Impedance modeling and stability analysis of dual active bridge converter with LC input filter

Abstract

The dual active bridge (DAB) converter is gaining more and more attention in various applications such as energy storage systems, electric vehicles and smart grids. To improve the quality of the input current, a LC filter is often cascaded at the input side of the DAB converter. However, there are instable problems of this cascaded system due to the impedance interactions of the DAB converter and the LC filter, although the DAB converter is stable at the individual operation mode. To assess the stability of the cascaded system of the DAB converter and the LC filter, the impedance model of the DAB converter is firstly developed based on generalized state-space averaging method. The developed impedance model can be used to accurately predict the stability of the DAB converter with its LC input filter. Based on the stability analysis, the optimum filter parameter design guideline is determined. The impedance model and stability analysis are validated by the simulation and experimental results.