Transient Simulation of AMB Supported Electric Motor during Rotor Drop on Retainer Bearings

Active magnetic bearings present a new technology which has many advantages compared to traditional bearing designs. Active magnetic bearings, however, require retainer bearings in order to prevent damages in the event of a component, power or control loop failure. In the drop-down situation the design parameters of the retainer bearings have a significant influence on the behavior of the rotor. In this study, the dynamics of an active magnetic bearings supported electric motor when the rotor is dropped on retainer bearings is studied using a multibody simulation model. The retainer bearings are modeled using a detailed ball bearing model, which accounts damping and stiffness properties, oil film and friction between races and rolling elements. The model of the magnetic bearing system contains unbalances of the rotor and stiffness and damping properties of support. In this study, a computationally efficient contact model between the rotor and the retainer bearings is proposed.