Investigation of a Novel Phase-Unit Axial-Modular Permanent Magnet Vernier Machine With Integral-Slot Non-Overlapping Concentrated Windings

This article proposed and analyzed a novel phase-unit axial-modular permanent magnet vernier machine (PUAM-PMVM) with integral-slot non-overlapping concentrated windings (ISNOCW) for direct-drive applications. In PUAM-PMVM, all phases are separated and distributed along the axial direction with a fixed mechanical angle between two adjacent phases. Firstly, the machine topology and working principle are illustrated and the theoretical expressions are derived. Besides, the characteristic of slot-pole combinations for PUAM-PMVM is summarized, and the integral gear ratio is obtained. Moreover, the topology extension is also deeply investigated, including the multi-phase, multiple three-phase windings, and hybrid-modular stator designs. Secondly, the optimization and analysis in terms of slot-pole combinations, PM configurations, and slot opening width are conducted. To get a full picture of proposed PUAM topology, the performances between PUAM and conventional models are compared by finite-element analysis (FEA), including the no-load back-EMF, torque, power factor, losses, efficiency, and flux weakening capability. Finally, a prototype was manufactured and tested to validate the FEA and theoretical analysis, which has a good agreement. This article aims to provide an alternative of topology for direct-drive application.