A family of interleaved isolated three‐level DC/DC converters

Abstract

This paper proposes a family of bipolar step‐up cells (BSUCs). Additionally, a family of interleaved parallel isolated high‐gain DC/DC converters with bipolar outputs based on the BSUCs is proposed. Using one of these converters as an example, it is demonstrated that the converter inherits the advantages of DC three‐level characteristics, resulting in low component voltage stress and low output voltage ripple. Moreover, the converter features a low input current ripple, electrical isolation, bipolar outputs, high voltage gain and operates both switches and diodes in a soft‐switching state. Furthermore, the neutral point of the bipolar outputs in this converter possesses self‐balancing characteristics, effectively mitigating the impact of parasitic parameters on voltage balance. Even with a significant deviation of the duty cycles in the main switches, the influence on the neutral point voltage balance remains very slight. Besides, to address the difficulty of accurately calculating output voltage ripple using traditional methods, a voltage ripple calculation method based on linearizing the charging of the output capacitor is proposed, characterized by its high accuracy and simplicity in the calculation process. Finally, an experimental prototype is established to verify the performance of the proposed converter.