Research On EMI Filter Of Switched Mode Power Supply

As the auxiliary device of switching power supply, the EMI power filter caneffective suppress the common mode noise and differential mode noise, filter the spikeinterference which produced by switch circuit and rectifier as well. This paper is basedon the high-frequency model supplied by TDK company, then a better 2 stage passiveEMI filter is proposed, with the help of pspice software, a detailed simulation is donewhich mainly focused on the impedance property of source and load and also thegrounding location that affect the insertion loss of filter, by using a simple LC resonancecircuit, the insertion loss of filter both at low and high frequency is greatly increased, itscapability of filtering is much better than that of Hybrid EMI filter.Hybrid EMI filter is now as the most popular SMPS EMI filter, it remedies thedefect of passive and active EMI filter and also combine the advantage of both. Thispaper takes some simulation of it, meanwhile it obtains some preliminary conclusions.