Evaluation of Conducted EMI in GaN and Si based Isolated DC/DC Converters

Wide bandgap (WBG) semiconductors are ideally suited for isolated dc/dc converters that employ soft switching technology. Their faster switching speeds promote higher commutation frequencies while lower on-resistances improve efficiency. Many authors have demonstrated these strengths in a variety of topologies and applications. However, side-by-side comparisons of conducted electromagnetic interference (EMI) generated by WBG based and Si based isolated dc/dc converters are relatively limited. This research evaluates the EMI generated by the dual active bridge (DAB) converter and the LLC converter for both silicon (Si) and gallium nitride (GaN) based iterations. The power supply ratings are 400 V to 48 V at power levels up to 1 kW. Comparisons of the conducted EMI and efficiency are provided for the four prototypes. The preliminary findings indicate that GaN devices are able to improve the efficiency of isolated dc/dc converters with minimal impact on the conducted EMI.