异步电动机定子绕组匝间短路三维温度场计算与分析

Simulation and Analysis of 3D Temperature Field for Stator Winding Short-circuit in Asynchronous Motor

对异步电动机定子建立三维传热模型,通过有限元法对其温度场进行计算并与实验结果进行对比。在此基础上,利用该模型对定子绕组发生不同程度的局部短路故障时定子的温度场进行了研究。结果表明,电机在运行过程中即使发生匝间短路时,温升限值也有可能达不到该电机温升等级B级的75℃,因此单纯通过国标规定的温升限值和温度极值来判断电机状态是不够准确的;随着短路程度的变化,绕组温度场的分布规律相应也发生了变化,机壳表面温升也相应变化;不同的短路位置导致绕组温度场分布规律也有所不同,因此通过温度场的变化可以在短路故障的初期进行判断;通过温度场的变化规律及温升进行联合评估,可以区分判断出定子绕组槽内匝间局部短路、端部匝间局部短路和整槽绕组的短路故障。

A 3D heat transfer model for the asynchronous motor was built and was solved by the finite element method, and the computational result was compared with the experimental one so as to certify the correctness of the model. By using this model, the 3D temperature fields of the asynchronous motor correspond to several kinds of stator winding short-circuits were simulated and analyzed. Main conclusions can be drawn as follows： the temperature rise may not reach the national standard （75 ℃ in Level B） when short-circuit happens, hence it is not reliable to judge the status of the motor simply by the temperature limit of the national standard or the maximum temperature rise; the temperature rise and the temperature field vary with the fault degree; the short-circuit faults can be found earlier and more accurate through the temperature field. The type and grade of the short-circuit fault can also be judged through temperature field along with the temperature rise.