A New Multilevel Dual Active Bridge DC-DC Converter

Solid State Transformer (SST)is playing crucial role in implementation of MVDC grid integration with various energy sources. Bidirectional Isolated Dual Active Bridge (DAB) is an integral part of SST. When control scheme such as Single Phase Shift technique is used, it causes high circulating power and high dv/dt. It leads more voltage stress and less efficiency of the system. Moreover, this scheme has only one degree of freedom for controlling power i.e by changing phase shift only. It confines its ability to regulate power flow. In this paper, symmetrical five level Bidirectional Dual Active Bridge is proposed with five degrees of freedom. It increases its ability to regulate power flow. As number of voltage level increases, it leads to less dv/dt thus reducing the voltage stress on the system with elimination of the circulating power resulting in more efficient system. Performance of the proposed topology has been verified via simulation in MATLAB software.