Bidirectional Isolated Current-Source DAB Converter With Extended ZVS/ZCS Range and Reduced Energy Circulation for Storage Applications

This article proposes a bidirectional isolated dc-dc converter topology with the current-source and voltage-source terminals. Two bidirectional switches in the current-source bridge side and a novel modulation algorithm allow soft switching of all semiconductors under wide load conditions with a relatively low energy circulation and without any dedicated snubbers or clamp circuits. Zero-voltage switching of high-voltage switches can be achieved even at no-load conditions, which allows application of external snubber capacitors to reduce turn-off losses. Voltage regulation is provided using relatively simple phase-shift modulation. Design constraints of the converter are evaluated and analyzed for both energy transfer directions. The steady-state operation is presented and verified experimentally with a 500-W prototype. The efficiency of the power stage reached 96.7% and 97.2% at the maximum power in the boost and buck modes, respectively. The converter can be used in renewable, supercapacitor, battery, and dc microgrid applications.