Characteristic analysis of a vernier motor from magnetic perspective

In this paper, the air gap flux density distribution of a surface PM vernier motor are analytically investigated, and principles of torque production are explained by not using lumped electrical circuit parameters but using magnetic quantities. To these ends, the equations of magnetic field waves, stored energy and torque are derived. The obtained equations are compared to those of a conventional PM machine, which shows that the vernier motor has substantially different characteristics of energy and peak flux densities in the core parts as well as air gap. Finally the design guides for vernier motor design to avoid saturation of core material are presented and verified through FE analysis for a practical model.