【作者】 张超；

【导师】 李俊琛； 赵江涛；

【作者基本信息】 兰州理工大学 ， 材料工程（专业学位）， 2022， 硕士

【摘要】 随着新能源汽车产业的迅速发展,汽车驱动电机外壳的研究和应用被越来越多的学者所关注。近年来,驱动电机单机功率不断增加,在提升电机性能的同时,使电机外壳温度迅速升高,为防止驱动电机外壳温升过高影响电机的性能及使用寿命,本文以一台额定功率为35 kW,峰值功率为110 kW的水冷永磁同步驱动电机外壳为研究对象,基于传热学和计算流体力学的基本理论,采用三维有限元软件ANSYS对驱动电机外壳的流场和温度场进行了数值模拟计算,分析了不同类型的冷却水道和散热性能敏感因素对驱动电机外壳温度的影响,对网格冷却水道驱动电机外壳进行了关键结构参数优化。本文的主要研究内容和成果如下:(1)从驱动电机外壳的冷却水道类型入手,设计了单螺旋冷却水道、双螺旋冷却水道和网格冷却水道驱动电机外壳,对比分析额定功率和峰值功率下不同类型的冷却水道对驱动电机外壳流场和温度场的影响。结果表明,单螺旋冷却水道模型冷却流体流动平稳,压降为20.46 kPa;双螺旋冷却水道和网格冷却水道模型,进水口和出水口排布在一端,水道内存在转角,压降较大,网格冷却水道模型由于水道结构复杂,流体压降最大,为85.56 kPa。网格冷却水道驱动电机外壳冷却效果最好,额定功率下驱动电机外壳最高温度为69.38℃,峰值功率下驱动电机外壳最高温度为82.35℃;双螺旋冷却水道驱动电机外壳最高温度高于网格冷却水道驱动电机外壳;单螺旋冷却水道驱动电机外壳温度最高且温度分布不均匀,散热效果最差。在相同服役工况下,网格冷却水道驱动电机外壳具有更好的散热效率,但所需水泵功率最大。(2)基于上述数值模拟中网格冷却水道驱动电机外壳散热性能的优势,对峰值功率下的网格冷却水道模型进行散热性能敏感性因素分析。计算了冷却流体浓度、入口流速和入口温度对驱动电机外壳流场和温度场的影响,计算结果表明:冷却流体乙二醇浓度由40%增加到60%时,驱动电机外壳最高温度由81.47℃增加至83.06℃,乙二醇浓度越低,驱动电机外壳的最高温度越低。在保证冷却流体防冻性的前提下,冷却流体乙二醇浓度40%时,驱动电机外壳散热效果最好;随着冷却流体的入口速度由0.9 m/s增加至1.2 m/s,流体压降由59.61 kPa增加至95.4 kPa,驱动电机外壳最高温度由83.62℃降至82.35℃,流体入口速度增加,流体的压降增大,驱动电机外壳温度逐渐减小,且温度减小的趋势逐渐变慢。流体入口流速为1.2 m/s时,驱动电机外壳散热效果最好;随着冷却流体入口温度的增加,驱动电机外壳最高温度和内壁平均温度是线性增加的。(3)对网格冷却水道模型的关键结构参数进行优化,分析峰值功率时水道关键结构参数对驱动电机外壳流场和温度场的影响。在冷却流体浓度50%,入口速度1.2 m/s和入口温度65℃的边界条件下,随着驱动电机外壳冷却水道深度由6 mm增加至8 mm,驱动电机外壳最高温度由83.83℃降低至82.35℃,且下降趋势越来越快;当冷却水道底部圆角半径由0 mm增加至3.5 mm时,驱动电机外壳的最高温度由82.35℃降低至75.43℃,其中冷却水道底部圆角半径由0 mm增加至1.5 mm时,驱动电机外壳最高温度降低幅度最大,温度降低了6.41℃,添加底部圆角半径极大提高了冷却流体的降温效率。把上述研究得到驱动电机外壳冷却最佳物理参数和关键结构参数结合,得到优化后的网格冷却水道驱动电机外壳模型。计算峰值功率下优化的网格冷却水道模型模拟结果,发现优化后冷却流体最高流速为6.31 m/s,流体压降为121.1kPa,压降在流体中的分布均匀,驱动电机外壳最高温度为75.31℃,比优化前降低了7.04℃,有效的降低了驱动电机外壳的温度。最后通过系统温升测试试验,得出模拟最高温度与实测值相对误差为3.4%,验证了本文模拟计算的有效性。更多还原

【Abstract】 With the rapid development of the new energy vehicle industry,more and more scholars pay attention to the research and application of the vehicle drive motor casting.In recent years,the single power of the drive motor has been increasing continuously.While improving the performance of the motor,the temperature of the motor casing has risen rapidly.In order to prevent the excessive temperature rise of the drive motor casing from affecting the performance and service life of the motor,this paper uses a rated power of 35kW,the water-cooled permanent magnet synchronous drive motor casing with a peak power of 110 kW is the research object.Based on the basic theory of heat transfer and computational fluid dynamics,the three-dimensional finite element software ANSYS is used to numerically analyze the flow field and temperature field of the drive motor casing.Through simulation calculation,the influence of different types of cooling water channels and heat dissipation sensitive factors on the temperature of the drive motor casing was analyzed,and the key structural parameters of the grid cooling water channel drive motor casing were optimized.The main research contents and results of this paper are as follows:(1)Starting from the cooling water channel type of the drive motor casting,the single-spiral cooling water channel,double-spiral cooling water channel and grid cooling water channel drive motor casting are designed,and different types of cooling water channels under rated power and peak power are compared to the drive motor casting.Influence of flow field and temperature field.The results show that the cooling fluid flows smoothly in the single-spiral cooling channel model,and the pressure drop is 20.46 kPa;in the double-spiral cooling channel and grid cooling channel models,the water inlet and outlet are arranged at one end,and there is a turning angle in the channel,and the pressure drop is large.The grid cooling channel model has the largest fluid pressure drop of 85.56 kPa due to the complex channel structure.The grid cooling water channel drive motor casing has the best cooling effect.The maximum temperature of the drive motor casing under rated power is 69.38℃,and the maximum temperature of the drive motor casing under peak power is 82.35℃;the maximum temperature of the double-spiral cooling water channel drive motor casing is higher than that of grid cooling.Water channel drive motor casting;single-spiral cooling water channel drive motor casting has the highest temperature and uneven temperature distribution,and the heat dissipation effect is the worst.Under the same service conditions,the grid cooling water channel drive motor casting has better heat dissipation efficiency,but the required pump power is the largest.(2)Based on the advantages of the heat dissipation performance of the grid cooling water channel drive motor casing in the above numerical simulation,the sensitivity factor analysis of the heat dissipation performance of the grid cooling water channel model under peak power is carried out.The effects of the cooling fluid concentration,inlet flow rate and inlet temperature on the flow field and temperature field of the drive motor casing were calculated.The calculation results show that when the ethylene glycol concentration of the cooling fluid increases from 40%to 60%,the maximum temperature of the drive motor casing increases from 81.47℃.Increasing to83.06℃,the lower the ethylene glycol concentration,the lower the maximum temperature of the drive motor casting.On the premise of ensuring the antifreeze of the cooling fluid,when the ethylene glycol concentration of the cooling fluid is 40%,the heat dissipation effect of the drive motor casing is the best;as the inlet velocity of the cooling fluid increases from 0.9 m/s to 1.2m/s,the fluid pressure drop From 59.61 kPa to 95.4 kPa,the maximum temperature of the drive motor casing decreases from 83.62℃to 82.35℃,the fluid inlet velocity increases,the pressure drop of the fluid increases,the drive motor casing temperature gradually decreases,and the decreasing trend of the temperature gradually slows down.When the fluid inlet velocity is 1.2m/s,the heat dissipation effect of the drive motor casing is the best;with the increase of the cooling fluid inlet temperature,the maximum temperature of the drive motor casing and the average temperature of the inner wall increase linearly.(3)The key structural parameters of the grid cooling water channel model are optimized,and the influence of the key structural parameters of the water channel on the flow field and temperature field of the drive motor casing at peak power is analyzed.Under the boundary conditions of cooling fluid concentration of 50%,inlet velocity of 1.2 m/s and inlet temperature of 65℃,with the increase of the cooling channel depth of the drive motor casting from6 mm to 8 mm,the maximum temperature of the drive motor casting decreases from 83.83℃to 82.35℃,and the decreasing trend is getting faster and faster;when the radius of the fillet at the bottom of the cooling water channel increases from 0 mm to 3.5 mm,the maximum temperature of the drive motor casing decreases from 82.35℃to 75.43℃,and the radius of the fillet at the bottom of the cooling water channel is reduced from 0 mm to 75.43℃.When it increases to 1.5 mm,the maximum temperature of the drive motor casing decreases the most,and the temperature decreases by 6.41°C.The addition of the bottom fillet radius greatly improves the cooling efficiency of the cooling fluid.Combining the best physical parameters and key structural parameters of the drive motor casting cooling obtained from the above research,the optimized mesh cooling water channel drive motor casting model is obtained.Calculate the simulation results of the optimized grid cooling water channel model under peak power.It is found that the maximum flow rate of the cooling fluid after optimization is 6.31 m/s,the fluid pressure drop is 121.1 kPa,the pressure drop is evenly distributed in the fluid,and the maximum temperature of the drive motor casing is 75.31℃,which is 7.04℃lower than before optimization,which effectively reduces the temperature of the drive motor casing.Finally,through the system temperature rise test,it is concluded that the relative error between the simulated maximum temperature and the measured value is 3.4%,which verifies the validity of the simulation calculation in this paper.更多还原