Research On Aging Behavior Modeling And Lifespan Prolongation Strategy Of Fuel Cell With External Characteristics

Hydrogen energy and fuel cell technology,as the focus of the current energy technology revolution,is an important part of building a safe,efficient,environment-friendly and sustainable energy economy,so it is widely used in the field of fixed and mobile power generation.However,the durability of fuel cell is the biggest obstacle to its large-scale commercial application,especially in the field of automobile,the road environment is complex and the air composition has regional differences,which will aggravate the performance degradation of fuel cell.Therefore,it is of great signifi-cance to study the modeling method of fuel cell aging behavior and the formulation of lifespan extension strategy in vehicle environment.Based on the external sensor in-formation,this dissertation constructs the mapping relationship between the external characteristics of fuel cell and the internal aging mechanism,and formulates targeted lifespan extension strategies from two different perspectives of prognostic health man-agement and power system structure optimization.The main work and innovations are as follows:1)Aiming at the problem of aging behavior characterization of fuel cell,the influ-ence of various working conditions on the lifespan of fuel cell in vehicle environment was analyzed,and the key factors of performance degradation in different working con-ditions were used to construct the causal chain of performance degradation of each com-ponent.Aiming at the problem that it is difficult to observe the physical and chemical processes inside the fuel cell,the mapping relationship between the external attribute characteristics and the internal aging mechanism is constructed based on the sensor in-formation,and the index system of quantitative characterization of the aging behavior of the fuel cell is established.2)In order to evaluate the state of health of fuel cell,an equivalent circuit model based on analytical method is proposed to quantify the fuel cell impedance character-istics,which can effectively match the topology of the equivalent circuit model and impedance spectrum geometry.Based on the complex nonlinear least square parameter method,the model parameters are identified,and the significant parameters that affect the life of fuel cell are extracted,and the functional relationship between aging param-eter and aging time is constructed.Four characteristic frequency point of impedances are used to evaluate the state of health of fuel cell,and the validity of the above model and method is verified by impedance data.3)In view of the coexistence of reversible aging and irreversible aging of fuel cells,the voltage information of the stack under steady-state condition is decomposed into aging trend information and voltage recovery information.According to the aging trend information,the aging model of fuel cell is established based on the semi empir-ical model of polarization curve.The parameters of the model are obtained by genetic algorithm,and the voltage aging trend is predicted based on the adaptive Kalman filter algorithm,and the voltage residual sequence is obtained.Aiming at the voltage recovery information,the reversible aging process is predicted by NARX neural network model and time series analysis method.The aging experiments show that the proposed method can capture the overall aging trend and voltage recovery information at the same time,and provide more accurate lifespan prediction results.4)In view of the slow start-up speed and poor durability of the fuel cell,the aux-iliary power supply is introduced to optimize the power system structure to eliminate the impact of load fluctuation on the lifespan of the fuel cell.Aiming at the topology structure of parallel connection of multi-stack system and auxiliary power supply,a rule-based energy management strategy is proposed,which can guarantee the fuel cell to work under the fixed load condition,reduce the service time and start-stop times of the stack,so as to extend the lifespan of fuel cell.Considering the life and safety of the auxiliary power supply,the state of charge and the charge/discharge power of the auxiliary power supply are limited.Based on the extended Kalman filter algorithm,the accurate estimation of the state of charge and the power prediction under multiple con-straints are completed,and the validity of the state estimation calculation method and the energy management strategy are verified by experiments.5)The design and development of a complete fuel cell management system can realize the refined management of the balance of plant,and ensure the efficient,safe and long-life operation of fuel cells,which has important engineering value.Combined with system simulation model and upper computer monitoring software,the validity and reliability of fuel cell management system are verified.