MULTIOBJECTIVE OPTIMIZATION OF A FLEXIBLE ROTOR IN MAGNETIC BEARINGS WITH CRITICAL SPEEDS AND CONTROL CURRENT CONSTRAINTS

This paper presents the single objective optimization and the multi-ob jective optimization for a flexible rotor system with magnetic bearing s. The weight of rotor shaft and the transmitted forces at the magneti c bearings are minimized either individually or simultaneously under t he constraints on the critical speeds and the control currents of magn etic bearings. The design variables are the cross-sectional area of th e shaft, the bias currents of magnetic bearings, and the positions of the disk and the magnetic bearings. The dynamic characteristics are an alyzed using the generalized polynomial expansion method and the sensi tivity analysis is also studied For single objective optimization, the method of feasible directions (MFD) is applied. For multi-objective o ptimization, the weighting method (WM), the goal programming method (G PM), and the fuzzy method (FM) are employed It is found that the syste m design can be significantly affected by the choices of the bias curr ents of magnetic bearings, the position of the disk with unbalance, an d the magnetic bearings. The results also show that a better compromis ed design can always be obtained for multi-objective optimization.