A new asymmetric bar winding concept along with the analysis and benefits for high-speed traction electric machines is presented. The objective is to reduce the ac losses, especially at high speeds, utilizing optimized and asymmetric conductor heights within a slot for bar-wound stators. Detailed winding diagram, height optimization, ac loss analysis, and thermal performance are presented for both symmetric, i.e., conventional, and asymmetric bar windings. The proposed idea is validated using the closed-form analytical equation and 2-D time-stepped finite-element analysis (FEA). A substantial reduction of ac losses and improvement in continuous power over the wide operation range is achieved as demonstrated for a 12-pole, 100-kW high-speed (15 000 r/min) PM traction machine. Thermal performance analysis using forced liquid cooling is also included. The design and analysis methodology is presented to support high-speed traction electric machine designers meet the ever-increasing demand on efficiency and performance with bar-type windings.

中文翻译：

---

高速牵引电机的非对称绕线

介绍了一种新的非对称条形绕组概念以及对高速牵引电机的分析和好处。目标是减少交流损耗，尤其是在高速时，利用优化和不对称导体高度在条绕定子的槽内。详细的绕组图、高度优化、交流损耗分析和热性能均针对对称（即传统）和非对称条形绕组提供。所提出的想法使用封闭形式的解析方程和二维时间步长有限元分析 (FEA) 进行了验证。正如 12 极、100 千瓦高速（15 000 转/分钟）永磁牵引机所证明的那样，在较宽的运行范围内实现了交流损耗的显着降低和连续功率的提高。还包括使用强制液体冷却的热性能分析。