Decision and Control Lecture Series

Decision and Control Laboratory, Coordinated Science Laboratory

On the Accuracy and Estimation of Battery Behavior

Professor Anna Stefanopoulou

Mechanical Engineering, University of Michigan

Wednesday, November 14, 2012

3:00 p.m. to 4:00 p.m.

B02 Auditorium CSL

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Abstract

Many multi-scale physics-based models and their reduced-order renditions are used to estimate the lithium concentration and over-potential distributions throughout the battery electrode. The models let us meet time varying power demands while avoiding locally damaging phenomena. We show how to evaluate the accuracy of various electrochemical battery models by using neutron imaging as in situ measurement of the lithium concentration along the anode and cathode electrode layers. The observations from an operating Lithium Iron Phosphate (LFP) pouch cell battery with typical commercial electrodes are used to define the limits of the validity of the electrode-averaged models used in observers.

We then establish a simple thermal model than can be parameterized using the surface temperature measurement of the cell casing. The algorithm employs non-uniform forgetting factors to capture the long term resistance growth, and thus heat generation, due to aging or degradation. The algorithm accounts for the nonlinear dependency of the electric resistance (hence heat generation) on temperature in healthy cells and can be critical for avoiding the onset of thermal run-aways.

Biography

Anna is a Professor of Mechanical Engineering at the University of Michigan and the Director of the Automotive Research Center (ARC), a U.S. Army Center of Excellence in Modeling and Simulation of Ground Vehicles.

She has a Diploma in Naval Arch. (NTUA, 1991) and a PhD in Electrical Engineering (UMICH, 1996). She was an assistant professor (1998-2000) at the University of California, Santa Barbara and a technical specialist (1996-1997) at Ford Motor Company. She is an ASME and an IEEE Fellow, the Chair of the ASME DSCD Energy Systems Technical Committee, a member of the SAE Dynamic System Modeling Standards Committee and a member of a U.S. National Academies committee on Vehicle Fuel Efficiency. She has a book, 12 US patents, 4 best paper awards and more than 150 publications on estimation and control of internal combustion engines and electrochemical processes such as fuel cells and batteries.

PLEASE JOIN US FOR COOKIES AND COFFEE PRIOR TO THE SEMINAR IN ROOM 154 CSL AT 2:30PM