Robust Mixed-Sensitivity Gain-Scheduled H∞ tracking control of a nonlinear Time-Varying IPMSM via a T-S fuzzy model

This article presents a robust Mixed-Sensitivity Gain-Scheduled H_∞ controller based on the Loop-Shaping methodology for a class of MIMO uncertain nonlinear Time-Varying systems. In order to design this controller, the nonlinear parameter-dependent plant is first modeled as several linear sub systems by Takagi and Sugeno´s (T-S) fuzzy approach. Both Loop-Shaping methodology and Mixed-Sensitivity problem are then introduced to formulate frequency-domain specifications, which will be used to devise a systematic design for choosing properly the weighting matrices. Furthermore, for each linear subsystem a H_∞ controller is designed by using linear matrix inequality(LMI) approach. Such controllers are said to be scheduled by the Time-Varying parameter measurements in real time. The Parallel Distributed Compensation (PDC) is then used to design the controller for the overall system and the total linear system is also obtained by using the weighted sum of the local linear subsystems. Several results show that the proposed method can effectively meet the performance requirements like robustness, good load disturbance rejection and tracking responses, and fast transient responses for the 3-phase interior permanent magnet synchronous motor (IPMSM). Finally, the superiority of the proposed control scheme is approved in comparison with the feedback linearization controller, the H₂/H_∞ Controller and the H_∞ Mixed-Sensitivity controller methods.