Comparing techniques used to estimate the state of charge of lithium-ion batteries for electric vehicles

Electric vehicles (EVs) are becoming popular in the industry as well as in automotive and aerospace systems. Currently, new technologies have been developed for Battery Management Systems (BMS), and consequently, they have improved energy efficiency and consumption. Among of many challenges, the State of Charge (SoC) of battery has become a key role in the BMS for lithium-ion batteries. Accurate State of Charge estimation also enables more optimized battery pack design for the electric vehicle. Many researchers have been developing new algorithms, technologies and practices to estimate the SoC of lithium-ion batteries. This paper presents a comparison of techniques used to estimate the State of Charge of lithium-ion batteries in EVs application. It is based on a review of literature, discussion and comparison of advanced techniques used to estimate SoC in lithium-ion batteries. This comparison goes through experimental data, modeling, and simulation. The results show: 1) The accuracy of model with the experimental data; 2) The main parameters that affects the estimation; 3) The pros and cons of each technique investigated.