Control and Study of the Three-Phase Three-Level Dual Active Bridge DC Converter

Multilevel DAB converters can share more effectively the reverse voltage compared to conventional dual active full-bridge converters, reducing the cost of switching tubes at the same power and voltage levels. At the same time, the increased control freedom of multilevel makes the control objectives more flexible, combining optimization objectives such as soft switching and inductor current reduction. In this paper, we propose a three-phase three-level dual active converter, based on the power transfer characteristics of dual phase shift control in the time domain, deriving the effect of inductor current with phase shift angle and variable voltage ratio, and determining the conditions for the switching tubes to work in soft switching, which effectively reduces the DC bus current fluctuation. Finally, the correctness of the theoretical analysis is verified by simulation.