Vibration Modal Analysis of Superconducting Levitation With LCR Shunt Damper

This study deals with the vibration suppression effect of an LCR parallel electromagnetic shunt damper on a superconducting magnetic levitation system. Superconducting magnetic levitation systems have the advantages of low energy loss due to friction because of the non-contact nature of the system and, furthermore, stable levitation without control. Therefore, it is expected to be applied to magnetically levitated trains and magnetic formation flights. On the other hand, the occurrence of resonance with large amplitude due to low attenuation can be a problem, so suppression of the amplitude is an important issue. We focused on the LCR electromagnetic shunt damper, which has the advantage of being non-contact, as a method of suppressing vibration. However, the coupling of the mechanical and electrical systems via a velocity term is essential for the parallel type, making conventional modal analysis inapplicable. Therefore, we used the impedance expression for the circuit equation of the subsystem. As a result, the velocity term coupling was eliminated, thereby allowing the application of conventional modal analysis. The analysis showed that the two natural frequencies depend on the excitation frequency, and based on this fact, the dependence of the frequency response of the system on the capacitance and the resistance was able to be determined by numerical analysis. Furthermore, the amplitude reduction effect predicted by this numerical analysis was confirmed experimentally. In summary, in this study, the vibration suppression of the superconducting magnetic levitation system by the LCR electromagnetic shunt damper was analyzed using vibration modal analysis and verified experimentally.