Winding Function-Based Stator Winding Layout Optimization of a Concentric Winding Squirrel Cage Induction Machine for Torque Enhancement

Weight, torque, and efficiency of induction machines (IMs) are directly affected by their stator winding configuration. To evaluate this, this paper presents the electromagnetic (EM) performance comparison of four squirrel cage IMs using different winding configurations, namely, integral slot distributed winding (ISDW), fractional slot concentrated winding (FSCW), integral slot concentrated winding (ISCW) and integer slot concentric winding (ISCW2). The same active volumes with identical electric and magnetic loading constraints were assigned for all IMs with the same materials. The weight, torque, EM losses, and efficiency values in both maximum torque per ampere (MTPA) and field weakening regions were assessed. The results indicate that the ISCW2 IM possessed the best overall performance and characteristics in terms of torque, torque density and efficiency in a wide speed range among the investigated IMs; except its lower developed torque compared to the ISDW IM in MTPA region. To resolve this issue, a winding layout optimization was carried out via a winding function-based analysis to improve the torque performance of the ISCW2 IM in MTPA region as well.