A Speed-Adaptive Sliding-Mode Observer with Extended State Variable for Speed-Sensorless Induction Motor Drives

To ensure the robustness of the speed estimation, this paper proposed a speed adaptive sliding-mode observer (SMO) with extended state variable for speed-sensorless induction motor drives. The extended state variable is introduced into the SMO, providing the basis for the speed adaptive law. The design of the speed adaptive law can avoid the dependence of the speed estimation on the motor parameters, making the estimated speed insensitive to motor parameter perturbation. Meanwhile, a saturation function with boundary layer is designed instead of a switching function to attenuates the chattering in the speed estimation. Finally, the simulation results confirm the effectiveness of the proposed speed adaptive SMO.