Concentrated winding PM machines: a pre-design approach

Purpose - The purpose of this paper is to discuss the design of concentrated winding permanent magnet (PM) machines dedicated to propulsion applications considering both surface-mounted and flux-concentrating arrangements of the PMs. Design/methodology/approach - Following the selection of a suitable distribution of the concentrated winding, a derivation of the machine inductances is carried out in order to highlight the increase in the flux-weakening range gained through the substitution of distributed windings by concentrated ones. Then, mmf and finite element analysis are carried Out in order to investigate the air gap flux density and the torque production capability of both surface-mounted and flux-concentrating PM machines. Findings - The paper finds that, although both machines provide almost the same average torque, the surface-mounted PM machine offers lower torque ripple with respect to the flux-concentrating arrangement: a crucial benefit in electric and hybrid propulsion systems. Research limitations/implications - The research should be extended to the comparison of the obtained results related to the torque production capability with experimental measurements. Practical implications - An increase in the efficiency associated with the extension of the flux-weakening range and a reduction of the volume make the concentrated winding PM machines interesting candidates, especially in large-scale production applications such as the automotive industry. Originality/value - The paper proposes an approach to design and performance investigation of concentrated winding PM machines considering both surface-mounted and flux-concentrating arrangements of the PMs.