Investigation on Electromagnetic Performance of Axial-Radial Flux Switched Reluctance Machines

This thesis presents a comprehensive investigation into axial flux switched reluctance machines (AFSRMs) and axial-radial flux switched reluctance machines (ARFSRMs), with emphasis on winding configuration, core material selection, and dual (axial and radial) flux path exploitation. While conventional radial flux SRMs have been extensively examined, axial and hybrid axial-radial variants remain comparatively underexplored despite their potential for enhanced torque density and compact topologies.
The research systematically analyses 3-phase, 12-slot/8-pole configurations using a half-analytical modelling framework supported by finite element analysis. For AFSRMs, four winding types—single- and double-layer conventional, and single- and double-layer mutually coupled—are evaluated under both square wave and sine wave excitation. The single-layer conventional configuration yields the highest torque capability and ~70% efficiency under rated conditions. Core material investigations indicate that a soft magnetic composite (SMC) rotor combined with a silicon steel stator achieves optimal electromagnetic performance with reduced torque ripple.
The principal contribution is the development of a novel ARFSRM topology that simultaneously employs axial and radial flux paths, thereby improving torque density and end-winding space utilization. Five winding configurations (SLC, DLC, SLMC, DLMC, FP) are implemented and optimized via genetic algorithms. Torque ripple reduction is addressed through two innovative approaches: mechanical phase shifting of the axial stator with a single current source, and electrical phase shifting through independent sources for axial and radial windings. Notably, FP-FP and SLMC-FP combinations deliver superior electromagnetic characteristics.
By transforming conventionally unused end-winding regions into active electromagnetic zones, the ARFSRM attains significant torque density enhancement while retaining the intrinsic advantages of switched reluctance technology, including mechanical robustness, fault tolerance, and rare-earth independence. The findings establish AFSRMs and ARFSRMs as viable candidates for next-generation electric vehicle traction systems, offering a balance of efficiency, reliability, and cost-effectiveness.