Optimurn Design of Flexible Rotor Shaft Configuration using Closed Loop System Redesign.

Abstract

A new optimum design method of flexible rotor shaft configuration using closed loop system redesign is proposed. The rotor system is supported by active magnetic bearings(AMB). The proposed method is constructed from two steps. First, unbalance resonance vibration control loop of AMB is designed for a rotor, that has intial configration, to realize the specified closed loop pole assignment. The pole assignment is specified by the user in advance. And then, the rotor shaft configuration is iteratively modified to minimize the objective function under the closed loop pole assignment constraint. Objective function is defined as a linear conbination of the measures of optimality of the control system design such as the control energy consumption of unbalance resonance vibration control, the magnitude of critical resonant of the rotor system. A ccording to the redesign method, closed loop pole assignment is not changed in each iteration of optimization process. It means that the critical speeds of the rotor system and the corresponding Q-factor of each critical speed before and after optimization remain unchanged. The effect of the proposed method will be shown by the numerical simulation results of the flexible rotor design example. Not only the rotor shaft configuration but also the control gains of AMB are successfully optimized by using the proposed method.