Evaluation of different methods for removing the conductor insulation of stranded conductors

Abstract

The ecological change in society and politics leads to an increased demand for alternative drives. In the field of mobility, this can be observed by ongoing innovations in research and development as well as in the production of electric machines. Currently, the automotive industry is focusing more and more on traction drives using hairpin technology. The reasons for this are the easier automation of the manufacturing process and the higher copper filling factors that can be achieved. The latter help to improve the power density. At high frequencies, which inevitably occur in high-speed applications, large conductor dimensions lead to additional losses due to eddy currents. To reduce these losses, twisted round wires can be used instead of flat conductors. Nevertheless, the manufacturing as well as the processing of this semi-finished product is more complex. The aim of this paper is to present and compare the possibilities for removing the required tape of the stranded conductor and to substantiate it with initial results. For this purpose, the general production chain of a hairpin stator is explained at the beginning of the paper in order to show the reasons why the removal of the bandage is of elementary importance. This is supplemented by technological aspects of stranded wire technology which cause-effect relationships serve as the basis for the main part of this paper.