Delevitation modelling of an active magnetic bearing supported rotor

Abstract

For active magnetic bearings (AMBs) to be used with confidence in industrial applications, the safe failure of the AMB system should be guaranteed. The exact behaviour of the rotor on the backup bearings (BBs) is relatively uncertain [1,2,3]. Uncertainty in a failure situation means that the safe failure of the AMB system cannot be guaranteed. The purpose of the presented rotor delevitation simulation model (RDSim model) is to eliminate some of the uncertainties associated with a rotor delevitation event. The simulation model includes a flexible rotor model [4], a non-linear AMB model [5], a non-linear BB model, stator effects, active rotor braking, rotor free running, inner race speed up, AMB/BB load sharing and sudden unbalance (blade-loss simulation). The RDSim model can be used to simulate any AMB failure on one or more locations. The failure modes include power amplifier (PA) malfunction, AMB coil short-circuit, total power failure and controller failure. This paper will discuss the BBSim model; a brief explanation of each of the sub-models of the BBSim model is also given.