Strucsture and Electromagnetic Characteristics of Pole-Piece Support Materials in Magnetic Gear

Studies on coaxial magnetic gears (CMGs) have been actively conducted. CMGs can replace mechanical gears because they can perform noncontact power transfer minimizing loss and damage from friction. In the design stage of a CMG, 2D electromagnetic finite element analysis (FEA), which is a highly reliable and cost-saving tool, is widely used. However, during prototyping and testing in the review phase of a project, the prototype's pull-out torque is lower than the pull-out torque predicted from 2D electromagnetic FEA, with up to a 40% difference. One explanation for this phenomenon is that the torsional stiffness of the pole-piece structure is low, causing the electrical angle to skew. There are high-frequency magnetic fluxes in the pole-piece structure in which magnetic losses are expected to be high. In many studies, non-metal pole-piece supports that can minimize this magnetic loss were used. The disagreement between analysis and experiment has been demonstrated, but no detailed examination of this effect has been conducted. In this study, metal pole-piece supports are used to remove the torsion possibility. Results from 3D-FEA and experiments are compared, and the results reveal that when torsion is accounted for, the analysis data can be reproduced the experimental data well or not. Furthermore, the magnetic loss on metal supports is analyzed in detail.