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Technical Dialogue

Bidirectional DC-DC Converters

D02.4 - Comparison of 2-Level and Quasi-2-Level Topologies in a Bidirectional Isolated DC-DC Converter for MVDC Networks

Thursday, March 20, 2025
11:30 AM – 1:30 PM ET
Location: Level One, Hall A3
With the development of DC networks, high power DC-DC converters will play a crucial role in efficiently converting power. The traditional 2-level topologies are one solution, but they produce elevated dV/dt, which may generate excessive stress on the insulation. Quasi-2-level operation stands out as an attractive solution to scale up medium voltage active bridges and DC-DC converters while maintaining dV/dt at an acceptable level, without sacrificing efficiency. With the recent interest towards this subject, multiple topologies have been presented as candidates for a medium voltage bidirectional or step-down DC-DC converter. This paper compares bridge topologies suitable for medium voltage isolated DC-DC converters, focusing on series connection of SiC MOSFETs, Flying Capacitor Converter, and Modular Multilevel Converter. Key performance indicators (KPIs) such as the number of semiconductor devices, dV/dt, energy of passive elements, losses, and efficiency are analyzed. KPIs are calculated for a range of voltage levels and two specific case studies. Based on the results, recommendations are provided to select the most suitable topology for given constraints.