Novel design of a coreless axial-flux permanent-magnet generator with three-layer winding coil for small wind turbines

Abstract

This study presents a novel design of the three-layer winding coil sets of a coreless axial-flux permanent-magnet generator applied to small wind turbines. The proposed generator design consists of two rotors and an integrated stator with flattened winding coil sets of three-phase three layers connected using a wye configuration. An analytical model of the inductance and resistance of the coil set is described to analyse the influence of the coil shape variation due to winding imperfection. The air gap magnetic flux distribution analysis shows the advantage of the integrated flatten coil sets compared with a typical stack up three layers stator. An experimental design is conducted for the parameter design of geometric variables to optimise the output power of the proposed axial-flux permanent-magnet design. A prototype generator is then constructed to compare with a benchmark generator that has a rated output power of 300 W at 800 rpm. The proposed design outperforms the benchmark generator by 26.5% in terms of generated power at a typical driving rotation velocity of 500 rpm for a small wind turbine, and demonstrates a superior performance at a lower driving speed range, which is particularly important in a small wind turbine application.