required control quality. The main disadvantage of the conventional version of integral Backstepping is the possibility of causing a bad behavior in the transient regimes, which is presented by an overcurrent and strong vibrations before the final stabilization of the system. In this paper, an optimized approach of Backstepping is applied to the speed control of an induction motor. The proposed solution for improving stability and efficiency is to introduce the variable gains property in the main speed regulator. Two different partial commands will perform the global control. The first one ensures the optimal convergence of the system in transient regimes without causing overshoot. The second command is intended for permanent regimes, where it can amplify the coefficients of the gains in order to reinforce the control robustness against applied loads. All control signals used in the algorithm are generated according to the Backstepping principle and the overall stability of the system is verified by Lyapunov's theorem. This technique was validated experimentally using a dSPACE-RTI-1104 card and empirical results showed remarkable real-time control in terms of stability, speed and robustness against external disturbances.