Self-humidifying Open Cathode PEMFC Control System Design And Experimental Study

Energy crisis and environmental issues are two global challenges facing mankind in the21 st century.As an efficient and environmentally friendly power plant,fuel cells are increasingly valued by governments and research institutes all over the world.Among the many types of fuel cells,Proton Exchange Membrane Fuel Cell(PEMFC)is increasingly used in transportation,military,aerospace,portable mobile power and other fields due to its low operating temperature,high energy conversion efficiency and ease of operation.In this paper,a self-humidifying open cathode PEMFC control system based on a mixed signal microcontroller is designed and implemented,and the design process of hardware and software are elaborated.The anode purge device and the cathode cooling fan are controlled to realize various functions such as manual purge,periodic purge,ampere-hour integral purge and stack operating temperature control.The application of the control system maintains a good water-heat balance within the PEMFC,thus ensures the stable output of PEMFC.At the same time,a single cell voltage monitor system based on data acquisition hardware module and LabVIEW software is designed for PEMFC,which realizes the real-time detection,display and storage of the single cell voltage data.This monitor system has the advantages of strong real-time performance and high accuracy,thus is of great significance for the safe and stable operation of PEMFC stack.A series of experimental studies are carried out on the self-humidifying open cathode PEMFC stack using the designed control system and single cell voltage monitor system.The experimental results of purge method comparison show that the purge frequency of ampere-hour integral purge method changes real-timely with the load current,and compared with the periodic purge method,almost 30% of hydrogen is saved with ampere-hour integral purge method,for pretty much the same performance.As the high produce cost of hydrogen,the application of ampere-hour integral purge method can significantly reduce the operation cost of PEMFC.The experimental results of stack temperature control show that the stability of stack output is significantly improved when adopting the temperature control.The single cell voltage monitor experiments show that the choice of purge cycle and the load of PEMFCstack have remarkable effects on the equilibrium of single cell voltage.The validity and stability of the designed control system and monitor system are verified by the above experimental studies.Based on the electrochemical fundamental theory,a simulation model of PEMFC stack is established.The experimental results show that the proposed model can effectively reflect the dynamic response and output characteristics of the self-humidifying open cathode PEMFC stack.This model can provide guidance for the optimization of self-humidifying open cathode PEMFC control system.