Automated acquisition of circulation characteristics for fuel cell ejector using 2-DOF control strategy

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ABSTRACT The recirculation ratio of ejectors is a crucial index to determine their performance. However, the acquisition of ejector flow characteristics is time-consuming and labor-intensive and often needs to be tested in conjunction with a stack. To this end, an ejector test platform is introduced that can simulate the ejector operation within fuel cell system. Then, a model-based two-degree-of-freedom (2-DOF) control strategy is proposed to realize the control of the buffer tank pressure and exhaust valve flow rate, which serve to simulate the anode pressure and hydrogen consumption. Moreover, the dynamic response and robustness of the control strategy are also verified by simulation and experiment on an 80 kW ejector test platform. The results show that the settling times of both pressure and flow rate are within 3 s and without steady-state error. In terms of robustness, the controller can cope with the fluctuation of the gas source pressure and even maintain dynamic performance under different anode volumes, circuit flow resistances, and ejectors. This study realizes the rapid automated acquisition of ejector circulation characteristics, contributing to the development of ejector-based hydrogen supply subsystem.