Design, analysis and loss minimization of a fractional-slot concentrated winding IPM machine for traction applications

This paper presents details of the design and analysis of a high-performance fractional-slot concentrated winding (FSCW) interior permanent magnet (IPM) machine that has been designed to meet demanding FreedomCAR traction machine specifications. Attention is focused on the design of the IPM rotor, including investigations of the impact of varying the magnet height and the depth of the magnet chevron midpoint on key performance metrics. This paper also addresses interaction between the electromagnetic and structural characteristics of the rotor as bridge and post widths are varied. Predicted performance characteristics of the machine are presented and design techniques are described for improving the machine efficiency at high operating speeds. Test results gathered from an experimental machine exhibit promising agreement with the predicted performance.