A comparative study of sliding mode and Model Reference Adaptive Speed observers for induction motor drives

The paper presents a comparative study of two different speed observer techniques for a sensorless induction motor drive. Both Model Reference Adaptive System (MRAS) and sliding mode control theories are considered. The speed estimation algorithms based on both techniques are derived and implemented in a simulation program. The robustness of both speed estimation algorithms against load torque changes and motor parameters variations is investigated. The problems of PI controller associated with MRAS speed observer under these conditions are also investigated. The convergence of sliding mode speed observer is examined using Lyapunov theory. Simulation results are presented and discussed.