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 is highlighted, including specific force, maximum acceleration, and cost. Not only are the advantages emphasized, 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 two-dimensional and three-dimensional finite-element analysis as needed. In addition, a comparison between predicted and measured performance on a motor prototype are reported.