Parameter Control Of Proton Exchange Membrane Fuel Cell Using MPC Method

In recent years,the price of fossil energy such as oil has been increasing day by day,and the shortage of fossil resources has become increasingly prominent.The energy departments of various countries urgently need to explore a sustainable,low-cost and high-efficiency energy source to solve the current energy shortage problem in various countries.Proton exchange membrane fuel cells(PEMFC)use hydrogen energy as fuel,and have the advantages of no pollution,high efficiency,and low noise,and have become the most widely used type of fuel cells.Aiming at the problems of large fluctuation of stack operating temperature and cathode relative humidity,difficult control and poor stability of PEMFC system under dynamic conditions,the voltage management model,temperature management model and humidity management model of PEMFC system are established.The MPC control strategy is applied to the key parameter control of PEMFC stack,which provides a new idea for the research on the operation parameter control of PEMFC stack.The main research contents of this thesis are as follows:Firstly,the voltage model,temperature management model and humidity management model of PEMFC system are established based on mass conservation and energy conservation.The simulation model of the system is established by MATLAB/Simulink,and the simulation data and experimental data under the same operating conditions are compared,and the data are in good agreement,which verifies the accuracy of the model.The effects of different cathode humidity on the output voltage of the PEMFC system are discussed.The results show that when the relative humidity of the cathode is 100%,the output performance of the stack is the best.Second,a model predictive control(MPC)-based control strategy for PEMFC battery temperature and voltage is proposed.An MPC temperature and voltage control system was established,taking cooling water flow and anode intake pressure as control variables,and battery operating temperature and output voltage as control targets,to achieve stable control of battery temperature and voltage.The temperature and voltage control performance of different controllers for PEMFC systems is discussed.Under the action of the MPC controller,the temperature and voltage of the stack fluctuate with the load current and return to stable values in time.Compared with PID controller and fuzzy PID controller,MPC controller has less overshoot in temperature and voltage control and can stabilize at the set value in a shorter time.Under different parameter changes,the MPC controller shows better performance in terms of stabilizing the voltage.The experimental results show that the overshoot of the working temperature of the stack can be precisely controlled within 1.1K.Finally,an unbiased MPC-based cathode relative humidity management control strategy for PEMFC battery packs is proposed.An unbiased MPC humidity control system was established,taking the inlet air humidity of the cathode as the control variable and the relative humidity of the cathode as the control target,to realize the stable control of the relative humidity of the cathode.The results show that,compared with traditional PID and fuzzy PID control,the unbiased MPC controller has smaller overshoot and shorter adjustment time in the control of cathode relative humidity.The voltage output efficiency of PEMFC under unbiased MPC control is 3.36% and 2.82%higher than that of PID controller and fuzzy PID controller,respectively.The control performance of unbiased MPC at different operating temperatures and intake pressures is investigated.The results show that the overshoot of the unbiased MPC is less than 1% and the response time is only 0.4s.