Nonlinear Thermal Modelling and Control of a PEM Fuel Cell Stack

The purpose of this paper is to present a nonlinear control method for accurately maintaining coolant temperature within a proton exchange membrane (PEM) fuel cell stack by controlling coolant flow rate. Due to the current sensitive nature of the membrane and a strict relative humidity requirement it is critical to precisely control the internal temperature of the fuel cell. First, an optimization-based parameter identification is applied to determine unknown coefficients to the nonlinear thermal model of the fuel cell stack. The stack is modelled according to a lumped parameter Continuous-flow Stirred Tank Reactor (CSTR) form. The paper then presents a nonlinear disturbance rejection control technique to accomplish the necessary temperature control. Experimental data from a 17-cell fuel cell stack is used for both the modelling and control portions of this work.