A Simplified DAB Converter Suitable for Low Voltage and Large Current Applications

In order to improve the efficiency of DAB converter in low voltage and large current applications, this paper proposes a simplified dual active bridge (SDAB) converter with reduced number of power electronic switches. By using a four-winding transformer and a coupled inductor, the SDAB converter inherits the wide range regulation ability of traditional DAB converter and combines the advantage of high voltage utilization of push-pull converter. The proposed SDAB is especially suitable for the applications where both input and output ports are with low voltage and large current, e.g. the equalization control of battery. In this paper, an improved extend-phase-shift (IEPS) modulation strategy is also proposed for SDAB converter, which makes the SDAB converter work with soft switching in a wide range. Besides, single-phase-shift (SPS) modulation strategy is also studied for comparison. A hybrid modulation strategy composed by SPS and IEPS are developed for SDAB converter on different power levels. The design methods of SDAB converter are presented as well. Finally, the effectiveness and rationality of the proposed topology and modulation strategy are verified by simulation analysis and experiments on prototype.