Spoke Type Axial Flux Permanent Magnet Motor and its Flux Switching Variants

This dissertation presents a detailed analysis of the axial flux permanent magnet (AFPM) motor having slotted double stator and single rotor (DSSR) configuration. An analytical comparative analysis is carried out to determine the placement of the permanent magnets (PMs) in or on the rotor for achieving better electromagnetic characteristics for the direct-drive applications. Spoke-type PM placement in the rotor shows more promising characteristics than the conventional surface-mounted permanent magnet (SPM) placement on the rotor. Stator winding analysis is carried out using the winding function theory. Spatial harmonics and winding factors of different slot-pole combinations are determined without resorting to complex mathematical equations. For the slotted double stator, tape-wound electrical steel is utilized. Therefore, a detailed analysis of magnetization characteristic analysis is carried out to examine the influence of the heat treatment, gluing and physical geometry. Along with the tape-wound electrical steel, magnetization characteristics of the soft magnetic composites (SMCs) are measured. Due to the low rated frequency and high airgap flux density, glued and heat-treated tape-wound electrical steel is selected for the stators of the spoke-type DSSR AFPM motor. A parametric electromagnetic analysis is carried out to determine the optimal spoke-type DSSR AFPM motor. However, a basic prototype is developed for the measurements, and a no-load characteristic analysis is carried out due to manufacturing complexities. The 3D FEA simulation results are validated and are in good agreement with the experimental results. The second part of this dissertation deals with the flux switching (FS) variants of the AFPM motor. Spoke-type PMs are placed inside the stator teeth and single-phase FS- AFPM motors are proposed and investigated. Single stator and single rotor (SSSR) type FS-AFPM motor models have unbalanced force on the rotor; therefore, DSSR type FS-AFPM motor models are proposed. For unidirectional rotation of the single-phase FS-AFPM motors, the rotor is chamfered. The impact of chamfering is investigated to avoid the single-phase FS-AFPM motor’s stand-still issues.