Analysis of Winding slot and Stator-Rotor Pole Combinations of Modular Transverse Flux-Switching Permanent Magnet Machine

This paper investigates the influence of winding slot and stator/rotor pole combinations on the electromagnetic torques of modular transverse flux-switching permanent magnet (MTFSPM) machine. Firstly, a unique winding factor calculation method for MTFSPM machines is proposed. By introducing the concept of virtual slots, the distribution factor of small virtual coils within a practical large coil and the distribution factor of the large coils are computed, which subsequently yields the overall winding factor of the MTFSPM machine. Additionally, based on the magnetic circuit method, the PM magnetomotive force (PM-MMF) amplitudes in slotted and unslotted regions are calculated, thus accounting for the influence of slot openings. Subsequently, based on different MMF permeance and winding function models, the back-electromotive force (back-EMF) amplitudes variation trends are calculated, leading to the identification of winding slot and stator/rotor pole combinations that offer higher output torque capability. Finally, the electromagnetic characteristics of candidate MTFSPM machines are compared through three-dimensional finite-element analysis, and experiments are conducted to verify the theoretical analysis.