Abstract
When the electric power of an active magnetic bearing (AMB) is shut down during a rotor system rotates in a high speed, the backup bearing is important to support and stop a system in safely. In this paper, we study the effect of the backup bearing on the dynamical characteristics of the rotor system during deceleration through the critical speed. We clarify that there are three kinds of whirling motions when the rotor passes the critical speed, and the determination of the motion which actually occuars depends on the parameters of the backup bearing .
