A performance analysis model with thermodynamic and superficial effects of the auxiliary bearings in AMB systems

The touchdown bearing is one of the essential parts of AMB. When the magnetic bearing fails, touchdown events will occur and the rub-impact between the rotor and the touchdown bearings will happen. In practice, the analysis of the process is complex as it is coupled with dynamics, superficial and thermal effects. A simulation model in which the kinetic equations of the rotor and the bearing are derived from Lagrange’s equations and the drag torque of the ball bearings is calculated by Palmgren’s empirical formula has been established. The simulation results show that the orbit response of the pendulum vibration appears when the rotating speeds and the friction coefficients are low, while the orbit response of the backward whirl appears when the rotating speeds and the friction coefficients are high. The critical whirl speed has been illustrated for the guidance of the safe landing of the rotor. The maximum contact forces and heat peak power have also been calculated. The maximum contact forces keep almost constant when both the rotating speeds and the friction coefficients are low. It increases with the growth of the rotating speed and the friction coefficient with high rotating speeds, high friction coefficients or both. The peak thermal power increases with the incline of the rotating speeds and friction coefficients.