Quantitative Comparison of Modular Linear Permanent Magnet Vernier Machines with and Without Partitioned Primary

A comparison of two modular linear permanent-magnet vernier (LPMV) machines is presented. A modular LPMV machine with a partitioned primary, which can significantly improve the modulation effect, is proposed. Benefitting from the partition design, the space conflict between the permanent magnet (PM) and the armature magnetic field is relieved. First, the topologies of modular LPMV machines with and without a partitioned primary are presented. Then, the effect of the partitioned primary on the modular LPMV machine is analyzed using flux modulation theory. Moreover, analytical expressions for the trapezoidal permeance are derived. In addition, the harmonic components, back electromotive forces, and thrust forces of the machines with and without the partitioned primary are comparatively analyzed. The results reveal that the thrust force density of the LPMV machine with a partitioned primary is increased by 32.3%. Finally, experiments are performed on a prototype machine for validation.