The partial-resonant single active bridge DC-DC converter for conduction losses reduction in the single active bridge

Abstract

The Partial Resonant Single Active Bridge (PR-SAB) introduced in this paper is able to reduce conduction losses in the Single Active Bridge (SAB) with the addition of partial resonant phases. In the SAB, current flows through the switch snubber capacitors only during the short quasi-ZVS turnoff phases. However in the PR-SAB, current flows in the snubber capacitors instead of the switches and diodes during the partial resonant phases which occupy up to 50% of each switching period. As capacitors have negligible losses as compared to switches and diodes especially at higher voltages, conduction losses are reduced when significant portion of current is diverted to the capacitors. By reducing conduction losses, higher overall efficiency is achieved in the PR-SAB. The conduction losses reductions of the components in the PR-SAB are analysed and compared with those in the SAB. IGBT switching losses reductions during quasi-ZVS turn-off in the PR-SAB are also discussed. With the analysed conduction and switching losses, the improved efficiencies of the PR-SAB over the SAB are analytically determined. As compared to the SAB, the PR-SAB also exhibits up to 20% lower peak currents resulting in lower component stresses. These analysis are verified with experimental results obtained with a 3.4 kW hardware prototype.