基于多场量的笼型感应电机三维瞬态磁热固耦合计算分析

The Calculations and Analysis of 3D Transient Magnetic-thermal-solid Coupling for Squirrel-cage Induction Motors Based on Multi Fields

以一台小型感应电机为例,参考样机转子斜槽结构,利用有限元法,对电机进行了三维瞬态磁-热-固单相耦合计算。首先计算了电机在额定负载情况下的三维电磁场,计算中考虑了端部绕组对电机的影响。以三维电磁场节点的损耗密度结果为载荷,耦合到三维温度场模型中作为热源,施加边界条件,模拟了电机在额定负载情况下的瞬态温度变化过程,得到了不同时刻电机温度分布及各点温度随时间变化曲线。对比不同时刻温度分布,总结出电机内部传热规律,通过温升实验验证了仿真计算结果的准确性。最后,以转子的瞬态温度场结果为载荷,施加相应约束条件,计算并得到了转子鼠笼热应力分布情况,找到了鼠笼易断裂的位置并分析受力的原因。该文采用的计算方法可为电机多物理场耦合计算,及研究该类电机断条故障原因及导条断裂过程分析提供参考。

The 3D magnetic-thermal-solid coupling for a small induction motor was calculated using the finite element method referencing the prototype with a skewed rotor. Firstly, the 3D-electromagnetic field of the motor on the rated load condition was calculated in consideration of the influence of the end windings. Results of the 3D electromagnetic field node loss density were coupled to the 3D temperature field model as heat sources. Then, the distribution of the temperature at different time and each point temperature changing curve versus time were obtained by exerting the boundary condition, and the aim was to simulate the transient thermal change process of the motor on the rated load condition. The internal heat transfer law was summarized from the temperature distribution at different time, and the simulation results were verified by experiments. Finally, the thermal stress distribution of the rotor cage was obtained based on the results of the rotor transient temperature field by exerting the corresponding constraints. Then the location easy to fracture was found and the cause of stress was analyzed. The calculation method used in this paper can provide a reference for the multi physical field coupling issues and lay the foundation for further research on the broken bar fault reasons and the fracture process in the squirrel-cage induction motor