基于噪声源阻抗提取的EMI滤波器高效设计方法

Efficient design method of EMI filter based on noise source impedance extraction

针对传统EMI滤波器设计方法存在单次设计不准确、多次设计调试周期长的问题,提出一种基于噪声源阻抗提取的EMI滤波器高效设计新方法。首先通过插入无源二端口网络准确、迅速地获得噪声源阻抗幅值和相位;其次依据阻抗失配原则进行EMI滤波器拓扑选择;然后综合考虑噪声源阻抗、LISN端等效负载阻抗以及EMI滤波器高频分布参数对滤波器插入损耗的影响,令滤波器的理论插入损耗等于传导EMI测试频段范围内所需的插入损耗,得到滤波器各元件准确参数,实现了EMI滤波器精确设计。最后,通过一台LED驱动电源进行实验,结果表明一次设计即可满足预期效果,验证了所提方法的准确性和高效性。

For the problems of inaccurate single design and long design cycle caused by multiple design debugging in the traditional EMI filter design method,a new method for efficient design of EMI filter based on impedance extraction from noise source was proposed.Firstly,in the new method the impedance amplitude and phase of the noise source was obtained accurately and quickly by inserting the passive two-port network.Secondly,the EMI filter topology was selected according to the impedance mismatch principle;then it was comprehensively considered the noise source impedance,the equivalent load impedance at the LISN end and the influence of the high-frequency distribution parameters of the EMI filter on the insertion loss of the filter,so that the theoretical insertion loss of the filter is equal to the insertion loss required in the conducted EMI test band range,and the accurate parameters of each component of the filter were obtained,and the accurate design of the EMI filter was realized.Finally,an LED drive power supply was used for the experiment,the experimental results show that the proposed method can meet the expected effect in one design,which verifies accuracy and efficiency of the proposed method.