A magnetic-circuit model for optimizing magnet-iron magnetic modulated ring of HIA used for flywheel energy storage system

Purpose This paper aims to deal with the issue of how to rapidly calculate the optimal diameter and length of the magnet-iron magnetic modulated ring (MMR) of homopolar inductor alternator (HIA) used for flywheel energy storage system. Design/methodology/approach In this paper, the authors propose a magnetic-circuit model for calculating the optimal diameter and length of the magnet-iron MMR. The accuracy of the magnetic-circuit model is verified through FEM simulations. Findings The research results show that the proposed magnetic-circuit model is highly accurate in calculating the optimal diameter and length of the magnet-iron MMR when the MMR iron is not saturated. The optimization of the mass of the magnet-iron MMR using the magnetic-circuit model and FEM is also studied. The research results indicate that the optimal length of the magnet-iron MMR should be as small as possible, provided that the MMR iron is not oversaturated. Originality/value The optimization results based on the magnetic-circuit model exhibit very small errors, and the model offers significant advantages over FEM in terms of computational costs.