Design of axial flux permanent magnet generators using various magnetic materials in locally manufactured small wind turbines

Abstract

Locally manufactured small wind turbines are most frequently used in off-grid battery based renewable energy systems and typically utilize coreless axial flux permanent magnet (AFPM) generators. Due to reports of neodymium magnet corrosion, the performance of coreless AFPM generators is investigated with the use of both neodymium and ferrite magnetic materials. Generator designs are conducted for rotor diameters between 2.4 and 4.2m, applying a Particle Swarm Optimization (PSO) in the generator design process, while the final designs are verified and fine-tuned with Finite Element Analysis (FEA) simulations. Optimal magnet dimensions are derived for both magnetic materials and for each rotor diameter, while a ‘universal’ magnet design is compared with commercially available magnets. Experimental comparison of a ferrite and a neodymium magnet generator design for a 2.4m rotor is conducted, proving that ferrite magnet AFPM generators are suitable for locally manufactured small wind turbines, making them less prone to corrosion, but also heavier in weight.