A Novel Bidirectional DC/DC Converter with Wide Voltage Gain Range for Energy Storage Device

A novel bidirectional DC/DC converter as interface between energy storage device and DC bus is proposed in this paper. Compared with bidirectional traditional cascaded DC/DC converter, this new converter is also composed of two conventional two-level DC/DC converters. However, the two two-level converters in this converter are connected in parallel on the input side rather than in series. In addition, the voltage gain of the proposed converter is higher than bidirectional traditional cascaded DC/DC converter, because this new converter establishes the higher charging voltage of inductor in the step-up mode, which makes the inductor store more energy and transfer more energy to the high voltage side. Besides, the high voltage sides of the two converters are connected in series to constitute the whole high voltage side of converter, which further enhances the voltage gain and reduces the voltage stress on the power switches and capacitors. The operating principle and the steady-state analysis are presented detailedly in this paper. Finally, a 400W experimental prototype of the proposed converter is developed to verify the correctness of the theoretical analysis. The maximum efficiency of the converter is 95.23% in step down mode and 94.54% in step up mode.