A Comparison Between Random and Hairpin Winding in E-mobility Applications

This paper presents a comparative study on traction motors built using random and hairpin winding. Advantages and disadvantages of each winding configuration are reported and challenges of using hairpin winding are detailed. The paper focus is placed on winding copper loss, which is the main root of performance differences in motor equipped by random and hairpin windings. A motor is designed using both winding types. Differences in losses and their effect on motor efficiency is studied. Considering the higher slot fill factor of hairpin winding, DC component of copper losses in hairpin winding has less contribution on the motor efficiency, however, higher AC copper loss is seen in hairpin windings. Thus, motors designed and manufactured using hairpin winding have higher efficiency in comparison to the equivalent random wound motors, especially at high load and low speed.