ANALYSIS AND CONTROL OF A FLYWHEEL ENERGY-STORAGE SYSTEM WITH A HYBRID MAGNETIC BEARING

This article presents the design, dynamic analysis, and control of a f lywheel energy storage system. At the heart of the system is a hybrid magnetic bearing. The bearing consists of ring and disk shaped permane nt magnets, and a synthetic ruby sphere on a sapphire plate. The beari ng is shown to be stable without active control. Equations of motion f or the flywheel are derived in a sensor based coordinate system. The r esulting equations are non-singular around the nominal operating condi tion and are feedback linearizable without the need for a coordinate t ransformation. A method of modeling rotor imbalance as a set of sinuso idal disturbances of magnitudes that do not depend on rotational speed is also presented To reject large external disturbances active contro l is applied to the flywheel. Two nonlinear control laws are applied a nd are shown to improve the initial condition response of the inherent ly stable system.