A Combination 5-DOF Active Magnetic Bearing for Energy Storage Flywheels

Conventional active magnetic bearing (AMB) systems use several separate radial and thrust bearings to provide a five-degree of freedom (DOF) levitation control. This article presents novel combination 5-DOF AMB (C5AMB) designed for shaft-less, hub-less, high-strength steel energy storage flywheel (SHFES), which achieves doubled density compared prior technologies. As single device, the C5AMB provides radial, axial, tilting levitations simultaneously. In addition, it utilizes low-cost more available materials replace silicon steels laminations, results in reduced costs convenient assemblies. Apart from unique structure low grade material, other design challenges include shared flux paths, large dimensions, relatively small air gaps. The finite-element method (FEM) is too computationally intensive early-stage analysis. An equivalent circuit (EMCM) developed modeling Nonlinear FEM then used detailed simulations. Both permanent magnets (PMs) electromagnetic control currents weight-balancing lifting force. During full-scale prototype testing, successfully levitates 5440-kg 2-m-diameter at an gap 1.14 mm. Its current position stiffnesses are verified experimentally.