Torque ripple reduction in permanent magnet synchronous machines with concentrated windings and pre-wound coils

Ideally, improvements of the manufacturing process do not cause deteriorations of the product characteristics. Pre-wound coils for electrical machines with concentrated windings are such an improvement. The easiest way to enable the assembling of pre-wound coils is simply the absence of pole shoes. This paper discusses the absence of pole shoes based on a sample machine. The focus lies on changes of cogging, avg. nominal and peak torque and the occurring torque ripple. Furthermore, different technologies as a variation of the tooth thickness, skewing, magnetic slot wedges and plug-in connections are investigated to compensate deteriorations of torque behavior. In addition, the effects of these technologies on the manufacturing process of a stator are discussed.