Dynamic analysis and control optimization of hydrogen supply for the proton exchange membrane fuel cell and metal hydride coupling system with a hydrogen buffer tank

Abstract

Dynamic response hysteresis in the hydrogen supply process of a proton exchange membrane fuel cell (PEMFC) and metal hydride (MH) coupling system (PEMFC-MH system) is a significant challenge, especially during transient loads. Accordingly, this study proposes a PEMFC-MH system equipped with a hydrogen buffer tank, and the heat required by MH tanks is supplied by PEMFC waste heat through the circulating water. Additionally, this study develops three control methods, including proportional-integral-derivative control (PID), fuzzy PID control, and PID coupled with model predictive control (PID-MPC) to address the response hysteresis issue. Furthermore, this study analyzes and summarizes the variation regulations of key performance parameters, and evaluates the overall performance and energy-saving effects of the system under periodic variable current conditions. Results demonstrate that dynamic response of the proposed system can be significantly improved by implementing the pressure control target in the buffer tank. Additionally, the PID-MPC control method exhibits the optimal comprehensive control effect, combining the fast regulation rate and strong anti-interference advantages. Under PID-MPC control, the main performance parameters such as the output voltage, output power, and hydrogen supply flow, can be rapidly stabilized following short fluctuations and hysteresis, even during current transient changes. Under periodic variable current conditions, the waste heat can provide sufficient heating power for MH to meet the required transient response when the hydrogen state of charge (SOC) is above approximately 3.1%. However, if the SOC drops below this level, the MH desorption flow will sharply decrease, necessitating prompt supplementation of external heaters or additional hydrogen. Moreover, the MH system can recover around 32.1% of the PEMFC waste heat under overall operating conditions, demonstrating significant energy-saving potential. This study can provide a theoretical basis and novel approaches for controlling the hydrogen supply process of such systems.