Common-mode Electromagnetic Interference Suppression Method for Full-Bridge LLC Resonant Converter

This paper introduces a noise source inverse compensation method to suppress common-mode electromagnetic interference (CM EMI) in the full-bridge LLC resonant converter. The suppression scheme employs an inverse compensation circuit to generate an opposite-phase EMI signal, effectively mitigating the periodic CM EMI generated during the switching process. CM EMI propagation paths of LLC resonant converter are analyzed, and its common-mode EMI equivalent circuit are obtained. Based on the time-domain characteristics of CM EMI, the inverse compensation circuit is paralleled with the original circuit to suppress CM EMI. Circuit simulations are conducted to investigate the suppression effect of CM EMI in the full-bridge LLC resonant converter under various operating conditions, validating the accuracy of the proposed noise source inverse compensation suppression scheme.