Present status of R&D on superconducting magnetic bearing technologies for flywheel energy storage system

Abstract We report on the NEDO project of superconducting magnetic bearing (SMB) technologies for flywheel energy storage system. We fabricated SMB modules which consist of a stator of roof-tile shape YBaCuO bulks and a NdFeB permanent magnet circuit. The levitation force density of the bearings was 9 N/cm 2 . It was confirmed that pre-loading and excess cooling methods are both effective for suppressing the gradual fall of rotor due to flux creep. We designed a basic concept of 10 kW h class flywheel energy storage system and investigated the feasibility of active magnetic bearings for the 10 kW h system. We also examined the fabrication condition of CFRP flywheels for the system.