Abstract: A new type catcher bearing with an elastic ring is proposed to enhance its working performance in active magnetic bearing (AMB) system. In order to improve the simulation model of rotor drop and obtain the accurate rotor vibration characteristics before AMB failure, the dynamic support stiffness of AMB is derived. The rotor model is obtained using the dynamic stiffness based on Finite element analysis. Model experiments are also carried out to verify the correctness of the stiffness curve. The rigid rotor dynamic model in AMB system is established to analyze the dynamic responses. Based on the Hertz contact theory, the collision model between rotor and catcher bearing inner race and the real-time dynamic stiffness of the bearing after AMB failure are respectively established. Utilizing those established models, rotor drop simulations for various elastic ring support stiffness and damping range are carried out. Moreover, the simulation results with and without elastic ring are compared. The results show that appropriate elastic ring helps to reduce vibration amplitude and collision force after rotor drop. And the experimental results for various initial states are consistent with the theoretical analysis results.

Key words: Active magnetic bearing, Elastic ring, Hertz contact theory, Real-time dynamic stiffness, Rotor drop, Stiffness curve