Efficiency-Aware and Constraint-Aware Control of PEMFC Air-Path using a Reference Governor and MIMO Internal Model Controller

In this paper, an internal model control (IMC) control scheme combined with reference governor (RG) for constraint management is proposed to regulate a nonlinear multivariable air-path system for a proton exchange membrane fuel cell (PEMFC) system. The control objectives are to avoid oxygen starvation, run at the maximum net efficiency, achieve fast tracking of air flow and pressure set-points, and be easy to calibrate. To operate at maximum efficiency, a set-point map is generated for air pressure at the cathode inlet. Considering that the conventional PEMFC system cannot independently control the inlet pressure using only the compressor motor, we formulated a new multivariable analysis and control scheme by considering an electronic throttle body (ETB) valve downstream of the cathode as a new degree of freedom in the control problem. Based on this new configuration of the fuel cell model, we designed an IMC controller with intuitive tuning parameters to simultaneously control airflow and pressure and achieve a fast and smooth response despite strongly coupled plant dynamics. Further, a RG using a computationally tractable linear prediction model is included with IMC-based Multi-Input Multi-Output (MIMO) controller to satisfy the constraint on oxygen level. Compared with a Single-Input Single-Output (SISO) air-flow control approach, the proposed MIMO control approach demonstrated up to 7.36 percent lower hydrogen fuel consumption.