Tubular linear permanent magnet motors: an overall comparison

This paper deals with tubular linear permanent magnet (TL-PM) motors, including different topologies, i.e. interior and surface-mounted PMs, slotted and slotless motors. After some preliminary analytical considerations, the performance of the TL-PM motor are highlighted, including specific force, maximum acceleration and cost. Not only the advantages are emphasised, but also the drawbacks such as detent forces and attractive radial forces due to eccentricity. Different models have been adopted in the various analyses, including 2D and 3D finite element analysis as necessary. In addition, a comparison between predicted and measured performance on a motor prototype are reported.