The thermal management of li-ion battery packs is crucial, as the cooling is directly related to the safety, reliability, performance and durability of battery packs. The thermal requirement of battery packs is specific. Not only should the average battery pack temperature be maintained within the given range, but also the spatial gradient of temperature and the direction of heat transfer are key factors for consideration in order to deliver a robust and reliable thermal solution. The target ranges of temperatures for cells and battery packs depend on the charge/discharge modes and also on manufacturing of battery cells.

The thermal design of battery packs should be evaluated in transient fashion at a wide range of conditions to ensure that all the thermal requirements are met. The design of experiment (DOE) includes conditions such as fast charging, cold start, charging at low temperature, discharging at low state of the charge (SOC) and different drive cycles.

Numerical simulation is known as a powerful tool to evaluate and optimize a thermal design solution at the early stage of design and development. Later, it is used to conduct trouble-shooting. However, developing a reliable simulation tool to study temporal-spatial temperature profile of battery packs remains a challenge.  Taking into account the large number of cases to be considered for a design validation, particularly at earlier development stages, conventional computational fluid dynamics (CFD) approaches are not practical.  Therefore, the majority of numerical analyses are limited to either transient 1D-system level type of simulations or steady-state three-dimensional CFD analyses. Either of the approaches is not sufficient and could lead to significant design problems.

The paper will present a Digital Twin model of li-ion battery packs operated in real-time. The Digital Twin model was developed in order to perform what-if scenarios, to conduct in-depth root cause analyses, to further optimize the cooling design, to make life-time predictions, and to optimize the operating parameters for thermal management.

The construction of a Digital Twin model required the generation of response curves, in this case real time temperatures as functions of SOC, pack temperature, coolant flow rate, etc. The response curves were generated utilizing simulation data or measured test data.

The model validation will be achieved by comparison of the Digital Twin model results to test data over a few dynamic driving profiles.

In the paper, it will be shown how live-sensor data was integrated into the Digital Twin system level model of a battery pack to create a real-time environment. The generated tool was then utilized to monitor the temperature of the battery pack remotely and have a predictive maintenance solution. Considering all the limitations on the installation of temperature sensors in battery packs (location, quantity, reliability), the above-mentioned feature of the developed tool resulted in precise monitoring of the pack temperature in a real-operation environment.

Furthermore, practical considerations in the design of thermal management system for battery packs will be provided in detail.


Real Time Prediction of Temperature and Heat Generation Rate of Li-Ion Battery Packs in Ev Vehicles

Division / Sponsors: 
Electronic & Photonic Packaging Division (EPPD)

Paper Proceedings: https://asmedigitalcollection.asme.org/InterPACK/InterPACK2020/volume/84041

InterPACK2020 - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.