A novel multi-pulse fractional rectifier system for hydrogen electrolyzers

Green hydrogen from water electrolysis using electricity generated by renewables will have a major contribution to the decarbonization and global energy transition. Electrolyzer (ELY) stacks are low-voltage and high-current DC loads, for which high-power rectifiers are required. Given that conventional rectifier solutions have their own limitation in terms of ac and/or dc power quality and current capability etc., this paper proposes a high-efficiency, grid-friendly rectifier system utilizing a Phase-Shifting Transformer (PST) based multi-pulse fractional converter topology. The system configuration enables harmonics cancellation at both ac-side and dc-side, and adoption of fraction converter configuration that facilitates a higher power conversion efficiency. The system also achieves higher electrical system reliability with modular converter design. The paper illustrates the detail design, analysis and validation through simulation.