On-line Fault Diagnosis For PEM Fuel Cells Based On Fast EIS Measurement

Proton exchange membrane fuel cells have the advantages of pollution-free,high efficiency,renewable fuel,high energy density,low noise,wide power range,refueling convenience,etc.,and are considered to be one of the most promising power technologies.Although many projects are underway in the world,lifetime and cost are still the two major bottlenecks in the development of proton exchange membrane fuel cells.For many reasons,the actual lifetime of a proton exchange membrane fuel cell is much lower than the experimental lifetime provided by the manufacturer.In the actual operation,the unavoidable faults such as membrane drying,flooding,and fuel starvation are the important reasons leading to the drastic decrease of lifetime.However,because of the structure of fuel cell stacks,it is impossible to place sensors inside for online monitoring.In this paper,an on-line fault diagnosis method for proton exchange membrane fuel cells is proposed based on a fast electrochemical impedance spectroscopy measurement.The contributions of this paper are summarized as follows(1)The m-secquence and continuous wavelet transform based impedance estimation algorithm greatly shorten the electrochemical impedance spectroscopy measurement time.The excita-tion current injection circuit provides a low cost,small-volume and effective solution for dis-turbance injection,demonstrating its commercial and engineering feasibility.With this method,the applications of the electrochemical impedance spectroscopy technology can be greatly ex-panded.(2)For the on-line proton exchange membrane fuel cells fault diagnosis based on electrochemical impedance spectroscopy,a diagnosis algorithm based on the electrochemical equivalent circuit model and the support vector machine classifier is proposed.Using the improved Randles equivalent circuit model and the binary support vector machine classifier,the feature extraction and fault classification is realized.(3)The fault diagnosis system for proton exchange membrane fuel cell based on fast electrochem-ical impedance spectroscopy is developed.Experiments show that the system can accurately diagnose several common faults of proton exchange membrane fuel cells,such as membrane drying,flooding and air starvation.