Battery Pack Modeling and Performance Assessment for Electric Vehicle Applications
Typ
Examensarbete för masterexamen
Program
Automotive engineering (MPAUT), MSc
Publicerad
2021
Författare
Srinivasan, Vinay
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Large traction battery packs are made up of several number of cells connected in
series and parallel to fulfill vehicle demanded voltage and capacity. For many years,
the operation of the battery packs has been overestimated by only scaling up battery
cell performance to mimic pack behavior. The inconsistencies in the current, State
of Charge (SOC) and temperature of the individual cells/modules originating from
the battery pack electrical topology and thermal circuit design, negatively influence
the pack overall performance. In the current thesis work, lumped battery pack is
modified to account for cell-to-cell variations. All simulations have been performed
in Siemens Amesim, a commercial software for the modeling and analysis of multidomain
systems.
The inhomogeneities within the battery pack are modeled by considering interconnection
resistance between parallel branches. The input current to the models is
given either as a constant value or through a current profile obtained from literature
survey and the software tutorial. Both the lumped pack and cell-to-cell discretized
models (C2C) are compared in terms of model predictability. The results show that
with C2C model the variations between the cells can be observed and quantified.
The C2C model discharges 11% faster compared to the lumped pack model when
Worldwide harmonized Light-duty vehicles Test Procedure(WLTP) current profile
is inputted. The maximum temperature attained by C2C model is 12 0C greater
than the lumped pack model. It can be concluded that when lumped pack modelling
approach is employed the vehicle achievable range is overestimated and the
maximum temperature is underestimated.
Beskrivning
Ämne/nyckelord
battery pack modelling , equivalent circuit method , cell-to-cell variations , electric vehicle