Model-Free Fractional-Order Sliding Mode Control of Electric Drive System Based on Nonlinear Disturbance Observer

Abstract

A model-free fractional-order sliding mode control (MFFOSMC) method based on a non-linear disturbance observer is proposed for the electric drive system in this paper. Firstly, the ultra-local model is established by using the mathematical model of electric drive system under parameter perturbation. Then, aiming at reducing the chattering of the sliding mode controller and improving the transient response, a model-free fractional-order sliding mode controller is designed based on fractional-order theory. Next, considering that the traditional sliding mode control can only suppress matched disturbance and that it is sensitive to mismatched disturbance, a non-linear disturbance observer is used to estimate disturbance, and the estimated variables are used in the design of a sliding mode surface to improve the tracking accuracy of the system. Finally, the experiment is completed on an asynchronous motor drive platform. Compared with the model-free integer-order sliding mode control (MFIOSMC), the results show that the proposed method has good dynamic response and strong robustness. Meanwhile, the proposed method reduces the dependence on mathematical models.