Impact of Low Frequency Narrow Pulse Current on the Degradation of Proton Exchange Membrane Fuel Cells

Multi‐phase DC/DC converter is widely used in fuel cell vehicles to adjust the voltage. Single phase mode of converter is adopted to increase efficiency when current ripple meets requirement. Therefore, it is necessary to commutate between different phases at low frequency, due to the temperature rising of each phase‐leg. However, narrow pulse current occurs during the phase commutation. Pulse current can cause variations in water and gas content inside the proton exchange membrane fuel cell (PEMFC), which is the driving force for degradation. To analyze the effect of low frequency narrow pulse current on fuel cell, an isothermal 1D‐PEM fuel cell model is presented to characterize the transient changes of these parameters: gas stoichiometry, relative humidity, water content and pressure difference. After comparing the influence on fuel cell of four types of pulse current, the results reveal that the 4 ms narrow pulse current cannot affect fuel cell lifetime, since no gas shortage occurred, the change of relative humidity and membrane water content are less than 1‰ and the pressure difference varies within specified range. Besides, the membrane lifetime reduces to 4,166 h as the width of narrow pulse current increased from 4 ms to 0.8 s.