Research On H_∞ Control Of Flexible Rotor System Supported By Active Magnetic Bearings

This paper introduced H∞control theory into the flexible rotor system supported by active magnetic bearings. H∞controller was designed under considering the uncertainties of the system model and external disturbance, and the impact of H∞control on dynamic characteristics of the system was studied..Based on establishing the mathematical model of the system, the appropriate weighting functions were selected and the H∞controller was calculated by MATLAB according to the mixed-sensitivity method which considers low-frequency parameter uncertainties, high-frequency unmodeled dynamics and the interference. The equivalent stiffness and equivalent damping under H∞controller were calculated. The modal shape and unbalance response of the system based on lumped parameter method were analyzed. On the basis of theoretical analysis, the program of H∞control based on TMS320F2812DSP was built, the experiments of static suspension and high rotation speed of the system were performed to validate the influence of different control parameters on dynamic characteristics of the system.The results show that, H∞control can improve equivalent stiffness and equivalent damping of the bearings and help to reduce the vibration amplitude of the rotor when the system operates over the first and second bending critical speeds.