Lithium-ion Battery Modeling Method Considering Temperature and Current

Abstract

The open circuit voltage(OCV) and internal resistance R are often used to evaluate the state of lithium-ion batteries, and they are nonlinearly coupled with state of charge (SOC), current I, and temperature T. It is difficult to accurately and completely build the analytical model of OCV and R. This paper proposes a lithium-ion battery modeling method that considers the effects of SOC, I, and T. This method firstly designs multiple constant current conditions experiments to obtain experimental data containing SOC, I, and T; secondly, it solves the nonlinear coupling problem of SOC and T, and accurately calculates OCV and R under the required operating point {SOC, I, T}; finally, the method of fitting and interpolation is adopted to construct the open circuit voltage model OCV(SOC, T) and the internal resistance model R (SOC, I, T), which could describe the complete mapping relationship from {SOC, I, T} to {OCV, R}. This modeling method has the advantages of short experiment time, rich information, and high output accuracy. Experiments show that the voltage estimation error is less than 0.4‰.KeywordsLithium-ion batteryOpen circuit voltageInternal resistanceTemperatureSOCCurrent