Control structure design and robust model predictive control for controlling a proton exchange membrane fuel cell

In this work, cell performance analysis, concept of control structure design, and controller design for a proton exchange membrane fuel cell (PEMFC) were implemented. Steady-state analysis was performed to determine suitable operating conditions. The effects of the input parameters on cell voltage and cell temperature were analyzed to investigate the dynamic behavior of a PEMFC that is important for control design. To obtain an efficient control system, the control structure design of the PEMFC was also considered to find suitable controlled and manipulated variables. Moreover, the selection of input-output pairings by considering the relative gain array (RGA) as a controllability index was applied to the control system design. Finally, model predictive control and offline robust model predictive control (MPC) based on a linear time-varying model were proposed for PEMFC control. The results showed that the steady-state operating points were selected at the current density = 0.51 A/cm2, cell voltage = 0.59 V, power density = 0.30 W/cm2, and cell temperature = 332 K. The cell voltage and cell temperature depend on the inlet molar flow rates, temperature of hydrogen and air, and operating current density. According to the RGA, the inlet molar flow rates of air and hydrogen are manipulated variables that regulate the cell temperature and partial pressure of hydrogen, respectively. Furthermore, controller design using MPC and robust MPC as a controller can demonstrate good results. Robust MPC can guarantee the stability of the PEMFC.