A Balanced Feedforward Current-Sense Current-Compensation Active EMI Filter for Common-Mode Noise Reduction

Abstract

This paper proposes a balanced feedforward current-sense current-compensation (CSCC) common-mode (CM) active electromagnetic interference (EMI) filter (AEF). The advantages of the feedforward CSCC-type AEF are theoretically demonstrated. The operation of the proposed AEF is completely analyzed, and practical design guidelines are developed regarding performance and stability. The proposed AEF is applied to an L-C-L EMI filter for a 2.2 kW resonant inverter, and CM noises are further reduced by 3 to 18 dB from 150 kHz to 10 MHz. The problem of CM-to-differential mode noise transformation due to an unbalanced AEF structure is also investigated by the measurements using a vector network analyzer.