Research On PEMFC Fractional Order State Space Modeling And Adaptive Control

Fuel cell,which has outstanding features of environmental friendliness,high efficiency and low emission,is widely used in new energy vehicles,distributed power plants and other fields.Proton exchange membrane fuel cell(PEMFC)is one of the most promising new energy sources due to its unique advantages in toggle speed,energy efficiency and low-carbon emissions.Advanced technology of modeling and controlling is one of the most important directions of PEMFC research,and is the key for in-depth understanding of PEMFC specific power generation process and improving the overall performance of power generation system.The related research indicated,there are some fractional order characteristics in gas diffusion,heat conduction and other processes of PEMFC.Based on the latest results of fractional order characteristics of PEMFC and fractional calculus.The fractional order modeling and control methods of PEMFC are studied.Firstly,the fractional state space model of PEMFC is obtained by identification.Then,based on the fractional Lyapunov stability theory,a new fractional order model reference adaptive controller which has combined with the identification results is designed for PEMFC.The main investigations are as follows:(1)The empirical modeling method of PEMFC fractional state space model is studied.Combining the theory of function filtering and matrix oblique projection,the subspace identification method of integer order uncertain systems is extended to the fractional domain.It is obvious that the fractional subspace identification algorithm can identify the PEMFC fractional model more accurately by comparing PEMFC fractional state space model with the experimental data.(2)According to the fractional Lyapunov stability theory,a new design method of adaptive law based on fractional inequality is proposed in this paper.According to this method,the adaptive laws of fractional model reference adaptive control based on state variable and system output error are derived respectively.The stability of the designed control system has been proved.The simulation results show that the fractional model reference adaptive controller can significantly improve the system toggle speed,reduce the steady-state error.(3)According to the specific PEMFC object,a fractional model reference adaptive controller by combining with fractional subspace identification algorithm and adaptive law derivation process is designed for PEMFC generation system in this paper.,At the same time,the control effect of fractional order model reference adaptive controller is verified by comparing the working states and load changes of the stack system at different stages.The simulation results show that the fractional order model reference adaptive controller can make the fuel cell system more stable in the start-up phase.When the load change,the controller can also adjust the PEMFC output more quickly to meet load fluctuation.