Evaluation and Optimization of Modulation Strategies of a Dual-Active-Bridge Converter for Electrolyzers

Electrolyzers operate as nonlinear low-voltage high-current loads, presenting significant challenges for power conversion systems. This article investigates state-of-the-art modulation schemes for the dual-active-bridge (DAB) converters, focusing on their performance and interaction with electrolyzer loads in electrolysis applications. The behavior of electrolyzers is compared with that of conventional constant voltage loads across various modulation schemes, using peak primary transformer current as the evaluation metric at three power levels: 1, 10, and 100 kW. A peak current optimization strategy tailored for electrolysis applications is proposed. Based on this, an optimized operating trajectory for the DAB converter during electrolysis is identified for each power level. The optimization results are validated experimentally using a 1-kW 20-kHz prototype, and through MATLAB simulations for the 10- and 100-kW systems. The proposed approach achieves peak current reductions of up to 15.75% at 100 W for the 1-kW system, 42.71% at 1 kW for the 10-kW system, and 60% at 10 kW for the 100-kW system, demonstrating its effectiveness in improving DAB converter performance for electrolysis applications.