Dynamic Bifurcations of the Active Magnetic Bearing-Rotor System

The Influence of nonlinear factors on the active magnetic bearing-rotor system (AMBRS) with closed loop controller can't be derived from the classical linear control theories. It was analysed for ther first time by the modern analylical methods used in nonlinear vibration. The Hopf bifureations of AMBRS at autonomous and no nautonomous cases were researched by the Normal Form theorem and the improved averaging method respectively. Results show that the non linear factor of magnetism is one of the important factors cauaing the self-excited vibration of AMBRS.