State of power estimation of power lithium-ion battery based on an equivalent circuit model

Abstract

State of power (SOP) is the maximum power that can be released or absorbed steadily by the power battery within a predetermined time interval. In order to provide stable and reliable output power for electric vehicles as well as ensure the safety of electric vehicles within a certain period of time, SOP estimation plays a very important role in the battery management system. SOP shows how quickly people can add energy to or remove energy from the battery without violating a set of design constrains. On the basis of a Rint model, this paper proposes a SOP estimation method based on two assumptions, and proves it in detail. The experimental results verify the model and the algorithm under various working conditions and temperatures as well as giving analysis and comparison. When the time period ∆T = 70min, the mean absolutely error (MAE) is less than 1.6 W for charging SOP estimation and less than 4.1 W for discharging SOP estimation respectively. Moreover, the affected of the predictive time on SOP estimation result is also studied.