Abstract—This paper presents a unique axial-flux permanentmagnet synchronous generator (AFPMSG), which is suitable for bothvertical-axisandhorizontal-axiswindturbinegenerationsystems.Anouter-rotordesignfacilitatesdirectcouplingofthegenerator to the wind turbine, while a coreless armature eliminates the magnetic pull between the stationary and moving parts. The design and construction features of the AFPMSG are reviewed. The flux-density distribution is studied, with the aid of a finite element software package, in order to predict the generated e.m.f. waveform. The performance equations of the AFPMSG are derived, and the condition for maximum efficiency is deduced, for both constant-speed and variable-speed operations. The experimental results, in general, confirm the theory developed.