scholarly journals A Time-Efficient and Accurate Open Circuit Voltage Estimation Method for Lithium-Ion Batteries

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1803 ◽  
Author(s):  
Yingjie Chen ◽  
Geng Yang ◽  
Xu Liu ◽  
Zhichao He
Keyword(s):  
Lithium Ion Batteries ◽  
Open Circuit Voltage ◽  
Estimation Method ◽  
Nonlinear Function ◽  
Lithium Ion ◽  
Open Circuit ◽  
Constant Current ◽  
Estimation Accuracy ◽  
Battery Modeling ◽  
The Difference

The open circuit voltage (OCV) of lithium-ion batteries is widely used in battery modeling, state estimation, and management. However, OCV is a function of state of charge (SOC) and battery temperature (Tbat) and is very hard to estimate in terms of time efficiency and accuracy. This is because two problems arise in normal operations: (1) Tbat changes with the current (I), which makes it very hard to obtain the data required to estimate OCV—terminal voltage (U) data of different I under the same Tbat; (2) the difference between U and OCV is a complex nonlinear function of I and is very difficult to accurately calculate. Therefore, existing methods have to design special experiments to avoid these problems, which are very time consuming. The proposed method consists of a designed test and a data processing algorithm. The test is mainly constant current tests (CCTs) of large I, which is time-efficient in obtaining data. The algorithm solves the two problems and estimates OCV accurately using the test data. Experimental results and analyses showed that experimental time was reduced and estimation accuracy was adequate.

Measurement and Prediction of Decomposed Energy Efficiencies of Lithium Ion Batteries With Two Charge Models

2021 ◽  
Vol 18 (3) ◽  
Author(s):  
Yuhao Huang ◽  
Yan Su ◽  
Akhil Garg
Keyword(s):  
Lithium Ion Batteries ◽  
Open Circuit Voltage ◽  
Prediction Method ◽  
Lithium Ion ◽  
Open Circuit ◽  
Constant Current ◽  
New Process ◽  
Artificial Neural Network Ann ◽  
Cv Model ◽  
Charge Discharge

Abstract A new process decomposed calculation method is developed to compare the cycle based charge, discharge, net, and overall energy efficiencies of lithium-ion batteries. Multi-cycle measurements for both constant current (CC) and constant current to constant voltage (CC-CV) charge models have been performed. Unlike most conventional efficiency calculation methods with one mean open-circuit voltage (OCV) curve, two OCV curves are calculated separately for the charge and discharge processes. These two OCV curves help to clarify the intra-cycle charge, discharge, net, and overall energy efficiencies. The relationships of efficiencies versus state of charge, state of quantity, and scaled stresses are demonstrated. Efficiency degradation patterns versus cycle numbers and scaled stresses are also illustrated with the artificial neural network (ANN) prediction method. The decaying ratios of the overall efficiencies are about 2% and 0.3% in the first 30 cycles, for CC and CC-CV, respectively. Hence, efficiencies of the CC-CV model are more stable compared with the CC model, which are shown by both experimental and ANN prediction results.

Influence of different open circuit voltage tests on state of charge online estimation for lithium-ion batteries

2016 ◽  
Vol 183 ◽  
pp. 513-525 ◽  
Author(s):  
Fangdan Zheng ◽  
Yinjiao Xing ◽  
Jiuchun Jiang ◽  
Bingxiang Sun ◽  
Jonghoon Kim ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Open Circuit Voltage ◽  
Lithium Ion ◽  
Open Circuit ◽  
State Of Charge ◽  
Online Estimation

Prediction Model and Principle of End-of-Life Threshold for Lithium Ion Batteries Based on Open Circuit Voltage Drifts

2017 ◽  
Vol 255 ◽  
pp. 83-91 ◽  
Author(s):  
Yingzhi Cui ◽  
Jie Yang ◽  
Chunyu Du ◽  
Pengjian Zuo ◽  
Yunzhi Gao ◽  
...  
Keyword(s):  
Prediction Model ◽  
Lithium Ion Batteries ◽  
End Of Life ◽  
Open Circuit Voltage ◽  
Lithium Ion ◽  
Open Circuit
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