A general framework for the analysis and design of tubular linear permanent magnet machines

TLDR

The paper presents a general framework for analyzing and designing tubular linear permanent magnet machines. Analytical expressions for open‑circuit and armature‑reaction fields are derived using magnetic vector potential in cylindrical coordinates and validated against finite‑element simulations. The closed‑form solutions enable accurate prediction of thrust, emf, and inductances, support machine characterization, design optimization, dynamic modeling, and have been validated for slotting and fringing effects.

Abstract

A general framework for the analysis and design of a class of tubular linear permanent magnet machines is described. The open-circuit and armature reaction magnetic field distributions are established analytically in terms of a magnetic vector potential and cylindrical coordinate formulation, and the results are validated extensively by comparison with finite element analyses. The analytical field solutions allow the prediction of the thrust force, the winding emf, and the self- and mutual-winding inductances in closed forms. These facilitate the characterization of tubular machine topologies and provide a basis for comparative studies, design optimization, and machine dynamic modeling. Some practical issues, such as the effects of slotting and fringing, have also been accounted for and validated by measurements.