Design and implementation of the digitally-controlled active EMI filter (DSP-AEF) for noise reduction applications

In this paper, a digitally-controlled active EMI filter (DSP-AEF) is presented to solve noise reduction problems. Of course, it is possible to achieve noise reduction by use of passive filter elements; however, for a well-designed converter, by proper diagnosis of EMI noise, DSP active/passive combined (hybrid) filters can be used for this purpose. Thus, filter elements can be minimized, leading to improved efficiency, lower size and cost. Time-domain analyses of the system are shown in this paper. Experiments are finally given in detail to illustrate the analysis.