A design approach to reduce the end effect in linear tubular PM machines

The paper is aimed at a design approach dedicated to the reduction of the longitudinal end effect in a linear tubular permanent magnet machine. The proposed approach consists in a two-step procedure, such that: (i) achieving a 2π/3-shift between the armature winding flux linkages by arranging the ratio of the stator pole pitch to the mover one, and (ii) balancing the amplitudes of these flux linkages by extending the stator magnetic circuit with teeth of appropriate dimensions. A magnetic equivalent circuit (MEC) of the linear PM machine is established taking into account the proposed approach. A FEA-based investigation of the flux linkage validates the MEC results.