Topology Optimization of the Reluctance Coaxial Magnetic Gear

The reluctance coaxial magnetic gear (RMG) has been recently considered for high-speed applications. Here, topology optimization (TO) is applied to the variable reluctance component of the RMG, with the objective of maximizing the RMG’s volumetric torque density (VTD) and gravimetric torque density (GTD). The optimization algorithm achieves a novel RMG topology with non-ferromagnetic material for the variable reluctance rotor core, outperforming the conventional topology. The novel RMG topology is optimized using parametric 2-D and 3-D finite-element analysis (FEA). The results reveal that VTD, GTD, and permanent magnet (PM)-GTD of the novel RMG are, respectively, ~5%, ~40%, and ~5% higher than those of the conventional RMG. Moreover, the novel topology exhibits ~20% less iron and PM losses. In addition, compared to the conventional RMG, the torque ripples of the high- and low-speed rotors of the novel topology, respectively, decrease from 10.3% to 7.6% and increase from 3.5% to 6.3%.