Selective Digital Active EMI filtering using Resonant Controller

Abstract

Conventional passive EMI filters are bulky and occupy up to 30% of converter volume and weight. Active EMI filters are a key technology that enables the reduction in the size of passive components. The performance of active EMI filters (AEF) with feedback control for volume reduction is limited by relatively low-gain on the feedback loop to ensure stability. A novel digital active EMI filter (DAEF) with resonant controller which provides ultra high-gain at frequencies of interest is demonstrated for DM noise attenuation. The filter consists of noise sensing circuit, resonant controller built in the Field Programmable Gate Array (FPGA), and noise injection circuit. 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 DAEF literature.