Common mode EMI evaluation of a single-switch forward converter

In switching power converters, electromagnetic emissions should be managed and reduced to avoid interferences with the normal operation of the converter or nearby systems. Forward converters are widely used in low and medium powers which need transformer-reset schemes. In this paper, conducted common-mode EMI prediction of a single-switch forward converter is presented considering main parasitics including PCB traces. The accuracy of simulation results is examined via experimental results. Also, effects of three traditional transformer-reset methods on the conducted common mode EMI are evaluated based on the EMI measurement to select the proper core reset scheme from the EMI viewpoint.