DC Bias Elimination and Soft Switching in Transient State of Dual-Active-Bridge DC-DC Converter

Dual active bridge is a promising isolated bidirectional DC/DC converter which has attracted more and more attention due to its advantages of zero-voltage switching, great voltage regulation ability, high power density, and fast dynamic response. However, the DC bias problem is seldom mentioned, which may lead to system instability and decreased efficiency. Besides, whether the converter can realize soft switching in the dynamic process is unclear. This paper proposed a novel phase-shift loading mode which can not only realize the DC bias elimination but also achieve zero voltage switching (ZVS) during a transient state. Finally, a 4.5 kW prototype is built and experimental results are provided to verify the conclusion.