An Improved Non-cascade Adaptive Integral Sliding Mode Control for PMSM Servo Systems

This paper addresses the problems of the non-cascade adaptive integral sliding mode control (ISMC) for permanent magnet synchronous motors (PMSMs). Firstly, by taking the external disturbances and internal parametric uncertainties into full consideration, a surface-mounted PMSM is modeled as a singularly perturbed system by singular perturbation theory. Then, the discrete-time nonlinear tracking differentiator and the disturbance observer (DO) are presented, arranging a favorable transition dynamic and estimating the lumped disturbances, respectively. As a result, a novel integral sliding mode surface function and the constructed DO-based adaptive ISMC law are subsequently designed, thus guaranteeing the reachability condition and closed-loop system stability. Furthermore, the H∞\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$H_\infty $$\end{document} control approach is employed to design the non-cascade controller gain, by solving a set of linear matrix inequalities. Finally, the advantages and effectiveness of the proposed methods are demonstrated by the comparison results.