Inter-turn Voltage in Hairpin Winding of Traction Motors Fed by High-Switching Frequency Inverters

In this paper, the voltage distribution in hairpin winding of traction motors fed by high-switching frequency inverters is discussed. The voltage distribution is calculated using a method based on a combination of analytical and numerical analyses, the final model parameters are computed using finite element approach. The proposed method enables estimation of voltage differences between different turns located in the same slot as a function of voltage rise-time. Additionally, influence of hairpin winding design on the voltage distribution in the motor winding is discussed and some winding configuration examples are presented. As shown, the winding configurations with less stress on the conductor insulation may result in challenges in the hairpin production that needs to be addressed.