A flywheel energy storage system (FESS) using a high-temperature superconducting magnetic bearing (SMB) with an electric power of 330 kW and a storage capacity of 10 kWh has been demonstrated at the Komekurayama photovoltaic power plant located in Yamanashi Prefecture. The storage capacity must be increased further before the FESS can be applied to railways as a system for preventing the cancellation of regenerative braking. In order to confirm the design validity of superconducting magnetic bearings, levitation tests up to 158 kN were conducted. In addition, a superconducting bulk flux creep test was performed for more than 200 hr, and it was estimated that the decrease in levitation force was slight, even after long-term operation. From these results, it was found that the current SMB design can be applied to FESS SMBs for railway applications.
