Modeling, optimization and experimental characterization of multi-air gap axial-flux permanent magnet machines with PCB windings

Details

Supervisors

Dehez, Bruno

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil électromécanicien, à finalité spécialisée: mécatronique

Abstract

Axial-flux permanent magnet motors were already extensively investigated for their advantages compared to radial-flux permanent magnet machines. They can have a higher torque density, better thermal capabilities, and present easier manufacturing. When the axial length of the machine increases, its performances tend to saturate. A way to further increase the torque capabilities of these motors is to multiply the number of windings, to use a multi-air gap structure. Besides, the flex-PCB technology paved the way to new, complex, and efficient windings of slotless PM motors. Applied to radial-flux machines, this technology increased their torque density by more than 20 percent. Therefore, this master's thesis aims to investigate the potential increase in terms of efficiency and power density of multi-air gap axial-flux permanent magnet machines with flex-PCB windings. To answer this question, electromagnetic models were developed to simulate and optimize motors around a given nominal point. The multi-air gap topology was compared to its single-air gap counterpart. It is shown that, for small outer radii and long axial lengths, multiplying the number of air gaps enhances the performance. Moreover, multi-air gap motors can develop a higher torque for the same amount of Joule losses when these dominate. Finally, an experimental study was conducted on a prototype of an optimized 2-air gap axial-flux permanent magnet motor to validate the models and confirm the obtained results.