Test Results of a Compact Superconducting Flywheel Energy Storage With Disk-Type, Permanent Magnet Motor/Generator Unit

A compact flywheel with superconducting bearings was developed and manufactured at our department, which integrates driving magnets (PM part of the motor generator (M/G) unit) and a bearing magnet (PM part of the SC bearing). Main goal of this development was to verify achievable losses with the proposed permanent magnets disc-type M/G unit. An early stage approach for specific no-load eddy current loss calculation is introduced, and by the application of the formulae I theoretically proved that it is possible to build industrial size double-rotor disc-type permanent magnet machines with no-load losses at the same order with the SC bearing losses. Practical verification of the method is also shown, and though according to the measurement results the existing stators do not show the expected low losses, the contradictions are discussed.