Since few years ago, electrical energy storage had been attracted as an effective use of electricity and coping with the momentary voltage drop. Above all, the flywheel energy storages using superconductor have advantages of long life, high energy density, and high efficiency. Our experimental machine uses a superconducting magnetic bearing (SMB) together with the permanent magnet bearing (PMB) and plans to reduce the overall cost and cooling cost. The purpose in this paper is to show the improvement of PMB and the motor drive, and estimate the system at momentary voltage drop by making a discharge system.