大功率AC/DC变流器传导电磁干扰分析与抑制

摘要

This paper discusses how to reduce conducted electromagnetic interference (EMI) in an AC/DC converter system to accord with EN class A. Herein some passive methods of suppressing conducted EMI noise, such as mixed-mode (MM) EMI filters, snubbing circuits, are used. Based on measurement, the sources of noise are detected with characteristics analyzed in detail. The MM EMI filter is valuable means with which the conducted EMI noise can be effectively reduced. A simple method of designing EMI filter, combining theoretical calculation with practical modification, is presented. It is easily implemented with only the amplitude of noise and sink impedances required. The experiment results prove that the methods adopted are viable and effective.%本文研究了AC/DC变流器中传导电磁干扰 (EMI) 的抑制问题.在系统干扰测量和干扰源及干扰传播通道分析的基础上,提出了传导EMI的抑制方法,如采用混合式EMI无源滤波器、加装吸收电路等.混合式EMI滤波器对系统传导EMI抑制起着主导作用,能有效的滤除传导电磁干扰的低频成分和部分高频成分.简要介绍了所采用的理论计算和实际微调相结合的EMI滤波器的设计方法,该方法的特点是易于实施,只要求测量噪声幅度和噪声接受体的阻抗即可开始设计.实验结果表明,所采用的方法使变流器的电磁干扰得到了有效的抑制,并使系统满足了EMC标准要求.