( Synthesis of Flexible Rotor Magnetic Bearing Systems

This paper is described about the research work with simulations and experiments concerned with µ synthesis for flexible rotor magnetic bearing system with five-axis control system of actual test rig. After modelling with the full order system for the flexible rotor system using finite element method, we obtained the reduced order model in modal domain. In this case, every flexible mode in high frequencies was truncated. And we tried to design µ synthesis for the reduced order model like rigid rotor. After choosing the appropriate weighting functions depending on frequency, we designed the µ control system using µ -toolbox in MATLAB. We tried the simulations of control system for the flexible rotor magnetic bearing system with five-axis-control system and obtained good performances on simulations. Next, we carried out experiments to verify the robustness based on robust control theory for the actual test rig in cases of levitations and rotations. Comparing the control system obtained by the second D-K iteration with the control system before D-K iteration like benchmark test on same conditions, we confirmed that the µ control system has excellent performances for robust pnformances with drastical parameter variations in this test rig.