Application of fractional slot concentrated windings to synchronous reluctance machines

Due to the advancement of electric vehicles, the desire for high torque density electric motors for traction applications is steadily increasing. It is advantageous to design such a motor with little or no rare earth permanent magnet (PM) material due to the associated environmental, political and economic challenges with its extraction and processing. This paper explores a novel synchronous reluctance machine (RSM), with fractional slot concentrated windings (cRSM) as an alternative to PM, induction machine (IM) and switched reluctance (SRM) traction motors. The impact of applying fractional slot concentrated windings to RSMs is presented and the outline of the design options for such a machine is detailed. Scaling of the fractional slot wound synchronous reluctance motor is also briefly discussed, in order to realise a torque dense synchronous reluctance machine for future traction applications. A finite element analysis comparison between IM and conventional synchronous reluctance with the proposed cRSM is also presented.