Reduction of Interference and Realization of Contactless Levitation in Multiple-Degree-of-Freedom AC Magnetic Suspension System

Abstract

　An AC magnetic suspension system with an LC circuit consisting of an electromagnet and a capacitor has self-stabilization property. Such property is achieved by setting the frequency of the applied voltage to be higher than the resonant frequency of the LC circuit. The AC magnetic suspension system with indirect damping can achieve stable suspension without active control. The previous study indicated that self-stabilization failed due to interferences among the electromagnets in a multiple-degree-of-freedom AC magnetic suspension system. In this paper, the influences of interferences among the electromagnets on floating characteristics are studied experimentally. It is found that the resonant frequencies of LC circuits vary according to the interferences among the electromagnets. It explains why stable suspension could not be achieved. A new apparatus with a larger size and a different structure for reducing the interferences are developed. Stable noncontact suspension is achieved in the apparatus. In addition, the interferences are further reduced by making the resonant frequency of each LC circuits different. It leads to the improvement of floating characteristics.