An Asymmetrical Additively Manufactured Hairpin Winding for increased efficiency and sustainability

Recently, hairpin windings (HWs) have been among the most studied and implemented winding topologies to enhance torque and power density of electrical machines (EMs), especially in the automotive sector. The aim of this work is threefold. First, it proposes an asymmetrical configuration for HWs, which exploits the possibility of reducing AC losses through the implementation of conductors featuring variable cross-section within the slot. Second, this asymmetrical winding is envisioned using additive manufacturing (AM), given the constraints imposed by the conventional manufacturing process of HWs. Third, a suitable aluminium (Al) alloy is selected as winding material, thus replacing copper (Cu), with the aim of achieving a more sustainable design. These three objectives are achieved through extensive analytical and numerical analyses and comparisons between conventional and asymmetrical windings, as well as among different materials. A practical demonstrator is then built to validate analyses, methodologies and concepts proposed in this paper. Finally, an experimental campaign is carried out on the asymmetrical winding demonstrator, highlighting the loss reduction and sustainability potentials of the proposed layout.