Rotor integrity design for a high-speed modular air-cored axial-flux permanent-magnet generator

The rotor integrity design for a high-speed modular air-cored axial-flux permanent-magnet (AFPM) generator is presented. The main focus is on the mechanical parametric optimization of the rotor, which becomes a more dominating design issue over electromagnetic optimization at high operational speeds. Approximate analytical formulas are employed for preliminary sizing of the mechanical parameters of the rotor, which consists of the permanent magnets, retainment ring, and back iron. Twodimensional (2-D) finite-element analysis (FEA) models are used to optimize the values of the parameters. Then, 3-D FEA models are developed to verify the final design. Finally, based on the final design, an AFPM prototype is built for experimental validation, and mechanical integrity tests for the rotor are undertaken. The results confirm the validity of the analytical and FEA models, as well as the overall design approach.