A novel isolated hybrid three-level DC converter with high voltage gain and wide voltage range

The isolated high-voltage gain DAB converter has extensive and significant applications in data centers, electric vehicles, and space power systems. Owing to the hardship for traditional DAB converters to attain high conversion efficiency over a wide output voltage range, this paper presents a novel type of isolated hybrid three-level DC converter. Incorporating the Boost converter into the traditional hybrid T-type three-level converter expands the output voltage range of the converter. Based on this, addressing the issue of increased conduction loss and decreased conversion efficiency caused by the excessive RMS value of the inductor current in the converter, a control strategy based on minimizing the RMS value of the inductor current is proposed. Simultaneously, in order to reduce the switching loss, the conditions for achieving ZVS/ZCS soft switching in the converter are analyzed. Finally, a 100V/15-55V converter experimental prototype is designed and established, and the performance of the new DC converter is experimentally examined. The experimental results demonstrate that the proposed new DC converter can not only achieve a high voltage gain but also attain high conversion efficiency within a wide output voltage range.