Design and Implementation of Selective Active EMI Filter with Digital Resonant Controller

In the power electronics equipment, passive EMI filters occupy up to 30% of system's volume and weight. In order to reduce the size of passive EMI filter in the power electronics system, active EMI filters (AEF) is introduced. With the AEF approaches, the size of the passive component within the EMI filter can be reduced by more than 50%. The higher attenuation achieved by AEFs, the more size reduction can be obtained through AEFs methodology. However, the performance of AEF with feedback control is limited to around 24 dB attenuation in the reported work. New methodology needs to be found to push forward the performance. In this study, a novel digital active EMI filter (DAEF) with the resonant controller, which provides ultra high-gain at frequencies of interest, is demonstrated for DM noise attenuation. The experimental test results show that the proposed EMI filter has 45 dB more attenuation at 150 kHz than the conventional passive EMI filter, which is also the highest attenuation reported in the AEF literature.