Multi Three-Phase Hairpin Windings for High-Speed Electrical Machine: Possible Implementations

Abstract

This work provides an in-depth critical analysis related to the feasibility of combining multi three-phase winding layouts with the ever-spreading hairpin technology. After an introduction on the advantages and challenges of both hairpin and multi-phase windings, more details on how these two technologies can be combined are provided. Then two similar stator geometries, with 72 and 96 slots, are analyzed in detail exploiting an 8 poles permanent magnet -assisted synchronous reluctance motor for traction applications. A relevant set of feasible winding configurations are modelled and analyzed through finite element simulations. For every machine, a breakdown of the power losses is provided and compared against that of the same machine topologies having randomwound windings with stranded round conductors. The main results and possible solutions to increase the machine performance are then provided.

AC losses reduction in Hairpin Windings produced via Additive Manufacturing

“…Of these, hairpin windings are becoming more and more popular, and many manufacturers are investing on this technology, especially in the automotive field [3]. The main reasons of their success relate to the higher fill factor, greater thermal conductivity, and higher automation of the manufacturing process compared to conventional random windings [4], [5]. On the other hand, hairpin windings present several challenges.…”

On the AC Losses in the End Conductors of Hairpin Windings

“… increasing the number of conductors such that a lower cross section and lower conductor current can be adopted. This solution usually requires also a higher number of machine parallel paths [10], [12];…”

Impact of Wire Selection on the Performance of an Induction Motor for Automotive Applications

“…Hairpins are conductors with a solid and rectangular cross-section, as opposed to the stranded wire ones utilized traditionally. Thanks to their higher slot fill factor (more than 0.75), better thermal slot propagation is ensured, meaning higher torque and power density values are possible when compared to classical round conductors [1][2][3][4][5][6][7][8][9][10].…”