Sensorless State of Temperature Estimation for Smart Battery based on Electrochemical Impedance

Temperature plays a significant role in the safety, performance, and lifetime of lithium-ion batteries (LIBs). Therefore, monitoring battery temperature becomes one of the fundamental tasks for the safe and efficient operation of LIBs. Given the limited onboard temperature sensors, this paper proposes a sensorless temperature estimation method suitable for the smart battery system by obtaining the electrochemical impedance of batteries online via bypass actions. A suitable frequency is selected from the battery electrochemical impedance spectroscopy (EIS) to achieve an accurate and robust estimation of the battery temperature through online impedance measurement. Using the battery impedance with this selected frequency, the battery temperature can be estimated under different scenarios, with RMSE less than 1.5 degrees C.