An Active Equalizer for Serially Connected Lithium-Ion Battery Cells

2013 ◽  
Vol 732-733 ◽  
pp. 809-812 ◽  
Author(s):  
Hong Rui Liu ◽  
Chao Ying Xia
Keyword(s):  
Lithium Ion Battery ◽  
Lithium Ion ◽  
State Of Charge ◽  
Experimental Results ◽  
Battery Cell ◽  
Charging Current ◽  
In Series ◽  
Battery Cells

This paper proposes an equalizer for serially connected Lithium-ion battery cells. The battery cell with the lowest state of charge (SOC) is charged by the equalizer during the process of charging and discharging, and the balancing current is constant and controllable. Three unbalanced lithium-ion battery cells in series are selected as the experimental object by this paper. The discharging current under a certain UDDS and 20A charging current are used to complete respectively one time balancing experiment of discharging and charging to the three lithium-ion battery cells. The validity of the balancing strategy is confirmed in this paper according to the experimental results.

scholarly journals Effect of Current Rate and Prior Cycling on the Coulombic Efficiency of a Lithium-Ion Battery

Batteries ◽  
2019 ◽  
Vol 5 (3) ◽  
pp. 57 ◽  
Author(s):  
Seyed Madani ◽  
Erik Schaltz ◽  
Søren Knudsen Kær
Keyword(s):  
Lithium Ion Batteries ◽  
Lithium Ion Battery ◽  
Coulombic Efficiency ◽  
Lithium Ion ◽  
Degradation Behavior ◽  
Battery Cell ◽  
The Third ◽  
Capacity Loss ◽  
Battery Cells

The determination of coulombic efficiency of the lithium-ion batteries can contribute to comprehend better their degradation behavior. In this research, the coulombic efficiency and capacity loss of three lithium-ion batteries at different current rates (C) were investigated. Two new battery cells were discharged and charged at 0.4 C and 0.8 C for twenty times to monitor the variations in the aging and coulombic efficiency of the battery cell. In addition, prior cycling was applied to the third battery cell which consist of charging and discharging with 0.2 C, 0.4 C, 0.6 C, and 0.8 C current rates and each of them twenty times. The coulombic efficiency of the new battery cells was compared with the cycled one. The experiments demonstrated that approximately all the charge that was stored in the battery cell was extracted out of the battery cell, even at the bigger charging and discharging currents. The average capacity loss rates for discharge and charge during 0.8 C were approximately 0.44% and 0.45% per cycle, correspondingly.

scholarly journals A Nonlinear-Model-Based Observer for a State-of-Charge Estimation of a Lithium-Ion Battery in Electric Vehicles

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3383 ◽  
Author(s):  
Woo-Yong Kim ◽  
Pyeong-Yeon Lee ◽  
Jonghoon Kim ◽  
Kyung-Soo Kim
Keyword(s):  
Lithium Ion Battery ◽  
Nonlinear Model ◽  
Open Circuit Voltage ◽  
Lithium Ion ◽  
Open Circuit ◽  
The State ◽  
State Of Charge ◽  
Battery Cell ◽  
Model Based ◽  
State Of Charge Estimation

This paper presents a nonlinear-model-based observer for the state of charge estimation of a lithium-ion battery cell that always exhibits a nonlinear relationship between the state of charge and the open-circuit voltage. The proposed nonlinear model for the battery cell and its observer can estimate the state of charge without the linearization technique commonly adopted by previous studies. The proposed method has the following advantages: (1) The observability condition of the proposed nonlinear-model-based observer is derived regardless of the shape of the open circuit voltage curve, and (2) because the terminal voltage is contained in the state vector, the proposed model and its observer are insensitive to sensor noise. A series of experiments using an INR 18650 25R battery cell are performed, and it is shown that the proposed method produces convincing results for the state of charge estimation compared to conventional SOC estimation methods.

Improving SOC accuracy using collective estimation for Lithium Ion battery cells in series

2014 ◽  
Author(s):  
Jariullah Safi ◽  
Michael Beeney ◽  
Michelle Kehs ◽  
Joel Anstrom ◽  
Sean Brennan ◽  
...  
Keyword(s):  
Lithium Ion Battery ◽  
Lithium Ion ◽  
In Series ◽  
Battery Cells

Lithium-Ion Battery Cell Health Monitoring Using Vibration Diagnostic Test

2013 ◽  
Author(s):  
Huan L. Pham ◽  
J. Eric Dietz ◽  
Douglas E. Adams ◽  
Nathan D. Sharp
Keyword(s):  
Mechanical Properties ◽  
Lithium Ion Batteries ◽  
Lithium Ion Battery ◽  
Diagnostic Test ◽  
Excitation Frequency ◽  
High Capacity ◽  
Lithium Ion ◽  
The State ◽  
State Of Charge ◽  
Battery Cell

With their superior advantages of high capacity and low percentage of self-discharge, lithium-ion batteries have become the most popular choice for power storage in electric vehicles. Due to the increased potential for long life of lithium-ion batteries in vehicle applications, manufacturers are pursuing methodologies to increase the reliability of their batteries. This research project is focused on utilizing non-destructive vibration diagnostic testing methods to monitor changes in the physical properties of the lithium-ion battery electrodes, which dictate the states of charge (SOC) and states of health (SOH) of the battery cell. When the battery cell is cycled, matter is transported from one electrode to another which causes mechanical properties such as thickness, mass, stiffness of the electrodes inside a battery cell to change at different states of charge; therefore, the detection of these changes will serve to determine the state of charge of the battery cell. As mass and stiffness of the electrodes change during charge and discharge, they will respond to the excitation input differently. An automated vibration diagnostic test is developed to characterize the state of charge of a lithium-ion battery cell by measuring the amplitude and phase of the kinematic response as a function of excitation frequency at different states of charge of the battery cell and at different times in the life of the cell. Also, the mechanical properties of the electrodes at different states of charge are obtained by direct measurements to develop a first-principles frequency response model for the battery cell. The correlation between the vibration test results and the model will be used to determine the state of charge of the cell.

scholarly journals Optimal SoC Balancing Control for Lithium-ion Battery Cells Connected in Series

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2875
Author(s):  
Chi Nguyen Van ◽  
Thuy Nguyen Vinh ◽  
Minh-Duc Ngo ◽  
Seon-Ju Ahn
Keyword(s):  
Lithium Ion Battery ◽  
Lithium Ion ◽  
Experimental Tests ◽  
Programming Algorithm ◽  
Estimation Algorithms ◽  
In Series ◽  
Problem Solving Process ◽  
The Cost ◽  
Balancing Control ◽  
Battery Cells

The optimal state of charge (SoC) balancing control for series-connected lithium-ion battery cells is presented in this paper. A modified SoC balancing circuit for two adjacent cells, based on the principle of a bidirectional Cuk converter, is proposed. The optimal SoC balancing problem is established to minimize the SoC differences of cells and the energy loss subject to constraints of the normal SoC operating range, the balancing current, and current of cells. This optimization problem is solved using the sequential quadratic programming algorithm to determine the optimal duties of PWM signals applied to the SoC balancing circuits. An algorithm for the selection of the initial points for the optimal problem-solving process is proposed. It is applied in cases where the cost function has no decreasing part. Experimental tests are conducted for seven series-connected Samsung cells. The optimal SoC balancing control and SoC estimation algorithms are coded in MATLAB and embedded in LabVIEW to control the SoC balancing in real time. The test results show that the differences between the SoCs of cells converges to the desired range using the proposed optimal SoC balancing control strategy.

Battery cell modeling and online estimation of the state of charge of a lithium-ion battery

2018 ◽  
Vol 41 (5) ◽  
pp. 412-418 ◽  
Author(s):  
I-Haur Tsai ◽  
Kuan-Hsun Yu ◽  
Alexander Tseng ◽  
Jia-Yush Yen ◽  
Tseng-Ti Fu ◽  
...  
Keyword(s):  
Lithium Ion Battery ◽  
Lithium Ion ◽  
The State ◽  
State Of Charge ◽  
Battery Cell ◽  
Online Estimation ◽  
Cell Modeling
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