Causes and effects of Geometric Deviation in Magnetic Gears

This paper presents a study of geometric deviations in a Coaxial Magnetic Gear. Large discrepancies between Finite Element Analysis and experimental performance are often reported. These are, in some part, often attributed to manufacturing error. Manufacturing error causes the physical geometry of a gear to differ from its modelled design which will clearly affect its performance. However, geometric deviations can also be caused by defection of the gears structure under the large cyclic electromagnetic loads exerted on the active components. A comprehensive overview of the causes of geometric deviation in the PM rotors and the modulation ring is provided, along with their potential manufacturing processes and expected tolerances. The effect of these deviations is assessed and the importance of proper treatment of such geometric subtleties is outlined.