A Multimode Self-Optimization Electrolysis Converting Strategy for Improving Efficiency of Alkaline Water Electrolyzers

Alkaline water electrolysis is widely employed for industrial-scale hydrogen production due to its simple structure, low cost, and mature technique. However, the low-load inefficiency of alkaline water electrolyzers (AWEs) results in a narrow operating range (usually 40%–100% of rated power), which makes AWEs hardly follow the fluctuating photovoltaic (PV) power over a wide range. Focusing on this issue, this article proposes a multimode self-optimization electrolysis converting (MMSOEC) strategy and its prototype converter to enhance the efficiency of AWEs. Through the proper combination of dc power and pulse power, the proposed MMSOEC technique can reshape the excitation electric field of AWEs; in this way, the performance of AWEs is greatly enhanced. The effectiveness of the proposed technique is verified through a commercial AWE directly driven by PV arrays. Experimental results show that the efficiency enhancement can be up to 15.4% under the low-load condition as compared to the conventional pure dc power supply.