Advanced BEV Battery Pack Thermal Simulation Model Development & Co-relation with Physical Testing 2021-28-0138

Battery Thermal management is a major challenge for occupant safety in an electric vehicle. Predicting the battery electrical losses and thermal behaviour is another challenge for the battery management system. Different virtual models are developed for cell level and pack level thermal evaluation. All these models have a varying degree of accuracy and limitation. The latest developed model is more accurate and can predict the battery cell & pack level temperatures.

The battery can be modeled in different ways, ECM (Electrochemical model), EIS (Electrochemical Impedance Spectroscopy) [1]. Newman model is a well-known electrochemical model. [2]. EIS uses a combination of DC and small AC signal [3,4]. ECM model also used for estimating SOC and in BMS [5].

The cell temperature in the battery pack not only depends upon the cell inside physics but also depends upon cell outside cooling physics. Cell outside physics is simulated by 3D CFD software during the design process [6]. The pack level simulations are performed considering extreme conditions and fixed boundary steady-state conditions. Heat transfer coefficient data from thermal simulations are extracted and used in the BMS model, and 1D thermal model is developed. There are two challenges that exist in BMS model. The first is to convert CFD data to 1D and the Second challenge is to simulate battery load variation under real driving conditions. All the literature available either discuss cell inside physics or cell outside physics.

A new approach was developed which overcomes the limitations known as ROM Model. The model is fast and more accurate than the conventional model.