Magnetic Relevitation of Flywheel Rotor With High Speed Backward Whirl

In this paper, the magnetic relevitation is conducted for a flywheel rotor rotating at 40,000 rpm in contacts with auxiliary bearings through numerical simulations. The high-speed flywheel rotor loses the magnetic suspensions and touches down onto the auxiliary bearings. Then, active magnetic bearings (AMB) relevitate the flywheel rotor in whirling and bouncing motion when the magnetic power is restored. To achieve this rotor dynamics control in challenge, three control algorithms are utilized and their performances are compared based on the steady-state response with respect to a bearing reference center and the power loss of AMBs required for the relevitation as the friction coefficient on rotor/auxiliary bearing contacts. The simulation results show that the sliding mode control (SMC), which is robust to dynamic uncertainty and nonlinear dynamics, is superior to the conventional linear controllers such as the PD and the LQR in the control performance and efficiency. Furthermore, the SMC successfully relevitates the flywheel rotor with a high-speed backward whirl, while the linear controllers fail to do.