交流电机电磁与热问题强耦合非线性网络法的理论与应用研究

The accurate numerical simulation of the electromagnetic-thermal coupled problem in the electric machine is the key to its design. At present, numerical calculation methods based on elements are widely used in the analysis of electromagnetic-thermal coupled problems, and the coupling is achieved by the loop iteration of the electromagnetic field and thermal field. However, for the analysis of transient problems with complex structures, remarkable difference in size and high degree of nonlinear, the calculation quantity is large and the calculation time is long. In this project, the electromagnetic-thermal strong coupled nonlinear network is put forward to solve above problems, the associated matrices between the electromagnetic network and thermal network are built based on the energy conservation relation between electromagnetic and thermal field, which will provide a rapid and accurate new method for the analysis of electromagnetic-thermal problems in electrical machines. Then, the proposed electromagnetic-thermal strong coupled nonlinear network method is applied in the research of losses and temperature rise for alternating-current windings. The leakage magnetic flux, losses and temperature rise for alternating-current windings with complex weaved transposition strands are achieved under transient operating condition, in which magnetic saturation in iron cores, main magnetic field of rotor and cooling structures, such as ventilating ducts, ventilating vents, are considered, which will improve the design precision of the alternating-current winding in electrical machine. Combined with NSGA-II optimization algorithm, the multi-variable and multi-objective optimization algorithm for alternating-current windings is proposed, which will provide theoretical basis for the optimization design of alternating-current windings and cooling structures.

电机电磁热耦合问题的准确数值模拟是电机设计的关键。目前，针对电机电磁热耦合问题的分析多采用基于剖分单元的数值算法，并且通过电磁与热场之间的循环迭代实现耦合，对于结构复杂、尺寸相差悬殊、非线性程度高的暂态问题分析，计算量大且费时。本项目提出基于节点的电磁热强耦合非线性网络法解决上述问题，通过磁场储能、电能以及热能之间的能量守恒关系构建电磁网络和热网络之间的关联矩阵，实现电磁热强耦合，为电机电磁热问题的分析提供快速、准确的新方法；将提出的电磁热强耦合非线性网络法应用到交流绕组损耗与温升问题的研究中，实现暂态运行工况下计及铁心磁饱和、转子主极磁场以及通风沟、通风孔等冷却结构情况下交流绕组复杂编织换位股线全域漏磁、损耗与温升的耦合求解，提高电机交流绕组的设计精度；与NSGA-II优化算法结合提出交流绕组的多变量多目标优化算法，为交流绕组和冷却结构的优化设计提供理论依据。

电机电磁热耦合问题的准确数值模拟是电机设计的关键。对于交流换位绕组这种复杂电磁热耦合问题的数值模拟，现有的基于剖分单元的数值算法存在计算量大、费时且易出现奇异解的难点问题，本项目围绕上述难点展开研究。.首先，提出了基于节点的电磁热耦合非线性网络法。以矢量磁位为未知量构建了新的非线性磁网络，以单根换位股线为基本单元构建了电网络，以感应电动势作为耦合项实现了非线性磁网络与电网络的直接耦合，建立了与电磁网络节点统一的三维热网络，以非线性电阻作为耦合项实现了电磁网络与热网络的耦合，为非线性程度高、尺寸相差悬殊的复杂结构电磁热耦合的高效、准确模拟提供了新方法。.其次，将提出的电磁热耦合非线性网络法应用到了交流绕组瞬态环流、损耗以及温升的研究中，并通过模型与真机实验进行了验证，实现了计及铁心磁饱和、转子主极磁场以及冷却结构情况下交流绕组复杂编织换位股线瞬态环流、损耗与温升的快速、准确计算，提高了电机交流绕组的设计精度，为新产品的开发与研制提供了技术支持。.然后，研究了铁心磁饱和、转子主极磁场、绕组结构以及冷却结构对交流绕组瞬态环流、损耗以及温升计算结果的影响。研究表明，在不同运行工况下的环流计算中，除全换位结构以外，其他换位结构均应考虑铁心磁饱和以及转子主极磁场的影响；在涡流损耗计算中，对于端部较长的交流绕组，应该同时考虑槽部和端部涡流损耗；在温升计算中需要考虑实际绕组换位结构与冷却结构。.最后，将电磁热耦合非线性网络法与NSGA-II优化算法结合，提出了交流绕组的多变量多目标优化算法，得到了可以减小环流损耗、改善股线温升分布的交流绕组结构优化方案，为交流绕组和冷却结构的优化设计提供理论依据。.通过本项目的研究，为电机电磁热耦合问题的分析提供了快速、准确的新方法，形成了新的交流绕组分析与设计方法，为大型交流电机的工程设计提供了设计准则。

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