EMI有源滤波器与阻抗失配问题的分析

EMI滤波器的阻抗失配往往使得滤波器不仅起不到应有的作用，反而加剧了干扰分量的强度，为了弄清有源滤波器的结构类型与阻抗匹配之间的关系，本文从滤波器的主要性能参数插入损耗的基本定义入手。推导了不同结构有源滤波器的插入损耗与阻抗、滤波器增益关系的表达式。由此得出滤波器结构类型与阻抗失配情况的合理搭配．经过实验验证该结论对选用和设计EMI有源滤波器有直接的指导意义。

Analysis of EMI active filter and impedance mismatch problem

The impedance mismatch of EMI filter always make the filter can not play the expected role, on the contrary, it intense the strength of interference component. In order to understand the relation between active filter structure and impedance match, this paper derivated the relation between insert loss expression of different type active filter and the impedance and filter gain based on the basic definition of filter main performance. According to the above work, the best combination for filter type and impedance mismatch was given. This conclusion provided direct guidance for choosing and designing EMI active filter, which is proved by experiment.