考虑散热与不确定性的永磁同步电机转子设计理论与方法

Permanent magnet synchronous motor has wide range of applications, and the rotor with excellent cooling effect is an important guarantee for continuously working of motor. Aiming at the heat dissipation design of rotor, combined fluid-solid coupling heat transfer model and uncertainty analysis, thermal structural optimization method of motor rotor will be studied. To investigate the coupled mechanism of the heat transfer, flow and friction on the moving contact interface of rotor, fluid-solid coupled heat transfer model with thermal analysis data between fluid domain and solid domain is established. On this basis, heat dissipation, maximum temperature, fluid energy consumption are chosen as the integrated objective function, the model of thermal structural topology optimization based on multi-objective function is demonstrated. Sparse grid function interpolation and sparse grid numerical integration will be extended to the uncertainty analysis for rotor design, and then the two techniques will be respectively used for reliability failure probability and robust moment estimation. The sizing optimization of thermal structural for rotor design will be achieved under the uncertainty condition. An empirical research on the motor design problem with independent intellectual property rights is studied, improving the rotor performance under the influence of flow-heat-solid coupling constraint and material properties, physical dimensions and loading conditions with uncertainty factors, and the reliability and robustness of optimal hole and groove structure on the rotor is achieved. The optimization results will contribute to the development of rotor toward the compactness, light weight, high power density and strong heat dissipation, then it provides a new theory and method for permanent magnet synchronous motor rotor design.

永磁同步电机应用广泛，转子良好散热是其持续工作的重要保证。项目以提升转子散热效果为主旨，结合流-固耦合传热模型和不确定性分析，开展电机转子结构优化设计方法研究。探讨转子移动接触界面上传热、流动与摩擦耦合机理，研究流体域与固体域之间的热分析信息传递，建立转子流固耦合传热模型。在此基础上，以散热弱度、最高温度与流体能耗为综合优化目标，构建转子结构多目标拓扑优化数学模型。研究基于稀疏网格函数插值与数值积分的转子不确定性分析，实现基于稀疏网格技术的可靠性失效概率估计和稳健矩估计，开展基于不确定性条件的转子结构尺寸优化方法研究。并针对某自主产权的电机进行实证研究，改善流-热-固耦合作用以及材料属性、几何尺寸与载荷工况不确定性对转子性能的影响，确保转子最佳孔槽结构设计的可靠性和稳健性，实现转子结构紧凑、质量轻、功率密度高、散热能力强的预期。为永磁同步电机转子结构设计提供一种新理念与方法。

本项目从电动汽车永磁同步电机热固耦合传热问题为出发点，结合多材料结构、多场耦合作用和不确定性因素，开展多材料-多场耦合不确定条件下永磁同步电机结构拓扑优化方法研究，为永磁同步电机结构设计提供一种新方法。将无网格广义有限差分法引入到热传导结构拓扑优化，将多元函数泰勒级数展开和加权最小二乘拟合相结合，探讨选取不同支撑域节点数量对复杂边界结构拓扑构型的影响机制；针对传统单材料热固耦合拓扑优化设计难以实现结构材料与性能综合最优的问题，提出一种基于变密度理论有序材料属性有理近似模型的多材料拓扑优化方法，借助归一化加权法定义以结构柔度最小化和散热弱度最小化的目标函数模型，推导多材料、多目标条件下热固耦合结构拓扑优化的迭代格式，分析对比不同权系数以及不同材料属性组合对优化结果的影响规律；针对材料与载荷不确定性设计问题，采用证据理论描述材料属性与载荷工况的非概率不确定性模型分布，借助均匀化处理方式与一阶可靠度方法完成可靠性约束下的结构拓扑优化设计；针对载荷工况满足随机场模型，建立基于稀疏网格技术的稳健拓扑优化数学模型，借助Larhunen-Loève展开将随机场载荷转化为有限个不相关的随机变量组合，将稳健设计问题转化为求解一组多工况加权多目标确定性设计问题；同时分析永磁体厚度、宽度、转子直径、永磁体外直径、永磁体N、S极距离、永磁体两块N极底部距离、永磁体到轴距离、转子上开孔直径以及定子槽宽对永磁电机气隙径向磁密、空载反电势、电磁转矩、转矩波动与定子铁芯损耗的影响规律。同时分析电机在额定转速额定功率、额定转速峰值功率、峰值转速额定功率和峰值转速峰值功率四个工况条件下电机定转子结构的温度场分布。在此基础上，以转子磁钢的极弧系数、磁钢厚度和定转子之间气隙径向距离为优化参数，采用田口优化算法对永磁同步电机转子进行优化设计；项目研究工作为我国电动汽车永磁同步电机结构自主创新提供重要的理论意义和应用价值。