AC Losses Analysis and Design Guidelines for Hairpin Windings With Segmented Conductors

In the last years, hairpin windings (HWs) are amongst the most studied and implemented winding topologies to increase torque and power densities of electrical machines, especially in the traction field. However, their main drawback remains the elevated ohmic losses generated at high-frequency operations. Recently, HWs with segmented conductors have been proposed to overcome this challenge, but an analytical model to predict the losses in such unconventional winding is missing, as well as a critical analysis of the extra manufacturing complexities needed. In this article, first, a simple analytical formulation for the estimation of ac losses in segmented hairpin conductors is proposed, developed, and validated at various operating frequencies, both through finite element (FE) analyses and experimental measurements. Then, an in-depth analysis of the main advantages and disadvantages of this winding topology is proposed with the aim of providing guidelines and recommendations for their practical realization, adopting standard methodologies for their connection and transposition.