Manufacturing and Testing of a Magnetically Suspended Composite Flywheel Energy Storage System

This paper presents the work performed to develop a multiring composite material flywheel and improvements of a magnetically suspended energy storage system. The flywheel is constructed of filament wound graphite/epoxy, and is interference assembled for better stress distribution to obtain higher speeds. The stationary stack in the center of the disk supports the flywheel with two magnetic bearings and provides power transfer to the flywheel with a motor/generator. The system operates under a 10-4 torr environment and has been demonstrated to 20,000 rpm with a total stored energy of 15.9 Wh. When this flywheel cycles between its design speeds (45,000 to 90,000 rpm), it will deliver 242 Wh and have a usable specific energy density of 42.6 Wh/kg.