Common-Leg Coupled Inductor Configuration in a Three-Level Interleaved DC-DC Medium Voltage SiC-Based Converter

The article proposes and investigates an alternative coupled inductor configuration in a three-level interleaved dc-dc converter. The new common-leg coupled inductor structure is introduced, and possible modulation methods are studied and theoretically analyzed, focusing on the impact on current ripples, power losses, and common-mode noise. The concept is validated using an MV-rated, SiC-based bidirectional converter dedicated to battery storage application in a bipolar EV charging station, tested up to 1 kV and 10 kW. Furthermore, the comparative study shows that the suggested method exhibits a smaller volume when compared to the conventional approach with several single inductors, comparable performance but with a more straightforward inductor design than the tapped inductor solution, and full section current controllability, unlike the single-inductor option. Finally, using the proposed technique, common-mode noise can be entirely limited, allowing the minimization of excess filtering. Overall, the proposed inductor configuration can be effectively and competitively used in modern SiC-based three-level dc-dc converters.