Synchronous reluctance motor/alternator for flywheel energy storage systems

This paper presents a synchronous reluctance machine design for high-speed high-power applications, such as the motor/alternator for a flywheel energy storage system. The rotor consists of alternating layers of ferromagnetic and nonmagnetic steel that are joined together by a process known as explosion bonding. Analytical expressions for the direct and quadrature inductances of the machine are presented, and are then used to optimize machine design. These expressions compare well with results obtained from finite element analysis. Structural and electrical analyses of a 60 kW, 48000 r.p.m. machine indicate that the design will be appropriate for flywheel systems. Current work involves construction and testing of the above design.