Second Order Sliding Mode Speed Observer for Field-Oriented Control of Induction Motor

In the following paper, we present a second-order sliding mode speed observer of induction motor using super twisting algorithm, whose purpose is to show the validity of the observer at very low speed. A speed observation system, which comprises two sliding mode stator current observers and rotor flux observer, are used in the proposed method. The effects of parameter deviations on the rotor flux observer can be alleviated by the interaction of these two current sliding mode observers. The adaptive speed observer is derived from a Lyapunov function, which guarantees the system convergence and stability. The speed sliding mode observer is implemented on the field-oriented control of induction motor drive (FOC). Experimental results of the speed sensorless control of field-oriented induction motor verifies the validity of the proposed sliding mode algorithm at very low speed and show the robustness and performance of the proposed adaptive observer structure.