分布式驱动电动汽车轮毂电机多场直接耦合设计理论与方法

In-wheel Motor has a complicated architecture, a high power density, a high Electromagnetic load, a high heat load and a complicated heat exchange in Distributed Drive Electric Vehicles, which belongs to typical Nonlinear coupling system. During system design, the multi-field Electromagnetic-thermal-fluid coupling becomes a key problem which seriously restricts the efficiency and reliability. The purpose is to break through linear decoupling of multi-physics sequential coupling of traditional modeling and solution method and to develop multi-physics directional coupling to reveal real nonlinear coupling regularity and improve design optimization in In-wheel motor system. Firstly, nonlinear effect of material, geometry and boundary is analyzed and multi-field direct coupling model is built for In-wheel motor. Approximate solution is obtained through multi-physics synchronized and bidirectional calculation. Secondly, distribution of electromagnetic field, temperature field and fluid field and parameter influence are researched to analyze and construct nonlinear mapping of motor structure, control parameters and motor loss. Finally, In-wheel motor/control unit and overall control unit models are developed combined with multi-field coupling analysis to design Multi-objective optimization with cost and mass of effective material and efficiency of motor by Fast Programming and evolutional Genetic Algorithm which can improve motor efficiency and reliability. The expected research achievements will have very important theoretical and application value for In-wheel motor design in Distributed Drive Electric Vehicles.

分布式驱动电动汽车轮毂电机结构复杂、功率密度大、电磁负荷与热负荷高，属典型的非线性耦合系统，系统中存在的电磁-热-流多场耦合效应已成为制约电动汽车高效和可靠运行的关键问题。本项目拟突破物理场顺序耦合线性解耦的传统建模和求解方法，探索多场直接耦合机理，揭示物理场真实的非线性耦合规律，提升电机系统优化设计水平。首先分析物理场的材料、几何与边界非线性效应，构建多场直接耦合模型，借助多物理场同步双向求解策略，获得近似直接耦合的解；其次研究多场耦合下电磁场、温度场、流体场分布及参数变化规律，分析并构建电机结构、控制参数与电机损耗的映射机制；最后建立轮毂电机/控制器与整车转矩分配控制模型，联合多场耦合分析，以有效材料成本、质量与效率为优化目标，利用快速寻优与改进遗传算法对电机结构与控制策略进行多目标优化设计，提高轮毂电机效率及运行可靠性。预期研究成果将为电动汽车轮毂电机系统设计提供理论基础与技术支撑。

分布式电动汽车轮毂电机电磁-热-流多场耦合关系是电机高效和可靠设计的难题。本项目突破单场分析和单向耦合方法模拟多物理场相互耦合的物理机理不够精确的问题，研究多场间相互耦合的多场双向耦合方法，建立电机的多场双向耦合模型，改进减小损耗的控制策略，优化电机的结构设计，提出轮毂电机基于多场耦合系统的设计理论和方法。首先，分析电磁场、热场、流场的分析方法及相互之间的耦合机理，热-流场之间是强耦合关系，电磁场本身是直接强耦合关系，模拟电磁-热流场间的双向耦合关系，建立了轮毂电机的多场双向耦合模型及同步求解方法，经实验验证，电机的温度模拟精度得到了明显提升；其次,在多场耦合的基础上，研究电磁场、温度场和流体场分布规律，提出电磁参数的估算方法，进行温度预测并提出改进的最小损耗控制策略；最后，研究永磁同步电机的结构参数设计优化，基于CLTP路谱，研究永磁同步电机转子结构的参数变化规律及对涡流损耗、转矩密度、齿槽转矩的影响，对永磁体轴向分段、磁桥厚度和槽机械角等结构参数进行了多目标优化设计，取得了较好的效果。研究成果将为轮毂电机高功率密度、高效率和高可靠性设计提供科学方法与实践依据。