The common-rail hydrogen supply concept represents a new design approach for high-power and multi-stack fuel cell systems (MSFCS) aimed at achieving low cost and low redundancy. However, inter-stack coupling poses major challenges to the uniform and stable hydrogen supply. To address this challenge, this study experimentally investigates the effects of hydrogen injector control strategies and operating frequency in a common-rail system on the system performance and hydrogen supply quality of a MSFCS. These characteristics are quantitatively evaluated using anode pressure fluctuation amplitude ( ΔP ), stack-to-stack pressure difference ( δP ), steady-state error of anode–cathode differential pressure ( ε ), and average single-cell voltage ( V cell ). The experimental results demonstrate that stable anode pressure is achieved at injector operating frequencies of 20-40 Hz for both strategies. The optimal performance with ΔP ≤ 1.1 kPa, δP ≤ 1.2 kPa, ε ≤ 0.8% is achieved at 30 Hz under the multi-injector independent control (MIIC) strategy. In contrast, injector operation at 50 Hz leads to pronounced low-frequency, large-amplitude pressure oscillations, indicating increased risk of unstable hydrogen supply. Overall, MIIC consistently provides superior stack-to-stack uniformity, reducing ε and δP by 85.6% and 24.3% on average compared with multi-injector unified control (MIUC). However, MIUC may suppress the propagation of local disturbances, by coordinating all injectors based on a global pressure constraint, providing improved tolerance to risks such as injector malfunction and thereby enhancing hydrogen supply reliability. These findings provide practical guidance for selecting injector operating frequency and control strategy to ensure stable and reliable operation of MSFCS.
Zhou et al. (Fri,) studied this question.