Hairpin Windings: Twists and Bends of a Technological Breakthrough [Scanning our Past]

Magnetic windings, in general, and small drives, in particular, are typically associated with thin round copper wires. This group of small drives includes electrical machines for automotive applications, ranging from ancillary units to traction machines for both hybrid electric vehicle (HEV) and battery electric vehicle (BEV) A. Hughes and B. Drury, Electric Motors and Drives: Fundamentals, Types and Applications, 5thed., Elsevier Newnes, 2019., J. R. Hendershot and T. J. E. Miller, Design of Brushless Permanent-Magnet Machines. Venice, FL, USA: Motor Design Books, 2010. Wire-wound machines can refer to well-established techniques for widely automatic manufacturing except for traction machines with distributed windings, which still contain manual steps in most assembly lines, particularly after the insertion process J. Hagedorn, F. Sell-Le-Blanc, and J. Fleischer,Handbook of Coil Winding. Berlin, Germany: Springer, 2018. Machines typically wind the loops of continuous wires on a bobbin with a linear or flyer-winding technique outside the stator and pull them from one side of the stator to the other into the slots. The overhang on both ends of the stator, the so-called end turns, forms automatically from the continuous loops.