Hybrid PBF-LB/M of Pure Copper for Hairpin Winding Heads of Electric Traction Drives

Abstract

In the automotive sector, the so-called hairpin technology currently dominates the copper winding of stators in traction drives. In addition to the advantages of higher power density and deterministic production process steps, the winding technology also entails complexities and disadvantages. The production of hairpin stators requires high investments for production machines and their highly complex tools for manufacturing the windings. In addition, it is a major challenge to integrate variant flexibility in these production lines. Producing different product variants of a hairpin stator is only possible with additional costs for tools of the individual lines. In contrast, additive manufacturing technologies enable tool-free production of complex 3D geometries.In the field of PBF-LB/M, the processability of pure copper for electrical applications has been intensively researched and improved in recent years. Therefore, the approach of printing complex winding heads of a hairpin winding directly on conventional copper conductors using PBF-LB/M process is researched in this study. Challenges regarding alignment in the hybrid process as well as redesign using design automation methods considering restrictions and boundary conditions are faced and investigated. By integrating additive manufacturing in hairpin stator production and developing an innovative production process chain, process steps, machines and tools can thus be substituted. By exploiting design potentials of additive manufacturing, winding head heights can additionally be reduced, thus reducing losses in the e‑machine and saving quantities of copper material. The approach is validated using a hairpin stator from the automotive sector. The same conventionally produced hairpin stator is used as a benchmark to evaluate the results achieved by the hybrid stator in a production engineering context.