New Concept for Flywheel Energy Storage System Using SMB and PMB

Since a few years ago, electrical energy storage has been attractive as an effective use of electricity and coping with the momentary voltage drop. Above all, flywheel energy storage systems using superconductor have advantages of long life, high energy density, and high efficiency. Our experimental machine uses a superconducting magnetic bearing (SMB) together with a permanent magnet bearing (PMB) and plans to reduce the overall cost and cooling cost. Flywheel energy storage systems operate by storing energy mechanically in a rotating flywheel. The generating motor is used to rotate the flywheel and to generate electricity from flywheel rotation. The generating motor consists of a 2-phase 4-pole brushless DC motor and a Hall sensor. A purpose of this study is the development of a compact flywheel energy storage system using SMB and PMB with new concept. This paper shows the new model of flywheel by using the concept of yajirobei (balancing toy) that the center of gravity of mass is lower than supporting point. By using this concept, the flywheel has higher storage energy compared with conventional ones. Furthermore, we also purpose to improve and evaluate motor drive (DC motor) to increase the rotational speed, and estimate the system at momentary voltage drop.