Comparison of Coaxial Magnetic Gears With and Without Magnetic Conducting Ring

This paper quantitatively compares four coaxial magnetic gears (CMGs) with and without magnetic conducting ring (MCR), which are artfully integrated into a permanent-magnet (PM) machine. In addition, different gear ratios are investigated for both topologies. By using the finite-element method, their torque and loss performances are compared and evaluated. Analysis results show that the CMGs without MCR and low gear ratio can offer higher pull-out torque and lower torque ripple, whereas the CMGs with MCR and low gear ratio have lower PM eddy current and iron loss. Finally, a 9/6 slot–pole CMG machine without MCR is prototyped for verification.