Small-Signal Model for Dual Active Bridge Series Resonant DC-DC Converters with Variable-Frequency and Phase-Shift Modulation

Variable frequency and phase shift modulation can achieve zero-voltage switching (ZVS) of dual active bridge series resonant DC-DC converters(DABSRCs) over a wide operating range so as to effectively improving system efficiency and reliability. In order to study the dynamics of DABSRCs and provide the basis for the closed-loop compensator design, a continuous-time small-signal model is proposed. The generalized average modelling approach is adopted, in which the DC component of the output voltage and the fundamental component of the inductor current and resonant capacitor voltage are selected as the state variables, precisely describing impacts of the resonance on the system dynamics. On the above-mentioned basis, a closed-loop compensator is designed, which achieves the stable operation with the ZVS variable frequency and phase shift modulation. The analysis results are verified by the simulation and experimental results