Improvement in Performance of Flux-Torque Regulation Hybrid Excitation Machine With Fractional Slot Concentrated Winding

High output torque performance and wide flux regulation range are the focal points of motors, but in most cases, these two aspects conflict with each other. This article studies a flux-torque regulation hybrid excitation machine (FTRHEM) with the capability to boost torque at flux weakening and enhance flux regulation and torque performances by investigating the influence of different stator slot numbers on the FTRHEM with fractional slot concentrated winding (FSCW). First, the flux regulation principle and additional torque mechanism of the FTRHEM are illustrated by combining the structure, mathematical model, and virtual work method. Then, the feasible pole slot combinations are investigated considering the harmonic magnetomotive force (MMF) and winding factor. The influences of different slot numbers on flux regulation capacity are analyzed. Moreover, the effect of stator slot numbers on cogging torque, torque characteristic, and additional torque performances is studied by using three-dimensional finite-element analysis (3D FEA). In addition, vibration characteristics are compared. Finally, prototypes are designed, manufactured, and tested. Experimental results verify the feasibility of the analysis.