Common-mode EMI evaluation of forward converter with various core-reset schemes

Authors: MOHAMMAD ROUHOLLAH YAZDANI, NAHID AMINI FILABADI

Abstract: In switching power converters, electromagnetic emissions can interfere with the normal operation of the converter or other adjacent systems. Among various power converters, forward converters are widely used at low and medium powers that need a transformer core-reset scheme. In this paper, a prediction procedure for conducted common-mode EMI of a single-switch forward converter is presented, and common-mode EMI levels are predicted considering heat-sink parasitic capacitors and main PCB parasitic elements. The accuracy of prediction results is examined via experimental results. In addition, effects of conventional passive core-reset schemes on the conducted EMI are evaluated via experimental results. Along with the passive reset scheme, common-mode EMI of the low-side and high-side active clamps are evaluated. Finally, the EMI comparison between various core-reset techniques is presented.

Keywords: Electromagnetic interference, common-mode EMI, core-reset, electromagnetic compatibility, forward converter

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