Analysis of distributed integer slot round wire windings with combined star-delta connection

Combined star-delta windings offer an improved magnetic field distribution with higher fundamental component and reduced harmonic content, compared to standard windings. Therefore, this winding configuration contributes to increasing the efficiency of electric motors. As efficiency improvements become more and more important, combined star-delta windings are increasingly investigated. They are commonly introduced for distributed integer slot round wire windings, albeit not restricted to them. Nevertheless, there is no general analytical comparison between combined star-delta and standard windings for this winding type. However, such a comparison is important to decide whether or not a combined winding will be applied in an early design state of an electrical machine. Therefore, this paper introduces the combined star-delta winding in detail and gives a general comparison to standard windings regarding mmf distribution, winding factors and harmonic leakage. Finite Element Analysis and experimental data of a permanent magnet synchronous machine verify the results exemplarily.