Temperature And Humidity Transients Synergy Control Of Proton Exchange Membrane Fuel Cells

With the rapid development of social economy,the consumption of non-renewable energy such as petroleum and fossils has increased a lot.Therefore,exploring and developing renewable energy such as hydrogen energy has gradually become the focus of current research.Proton exchange membrane fuel cell(PEMFC)because of its advantages of renewable high efficiency and no pollution became one of the most widely used fuel cells.In view of the traditional temperature and humidity control of PEMFC difficult,leading to poor cell performance problems.In this paper,the dynamic hydrothermal management system of PEMFC is established,and the humidity control strategy based on ADRC method and the temperature and humidity transient cooperative control strategy based on MIMO fuzzy control are proposed,which provide a new method for temperature and humidity control of PEMFC stack.Moreover,a degradation model for predicting the lifetime and degradation progress of PEMFC stack is proposed,the thermodynamic and economic performance is analyzed.The main contents of this paper are as follows:Firstly,the dynamic model of 5kW PEMFC stack,including water management model,thermal management model,voltage model and membrane hydration model,is established,and the experimental data are used for verification and analysis.The influence of humidity and temperature on the output voltage of PEMFC is discussed.The results suggest that when the humidity is 100%and the temperature is 343K,the output voltage of the stack is the highest.Secondly,a PEMFC humidity control method based on ADRC control strategy is proposed.In view of the difficulty of humidity control in PEMFC due to strong non-linearity and uncertain parameters,the ADRC with the characteristics of eliminating and reducing the uncertainty of the system was used to control the humidity of PEMFC.The ADRC was compared with the traditional fuzzy PID and PID humidity control methods.The results show that the generation efficiency of PEMFC under ADR is 2.36%and 1.48%higher than that of traditional PID and fuzzy PID control,respectively.Thirdly,a PEMFC temperature and humidity transient cooperative control method ground on MIMO fuzzy strategy is proposed.On the basis of the humidity control model of PEMFC,the MIMO fuzzy controller is introduced and applied to the PEMFC’s temperature and humidity transient cooperative control,where the performance comparison between the temperature and humidity transient cooperative control and the traditional temperature and humidity control is explored under the disturbance of load and other parameters.According to the results,the temperature and humidity transient cooperative control based on MIMO fuzzy strategy has good dynamic response,and the output voltage is increased by 4.2%and 3.1%compared with the traditional PID humidity control and the traditional PID temperature control.Finally,a degradation model for predicting the lifetime and degradation progress of PEMFC stack is proposed.The thermodynamic and economic performances of PEMFC stack over the lifetime are conducted.The results show that the high working current density accelerates the degradation of the cell and shortens the cell life greatly.With the increase of current,single cell degradation rate rise to 4.87×10-5V h-1,shorten the life of 25.9%.At 80A,the electric efficiency of the stack can reach 38.3%.In addition,the average cost of the stack can be as low as 17.6 $h-1 as the degradation rate increases,fuel consumption and total cost increases.