Sliding mode control of a linearized polymer electrolyte membrane fuel cell model

The well-known nonlinear fifth-order model of a proton exchange membrane (PEM, also known as polymer electrolyte membrane) fuel cell (PEMFC) appears to be pretty complex. In this paper, we introduce the linearized model of the original nonlinear system and propose a sliding mode technique to keep the pressures of hydrogen and oxygen at the desired values despite of changes of the fuel cell current. Since the equilibrium point at steady state is unique, we perform Jacobian linearization of the original model at steady state and find the state space matrices of the linearized system using the MATLAB Symbolic Tool Box. The linearized system is asymptotically stable as well as controllable and observable. In this paper we show that a sliding mode control technique copes very well with the fuel cell external disturbance (changes of the fuel cell current) and produces excellent results for hydrogen and oxygen required pressures.