Comparison of coaxial magnetic gears with parallel and series magnetic circuits

This paper quantitatively compares two coaxial magnetic gears (CMGs) with parallel magnetic circuit and series magnetic circuit, which are artfully integrated into a permanent magnet (PM) brushless DC motor. By using the finite-element method, the performances of both CMGs are compared and evaluated. Analysis results show that the CMG series magnetic circuit can offer higher pull-out torque and back-EMF than the CMG parallel magnetic circuit, while the CMG parallel magnetic circuit has lower PM eddy current loss, iron losses and lower distortion of back-EMF.