A novel approach for dynamic gas conditioning for PEMFC stack testing

The air supply to the polymer electrolyte membrane fuel cell (PEMFC) stack is crucial for the performance of a PEMFC system. To enable modular and transient testing of the stack during development, a novel dynamic gas conditioning system is presented. To meet the requirements of transient stack testing, different hardware concepts for the testbed are evaluated and an experimental setup is realised. The thermodynamic states of this system are coupled through various relations and represent a nonlinear multivariate control problem. For controller design a dynamic nonlinear model of the system is derived and parameterised with measurements from the testbed. To decouple the system and achieve a good transient response the model-based nonlinear control concept of exact input-output linearisation is applied. Based on the decoupled system, a Two-Degree-of-Freedom (2DoF) controller is designed. The application of this nonlinear control concept on the realised hardware setup shows that accurate trajectory tracking during dynamic set point changes is ensured. Experimental results are presented to validate the control performance.