Investigation on a Shutdown Control Strategy with Residual Oxygen Rapid Elimination for Proton Exchange Membrane Fuel Cell System

Abstract

During the shutdown process of the fuel cell system for vehicles, the air entering the anode chamber can form the hydrogen/air interface, accelerating the carbon corrosion of the catalytic layer. According to optimized control strategies, the carbon corrosion of fuel cells can be reduced. Nowadays, the main control strategies include gas purging and the consumption of residual oxygen in the stack by the auxiliary load. However, the oxygen in the fuel cell stack cannot be fully consumed or can cause the single-cell voltage to rise to 0.8 V with an inappropriate discharge current drop rate and auxiliary load resistance value, thus affecting the protective effect of the shutdown strategy. In this work, a shutdown strategy of the fuel cell system is studied. After the experiment, the optimized value of the discharge current drop rate and the auxiliary load resistance were obtained. With the resistance value of 50 Ω and the current drop rate of 7 A/s, the shutdown time of the fuel cell system is 13.5 s and the time of single-cell voltage above 0.82 V in the fuel cell stack is 0.1 s. Thus, the optimized shutdown strategy can reduce the shutdown time.