Analysis and reduction of conducted EMI from an AC/DC high power converter

This paper discusses how to reduce conducted electromagnetic interference (EMI) from an AC/DC high power converter to agree with EN class A. Herein some passive methods of suppressing conducted EMI noise, such as mixed-mode (MM) EMI filters, snubber circuits, are used based on measurement, the sources of noise are detected with the characteristics analyzed in detail The MM EMI filter is valuable means with which the conducted EMI noise can be efficiently 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 the noise and sinks impedances required. The experiment results prove that the methods adopted are viable and effective.