Sensitivity of the Commonmode Characteristics of a Stator Winding Regarding the Assumed Hairpin Position in a Slot

This paper investigates the sensitivity of commonmode prediction results for electrical machines to the assumed position of hairpins of a stator winding within a slot. The effect of the conductor's position on the parasitic motor capacitance between the winding and the stator core as well as on the high-frequency behavior of the machine, i.e., the commonmode current, is investigated using a stator sample. The limiting cases of the conductor position for maximum and minimum capacitances are presented. Based on the resulting variance of the capacitance and the frequency response, it is deduced whether or not a common estimation approach using a symmetrical conductor position is valid.