Core Temperature Estimation for a Cylindrical Cell Battery Module

Lithium ion (Li-ion) batteries in electric vehicle (EV) applications must operate within a narrow temperature range to ensure safety, performance and longevity. Hence, advanced thermal management strategies should have access to internal cell temperatures in a battery pack. In real world application, surface temperatures can be measured, but it is difficult to place a sensor at the core (which can be more than 10°C higher that the surface) due to the added cost and intrusive nature.In this paper, a pack level thermal model is developed for a cylindrical cell battery module which is modular and scalable. This model is used in a Kalman filter based Thermal State Observer (TSO) which is constructed to be real-time capable for application in a Battery Management System (BMS). The TSO uses limited cell surface measurements to estimate the core temperature of the full battery pack. The paper also discusses the methodology for characterization and validation of the thermal model and TSO.