大功率高速永磁电机三维全域热-流场分析

Analysis of Three-dimensional Global Heat and Fluid Field of High Power High Speed Permanent Magnet Motor

大功率高速永磁电机采用空-水冷混合冷却系统,同时存在水流域和空气流域,常规的单流域数值计算简化模型很难精确计算电机温度场。本文以一台1.12MW、18000r/min的空-水冷高速永磁电机为例,建立三维全域流-固求解域模型,提出多层变尺度网格划分方法,实现对电机网格的精细化控制。采用有限体积法对流体场及温度场进行耦合计算,揭示了水流场与空气流场的流动特性以及电机内各个部件的温度场分布特性。将全域热流场计算结果与实验结果进行对比,验证了计算方法的准确性。基于全流域计算结果,拟合出对流换热系数与双螺旋水道轴向位置的关系式。为高速永磁电机冷却系统优化设计等相关研究奠定基础。

The high power and high speed permanent magnet motor adopts air-water mixed cooling system, and there are water flow region and air basin at the same time. It is difficult to calculate the temperature field of motor accurately by the conventional simplified model of single basin numerical calculation. In this paper, a 1.12MW, 18000r/min air-water-cooled high speed permanent magnet motor is taken as an example to establish a three-dimensional global fluid solid solution domain model, and a multi-layer variable scale grid generation method is proposed to realize the fine control of the motor grid. The coupling calculation of fluid field and temperature field is carried out by using the finite volume method. The flow characteristics of the flow field and air flow field as well as the temperature field distribution characteristics of each component in the motor are revealed. The accuracy of the calculation method is verified by comparing the calculation results of the whole heat flow field with the experimental results. Based on the whole basin calculation results, the relationship between the convective heat transfer coefficient and the axial position of the double helix channel is fitted. It lays a foundation for the research of cooling system optimization of high speed permanent magnet motor.