High Tc Superconducting Levitation Pulse Motor without Contact

A simple but stable non-contact high Tc superconducting levitation system with a vertical shaft has been presented. The system consists of a superconductor and permanent magnets. In the system, only a lower end of the shaft is supported by a high Tc superconductor, and the other end is supported by two ordinary permanent magnets. Since the restoring force is small with respect to the radial direction the system becomes unstable when the force act in the radial direction, so it is difficult to drive the shaft by electromagnetic forces in using such as motors. Then, a driving system using electromagnets has been presented, in which the balanced forces act on two opposite sides of the disc type rotor in the axial direction. Since the system has no unbalance force from an analytical point of view, the rotor will be able to rotate without control. In the system, however, since there is the eccentricity between the center of rotation and magnetic center, so vibrations are generated. This study also presents an optimal control method of the vibrations. To validates the proposed system, and the control method, experimental tests have been carried out.