Motor stator with thick rectangular wire lap winding for HEVs

A stator structure with rectangular wire distributed winding exhibiting high productivity and high design flexibility was designed for HEV motors. We devised a method of forming thick rectangular wire diamond coils and determined the best conditions for high density coil forming. A terminal connection structure was also devised to achieve a short coil end. The slot-fill rate of a prototype stator was 80.5% and its total coil end was 45 mm, which is roughly the same motor performance of a stator with segmented coil wave winding. The key advantage here is that the proposed stator has fewer coils and welding points than the stator with segmented coil wave winding and that the possible number of conductors per slot is higher than four, which is the limit of the stator with segmented coil wave winding.