Load test of Superconducting Magnetic Bearing for MW-class Flywheel Energy Storage System

Abstract

A flywheel energy storage system (FESS) stores electrical power as kinetic energy of a rotating flywheel rotor. Since the storage energy of the FESS is proportional to the weight of the rotor and the square of the rotating speed, the heavy weight and high speed rotor leads a FESS to a high power and a high capacity. However a conventional FESS limits in both the rotor weight and the rotating speed because of using mechanical bearings. A superconducting FESS (SFESS) utilizes a superconducting magnetic bearing (SMB) to levitate and rotate the flywheel rotor that has ton class weight and high speed rotation without mechanical contact. As the SFESS with 300 kW demonstrated at Mt. Komekura in Yamanashi prefecture, the SMB in the SFESS levitated the 4-ton rotor. The SMB consisted of a high temperature superconducting magnet (HTS magnet) and a HTS bulk, and utilized a repulsive force between the HTS magnet and the HTS bulk. The demonstration of the SFESS has been carried out successfully at Mt. Komekura. Now the next step development was started to aim a MW-class SFESS. The MW-class SFESS needs the SMB levitated and withstood a 10 ton-class load. This paper describes a design of the 10 ton-class SMB and the result of the load test of the developed SMB.