Impacts of Stator Current Angle and Rotor Current on Solid Losses of Hairpin Windings in Traction Electrically Excited Synchronous Machines

Paper in proceeding, 2024

Hairpins in motor windings have attracted growing interest in the industrial community. However, the AC losses in the hairpins are much greater than those in the round wire when a high frequency current passes through, resulting in a reduction in the efficiency of the motor. Generally, AC losses are categorized into skin effect and proximity effect, which are caused by flux leakage. In this case, the magnetic leakage is due to the interaction of stator and rotor magnetic field variation, resulting in flux leakage at the slots opening. The synthesized magnetic field built by the stator current, including amplitude and angle, and the rotor current decides the level and position of stator iron-core saturation. Such saturation affects the flux leakage and furthermore hairpin AC losses. In this article, a model built in ANSYS to study the effect of current angles and rotor current on AC losses and AC resistance at different operation situations. The results of this paper can help improve the existing model of AC losses and therefore contribute to a more accurate motor control method.