Distributed, Concentrated, and Hairpin Windings
Distributed, concentrated, and hairpin windings are terms used to describe how stator coils are arranged and how their conductors are formed, but they are not three mutually exclusive categories.
Distributed windings
A distributed winding spreads each phase coil across several slots. The arrangement can create a smooth rotating magnetic field with low harmonic content. Its end turns may be relatively long, adding copper mass and resistance outside the active part of the stator.
Concentrated windings
A concentrated winding places each coil around one tooth or a small group of teeth. Short end turns and modular assembly can reduce inactive copper and simplify production. Depending on the slot, pole, and phase combination, stronger space harmonics may increase rotor loss, torque ripple, vibration, or noise.
Hairpin windings
Hairpin describes a formed-conductor process. Rectangular copper bars are bent, inserted into stator slots, and joined—often by welding—into the phase circuit. The regular shape can support high slot fill, repeatable automation, and controlled thermal contact. Large solid conductors can develop additional AC resistance at high electrical frequency, and every joint requires insulation and quality control.
How the terms relate
Distributed and concentrated describe the electromagnetic placement of coils. Hairpin describes conductor shape and manufacturing. A hairpin stator still has a winding layout, so “hairpin versus distributed” is not a clean technical comparison.
For slot geometry, laminations, conductor loss, and production trade-offs, see EV Motor Construction and Windings.