Onboard impedance diagnostics method of Li-ion traction batteries using pseudo-random binary sequence
Environmental and economic reasons have lead automotive companies
towards the direction of EVs and HEVs. Stricter emission legislations
along with the consumer needs for more cost-efficient and
environmental friendly vehicles have increased immensely the amount of
hybrid and electric vehicles available in the market. It is essential
though for Li-ion batteries, the main propulsion force of EVs and
HEVs, to be able to read the battery characteristics in a high
accuracy manner, predict life expectancy and behaviour and act
accordingly. The following thesis constitutes a concept study of a
battery diagnostics method. The method is based on the notion of a
pseudo-random binary signal used as the current input and from its
voltage response, the impedance is used for the estimation of
parameters such as the state of charge and more. The feasibility of
the PRBS method at a battery cell has been examined through various
tests, both in an experimental manner at the lab but also in a
simulation manner. The method is compared for validation against the
electrochemical impedance spectroscopy method which is being used as a
reference. For both the experimental and the simulation examinations,
the PRBS method has been validated and proven to work. No matter the
change in the parameters of the system, the method behaves in a
similar manner as in the reference EIS method.
The level of detail in the research and the performed experiments is
what makes the significance of the results of high importance. The
method in all ways has been proven to work in the concept study and
based on the findings, if implemented on an EV’s or HEV’s electric
drive line and the same functionality is observed, be used as a
diagnostics method of the battery of the vehicle.
Charalampos Savvidis and Zeyang Geng
2015
Informationsansvarig: webmaster
Senast uppdaterad: 2021-11-10
LiU Homepage
