Research On Nonlinear Dynamic Output Feedback Control Method Of Fuel Cell Air Supply System

The automobile transportation sector is the main energy consumption scenario,so changing the energy form of the automobile power source is essential to improve the environment and alleviate the energy crisis.With the development of technology and the improvement of people’s requirements for automobile performance,lithium battery vehicles and fuel cell vehicles will gradually replace fuel-burning vehicles.Compared with lithium batteries,hydrogen fuel cells have strong endurance,short hydrogenation time,and hydrogen is a clean and easily available renewable energy source.Therefore,hydrogen fuel cell vehicles play an important role in stabilizing energy supply,developing low-carbon transportation,and improving energy structure.However,the performance of hydrogen fuel cell vehicles largely depends on the performance of the air supply system.Therefore,a stable and efficient air supply system is essential to extend the life of the system and improve the efficiency of the system.This paper takes the vehicle proton exchange membrane fuel cell engine as the research object.The main work is carried out around the modeling of the air supply system and the design of the controller.The main research contents are as follows:(1)Aiming at the problem that some components of the fuel cell air supply system are difficult to accurately describe by mechanism,a mechanism + data mixing method is used to model the stack and the auxiliary equipment of the air supply system.The stack model includes the output voltage model,the dynamic model of each gas component inside the stack,and the membrane water content model;the air supply system auxiliary equipment model includes the compressor model,the supply/exhaust manifold model,the cooler and the humidifier static model,and the Back pressure valve model.Finally,the dynamics of the system were tested under different working conditions.(2)Aiming at the problem that the fuel cell air supply system model has a high order and the cathode pressure is not measurable in actual engineering.First,the working mechanism of the fuel cell is analyzed to clarify the control requirements and objectives,and a fourth-order oriented control model is established and verified through reasonable simplification.Then,a nonlinear reduced-order observer is designed to realize its online estimation,and the stability and robustness of the designed observer are theoretically proved.(3)Aiming at the problem that the fuel cell air supply system is a complex system with multiple inputs and multiple outputs,strong nonlinearity and strong coupling,unmeasured states,and internal and external disturbances,an observer-based nonlinear dynamic output feedback decoupling controller is proposed to realize the control of cathode pressure and supply manifold pressure,and theoretically prove the stability and robustness of the proposed control system.The two dimensions of transient verification under nominal parameters and perturbed stack temperature prove the effectiveness of the designed controller.