Development of thermal model for estimation of core temperature of batteries

Abstract

Core temperature (Tc) estimation plays an important in role in establishing an effective thermal management system of a battery. In the present work, Tc of a lead acid (Pb) battery was estimated using a Kalman filter, based on a thermal model of the battery using convection resistances and capacitances. The governing equations based on measured surface temperature (Ts) and ambient temperature (Tamb) were derived. Since Tc cannot be measured directly, estimation technique was used to predict the same using measured Ts and Tamb. Five test cases for which the profiles of Tc versus time were available were analyzed. It was found that the errors in the predictions varied from 0.25 °C to 3.5 °C., depending on the nature of Tc profiles, with minimum errors when Tc has slow variations with time.

Core Temperature Estimation for a Lithium ion 18650 Cell

“…In order to estimate T c , OCV, V T , T s and T amb are required [6]. The OCV of a Li ion battery can be estimated using V T .…”

Smart Core and Surface Temperature Estimation Techniques for Health-conscious Lithium-ion Battery Management Systems: A Model-to-Model Comparison

“…Since these parameters are not present in the C and D matrices of the first-order model, a large increase in Tc was observed. The thermal parameter sensitivity analysis as conducted in references [58,60] also confirmed the same reason behind the error in temperature estimation by the first-order thermal model. It is found that the error between Ts and Tc is increased if the discharge current increased.…”

“…Secondly, a similar study is also conducted for the second-order model and finally, compared the results. All experiments are carried out with different current profiles as per manufacturer recommendation to ensure no battery health degrade [58]. In all cases, the initial currents are kept high for rapid charging of the cell.…”

“…KF is used to estimate and predict an unknown parameter from known parameters. The state model for a KF is shown in [43,58] and the first-order model was shown in [59]. However, the mathematical model for KF was not presented.…”

“…Moreover, while comparing Equations ( 7), (8), and ( 9) with Equations ( 12), ( 13) and ( 14) it is noticed that the output parameter Ts in KF showed no dependence on the state Tc,t-1 which is also a major reason behind the estimation error in case of the first-order model. Further, references [58] and [43] demonstrated that Cc and Ru of the second-order thermal model have a significant effect on Tc. Since these parameters are not present in the C and D matrices of the first-order model, a large increase in Tc was observed.…”