An experimental study of common- and differential-mode active EMI filter compensation characteristics

Most reported compensation schemes for active electromagnetic interference filters (AEFs) use either voltage canceling or current canceling to deal with high-frequency noise interference. The purpose of this paper is to investigate the compensation characteristics of these two kinds of AEFs for different types of noise sources, i.e., common mode (CM) and differential mode (DM) noise source. This is examined by experimental identification and theoretical analysis of the insertion losses of AEF with voltage- or current-cancellation scheme. It is demonstrated that current-canceling AEFs are effective in eliminating high-impedance CM noise, while voltage-canceling AEFs are good compensation solutions for low-impedance DM noise. The results reported in the paper enable the choice of optimized compensation schemes, using the aforementioned indicated aspects.