The power needs for extended all-electric operation of plug-in hybrid electric vehicles (PHEVs) require much more on-board energy than the lower-density energy typically provided by nickel-metal-hydride batteries. The current engineering solution is to link several parallel strings of lithium-ion battery cells within a battery module and to link several modules into larger battery packs.
But, these configurations had not been empirically tested to determine how changing temperature and energy loads on individual cells affect battery life. To accomplish this, Benjamin “BJ” Yurkovich, a graduate research fellow at The Ohio State University’s Center for Automotive Research, first identified the model parameters of individual cells.
“Each cell in a battery pack is unique,” said Yurkovich. “They vary in manufacturing variability, cell history and existing conditions, such as temperature, current and stateof- charge. These factors must be considered by a battery management system to achieve optimum voltage equalization.”
Yurkovich then used the Ohio Supercomputer Center’s Glenn Cluster and Remote MATLAB Services to develop and run a battery model based on the battery cell data and simulation algorithms.
“The simulations considered two different battery pack configurations, profiles for both hybrid and plug-in hybrid vehicles, three different temperatures, two different variations of internal resistance and capacity, three different states-of-charge and three different variations for the standard deviation,” Yurkovich explained.
With his results, Yurkovich was able to provide a foundation for the design of more intelligent battery management system design in PHEV battery packs.
Project lead: Benjamin Yurkovich, The Ohio State University
Research title: Electrothermal battery pack modeling and simulation
Funding source: The Ohio State University