Hyundai Motor Company recently awarded a $100,000 contract to the Modeling, Analysis and Process-control Laboratory for Electrochemical systems (MAPLE) Lab at Washington University to incorporate electrochemical model-based code in a battery management system for advanced automotive batteries. The contract, says MAPLE, is probably one of the first of its kind (publicly announced).
If this approach is successful, this could have a transformative effect on how batteries are used in the electric cars—bringing down their cost, environmental footprint and improving their safety, MAPLE suggests.
Designing a battery management system (BMS) for lithium-ion batteries that can guarantee their longevity, safety and performance is challenging since the electrochemical mechanisms inside the battery are not well understood yet.
To address such difficulties, a physics-based electrochemical model that is capable of observing the internal states of the battery is required for the BMS rather than the empirical circuit-based models which are currently in use, MAPLE says. Transport phenomena-based electrochemical engineering models were first developed in 1993 by Professor John Newman and coworkers at UC Berkeley, and have been further improved by many modelers and scientists; however, their long computational time and extensive complexity prevent their application into real-time on-board embedded systems.
A computationally efficient reformulated physics-based electrochemical model is therefore essential for use in applications such as a BMS. Dr. Venkat Subramanian, an associate professor in the Department of Energy, Environmental and Chemical Engineering at Washington University and the principal investigator of the MAPLE group, has advocated the use of spectral methods coupled with mathematical reformulation for lithium-ion battery models.
This approach is guided by the mathematical analysis of nonlinear partial-differential-algebraic equations coupled with highly efficient adaptive solvers in time and optimization routines in multiple software platforms. The MAPLE group claims that to date, the model and codes it developed are the most computationally efficient reported in the literature (CPU time < 15 ms for a discharge curve, and at least 1 order of magnitude faster than any other model or code).
For the HMC contract, the models will be tested in an application where battery specifications are varied according to the different vehicle specifications. The battery model for electric vehicles will be validated with diverse conditions in terms of the charge/discharge, state of charge (SOC), temperature and charging rate with plans to test for state of health in the future.
This project involves delivering source codes of both full-order finite difference and reformulated models to enable the car manufacturer to validate and implement the reformulated code in the BMS. In addition, experimental validation and hands-on training on model development and code simulation are provided.
Source: Green Car Congress
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