Durability Modeling And State Estimation For Vehicular Fuel Cell System

With the development of human society for energy conservation and emission reduction,clean energy is playing an increasingly important role in the energy system.Among them,proton exchange membrane fuel cells(PEMFC)have the advantages of high energy density,zero emission,high efficiency,high adaptability,etc.,and have great prospects in the application of new energy vehicles and other fields.Durability is one of the most important factors restricting the development of PEMFC vehicle.Vehicular fuel cell is composed of hundreds large format single cells in series,subject to ‘buckets effect': the actual life of PEMFC is decided by the performance of the worst cell,and the final failure modes generally are the deterioration of cell consistency or uniformity.Due to the lack of corresponding diagnostic methods and decay analysis models,studies on the degradation of consistency and uniformity of vehicular fuel cells are still scarce.Therefore,it is necessary to further strengthen the research on test methods and decay mechanism modeling.This paper studies vehicular fuel cell stack deceline modleling and analysis method.Based on the characteristics of vehicle fuel cell,an operating condition based estimation model of vehicular fuel cell life degradation is proposed,and the estimation accuracy is more than twice that of the original algorithm.A pseudo-two-dimensional model of fuel cell is proposed based on the assumption of non-equipotential of bipolar plate.The phenomenon of "voltage spoofing" is analyzed in detail for the first time and verified by experiments.This paper develops an internal differential decay diagnosis method for automotive fuel cell stack.By algorithm and test method optimization,the accuracy of galvanostatic charge method(GSC)is improved in this paper.And GSC is used for electrochemical active area,crossover current and double layer capacity consistency diagnosis.Aiming at the phenomenon of "voltage cheat",a multi-point voltage monitoring method is developed to estimate the deterioration of uniformity between cells.Based on several test methods,the differential decay diagnosis process of fuel cell stack is proposed and verified by experiments.This paper studies the uniformity optimization method from the fuel cell stack level to the hybrid power system level.Based on the multi-point voltage detection method,this paper presents a differential decay optimization control strategy for vehicular fuel cell.In order to solve the problem of anode flooding resulted gas starvation,a two-chamber nonequalpotential model of the fuel cell is proposed,and the optimization method of the uniformity of the fuel cell in the condition of anode flooding is studied.Based on the dual recirculation fuel cell system,a method for improving the uniformity of idling conditions is proposed.Aiming at the multi-objective optimization problem of fuel cell hybrid power system,a joint optimization method of power system parameter matching and energy management is studied.On the basis of the existing research,this paper makes a new exploration in the differential decline of vehicle fuel cells,which has reference value for researchers in related fields.The research results of this paper have been applied to several fuel cell demonstration projects such as the Bei Jing-Zhang Jia Kou winter Olympics demonstration,and the related theoretical research results have also been applied to the development of domestic long-life fuel cell stack.Based on the test results of the accelerated stress test of test bench,the predicted life of the fuel cell stack reaches more than 10000 hours.