Transformerless High Step-Up DC-DC Converter With Low Voltage Stress for Fuel Cells

Conventional dc-dc boost converter has limited boost capacity, and its power device suffers high voltage stress. A novel hybrid Z-source dc-dc converter featured with high step-up capability and low device voltage stress is proposed in this article. Compared with the basic structure, the proposed topology can achieve higher voltage gain under the same duty ratio, and reduce the voltage stresses on the switch and diode under the same output condition. Moreover, the duty ratio is not limited. The detailed analysis and a comparison considering the proposed and other structures are also presented, which confirms its unique advantages. To verify the proposed converter performance, a prototype circuit with 40V-60V input voltage, 400V output voltage and 200W output power is built in the laboratory. Experiment results confirm the analysis and the boost capacity of the proposed converter.