High Efficient Electric Motors with Bar Windings for Serial Production

Authors

Dr. A. Eilenberger, Dipl.-Ing. R. Hintringer MBA, Dipl.-Ing. M. Primorac, Dipl.-Ing. D. Scherrer, Miba AG, Laakirchen

Year

2018

Print Info

Fortschritt-Berichte VDI, Series 12, No 807

Summary

Electric motors with bar windings are one of the most important innovation directions in the electrification of vehicles. Compared to round wire windings, in most cases bar windings show a higher copper fill factor in the slot and a better thermal connection. The result is advantages in efficiency and power density. First applications of bar windings (hair-pin) were established by American and Japanese OEMs. Other advantages can arise when straight bars (i-pin) are used. The thermal and electrical efficiency in particular can be improved. The thermal efficiency is optimized by using a highly flexible winding head cooling for efficient head dissipation behavior. The electrical efficiency is optimized by using parallel pins to lower existing AC resistance effects at higher frequencies. Additionally, more flexible variations of performance and torque classes are possible by using uneven pins. Furthermore, cost and quality benefits are present when applying the simpler production process of i-pins. The undesirable and complex process steps of the hair-pin forming, the insertion into the lamination core and the cutting are not necessary. This influences the product cost for high-volume serial production. Because of the aforementioned advantages, we are sure that the next generation of high efficient electric motors capable for high volume serial production will use i-pin technology.