Research And Control Strategy Design Of A Water-cooled Fuel Cell System

In order to solve the contradiction between increasing energy demand and environmental pollution,global warming and resource shortage,researchers have gradually turned their attention to the development and utilization of renewable energy,especially hydrogen energy.Proton exchange membrane fuel cells can convert hydrogen energy into electricity at room temperature without combustion and produce no pollution.Compared with traditional energy storage and power generation devices,it has higher energy conversion efficiency and larger energy density.Due to strong nonlinearity and multiple strongly coupled state variables of fuel cells,the output changes slowly when the load current fluctuates in a large range.Therefore,the operation control and optimization of fuel cell system have become one of the research hotspots of new energy technology.To meet the control requirements of the quick response of multiple targets and parameters of a high power water-cooled fuel cell system,this paper proposes two operation control strategies with faster adjustment speed.Firstly,an isothermal two-phase model and auxiliary system model are established in one dimension by combining mechanism modeling with empirical modeling.The model can simulate the transmission,reaction and circulation process of hydrogen,nitrogen,oxygen,water and other mixed gas in the cathode,anode and pipelines,the transmembrane penetration and phase change of water vapor and the static and dynamic performance of the stack.Secondly,two control are proposed in this paper based on the above model.One is a linear optimal control strategy based on a Kalman filter,and the other is a second-order sliding mode super twisting nonlinear control strategy based on a linear extended observer.It is verified by Matlab/Simulink that both algorithms have large advantages and their adjusting time is shortened by about 30%compared with the traditional PID control strategy.Lastly,this paper designs a fuel cell system operation controller based on STM32 The start-up,shutdown and normal working process of the stack are all performed on an experimental platform,which proves the controller can achieve the system control target and guarantee stable and efficient operation of the stack,and has certain practicality.