Research On Ohmic Internal Resistance Estimation And Thermal Power Of Pemfc

With the further intensification of the energy crisis,the search for new alternative energy sources is critical to the automotive industry.Proton exchange membrane fuel cell（PEMFC）has the characteristics of high efficiency and environmental protection.The ohmic internal resistance and thermal power are important parameters during the operation of the fuel cell.The ohmic internal resistance can characterize the output performance,and the thermal power can determine the temperature change trend.Therefore,the research on these two has important theoretical significance and engineering value.This article introduces the structural principle and operating model of the proton exchange membrane fuel cell.The test device platform of the proton exchange membrane fuel cell system was designed,and the switch-on and switch-off strategies and the setting of air circuit parameters were discussed.Based on the monitored polarization curve of the proton exchange membrane fuel cell,the fuel cell output is set to stabilize in the ohmic polarization region.Using the equivalent circuit model and the dual Kalman filter algorithm,the UDDS operating condition simulation experiment was carried out on the designed test device platform to estimate the ohmic resistance of the proton exchange membrane fuel cell.The results show that:（1）The dual Kalman filter algorithm has shortcomings,and improvements have been made for this.One is to abandon the loop method of parameter crossover in the structure.The other is to set the state transition coefficient matrix in the first-level Kalman filter algorithm to a fixed value in the algorithm process,and remove the capacitance parameter in the second-level Kalman filter algorithm to optimize the prediction process.（2）Using the improved dual Kalman filter algorithm,the estimated relative error of the fuel cell ohmic resistance is1.111-1.517%,which is 3.544-4.69%lower than the improved dual Kalman filter algorithm.Using the designed proton exchange membrane fuel cell simulation model,the relationship between the estimated ohmic resistance and the fuel cell thermal power was established on the MATLAB/Simulink platform to carry out UDDS simulation experiments.The results show that:（1）The relationship between fuel cell thermal power and estimated ohmic resistance is:P_H（k）=K_stI_a²（k）R_Ω（k）,K_stis the fuel cell thermal power correction coefficient,and the value range is 1.415-1.656.（2）Compared with the thermal power obtained by the thermal model in the literatures^{[20-25,74-76]},the thermal power error calculated from the estimated ohmic resistance is0.03-0.343%.（3）Use the calculated value of thermal power to control the internal temperature of the fuel cell on the test device platform.The temperature range of the fuel cell is 59-71℃,and the temperature difference is within 2-6℃,which is lower than the preset fuel cell temperature difference（6℃）,while the traditional fuel cell internal temperature control strategy is used to control the temperature,the temperature difference range is 3-17℃,which shows that the method of calculating the fuel cell thermal power based on the estimated ohmic resistance is feasible.