Advanced high torque density non-overlapping winding PM vernier machines

In recent years, permanent magnet (PM) vernier machines have gained more and more attentions due to their high torque density and simple mechanical structure. However, vernier PM machines with lap windings always suffer from long end winding length, and regular non-overlapping winding may result in torque reduction for PM vernier (PMV) machines. In this paper, an advanced PM vernier (APMV) machine topology with multi working permeance harmonics is proposed. This topology is equipped with non-overlapping winding, i.e. short end winding length, and could achieve ~20% higher torque density than that of regular non-overlapping winding PMV machine, with the same magnet usage. Furthermore, both the theoretical analysis and finite element algorithm (FEA) are used to study the performances of this topology, such as back EMF, output torque as well as structure parameter effect. Finally, analysis results are verified by experimental test on a 21Nm prototype, which is designed to have similar volume and weight with a 14Nm regular commercial PM machine.