Improved PNGV equivalent circuit model for battery characteristics

The Partnership for a New Generation of Vehicle (PNGV) model adds battery capacitance on the basis of Thevenin model for the purpose of representing the change of open circuit voltage with the accumulation of load current, which makes up for the disadvantage of constant open circuit voltage of Thevenin circuit to a great extent. In this paper, the PNGV circuit is improved, and a parallel RC link is added, which corresponds to the two poles in the impedance spectrum of the lithium iron phosphate battery, thus being able to more accurately describe the polarization phenomenon of the lithium iron phosphate battery. Besides, the PNGV equivalent circuit model and the improved PNGV equivalent circuit model are established in MATLAB/Simulink, and the accuracy of the two models is compared through the pulse current experiment. Then, it is found that the error of the improved PNGV equivalent circuit model is over 50% less than that of the PNGV equivalent circuit model, which proves the dynamic adaptability of the model.