高温超電導浮上回転軸の無制御安定化浮上と回転磁気ダンパによる危険速度の乗越し法

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This article presents a new levitation technique, which uses a small superconductor and a set of permanent magnets. In the system, a small superconductor is connected to the bottom of the vertical shaft. The gravity force and axial vibration force are supported by the superconductor. A circular permanent magnet is attched to the top of the shaft, and the other circular permanent magnet lies at the frame. The N-pole of one of the magnets faces to the S-pole of the other magnet, so a drag force acts between the magnets. The drag force is unstable in the axial direction, but the pinning force in the axial direction of the superconductor makes it stable. There is a restoring force in the horizontal direction between two permanent magnets, and in addition, there is a pinning force of the superconductor, so that both ends of the shaft are stable in the horizontal direction. This implies that the levitated shaft is stable without control. In general, controls have to be made in either axial or horizontal direction when the ordinary magnets are used. The levitation technique presented in this paper has advantages, Because, in order to have stable levitation, only one small superconductor is required, and a cooling system is simple. A method for passing through the critical speeds is also presented. In the method, rotating conductor disc is used to have the electromagnetic damping. Both the analysis and experiment are presented.
2000-04-25