Query:  Individual cell voltage equalizer for lithium ion battery

Candidate papers:

abstract: Now a days, lithium ion (Li ion) battery is the primary choice for the Electric Vehicle's (EV) power supply. Energy density in lithium ion battery is very high. In a battery pack, thousands of Li ion cell are placed in series parallel combination. Some issues like overcharging and undercharging are always associated with series connected battery. To overcome this problem, each cell voltage is equalized by using a non dissipative technique. This paper describes the technique which equalizes the cell in very short time. The individual cell of a battery pack will be quickly, efficiently and simultaneously balanced by triggering the MOSFET (metal oxide semiconductor field effect transistor) associated with each cell. Using MATLAB/Simulink balancing circuit with equalization technique is modelled and outputs are produced with series connected 4 Li ion battery cells. In order to interface the developed model in real time MicroAutoBoxII is used.
author_names: Monojit Goswami

T B Isha
title: Individual Cell Voltage Equalizer for Lithium Ion Battery
venue: 2018 4th International Conference on Electrical Energy Systems (ICEES)
year: 2018

abstract: This digest proposes an individual cell voltage equalizer using selective two current paths for series connected lithium ion battery strings. In the proposed equalizer, a central equalization converter is shared by every battery cells through the cell selection switch, instead of a dedicated charge equalizer for each cell. The central converter is utilized as a controllable current source by a modified rectifier. With this configuration, although the proposed equalizer has a central dc dc converter, individual charge equalization can be effectively achieved for the each cell in the strings. Furthermore, great size reduction and low cost can be obtained for an industrial battery equalizer. In this digest, an optimal power rating design guide is also employed to obtain a minimal balancing size while satisfying equalization requirements. A prototype for eight lithium ion battery cells is optimally designed and implemented. Experimental results verify that the proposed equalization method has good cell balancing performance.
author_names: Chol-Ho Kim

Young-do Kim

Gun-Woo Moon

Hong-Sun Park
title: Individual cell voltage equalizer using selective two current paths for series connected li ion battery strings
venue: 2009 IEEE Energy Conversion Congress and Exposition
year: 2009

abstract: In lithium ion battery system for hybrid electric vehicle, charge equalizer is essential to enhance the battery life cycle and safety. However, for a large number of battery cells, a conventional equalizer has the difficulty of individual cell balancing and the implementation size problem as well as the cost. Moreover, it shows high voltage stress of electrical elements in the equalization converter due to the high voltage of battery pack. To improve these drawbacks, this paper proposes a modularized two stage charge equalizer with cell selection switches. The proposed circuit employs the two stage dc dc converter to reduce the voltage stress of equalization converter. Contrary to conventional method, the proposed equalizer can achieve the individual cell balancing only through the cell selection switches. With the two stage converter and the cell selection switches, the proposed equalizer leads to the great size reduction with lower cost which brings advancement of individual cell balancing in a large number of battery cells. In this paper, a prototype for 88 lithium ion battery cells is optimally designed and implemented. Experimental results are presented to verify that the proposed equalization method has a good cell balancing performance showing the low voltage stress and small size with the lower cost.
author_names: Chol-Ho Kim

Moon-Young Kim

Hong-Sun Park

Gun-Woo Moon
title: A Modularized Two Stage Charge Equalizer With Cell Selection Switches for Series Connected Lithium Ion Battery String in an HEV
venue: IEEE Transactions on Power Electronics
year: 2012

abstract: Lithium ion(Li ion)batteries have a higher power density and can operate at a higher state of charge(SOC)compared with the Nickel Hydrogen(NiH2)batteries commonly used on spacecraft.This reduces the launch mass of the EPS(Electrical Power System).This paper describes a Lithium ion battery cell Equalization method,which employs bi directional forward DC AC converters,plus a unique common node "Share Bus"to provide autonomous charge distribution,until all the cells of the battery are balanced at the same voltage.It also includes individual cell voltage monitoring,telemetry data.Multisim is used to analyses the function and performance,simulation result proves that the method is effective for Lithium ion battery equalization.
author_names: Song Din
title: Research on Non dissipative Cell Equalizer for Space Lithium ion Battery
year: 2014

abstract: The necessity of a charge equalizer is increasing for series connected lithium ion cells in electric vehicles. It is used to enhance the battery's safety and life cycle. For these reasons, the cell voltage levels should be individually monitored and effectively balanced in the battery string. However, individual cell balancing has the problem of size as well as the control complexity for a large number of battery cells. To alleviate these drawbacks, this paper proposes an individual cell equalizer with simple structure. In the proposed equalizer, each cell has its own active clamp flyback DC DC converter. A main switch and clamp switch in the converter are shared by every separated transformer through parallel primary connection. This converter is utilized as a selectable current source by using selection switches in the primary winding of transformer. With this configuration, the simple structure and easy control can be effectively achieved for each cell even if the proposed equalizer has separated transformers as for the counts of battery cells. Furthermore, high equalization efficiency and outstanding equalization performance can be obtained for a high capacity battery. In this paper, a prototype for eight lithium ion battery cells is optimally designed and implemented. Experimental results verify that the proposed equalization method has a good cell balanced performance.
author_names: Chol-Ho Kim

Moon-Young Kim

Gun-Woo Moon
title: Individual cell equalizer using active clamp flyback converter for li ion battery strings in an electric vehicle
venue: 2012 IEEE Vehicle Power and Propulsion Conference
year: 2012

abstract: A fuzzy logic control battery equalizing controller (FLCBEC) is adopted to control the cell voltage balancing process for a series connected Li ion battery string. The proposed individual cell equalizer (ICE) is based on the bidirectional Cuk converter operated in the discontinuous capacitor voltage mode (DCVM) to reduce the switching loss and improve equalization efficiency. The ICE with the proposed FLCBEC can reduce the equalizing time, maintain safe operations during the charge/discharge state and increase the battery string capacity.
author_names: Yuang-Shung Lee

Ming-Wang Cheng

Shun-Ching Yang
title: Fuzzy Controlled Individual Cell Equalizers for Lithium Ion Batteries
venue: IEICE Trans. Commun.
year: 2008

abstract: A systematic approach to the analysis and design of a bi directional Cuk converter for the cell voltage balancing control of a series connected lithium ion battery string is presented in this paper. The proposed individual cell equalizers (ICE) are designed to operate at discontinuous capacitor voltage mode (DCVM) to achieve the zero voltage switching (ZVS) for reducing the switching loss of the bi directional DC/DC converters. Simulation and experimental results show that the proposed battery equalization scheme can not only enhance the bi directional battery equalization performance, but also can reduce the switching loss during the equalization period. Two designed examples are demonstrated, the switch power losses are significantly reduced by 52.8% from the MOSFETs and the equalization efficiency can be improved by 68 86.9% using the proposed DCVM ZVS battery equalizer under the specified cell equalization process. The charged/discharged capacity of the lithium ion battery string is increased by using the proposed ICEs equipped in the battery string.
author_names: Yuang-Shung Lee

Ming-Wang Cheng

Shun-Ching Yang

Co-Lin Hsu
title: Individual Cell Equalization for Series Connected Lithium Ion Batteries
venue: IEICE Trans. Commun.
year: 2006

abstract: A systematic approach to reform and analyze a soft switching bidirectional dc to dc converter is proposed for cell voltage balancing control in a series connected battery string. quasi resonant converter circuits have been designed to achieve the zero current switching (ZCS) to reduce the switching loss in bidirectional battery equalizers. The results indicate that the switching loss and energy transfer efficiency can be substantially improved using the quasi resonant ZCS (QRZCS) technology in a battery charging system with an individual cell equalizer (ICE) The validity of the battery equalization is further verified using an experimental installation involving a battery string of three lithium ion cells. The simulation and experimental results show that the proposed QRZCS battery equalization schemes can achieve bidirectional battery equalization performance and reduce the MOSFET transistor switch power losses by more than 96% and increase the efficiency by around 20%~30% compared with the conventional battery equalizer during an identical equalization process
author_names: Yuang-Shung Lee

Guo-Tian Cheng
title: Quasi Resonant Zero Current Switching Bidirectional Converter for Battery Equalization Applications
venue: IEEE Transactions on Power Electronics
year: 2006

abstract: One of the most commonly used cell equalizers, the shunting equalizer, exhibits interactive performance with series connected energy storage cells. Experimental charging tests were carried out on series connected supercapacitors or lithium ion cells to investigate this interactive performance. This paper presents and analyzes the charging performance of series connected cells with shunting equalizers to provide a qualitative understanding of the interaction between the charge and shunt currents. The experimental results indicated that the inflection points in voltage and current profiles produced by the equalizers may be useful in detecting voltage imbalances without measuring individual cell voltages.
author_names: Masatoshi Uno
title: Interactive charging performance of a series connected battery with shunting equalizers
venue: INTELEC 2009 31st International Telecommunications Energy Conference
year: 2009

abstract: The variations in the manufacturing process and non uniform stress during usage makes the Li ion cells in a battery pack to have difference in parameters such as internal resistance, cell capacity, self discharge rate, etc. These variations aid the battery ageing process and limit the performance of the battery pack. To achieve higher performance and uniform ageing, a smart cell equalizer is proposed in this paper. Apart from the normal cell equalizer which causes further stress to the cells, this paper proposes a smart and dynamic cell equalizer using the forward converter to assist the individual cells in the battery pack. The equalizer tries to keep SoC levels of all cells near equal levels by dynamically supporting each cell. The proposed method is validated using MATLAB/Simulink simulations. The results show that the proposed scheme is able to balance SoC in all dynamic conditions and module level SoC balancing is also achieved without using additional circuits.
author_names: C Vishnu

Abdul Saleem
title: Smart Cell Equalizer for Lithium ion Battery Packs
venue: 2021 International Conference on Communication, Control and Information Sciences (ICCISc)
year: 2021