Design of an axial flux machine for an in-wheel motor application

Abstract

This master thesis deals with the design of an axial flux machine for an inwheel\nmotor application. Four double-sided axial flux machine topologies\nare compared to select the most suitable one for designing a high torque\ndensity machine that fits into a predefined geometry (diameter: 260 mm,\nlength: 72.5 mm). The yokeless and segmented armature (YASA) topology\nis chosen, due to its very compact structure. The design is made by using\nanalytic and 3D finite element analysis alternately.\nThe geometry of the electromagnetic circuit is optimized to find the maximum\nrated torque (≈80 Nm) for proposed values of magnetic flux and current\ndensities (1.7 T and 7 A/mm2). These densities are chosen with the intension\nof reaching a high utilization of both the copper and the iron in the machine,\nwhen their proportions are determined by the maximal product of electric\nand magnetic loading.\nWhen the geometry of the electromagnetic circuit is determined, it is held\nfixed. Possible different torque speed characteristics of the machine are then\ninvestigated, with respect to current and voltage limitations together with\nthe turn selections of the windings.\nA final design is proposed and its theoretical characteristics are evaluated and\npresented. The power density, at 2400 rpm and 7 A/mm2, is calculated to\n5.3W/cm3. Furthermore, some suggestions for future work and modifications\nare made.