A Novel Switching Strategy of Dual Active Bridge Converter with Hybrid Switch for Efficiency Optimization

In this paper, a switching strategy is proposed for the extended phase shift (EPS) controlled dual active bridge (DAB) converter which using the hybrid switch (HyS) configured by paralleling SiC MOSFET and Si IGBT, considering the special soft switching characteristic of DAB. For most of the existing literature, the common switching strategy of HyS is to switch on the SiC MOSFET before Si IGBT and switch off the SiC MOSFET after Si IGBT. However, if only using this switching strategy, the SiC MOSFET may be damaged by long-time operating at the over rated current condition. The proposed switching strategy for the HyS is that the SiC MOSFET is only conducted for a short while during the process of switching Si IGBT on or off. The proposed switching strategy can shorten the conduction time of SiC MOSFET, decrease the losses of HyS and extend the safe operation area of HyS. Simulation results on a 30 kW HyS DAB converter verify the availability of the proposed switching strategy.