Modelling, Analysis and Mitigation of the Transformer Current Ringing in Dual Active Bridge Converters

Due to the parasitic capacitances of the transformer and inductor in Dual Active Bridge (DAB) converters, ringing may happen in the transformer currents especially when the transformer turns ratio is high. This high frequency current ringing may lead to EMI issues. It is found in this paper that the inductor connected on the low voltage side rather than the high voltage side of a DAB converter can help to mitigate the current ringing. The impedance of the magnetic tank is modelled to analyze the current ringing. The analysis is verified on a 2.5 kW DAB prototype.