Enhanced Zero-Voltage-Switching Conditions of Dual Active Bridge Converter Under Light Load Situations

Generally, power electronic converters are designed to obtain the highest efficiency at the rated power while they are partially loaded during most of their operation time. For dual active bridge (DAB) converters, the zero-voltage-switching (ZVS) is prone to failure in light load situations, where precise ZVS conditions are needed but the commonly used current-based and energy-based methods are not good enough to characterize the operating boundaries of the ZVS realization. In this paper, based on the practical turn-on procedure, an improved calculation method of the ZVS condition is introduced here. The method mainly focuses on analyzing the transient procedure during the dead time, by taking into account the non-linearity of the parasitic output capacitance of the transistors. Also, comparative experimental results are shown to validate the feasibility of the analysis.