Optimization Design of Low Speed Axial Flux Halbach Permanent-Magnet Generator with PCB Winding

Multi-objective design of a coreless non-overlap winding axial-flux permanent-magnet generator (AFPG) has been done for use in direct-drive vertical axis wind turbines. A comparative study has been performed to determine the most appropriate configuration of Halbach permanent-magnet poles for coreless rotors. Considering the actual constraints of the wind turbine, the Non-dominated Sorting Genetic Algorithm II (NSGA II) technique has been used to optimize the efficiency, size and mass of the generator. Reasonable design value of air gap has been proved to be an important factor in reducing eddy current loss of stator windings and avoiding collision of rotor due to mechanical stress bending. A prototype of the designed generator of the selected optimal configuration has been fabricated and tested by 3-D finite element analysis (FEA). The results of simulation show good agreement with the optimization conclusion.