Fast Transient Modulation of a Dual-Bridge Series Resonant Converter

In a dual-bridge series resonant dc-dc converter (DBSRC), improper transient modulation may cause dc bias current and overshoot current/voltage in the resonant tank and transformer during the step load change process. Consequently there is a long duration of oscillation before the converter may enter into the new steady state. Based on the root locus of resonant capacitor current and voltage, a fast transient modulation (FTM) is proposed in this paper. Through the adjustment of the durations of the adjacent switching intervals temporarily, the step load change transition can be a fast and overshoot-free procedure. Both simulation and experimental test prove that this modulation method can effectively eliminate dc bias current and overshoot current/voltage in the DBSRC transient process and obtain a fast transient response.