Abstract—The hybrid active electromagnetic interference filter (HAEF) is considered one of the best options for improving power quality for a number of considerations. A systematic classification and identification of HAEF configurations is given, including their insertion losses, impedance compatibilities, potential applications, and comparative features. It is aimed at providing a broad per-spective on the status of HAEF technology to researchers and application engineers dealing with EMI issues. The basis of dis-cussion is an equivalent circuit model that includes all possible combinations of active and passive elements and matches these to the desirable attributes. The evaluation indicates those topologies that are known and those topol...