Subdomain Model for Predicting Armature Reaction Field of Surface-Mounted Permanent-Magnet Machines Accounting for Tooth-Tips

A subdomain model considering the influence of tooth-tips is developed for predicting the armature reaction field in surface-mounted permanent-magnet machines having either non-overlapping or overlapping windings. In the developed model, the field domain is divided into three types of subdomains, viz. air gap including magnet, slot openings, and slots. The expression of the vector potential distribution in each subdomain is obtained by the variable separation method, and the field solution is obtained by applying the boundary and interface conditions. Compared with the conventional subdomain model, the subdomain model considering the tooth-tips predicts similar flux density in the air gap and magnets, but exhibits much higher accuracy for the flux density in the slot openings and slots. The finite-element results validate the analytical prediction.