Wide Voltage-gain Range DC-DC Converter For Fuel Cell Vehicles

Electric vehicles,which can effectively mitigate the energy crisis and the environmental pollution,has been a focus in vehicles field.In order to achieve energy control of fuel cells and supercapacitors in Fuel cells&Supercapacitors hybrid energy source electric vehicles system,DC-DC converters,which suit for fuel cells and supercapacitors respectively,are studied and proposed in this paper.Firstly,a quasi-Z-source Boost DC-DC converter for the output characteristic of fuel cell,which uses a switched-capacitor is proposed.The topology can obtain a high voltage gain with a wide input-voltage range,and requires only a low voltage stress across each of the components.The performance of the proposed converter is analyzed and compared with other converters which use Z-source networks.A scaled-down 400V/400 W prototype is developed to validate the correctness and feasibility of the proposed quasi-Z-source Boost DC-DC converter.What's more,a no-isolated wide voltage-gain range soft-switching bidirectional DC-DC converter and the modified frequency closed-loop modulation strategy for it are proposed.The output parasitic capacitors of power switches and leakage inductance of couple-inductor are used for realizing soft-switching,when the propsed converter works in the state of bidirection and high frequency.A SiC-based prototype is build,which has a voltage of 400 V at the high voltage side,a voltage of 50~100V at the low voltage side,a maximum switching frequency of 200 kHz and a power of 320 W.The efficiency of the prototype is 93.3%~95.4%.The experiment results validate the correctness and feasibility of the proposed bidirectional DC-DC converter.