Three-Phase Parallel Quasi-Z-Source Low-Ripple High-Gain Grid-Connected Converter for Hydrogen Fuel Cells
Existing grid-connected converter systems for hydrogen fuel cells suffer from insufficient voltage step-up capability, weak ripple suppression, and elevated switch overcurrent risk. This paper proposes a three-phase parallel quasi-Z-source two-stage DC-boost hydrogen fuel cell grid-connected converter (TPPQZSTSDBHFC-GCC). A mathematical model of proton exchange membrane fuel cell (PEMFC) output voltage, current, and power is established to reveal the power-voltage-current relationship and response characteristics. Based on the fuel cell output characteristics, the TPPQZSTSDBHFC-GCC topology is proposed, and its operating principle and ripple suppression capability are analyzed in detail. Results demonstrate that the proposed topology achieves high voltage gain while maintaining low ripple, low overcurrent risk, and superior steady-state performance. Simulation and experimental verification confirm the correctness and effectiveness of the proposed topology. The system addresses the critical challenge of wide-range voltage fluctuations (213–323 V) and high output currents (up to 700 A) in high-power PEMFC stacks, enabling safe grid integration and extended fuel cell lifespan.