Fault-Tolerant Fractional-Slot PMSMs with One Coil Parallel Branches Made Phases – Part 2: Circulating Harmonic Current Rejection Potential

The paper is aimed at a class of fractionalslot

permanentmagnet synchronousmachines (FSPMSMs)

equipped with phases made up of one coil parallel

branches, with emphasis on their potential to reject the

harmonic currents circulating in the loops created by the

parallel branches. Following the identification and topological

characterization of this class of machines in Part 1,

the star of slots approach is extended to the analysis of

the back-EMF harmonic content. This makes it possible the

investigation of the possible circulating harmonic currents

by checking the phase shifts between the different back-

EMF harmonics induced in the coils belonging to each

phase. It is shown that all identified candidates exhibit

the potential to reject the circulating harmonic currents.

The paper is achieved by a case study dedicated to a

candidate equipped with three phases made up of six

parallel branches including a single coil each. Following

an analysis of its back-EMF harmonic content, the torquespeed

characteristic is analytically-predicted and validated

by 2D finite element analysis and by experiments.