基于环形“感容”集成结构单元的平面EMI滤波器设计理论及实施

Design Theory and Implementation of Planar EMI Filter Based on Annular Integrated Inductor-Capacitor Unit

平面EMI滤波器以其体积小、高频性能好等优点在电力电子领域有较好的应用前景,然而目前尚未形成一个完整的理论体系用于指导该类滤波器的设计。本文首次提出一种圆环形"感容"集成结构(LC单元),以其作为平面EMI滤波器的基本组成单元;提出一种广义弧形传输线理论,基于该理论建立了LC单元的分布参数模型,利用模量转换法将LC单元等效为二端口网络;利用有限元法提取了LC单元线匝间的电磁参数,为准确研究该单元以及滤波器的电磁特性奠定了基础;详细阐述了整个平面EMI滤波器的设计流程及实施过程,并给出了相关结构尺寸初始值的经验取值。根据具体技术指标设计了若干基于LC单元的平面EMI滤波器,对其共模插入损耗特性进行了理论计算与测量,验证了设计理论的可行性。

Planar EMI filter has good application prospect in power electronics system for the advantages of small volume and good high-frequency performance.However,a complete theoretical system for the design of planar EMI filter has not been proposed yet.In this paper,an integrated structure formed by an annular 'inductor-capacitor'(LC unit) is proposed firstly,which can be used as the basic cell of the planar EMI filter.A general arc transmission theory is also proposed,based on which the distributed-parameter model of the LC unit is established.Then,this LC unit can be equivalent to the two-port network by employing the model transformation method.Besides,the turn-to-turn electromagnetic parameter is extracted by using finite element method,which provides the foundation for the research of LC unit and its electromagnetic performance of filter.The design method and the implementation of the whole planar EMI filter are elaborated in details,and the empirical initial values of the related structural sizes are also presented in this paper.In order to verify the proposed design theory,several EMI filters formed by LC units are designed according to the specifications.Common mode insertion losses of the EMI filter are calculated and measured,respectively.The results verify the feasibility of design theory.