Multi-Objective Optimization for a Dual-Flux-Modulator Coaxial Magnetic Gear With Double-Layer Permanent Magnet Inner Rotor

To improve the torque capability and permanent magnets (PMs) utilization efficiency of the dual-flux-modulator coaxial magnetic gear (DFM-CMG), a double-layer PMs (DLPM) layout on the inner rotor (IR) is proposed. In this article, the torque performance of the DFM-CMG is investigated by 3-D finite element analysis and validated by the corresponding experiment. According to the parametric analysis results, it is found that 6-D design parameters can significantly affect the stall torque (ST) and ST per PM volume (STPPV) of the DFM-CMG. To achieve multi-objective optimization (MOO) of the DFM-CMG given that the ST and STPPV normally conflict with each other, a metamodel-based MOO method is used under the premise of the constant active region volume. The optimized DFM-CMG with DLPM IR shows a 19.7% and 2.2% growth in the STPPV than the initial design and the optimized counterpart with single-layer PMs (SLPMs) IR under the same constraint of the ST. Furthermore, the optimized DFM-CMG with DLPM IR possesses excellent PMs utilization efficiency compared with other typical CMGs.