scholarly journals An Accurate Time Constant Parameter Determination Method for the Varying Condition Equivalent Circuit Model of Lithium Batteries

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2057 ◽  
Author(s):  
Liang Zhang ◽  
Shunli Wang ◽  
Daniel-Ioan Stroe ◽  
Chuanyun Zou ◽  
Carlos Fernandez ◽  
...  
Keyword(s):  
Equivalent Circuit ◽  
Time Constant ◽  
Lithium Battery ◽  
Equivalent Circuit Model ◽  
Circuit Model ◽  
Parameter Determination ◽  
Accurate Estimation ◽  
Model Parameters ◽  
Accurate Identification ◽  
Battery Model

An accurate estimation of the state of charge for lithium battery depends on an accurate identification of the battery model parameters. In order to identify the polarization resistance and polarization capacitance in a Thevenin equivalent circuit model of lithium battery, the discharge and shelved states of a Thevenin circuit model were analyzed in this paper, together with the basic reasons for the difference in the resistance capacitance time constant and the accurate characterization of the resistance capacitance time constant in detail. The exact mathematical expression of the working characteristics of the circuit in two states were deduced thereafter. Moreover, based on the data of various working conditions, the parameters of the Thevenin circuit model through hybrid pulse power characterization experiment was identified, the simulation model was built, and a performance analysis was carried out. The experiments showed that the accuracy of the Thevenin circuit model can become 99.14% higher under dynamic test conditions and the new identification method that is based on the resistance capacitance time constant. This verifies that this method is highly accurate in the parameter identification of a lithium battery model.

scholarly journals Cranking Capability Estimation Algorithm Based on Modeling and Online Update of Model Parameters for Li-Ion SLI Batteries

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3365
Author(s):  
Tae-Won Noh ◽  
Jung-Hoon Ahn ◽  
Byoung Kuk Lee
Keyword(s):  
Equivalent Circuit ◽  
Voltage Drop ◽  
Equivalent Circuit Model ◽  
Estimation Algorithm ◽  
Circuit Model ◽  
Estimation Accuracy ◽  
Voltage Response ◽  
Model Parameters ◽  
Voltage Range ◽  
Terminal Voltage

The terminal voltage of a starting–lighting–ignition (SLI) battery can decrease to a value lower than the allowable voltage range because of the high discharge current required to crank the engine of a vehicle. To avoid the safety problems generated by this voltage drop, this paper proposes a cranking capability estimation algorithm. The proposed algorithm includes an equivalent circuit model for describing the instantaneous voltage response to the cranking current profile. This algorithm predicts the minimum value of the terminal voltage for the cranking transient period by analyzing the polarization voltage and dynamic characteristic of the equivalent circuit model. The estimation accuracy is adjusted by an online update for the parameters of the equivalent circuit model, which varies with temperature, aging, and other factors. The proposed algorithm was validated by experiments with a 60Ah LiFePO4-type SLI battery.

scholarly journals Improvement of an Equivalent Circuit Model for Li-Ion Batteries Operating at Variable Discharge Conditions

Electronics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 78
Author(s):  
Gabriele Maria Lozito ◽  
Valentina Lucaferri ◽  
Francesco Riganti Fulginei ◽  
Alessandro Salvini
Keyword(s):  
Energy Harvesting ◽  
Equivalent Circuit ◽  
Discharge Current ◽  
Equivalent Circuit Model ◽  
Circuit Model ◽  
Model Parameters ◽  
Estimation Algorithms ◽  
Harvesting Systems ◽  
Li Ion ◽  
Global And Local

A real time simulation of battery conditions is an essential step in the development of energy harvesting devices. Since it is not possible to have a direct measurement, the battery information, such as the remaining charge, need to be estimated by means of model-based estimation algorithms. Most of the existing models describing battery behaviour, are suitable only for a constant discharge current. This paper proposes a study of the dependence of the equivalent circuit model parameters on different discharge conditions. The model presented provides a powerful tool to represent the batteries’ behaviour in energy harvesting systems, involving continuous charge and discharge cycles. The extraction of parameters was performed, starting from a set of reference curves generated in Matlab Simulink environment, referring to Li-ion technology batteries. The parameters were extracted by means of a cascade of global and local search identification algorithms. Finally, the relations describing parameters’ behaviours as functions of the discharge current are presented.

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