Thermal and Air Management of an Open Cathode Proton Exchange Membrane Fuel Cell Using Sliding Mode Control

The paper presents a simplified nonlinear model for an open cathode proton exchange membrane fuel cell (PEMFC) and its control using three different control strategies. The model presented uses four state variables. The mass flow of oxygen, hydrogen flow, water flow, and temperature were taken to be the critical dynamics in the system. The unknown parameters were estimated using the experimental data of a 1.2 kW PEMFC. The simplified model showed good agreement with experimental results. Control schemes were implemented to control the stack temperature and the oxygen excess ratio of the PEMFC. The proportional (P) and proportional–integral (PI) control performed well but had a poorer response compared to the sliding mode control (SMC) scheme. The study of the different control schemes reveals the dangers of solely controlling either the oxygen excess ratio or the temperature. Results show that the best control is achieved when the excess ratio is controlled together with the reference temperature. The study also compares the parasitic losses from the fans caused by the different controllers. Overall, the results provide a good insight into designing a robust control system for an open cathode PEMFC for faster response and greater durability of the PEMFC.