Hybrid Excited Stator Slot PM Machines with Overlapping Windings

In this paper, the overlapping winding (OW), i.e. the coil pitches of field and armature windings equal 3 slot pitches (F3A3), is proposed and applied to 12-slot/17-rotor pole (12s17r) hybrid excited stator slot permanent magnet machines (HESSPMs) in order to enhance the torque density. The influence of stator/rotor pole number combinations on the HESSPMs with both non-overlapping winding (NOW) and OW is considered and analyzed. The 12s17r HESSPMs with NOW and OW are selected from the candidates in 12-stator machines for high average torque and low torque ripple under the same copper loss. Their electromagnetic performance is comparatively studied. By adopting OW, it shows that the proposed 12s17r-F3A3 HESSPM improves the fundamental value of the phase back-EMF by 125% than the 12s17r-F1A1. Consequently, the torque density in 12s17r-F1A1 HESSPM have been improved by 100.24% in F3A3 HESSPM.