AiVibeTextile & Automotive Manufacturing
Hairpin Stator Winding
Hairpin winding builds an electric motor stator from rectangular copper conductors bent into U-shaped hairpins, inserted into the stator slots, twisted and welded in pairs. It is widely used in EV traction motors.
Rectangular enamelled copper wire is straightened, stripped of insulation at its ends and formed into hairpins. The hairpins are assembled into a pattern, inserted axially into the slots of the stator core, and their free ends are twisted and joined in pairs, usually by laser welding, to complete the winding circuits. The connections are then insulated and the stator is impregnated with resin.
Compared with windings of round wire, hairpin windings achieve a higher slot fill factor, which supports higher power density, and their flat conductors in contact with the slot wall improve heat transfer. The geometry is also well suited to automated, high-volume production, which is why many EV traction motors use it.
At high electrical frequencies, skin and proximity effects increase AC losses in the large conductors, which designers manage through conductor size and arrangement. Weld quality, insulation integrity and dimensional accuracy are critical, so production lines inspect welds optically and run electrical tests such as resistance, high-voltage and partial discharge tests. Process equipment and test limits follow the motor design specification and OEM documentation.
Key points
- U-shaped rectangular copper conductors are inserted and welded in pairs
- Higher slot fill and better heat transfer than round-wire windings
- Well suited to automated, high-volume EV motor production
- Welds and insulation are checked optically and electrically
Where AiVibe comes in
AiAmbA use cases include visual inspection on textile and automotive lines, predictive maintenance and digital twins. Existing lines are retrofitted with edge devices, and AI agents only propose changes for a trained operator to confirm.
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