Novel Polarization Voltage Model: Accurate Voltage and State of Power Prediction

Abstract

Accurate prediction of battery voltage and state of power (SOP) is a challenge for a battery management system to achieve charge/discharge safety protection and power distribution. An accurate, simple and implementable battery model is key to realizing battery simulation and state estimation/prediction. To establish a battery model that can easily realize battery voltage and SOP prediction, this paper proposes a novel polarization voltage (NPV) model based on current and time by simplifying the equation describing the polarization characteristics in the electrochemical model. The NPV model is implementable for high-precision prediction of battery voltage and SOP at t-second (t > 0) under any constant current (I ≠ 0). Based on the relationship between model parameters and state of charge (SOC), the SOP prediction model with different SOC is successfully realized. The prediction results show that the battery is charged from SOC = 0 to cut-off voltage with 3C, and the high-precision prediction of polarization voltage and terminal voltage can be obtained by using the NPV model. The average errors of the polarization voltage and voltage terminal are only 1.4% and 0.4%, respectively. For the 3C discharge process, the maximum prediction error of terminal voltage is -4.7%, and the error at the end of discharge is only -1.1%, with an average error of 0.6%. The average error of SOP at t-second = 10s predicted by the NPV model is only 0.78%. More importantly, the NPV model parameters are obtained from just small-batch data, and it is timesaving for practical testing with simple structures. Therefore, the NPV model is suitable for battery simulation, state prediction, fast charging security and energy management with broad application prospects.