Comparison Analysis of PM Transverse Flux Outer Rotor Machines with and without Magnetic Shunts

This paper presents electromagnetic analysis of two permanent magnet transverse flux outer rotor machines with and without magnetic shunts. The research started with designing and analysing a permanent magnet transverse flux machine with inner rotor, previously patented by J. Giearas in 2010. However, the results obtained from the prototype test differed significantly from the estimated results. Applying 3D Finite Element Method tool main problem of the machine was detected. The problem was in high flux leakage which 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 performance of the machine. Electromechanical parameters of both outer rotor machines, with and without magnetic shunts, are compared in the paper. 3D Finite Element Method results are supported by laboratory analysis of the machines' prototypes. Experimental measurements proved that the machine with magnetic shunts demonstrated better performance comparing to the machine without magnetic shunts. Presence of the magnetic shunts in the machine resulted in reducing of flux leakage and cogging torque.