A study on the relaxation of levitation property in an HTSC magnetic bearing

For realization of the flywheel system using high Tc superconductors (HTSCs), AC loss is one of the serious problems to be solved. An un-uniformity of magnetization of permanent magnets rotating at high speed generates AC field around HTSC. This causes AC losses. In this study we assumed that AC field generated by a rotating permanent magnet is equivalent to AC field generated by coil current. Based on this model the experiments were done. These results were compared with those of numerical simulation. Furthermore, to suppress AC loss, a pre-loading method was suggested.