Vibration reduction of rotor supported by superconducting magnetic bearing utilizing electromagnetic shunt damp

A superconducting magnetic bearing can levitate a rotor without control and is expected to be applied to flywheel energy storage systems. However, because the levitation force has nonlinearity, the rotor can show nonlinear vibrations such as subharmonic resonance and superharmonic resonance. Therefore, it is necessary to suppress the amplitude of nonlinear vibration of the rotor. Recently, an 'electromagnetic shunt damper,' which can replace a dynamic vibration absorber, has been researched. The purpose of this study is to investigate whether an electromagnetic shunt damper can suppress the nonlinear vibration of a rotor supported by a superconducting magnetic bearing. We obtained the system's governing equations via an analytical model and nondimensionalized the equations. Linear analysis was performed, and we confirmed that an electromagnetic shunt damper is effective against linear systems. Furthermore, numerical calculations via the Rung-Kutta method were carried out. The obtained results show that an electromagnetic shunt damper can suppress the vibration amplitude of primary resonance and subharmonic resonance of order 1/2.