Amplitude Reduction of a Rotor Supported by a Superconducting Magnetic Bearing Using Nonlinear Coupling Caused by Magnetic Force

In this paper, we propose a system in which a couple of movable superconducting bulks (SCs) support a rotor. Around the critical rotational speed, we investigated the whirling amplitude of the rotor in the system by theoretical, numerical, and experimental methods. From an analytical model, we derived governing equations of the system and predicted that an internal resonance between the whirling rotor and the SCs can occur by a nonlinear coupling. Numerical results indicated that the internal resonance can occur and that the resonant whirling amplitude of the rotor can be reduced in the system. Finally, we verified these results by an experimental method. The experimental results show that the whirling amplitude can be reduced when the SCs are swinging, confirming the maximum whirling amplitude reduction of the rotor utilizing internal resonance caused by the nonlinear coupling.