Development of magnetic assist system in flywheel energy storage system for power load-leveling

This paper presents a flywheel energy storage system (FESS) for load-leveling. In order to improve the efficiency and the lifetime, a permanent magnet synchronous motor, a spherical spiral groove bearing (SSGB) and a magnetic assist system are applied to the prototype. The variable thrust by the proposed magnetic assist system is evaluated. As a result, the variation of thrust becomes 16.4%. In addition, it is observed that the loss of the SSGB relates to the precession movement of the flywheel. Besides, it is observed that the loss of the SSGB depends on the temperature of the lubricating oil.