Modeling, simulation, and parameters identification of a lithium-ion battery used in electric vehicles

Batteries are the most important part of every Electric Vehicle(EV) and have an underlying role that is supplying power to all parts of the vehicle. Among different kinds of batteries, the lithium-ion family is considerably used in several industries. The electrical model of the battery gets remarkable attention and, numerous equivalent circuits have been proposed in recent years since the parameters of the batteries are not available in their datasheets. The main goal of this paper is to estimate the parameters of a second-order RC equivalent circuit of a 2600mah lithium-ion battery which can be used for different purposes. Besides, the parameters of a first-order RC equivalent circuit are identified in advance to make a comparison between the results of the two models. For this purpose, some standard tests are performed multiple times in the laboratory to achieve the best results. Afterward, these models are simulated in Simulink/Matlab environment in order to verify the output precision of these models by using the real data at 25°C. It is concluded that the second-order circuit is more efficient and precise than the first-order one and, the amount of three different errors of the second-order circuit is less than those of the first-order one. It should be noted that in this article the hysteresis and temperature effects on the battery are neglected.