Vibration and control of a flexible rotor in magnetic bearings using hybrid method and H^∞ control theory

The vibration and active control of a flexible rotor system with magnetic bearings are investigated using Hybrid Method (HM) and Hm control theory with consideration of gyroscopic effect. The hybrid method, which combines the merits of the finite element method (FEM) and generalized polynomial expansion method (GPEM) is employed to model the flexible rotor system with small order of plant. The mixed sensitivity problem of H^∞ control theory is applied to design the control of system vibration with spillover phenomena for the reduced order plant. The H² control design is also employed for comparison with the H^∞ design. The experimental simulation is used to illustrate the effects of control design. It is shown that the H^∞ controller design can be very effective to suppress spillover phenomena. In addition, the H^∞ control design has robustness to the variation of the model parameters. The application of the hybrid method (HM) together with H^∞ control design is highly recommended for vibration control of flexible rotor systems with magnetic bearings.