Fractional-Slot PMSMs With One Coil Parallel Branches Made Phases—Part I: Investigation Study

This work proposes an approach to design fractional-slot permanent magnet synchronous machines (FSPMSMs) equipped with phases made up of one coil parallel branches. These machines exhibit attractive potentialities, especially their enhanced open-circuit fault tolerance capability. Beyond their intrinsic fault tolerance, an open-circuit affecting the targeted topologies leads to a torque step-down limited to the one developed by the concerned coil rather than the torque produced by the total phase in FSPMSMs equipped with phases made up of series-connected coils. Furthermore, these topologies are suitably-adapted to low-voltage power supply that makes them viable candidates in automotive applications. This potentiality is by far vital in battery electric vehicles with the risk of electrocution in case of accident totally-eradicated thanks to the reduction of the DC bus voltage. Part 1 of the developed work is aimed at a star of slots-based identification and topological characterization of the FSPMSMs enabling the arrangement of the armature phases according to one coil parallel branches. The study distinguishes the topologies with odd and even number of phases, arranged in single- and double-layer slots. A case study is treated using a 2D finite element analysis and validated by experiments.