New nonlinear controller for induction motor based on sliding-mode control and adaptive observer

A new nonlinear control scheme is proposed for induction motor(IM) drives.The IM model is represented in a fixed axis reference frame by using stator currents and stator fluxes as state variables;the error dynamics of torque and flux are obtained through the nonlinear analysis.An adaptive sliding-mode(SM) torque and flux controller is then designed in order to track a linear reference model,and the required reference stator voltages are deduced.Based on the model reference adaptive approach,an adaptive observer is designed for the estimation of the flux and the rotor speed.The stability analysis of the scheme is also given.This scheme has many advantages and features such as the reduced torque ripple,reduced stator flux distortion,normal operation in low speed and the robustness to parameter perturbation.Finally,simulation and experimental results verify the effectiveness and correctness of the proposed scheme.