Design and optimization of interior PM machines with distributed and fractional-slot concentrated-windings for hybrid electric vehicles

This paper presents an optimization of an interior permanent magnet (PM) machine with fractional-slot concentrated windings (FSCW) based on a machine with integer-slot distributed windings (ISDW), and a performance comparison between the two machines for use in hybrid electric vehicles. Finite element analysis (FEA) is used to investigate the characteristics of the two machines which have the same dimensions and rated power. The effect of the number of slots on the back-EMF, cogging torque, d- and q-axis inductances and efficiency is analyzed for the two machines. The measured results have good agreement with the finite element analysis results.