CONCEPTUAL DESIGN OF A HOOP ENERGY-STORAGE SYSTEM

The hoop energy storage system (HESS) was conceptually designed for th e diurnal load leveling of an electric power supply. It consists of an approximately 6 m diam carbon fiber composite hoop with permanent mag netic bearings and a linear motor/generator system with solid-state cy cloconverter circuits for the energy conversion between kinetic energy and electric energy. With a vacuum chamber and strong tensile strengt h structure for nonresistive high-speed rotation, the HESS is expected to have a large capacity of energy storage. The optimization of magne t arrangement through the analysis of the magnet's characteristics was suggested to reduce the power loss and instability. By the measuremen t of magnetic-field configuration and numerical calculations with a th ree-dimensional code (TOSCA), it is proved that NdFeB magnets have suf ficient magnetic-field strength to support the levitation of the hoop. This analysis also led to minimum drag force and eddy-current loss to make use of the uniform field. As a result of analysis, construction of the HESS has begun in our laboratory and the fabrication procedure will be reported. (C) 1997 American Institute of Physics.