The Effect of DAB Converter Series Inductor Configurations on the Transformer Interwinding Capacitance Voltage Waveform

This paper presents a detailed analysis of the voltage waveform across the transformers interwinding capacitance in an isolated dual-active-bridge converter operated with the single-phase-shift scheme. Three scenarios are analyzed, varying in the way the series inductor is connected to the transformer. It is shown that the interwinding capacitance voltage waveform variation can be eliminated by replacing the converter series inductor with either a split inductor or by using the transformer leakage inductance as the series inductor. The experimental results demonstrate the accuracy of the presented analysis with negligible off-set. Second-order resonances are observed on top of the underlying shape of the measured waveforms, and the experimental results show a reduction in its amplitude by more than a factor of 7 by exchanging the single series inductance with a split inductor or by using the transformer leakage inductance as the series inductor. Finally, it is demonstrated that the total power loss of the converter is reduced by up to 29 % when the single series inductor is exchanged with a split series inductor.