Due to the increasing concern for energy efficient
storage devices, extensive research is being done on the mechanisms
which are involved in the battery degradation process. The
electric battery loses capacity with use throughout its lifetime,
decreasing the total amount of energy it can store and deliver.
As the battery degrades, the internal resistance also increases
resulting in a difficult extraction of the stored energy as well as
the loss of part of this energy, during charging and discharging,
in the form of heat.
Optimality in electric vehicle energy management has been
traditionally pursued from the perspective of efficient grid
operation, but barely considering battery degradation in the
process. The objective is to formulate a battery degradation
model which will yield the degradation suffered by a battery
as a function of its use, allowing both the comparison between
different energy management strategies as well as including the
model in linear optimization algorithms.
A number of Li-ion battery cells experimentally subjected to
different depth-of-discharges, currents and temperatures, were
studied in order to identify the variables which categorize best,
using self-organizing maps, the degradation suffered by the cells.
A model is proposed which yields the rate of degradation of the
battery as a function of both temperature and depth-of-discharge.
This model is then linearized and used in an electric vehicle
energy management optimization problem where the degradation
suffered by the battery, due to a managed charge, is minimized
as a function of the depth-of-discharge and the temperature. The
results are compared with other charging methods.
Director: Álvaro Sánchez Miralles
Autor: Ismael J. Fernandez
Lugar: Aula de seminarios
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