A Wide Range Input Buck–Boost Converter With Duty Cycle Symmetric Shift Control for Hydrogen Fuel Cell System

ABSTRACT To address the voltage matching issue in hydrogen‐electric hybrid power systems of fuel cell vehicles, this paper proposes a buck–boost DC–DC converter for the hydrogen fuel cell system, which features a wide voltage conversion range, common ground structure, continuous input current, and positive output voltage. The converter adopts a duty cycle symmetrical shift control method, enabling high voltage conversion with a narrow duty cycle at a fixed frequency, effectively reducing switching losses and voltage and current stresses on power components. This paper deeply analyzes the operation mechanism of the converter, determines the stability conditions of the critical working mode, and makes relevant characteristic comparisons with other similar converters. A 300 W experimental prototype was fabricated, accommodating a wide input voltage range from 40 to 300 V while maintaining a regulated 200 V output. The experimental results show that when the input voltage rises/falls/jumps slowly and the load switches, this system can effectively reduce the inrush current and starting current and stably output a 200 V voltage, and the output voltage ripple rate remains below 1%. Under full load, the converter's maximum efficiency can reach 96.36%. The experiments verify the correctness of the theoretical analysis and parameter design.