A flywheel system incorporates a variable speed synchronous reluctance motor-generator and a variable speed permanent magnet generator for providing backup power. Rotating elements are supported by electromagnetic bearings and electric power provided by the backup generator maintains electromagnetic bearing operation during that portion of a coast down period when shaft speed falls below the minimum speed required for operation of the synchronous reluctance motor-generator.
This application is a divisional of U.S. application Ser. No. 10/863,868 filed Jun. 7, 2004, which claims priority from Provisional Application 60/476,226 filed Jun. 6, 2003.
