OSCILLATION AMPLITUDE REDUCTION OF A HIGH-TC SUPERCONDUCTING LEVITATION SYSTEM BY AN ELECTROMAGNETIC SHUNT DAMPER COUPLED NONLINEARLY

Abstract

An electromagnetic shunt damper, consisting of an electric circuit, can work as a kind of dynamic vibration absorber for a mechanical system. It can convert a portion of mechanical vibration energy into electricity, and the vibration amplitude of the main system can be reduced as a result. This energy conversion can be achieved by electromagnetic coupling and no mechanical contact is required. Thus, this damper is convenient for a superconducting levitation system where a magnet, the target of damping, levitates with no contact support. However, since the natural frequency of such a levitation system is commonly much lower than that of an electric circuit, it is difficult to tune the parameter values of both systems. In this research, we introduced a different type of electromagnetic shunt damper, which is nonlinearly coupled with a high-Tc superconducting levitation system. Our experimental results, showing successful suppression of vibration, verified the effectiveness of this type for reducing the required value of the circuit to one fourth of the conventional one through internal resonance.