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Design of a High-Speed Homopolar Inductor Machine for Flywheel Energy Storage System

The armature winding and the field winding of the homopolar inductor machine (HIM) are fixed on the stator, and the rotor is composed of a solid salient core. Therefore, HIM can realize brushless excitation and has high mechanical strength, which is especially suitable for flywheel energy storage system. In addition, HIM has a typical three-dimensional magnetic circuit structure, and its air-gap flux density distribution is different from that of the general machine, resulting in differences in the design with the general machine. In this paper, based on a 400kW homopolar inductor machine/generator for flywheel energy storage system, the design method is proposed, and the no-load back electromotive force is calculated by magnetic circuit method according to its design parameters. Finally, the experiments of the prototype are carried out, and the results calculated by magnetic circuit method are compared with the finite element calculation results and experimental results to verify the correctness of the theoretical analysis.