Reduction of Third Harmonic by Redesign of Magnetic Circuit in a Magnetically Geared Permanent Magnet Generator

Magnetic gears with integrated permanent magnet machines have been of increasing interest over the past years, and research on several demonstrators have been presented. Demonstrators rarely perform perfectly as intended, and not much effort is put into proposing redesigns to improve the demonstrator or future iterations of it. In this paper the design of an experimentally evaluated demonstrator will briefly be presented, and afterwards a theoretical method with regards to reduction of the 3
^rd
harmonic of the electromotive force will be presented, and also how this method will affect the slip torque, iron losses, inductance and cogging torque. It is found that the 3
^rd
harmonic of the electromotive force can be reduced by more than 90% by phase shifting the high speed magnets from the machine magnets with 75
^°e
, with decrease in slip torque of 5.6 % and a decrease of 2.3 % in the 1
^{s t}
harmonic of electromotive force. Additionally, there is seen a reduction in the rotational losses in the high speed yoke of more than 70%.