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Skinning of Insulated Copper Wires within the Production Chain of Hairpin Windings for Electric Traction Drives

Abstract— Due to the influence of electric mobility drives used in the automotive powertrain are experiencing a boost in innovation. Caused by the accompanying demand for an increase in power density and the necessity to reduce costs in series production, the winding of electric machines and associated production processes are being improved. A promising novel type of winding with numerous advantages is the bar-wound winding, which introduces new demands on technologies for their production. This winding is manufactured from a wide range of preformed elements made of enameled copper wire, that must be connected to each other mechanically and electrically. For this purpose, it is necessary to remove the insulation of the conducting elements in the joining area. Due to the large number of contacts that have to be prepared in this way, it gets essential to use productive and in particular process-safe skinning technologies. In this paper, the motivation for the application of bar-wound windings and the corresponding production chain is expounded. A method for the metrological quality control of insulation residues in the skinned area is qualified and technologies for the realization of the skinning process are compared. In addition, experiments to create process knowledge for the laser-based removal of the insulation and the skinning by means of rotating brushes are presented. 

Index Terms— electric traction drives, hairpin winding, laser-based skinning, fluorescence based quality assurance