Analysis of PM Transverse-Flux Outer Rotor Machines With Different Configuration

This paper presents the electromagnetic analysis of two permanent magnet transverse-flux outer rotor machines with and without magnetic shunts. The research started with designing and analyzing a permanent magnet transverse-flux machine with an inner rotor, previously patented by J. Giearas in 2010. However, the results obtained from the prototype test differed significantly from the estimated results. Applying three-dimensional (3-D) finite element method (FEM), the main problem of the machine was detected. The problem was in high flux leakage that weakened magnetic flux density in the stator poles. Such observation led to designing two machines with outer rotor, with and without magnetic shunts. The role of the magnetic shunts is to minimize flux leakage in the stator in order to improve the performance of the machine. Electromechanical parameters of both outer rotor machines, with and without magnetic shunts, are compared in the paper. Three-D FEM results are supported by laboratory analysis of the machines' prototypes. Experimental measurements proved that the machine with magnetic shunts demonstrated better performance as compared with the machine without magnetic shunts. Presence of the magnetic shunts in the machine resulted in reducing of flux leakage and cogging torque.