Robust speed controller design for permanent magnet synchronous motor based on gain-scheduled control method via LMI approach

In recent years, permanent magnet synchronous motors (PMSMs) have received more attention in industries due to their higher efficiency in comparison to induction motors. Moreover, they play a g rowing ly important role in applications where variable speeds are necessary. This paper is concerned with the speed control of PMSMs, and the controller design procedure is developed in two steps. Firstly, a novel robust controller is designed via linear matrix inequalities (LMIs) approach in order to guarantee the robustness of the speed control under the load variation and uncertainty. The design of the main LMI, uncertainty, and disturbance elimination LMI involves several steps which are presented in the paper. For comparison, classic state feedback controller and proportional-integral-derivative controller with parameters optimized by genetic algorithm are implemented in different scenarios. Secondly, a gain-scheduled controller is designed and simulated. The controller design conditions are derived in terms of LMIs, which can be solved via convex optimization in MATLAB using YALMIP toolbox. It is observed that instead of using one robust controller for all operating points, several ones can be used, and by measuring the speed feedbacks, the control system opt for the appropriate controller. The suggested gain-scheduled control method via LMI approach gives excellent performance over the complete operational range, and the results validate the robustness and effectiveness of the proposed method.