On the AC Losses in the End Conductors of Hairpin Windings

Abstract

In the last years, several resources have been employed to increase torque and power density values in electrical machines, especially in those intended for transport applications. In this context, the adoption of hairpin conductors is spreading thanks to their inherently high fill factor. Their main drawback is represented by their sensitivity to highfrequency phenomena, which can have a significant impact on the Joule losses and thus on the overall efficiency.While several researches have recently focused on ways to model and reduce such high-frequency losses in the slots, i.e. within the conductors' active sides, a few data are available on their impact in the end winding regions.This work provides an investigation on the AC losses occurring in the end conductors of a hairpin winding traction motor. The losses are determined through 3D finite element simulations for a wide frequency range, and compared against those occurring in the active part of the machine.

Investigation on the Torsional–Flexural Instability Phenomena during the Bending Process of Hairpin Windings: Experimental Tests and FE Model Validation

“…A potential solution to mitigate these issues is the adoption of segmented hairpins, where one or more conductors near the air gap are divided into two or more subconductors [7]. Consequently, the radial thickness of the rectangular cross-section is actually scaled along the radial direction of the stator slot (Figure 1c) to optimise the current distribution within the conductor section [8,9].…”