Reducing differential-mode EMI and low-frequency common-mode voltage in switching-mode power converters

This paper presents a design for an electromagnetic interference (EMI) power filter which is serially-cascaded with a conventional off-line switching-mode power converter to reduce the non-intrinsic differential-mode (DM) EMI and low-frequency common-mode (CM) output voltage in switching-mode power converters (SMPCs). The circuit configuration is extremely simple so that the size of the component can be reduced as well as its cost. Additionally, the operating principle of the proposed EMI power filter is also quite straightforward. An off-line flyback-type power converter, using the proposed EMI power filter, is analyzed in detail. Finally, some experimental results are provided in order to verify the performance and effectiveness of this converter.