Fuzzy variable gain robust control of active magnetic bearings rigid rotor system

A high speed rigid rotor system supported by active magnetic bearings (AMBs) puts forward higher requirements on the performance of controllers. The fuzzy variable gain H-infinity robust control (FVGRC) method is proposed to simplify controller design while suppressing system uncertainty. First, the T-S fuzzy model of four-degree-of-freedom (4-DOF) AMBs was established based on the 4-DOF AMBs rigid rotor equivalent coupling model optimised by the μ-gap metric. Then, based on the fuzzy models of AMBs systems under different operating conditions, the relative optimal weight function value of H-infinity robust controller was calculated when AMBs system was at value of the speed endpoint, and the fuzzy variable gain H-infinity robust (FVGR) controller was designed on this basis. Finally, the simulation and experimental results showed that the FVGRC can simplify the model of controller and ensure the stable operation of AMBs rigid rotor system in the full speed range under high-speed conditions.