Generalized Model for LC Resonant Dual Active Bridge DC-DC Converter for Varied Control Techniques

This paper proposes a unified mathematical model for varying control schemes of the Series Resonant Dual Active Bridge (SRDAB) Converter. The small-signal models and steady-state models of Single Phase Shift (SPS), Extended Phase Shift (EPS), Dual Phase Shift (DPS), and Triple Phase Shift (TPS) control schemes are developed, and the results are validated using MATLAB/PLECS. Since the current flowing through the resonant tank of the SRDAB is alternating in nature, the conventional averaging modeling technique fails. The state variables used in the proposed model are resonant inductor current, resonant capacitor voltage, and output capacitor voltage. The dc terms and fundamental terms of state variables have been considered for modeling. The proposed model considered two switching variables to represent the pole voltage of the input and output bridge of SRDAB for different control schemes. The legs of the two bridges have a phase angle and are represented as control parameters D1 and D2, whereas, between the bridges, there is another phase angle represented as control parameter D. In order to model the converter more accurately, transformer leakage resistance is considered. From the proposed model, it is easy to develop the small-signal models and steady-state models using different control parameters for different control schemes. The analytical expression of control to output transfer function is developed, which can further help in controller design.