A Structure-Reconfigurable Series Resonant DC-DC Converter with Wide-Input and Configurable-Output Voltages

This paper proposes a new series resonant dc-dc converter with four configurable operation states depending on the input-voltage and output-voltage levels. It suits well for the dc-dc stage of grid-connected photovoltaic systems with a wide-input voltage range and different grid voltage levels, i.e., 110/120 V and 220/230/240 V. The proposed converter consists of a dual-bridge structure on the primary side and a configurable half- or full-bridge rectifier on the secondary side. The root-mean-square (RMS) currents are kept low over a fourfold voltage-gain range; the primary-side mosfets and secondary-side diodes can achieve zero-voltage switching on and zero-current switching off, respectively. Therefore, the converter can maintain high efficiencies over a wide voltage gain range. A fixed-frequency pulsewidth-modulated control scheme is applied to the proposed converter, which makes the gain characteristics independent of the magnetizing inductance and thereby simplifies the design optimization of the resonant tank. The converter topology and operation principle are first described. Then, the characteristics, i.e., the dc voltage gain, soft switching, and RMS currents, are detailed before a performance comparison with conventional resonant topologies is carried out. Furthermore, the design guidelines of the proposed converter are also presented. Finally, the experimental results from a 500-W converter prototype verify the feasibility of the proposed converter.