Axial-flux permanent-magnet synchronous generator with coreless armature and non-integral coil–pole ratio

This article presents a study on an axial-flux permanent-magnet synchronous generator (AFPMSG) with a double-sided rotor, coreless armature. The armature winding consists of non-overlapping concentrated coils and has a non-integral coil-pole ratio. It is shown that, with an appropriate choice of armature coil number to pole number, the fundamental winding factor of the AFPMSG can be made close to that of a full-pitched integral slot winding. The field distribution and load performance are computed for a prototype machine based on a two-dimensional, time-stepping finite element method. A study of the armature reaction effect of the coreless armature winding and the origin of torque ripple is also carried out. The computed voltage and current waveforms, as well as the load characteristics, are verified by practical experiments.