Comparative study of double-sided toroidal-winding linear PM vernier machines with different secondary configurations

Permanent magnet vernier machines are receiving more and more attentions in low-speed high-torque applications due to their inherent features such as compact structure, high torque density, low torque ripple, etc. This paper presents and compares several linear topologies of permanent magnet vernier machines, all of which have double-sided secondary and toroidal-winding configuration. By using finite element analysis, the no-load and on-load performances for three proposed linear vernier machines are compared. Additionally, the influence of the main parameters, such as PM thickness, pole-arc coefficient and slot opening ratio, on the thrust force and force ripple are analyzed.