A comparative study of different online model parameters identification methods for lithium-ion battery

Precise states estimation for the lithium-ion battery is one of the fundamental tasks in the battery management system (BMS), where building an accurate battery model is the first step in model-based estimation algorithms. To date, although the comparative studies on different battery models have been performed intensively, little attention is paid to the comparison among different online parameters identification methods regarding model accuracy, robustness ability, adaptability to the different battery operating conditions and computation cost. In this paper, based on the Thevenin model, the three most widely used online parameters identification methods, including extended Kalman filter (EKF), particle swarm optimization (PSO), and recursive least square (RLS), are evaluated comprehensively under static and dynamic tests. It is worth noting that, although the built model’s terminal voltage may well follow a measured curve, these identified model parameters may significantly out of reasonable range, which means that the error between measured and predicted terminal voltage cannot be seen as a gist to determine which model is the most accurate. To evaluate model accuracy more rigorously, battery state-of-charge (SOC) is further estimated based on identified model parameters under static and dynamic tests. The SOC prediction results show that EKF and RLS algorithms are more suitable to be used for online model parameters identification under static and dynamic tests, respectively. Moreover, the random offset is added into originally measured data to verify the robustness ability of different methods, whose results indicate EKF and RLS have more satisfactory ability against imprecisely sampled data under static and dynamic tests, respectively. Considering model accuracy, robustness ability, adaptability to the different battery operating conditions and computation cost simultaneously, EKF is recommended to be adopted to establish battery model in real application among these three most widely used methods.