Abstract—This paper presents a unique axial-flux permanentmagnet
synchronous generator (AFPMSG), which is suitable for
both vertical-axis and horizontal-axis wind turbine generation systems.
An outer-rotor design facilitates direct coupling of the generator
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.