大容量高频变压器在轨道交通、配电等领域具有重要的应用价值。相较传统工频变压器，其一方面应用场景及电压、电流、频率等级多样，传统变压器的经验设计法不再适用，另一方面高频下体积的大幅度减小使得变压器绝缘和散热问题更为严峻。需对高频变压器进行多物理场精准建模，将高频变压器设计问题转换为多目标优化问题，实现功率密度和效率综合最优的变压器设计，基于此，本文主要研究内容包括：在变压器绝缘电场建模方面，提出了基于多重迭代镜像法的八柱等效模型，将实际复杂几何结构变压器电场求解转化为空间内八个带电圆柱体的电场分布求解，降低计算复杂度，提升绝缘电场计算精度。在漏感建模方面，基于叠加定理和洛氏高度等效方法，提出一种通用的适用于非理想几何结构变压器的漏感精准解析模型，基于此模型，得到漏感调整的新的自由度，严格证明基于此自由度的漏感上下确界，并给出在此边界范围内的变压器漏感精准调整方法，实现变压器的灵活设计。在损耗建模方面，通过多区域电导率等效的方法将空心铜导体绕组等效为多个电导率不同的铜箔绕组并联的形式，提出变压器空心铜导体绕组交流损耗的精准解析模型。为应用空心铜导体绕组的大容量高频变压器优化设计提供理论基础。在温度场建模方面，提出综合考虑结构热各向异性和多种散热方式的集总参数热阻网络，该热阻网络同时将损耗和温度的耦合影响考虑在内，极大提升模型计算精度。在变压器优化设计方面，首先提出一种基于定制水冷板和高导热铝块填充的高散热效率散热结构，在此结构下提出高频变压器通用的理论参数优化设计方法。基于优化方法得到的理论优化结果，本文重点解决样机制作过程中的工艺难题，最终实现理论与实验结果吻合的高功率密度高效率变压器样机制作。本文研究成果为大容量高频变压器提供了系统的整体优化设计方案，对于提升变压器功率密度、运行效率、可靠性有重要参考价值。
High-power high-frequency transformers have important application value in rail transit, power distribution and other fields. Compared with the traditional power frequency transformer, on the one hand, the application scenarios and voltage, current and frequency levels of high frequency transformers are diverse, and the empirical design method of the traditional transformer is no longer applicable. On the other hand, the large volume reduction at high frequency makes the insulation and heat dissipation problems of the transformer more serious. It is necessary to carry out accurate modeling of multi-physics fields for high-frequency transformers, convert the design problem into multi-objective optimization problems, and realize the comprehensive optimization design of power density and efficiency of the transformer. Based on this, the main research contents of this thesis include:In the research of insulation electric field modeling, an eight-column equivalent model based on the multiple iterative mirroring method was first proposed, which transformed the electric field distribution solution of the actual complex geometric structure transformer into the electric field distribution solution of eight charged cylinders in space, reducing the computational complexity. The proposed model can improve the accuracy of transformer insulation electric field.In the research of leakage inductance modeling, based on the superposition theorem and the Rogowski height equivalent method, a general accurate analytical model of leakage inductance suitable for transformers with non-ideal geometric structures is proposed. Based on this model, a new degree of freedom for leakage inductance adjustment is obtained. The thesis also strictly proved the upper and lower bounds of the leakage inductance based on this degree of freedom, and give a precise adjustment method for the leakage inductance of the transformer within this boundary range, so as to realize the flexible design of the transformer.In the research of loss modeling, an accurate analytical model for the AC loss of hollow copper conductor winding of high frequency transformer is proposed. In this model, the hollow copper conductor winding is equivalent to the parallel connection of multiple copper foil windings with different conductivities. It provides a theoretical basis for the optimization design of high-power high-frequency transformers using hollow copper conductor windings.In the research of temperature field modeling, a lumped parameter thermal resistance network that comprehensively considers structure thermal anisotropy and multiple heat dissipation methods is proposed. The thermal resistance network also consideres the coupling effect of loss and temperature, which greatly improves the calculation accuracy of the model.In the research of transformer optimization design, a heat dissipation structure with high heat dissipation efficiency based on custom-made water-cooled plates and high thermal conductivity aluminum block filling is firstly proposed. Under this structure, a general theoretical parameter optimization design method for high-frequency transformers is proposed. Based on the theoretical optimization results, the thesis focus on solving the technical problems in the process of prototype production, and finally realize a high-power density and high-efficiency transformer prototype that matches the theoretical results.The research results of this thesis provide an overall optimization design scheme for the high-power high-frequency transformer, and have important reference value for improving the power density, operating efficiency and reliability of the transformer.
