Dual Active Bridge Bidirectional DC-DC Converter Modeling for Battery Energy Storage System

This paper studies the mathematical model of dual active bridge (DAB) DC-DC converter under the variations of bus voltage and battery voltage. In view of the fact that the DAB converter has a bounded change of the power supply voltage on the high-voltage side and a controllable change of the electromotive force (EMF) load on the low-voltage side, the power supply voltage on high-voltage side and the EMF load voltage on low-voltage side are taken as control variables. The states of DAB converter during a switching cycle are analyzed, and the averaged model (HL model) of the DAB converter under the condition of continuous conduction mode (CCM) is established as well as the small-signal model. The comparisons are made between the output voltage of the HL model and the topology circuit with simulation. And according to the small-signal model, the dynamic performance of the DAB converter is analyzed under the variations of the power supply voltage, the EMF load and phase-shift radio. The result shows that the proposed HL model has the same steady and dynamic performance as the circuit topology model. The relative error of the model at steady state is only 0.35%. Therefore, the applicability and the accuracy of the proposed model in battery energy storage system can be verified.