The magnetic field of end windings affects the leakage reactance of end windings and the eddy current losses of end structures in the large electrical machine. With the rising of single-machine capacity, such effect becomes more obvious. However, due to the complexity of end structures of large electrical machine, it will cause difficulty in meshing and long calculation time to calculate the magnetic field of end windings by using 3-D finite element method (FEM). In order to calculate the magnetic field of end windings quickly and accurately, an improved analytical algorithm (IAA) is proposed based on the mirror image principle, which takes into account the influence of stator back core and air-gap on the magnetic field of end windings by adding the fictitious boundary current and air-gap current, respectively. Taking a 300Mvar synchronous condenser (SC) as an example, the boundary current, air-gap current and magnetic field of end windings are calculated. Then, the influence of stator back core and stator involute segment current on the magnetic field of end windings are analyzed, which provides a theoretical support for the design and optimization of SC. To validate the accuracy of IAA, the calculation result is compared with 3-D FEM.

中文翻译：

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300Mvar同步调相机端部绕组磁场的改进解析算法


大型电机中端部绕组的磁场影响端部绕组的漏抗和端部结构的涡流损耗。随着单机产能的提高，这种效果更加明显。然而，由于大型电机端部结构的复杂性，采用三维有限元法(FEM)计算端部绕组磁场会造成网格划分困难、计算时间长等问题。为了快速、准确地计算端部绕组磁场，考虑了定子背铁芯和气隙对端部绕组磁场的影响，提出一种基于镜像原理的改进解析算法（IAA）。通过分别添加虚拟边界电流和气隙电流来计算绕组。以300Mvar同步调相机(SC)为例，计算了端部绕组的边界电流、气隙电流和磁场。然后，分析了定子背铁芯和定子渐开线段电流对端部绕组磁场的影响，为SC的设计和优化提供理论支持。为了验证IAA的准确性，将计算结果与3-D FEM进行比较。