Abstract: A novel controllable flexible backup bearing for active magnetic bearings is presented which is constructed on the basis of the controllable radial eddy current damper, flexible support and rolling element or bushing type. The basic structure and the operating principle of the novel backup bearing are introduced. The transient responses of the rotor system dropping in the bearing are measured after the active magnetic bearing fails at different rotating speeds and rotor unbalances. The effectiveness of the novel backup bearing is analysed for improving the transient impact dynamic characteristics of the rotor dropping on the backup bearing after the active magnetic bearing failure. It is found that the novel controllable flexible backup bearing not only possesses such advantages as simple structure, no need for working fluid and easily controllable dynamic behavior, but also can significantly reduce the transient impact responses of the rotor system and the impact effect during dropping on the backup bearing after the active magnetic bearing failure. It is a useful prospective backup bearing for active magnetic bearings.

Key words: active magnetic bearing, backup bearing, eddy current damper, rotors, drop