A Comparative Analysis of Cell Balancing Techniques For Battery Management System

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 09 Issue: 04 | Apr 2022 www.irjet.net p-ISSN: 2395-0072
© 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 3817
A Comparative Analysis of Cell Balancing Techniques For Battery
Management System
Tejaswini S, Subhash Kumar N, Surakshitha P, Swarna K R, Varshitha H M
Tejaswini S, Assistant Professor, Department of Electronics and Communication Engineering, VidyaVardhaka
College of Engineering, Mysore, Karnataka
Subhash Kumar N, Department of Electronics and Communication Engineering, VidyaVardhaka College of
Engineering, Mysore, Karnataka
Surakshitha P, Department of Electronics and Communication Engineering, VidyaVardhaka College of
Swarna K R, Department of Electronics and Communication Engineering, VidyaVardhaka College of Engineering,
Mysore, Karnataka
Varshitha H M, Department of Electronics and Communication Engineering, VidyaVardhaka College of
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Abstract - Automobile industry is moving toward the
development of fully electric vehicles (EVs) in near future.
This new architecture requires a large battery pack that
serves as the vehicle's main source of energy. This larger
battery pack allows electric vehicles to run longer distances
by utilizing more parallel strings to increase the overall
energy storage capacity of the system. The longevity and
performance of the battery pack are of prime importance. It
is critical to maintain a charge balance of a series/parallel
configured battery module because of manufacturing
inconsistencies and unique performance characteristics of
individual cells. Two balancing techniques are proposed and
analyzed in this paper. An active balance system and a
passive balance system are proposed and applied to a
battery module that has such a configuration in order to
balance the individual battery cell voltages. The effects of
these balancing techniques have been simulated using the
MATLAB simulation tool over a series/parallel battery pack.
The simulator provides a way to measure and compare both
balancing techniques by varying circuit parameters. This
allows a thorough examination of the balancing system by
establishing a trend based on the effects of circuit
parameters on system performance.
Key Words: Battery pack, Cell Balancing, Battery
Management system, Passive balancing, Active
balancing, Capacitors, Resistors.
1. INTRODUCTION
In lithium-ion battery packs, cell balancing is
necessary when multiple cells are arranged serially.
Designing electronic components in such a way that they
continuously balance the cell voltages is very important.
Not only is it vital for the battery pack's performance, but
it is also essential for
optimal life. We can design a battery with a larger capacity
for an application, since the battery is able to achieve a
higher State of Charge (SOC) because of cell balancing. Cell
balancing is not used by many companies at the beginning
of their design process to reduce cost; however, the SOC
cannot proceed to 100 percent without investing in
balancing the hardware and software.
1.1 Cell Imbalance
Lithium cells are subject to accelerated degradation either
when they are overheated or overcharged. As a result of
thermal runaway conditions, they can catch fire or even
explode. When the voltage of a lithium-ion cell goes
beyond 4.2 V by just a few hundred millivolts, it can still
experience the above mentioned conditions.
1.2 Cell Balancing
Fig 1 depicts the process of cell balancing. The process of
balancing cells after they have been fully charged, or when
they are at their maximum charge, can be defined as
equalizing the voltage among them. Negligible differences
are always there in the Self-discharge rate, State of Charge,
capacity, characteristics of temperature and impedance
between two cells. Though they are of the same
manufacturer, model, and production lot, this remains to
be true. Manufacturers will group the cells with similar
voltage so that they coordinate as closely as possible, but
still, there can be slight differences in the capacity,

impedance of individual cells and self-discharge rate over
time which can contribute to voltage separation.
Full charge will be detected by typical battery chargers
through validating if the voltage regulation point has been
reached by the voltage of all the cells. As long as the
overvoltage protection limits aren't exceeded, individual
cells may vary their voltage. In contrast, weaker cells tend
to exhibit higher voltage at full charge termination than
the cells in series. The weakened cells are then subjected
to continuous overcharging. At charge completion, the
weaker cells' voltages are higher, which accelerates their
degradation. The rate of degradation will increase by
thirty percent even in the case of maximum charging
voltage being exceeded by just ten percent.
Either due to a faster rate of discharge or higher internal
resistance caused by their lesser capacity, weak cells tend
to discharge at a lower voltage. As a result, when any of
the weak cells hit the cell under voltage protection, the
battery’s complete capacity will be never used even when
sufficient voltage of the pack is available to power the
system, because over discharge will be prevented by the
pack protector by stopping the discharge of the entire
pack in the case of any cell voltage being below the cell
under voltage threshold, which is approximately 2.7 V.
Fig -1: Cell Balancing
1.2.1 Passive Cell Balancing
It is a simple and straightforward cell leveling approach in
which the cells are discharged via a dissipative bypass
route. This strategy is advantageous in the application of a
low-cost system. The passive cell balancing approach is
the least popular since one hundred percent of the excess
energy of a higher-energy cell is wasted as heat during
discharge, resulting in a significant reduction in battery
runtime.
Fixed and switching shunting resistors are the two types
of cell balancing methods. The one which prevents the
circuit from being charged too much is usually linked to
the fixed shunting and is known as the Fixed shunting
resistor. The maximum voltage of every cell can be
regulated without
causing harm to them by using resistors in the passive
balancing circuit. As a result of the energy consumed by
these resistors, thermal losses may occur to balance a
battery in the management system of the battery. Hence,
Fixed shunting resistor method is demonstrated to be
inefficient.
The most common cell equalization approach is the switch
shunting resistor cell balancing circuit. It has two modes,
one of which is continuous and the other of which is
sensing. The continuous mode instructs All switches are
instructed to turn on or off simultaneously in the
Continuous mode. Each cell, however, needs a voltage
sensor which is concurrent in the sensing mode. Due to
the presence of balancing resistor, this cell balancing
circuit consumes a lot of energy. For a battery system that
needs to be charged or discharged at a low current, this
kind of Cell balancing circuit is designed. This cell
balancing circuit uses a lot of energy because of the
resistor used for balancing. This circuit is suited for a
system of battery which requires less current when it is
either discharged or charged. Passive cell balancing with a
switched shunt resistor is shown in Fig 2.
Fig -2: Passive Cell Balancing
1.2.2 Active Cell Balancing
Energy is transferred from one cell to another using active
cell balancing, which uses capacitive or inductive charge.
That is, from a cell with a greater charge state to one with
a lower charge state. By transferring energy from the cell
having more energy than the other in the pack, the active

balancing technique tries to extend the life or state of
charge of a pack of lower capacity cells. Instead of
squandering energy as heat through tiny converter
circuits, an active cell balancer efficiently balances cells by
sending energy from the highest voltage cells to the lowest
voltage cells. Charge shuttling and energy converters are
two forms
of active cell balancing technologies. The process of
actively shifting charges from one cell to another to
maintain equal cell voltage is known as charge shuttling.
Energy converters transmit energy between the cells of a
battery pack using transformers and inductors. Active cell
balancing with a switched capacitor is shown in Fig 3.
Fig -3: Active Cell Balancing
2. LITERATURE REVIEW
Jonathan Carter, Zhong Fan, and Jun Cao[1] have
highlighted the strategies utilized for cell balancing, such
as the Active and Passive methods. The best solutions are
split down into resistor, capacitor, inductor, and
transformer-based methods. Each circuit is described in
length, including its benefits and drawbacks, as well as
noticeable variations. The differences between the various
methods are compared, and the issues that arise are
examined. A
suitable solution is proposed. The paper then goes on to
explore the difficulty in directly comparing the
performance of different CECs (Charge Equalization
Circuits) as well as the ambiguity of a CEC's industrial
needs. Finally, future study will consider modern
components in order to improve existing solutions.
Finally, it includes a fully flexible battery pack that can be
adjusted to meet a variety of voltage and current needs.
Hemavathi Sugumar[2] has highlighted the major
characteristics of Cell balancing techniques for battery
packs of Lithium-ion. They are evaluated and contrasted in
terms of charge/discharge capability, cell balancing speed,
cost, applications, complexity of regulation, and key
components necessary to equalize the cells. According to
the author, Lithium-ion batteries are affected by
overcharge and discharge current, thermal runaway,
undervoltage, overvoltage, and cell voltage imbalance.
Following a thorough examination, we have determined
that the Passive cell balancing technique is best suited for
applications with low power, whereas the Active cell
balancing technique is best suited for applications with
high power. Since a result, cell balancing is a key aspect of
the Battery Management System, as it improves the
battery pack's performance, extends its cycle life, and
assures safe operation under all conditions.
Paul Sathiyan S and Calvin Immanuel S[3] have discussed
the importance of Lithium-ion batteries in electrical
applications, as well as the need for safe battery pack
operation. The requirement for cell balancing is also
mentioned in order to extend the battery pack's life cycle.
It is mentioned what considerations should be taken when
integrating Lithium-ion batteries. The authors go on to say
that because Lithium-ion batteries are the most popular,
proper methods for extending the battery's life cycle and
efficiency should be used. This study aims to convey
complicated information and concepts concerning
Batteries, Systems of battery management, Procedures of
cell balancing, and other related topics. The work is
primarily concerned with the design, development, and
modeling of a passive cell balancing circuit in detail.
Peter Van, Noshin Omas, Joeri Van Mielro, Den Bossche,
Mohamed Daowd[4] have worked on Battery balancing
using Capacitor for balancing. Capacitor for Battery
Balancing System being the title. The system of battery
management is the most vital as it helps in increasing of
the
life of a battery pack. The paper studied talks about the
capacitor-based topologies for battery balancing. The
paper compares between the methods. It is simulated with
the MATLAB Simulink. The highly charged cell, capacitor
and lovely charged cell energy shuttling has become

function of the capacitor, switching frequency, voltages
between the unbalanced cells and also duty cycle. Based
on the above factors the SSC balancing was proposed. The
proposed methodology has helped in control strategy to
reduce system cost and also balancing time.
Mailier Autoine, Peter Van,Mohamed Dawod, Noshin
Omar, Joeri Van Mierlo, De Bossine[5] The title of the
report is Single switched capacitor-based balancing of
battery for improvements of the system. The paper
explains the methods for reducing size of used system for
battery management. This paper has reviewed the battery
balancing using the Single Switched capacitors. This was
achieved by increasing transferring of the energy between
cells and also the capacitors.
Adha Imam Cahyadi, Erika Loniza, Dwi Dharma Arta
Kusuma, Johans Andrino Situmorang [6] The title for the
report Passive balancing of a Lithium Polymer battery
using fixed shunt resistor method. In the above study,
condition of voltage of every battery was designed. The
technique used for the study was Passive shunt resistor
for balancing. The resistor and removing of excess voltage
was done to balance value of voltage of the battery cell
using resistor. The circuit designed was able to do
balancing of the voltage in each cell.
Ali Farazan Moghaddam, Alex Van Den Bossche[7] explain
the Active cell balancing methods of li-ion batteries for the
single transformer which has two times fewer secondaries
than cells. A full bridge driver in the circuit is used in this
paper, having two times less number of transistors than
cells, that controls the N Channel MOSFETs as switch. As
result switching losses are less. Efficiency, Equalization
pace and complexity of implementation in terms of
performance.
Yunlei Zhang, Cungang Hu, Weixiang Shen and Xiudong
Cui[8] describe that the report is based in Fuzzy logic
controller for the balancing of a fast multi switched
inductor in Lithium-ion battery packs for electric vehicles.
Instead of using a proportional integral controller, a fuzzy
logic controller based on a multi-switched inductor circuit
is used to improve the performance of balancing in
Lithium-ion battery packs. Thus, paper also has low-cost
battery balancing for FL controller on basis of MSIBC.
Therefore, less time was taken by the proposed FL
Controller to achieve balancing of the battery pack.
Blanco Riesco, Angel[9] The title of the report An Efficient
Cell Balancing Method For LiFePo4 Batteries Based On
Inductors. In this paper a circuit has been designed and
programmed through which the balancing of cells is
performed using inductors. It is theoretically and
practically created to simulate the behaviour of an electric
vehicle battery. Inductor method more precision and
speed is achieved when charging the inductors.
Dwi Dharma Arta Kusuma, Johanes Andriano Situ Morang,
Adha Imam Cahyadi, Erika Loniza[10] devised a
mechanism to track the voltage of each battery cell. The
passive shunt resistor balancing approach was adopted in
this investigation. To stabilize the value of voltage in the
battery cells and further to remove the excess of it, an
electronic circuit was constructed with the help of
resistors. Simulation and execution of a three-cell Lithium-
ion battery series' balancing method are the main themes
of this article. The result implies that the electrical circuit
can keep each cell's voltage balanced. The 0.1 C rate of
discharge has the best performance based on the findings
of the experiment with various load values since it has no
significant effect on the battery voltage characteristic,
resulting in superior sensor reads.
3. CONCLUSIONS
A battery charging system that eliminated mutual
influence between adjacent cells in battery charging was
proposed by the papers studied, thereby demonstrating
that battery efficiency can be enhanced, size of system can
be reduced and charging time can be reduced. Mutual cell
balancing using passive and active elements is performed
by the conventional systems to balance each cell
individually. From the papers studied we infer passive cell
balancing methodology will be most suitable for less
powered applications whereas active cell balancing is
applicable in high power application. Therefore, Battery
Manage system is an essential feature in the balancing of
cell as it helps in enhancing battery pack performance,
also this increases the life cycle and hence ensures a very
safe operation during most challenging conditions.
ACKNOWLEDGEMENT
We would like to convey our wholehearted thanks of
gratitude to our guide Professor. Tejaswini S, our Head of
the Department Dr. Chandrashekar M Patil and our
principal Dr. B Sadashive Gowda who gave us a golden
opportunity to work for the wonderful project “A
Comparative Analysis of Cell Balancing Techniques for
Battery Management System”. This project has helped us
in researching and learning many new things and we are
wholeheartedly thankful for them.

REFERENCES
[1] Jonathan Carter, Zhong Fan; Making the case for Cell
equation circuits. Keele university Sep 2019.
[2] Hemavathi Sugumar; Making the case for Cell
balancing methods for Li-ion battery technology.
Electrochemical Research Institute April 2021.
[3] Calvin Immanual, Paul Sathiyan S; Making the case for
Development of simply battery management system
for cell balancing. IOP conference July 2021.
[4] Mohammed Dowad, Noshij Omar, Peter van Den
Bossche; Making the case for capacitor based battery
balancing system.Los angels May 6 2012.
[5] Mohammed Dowad, Mailer Autonie; Making the case
for single switched capacitor battery balancing system
enhancements. Energies 18 Arp 2013.
[6] Erika Loniza, Johanes Andino Situmorang; Making the
case for Passive balancing of battery lithium polymer
using fixed shunt resistor circuit method.
International conference 2015.
[7] Ali Farazan Mohammed, Alux Van Den bossche;
Making the case for A single transformer for active cell
balancing of lithium-ion batteries Aug 2019
[8] Xiudong Cui, Weixang shen; Making the case for Multi-
switched Inductor balancing system July 2017
[9] Blanco Riesco, Angel; Making the case for An efficient
cell balancing Method for LiFePo4 batteries based on
inductor. Science Technikum wiener 2021.
[10] Erika Loniza; Johanes Andriano Stumrang; Dwi
Dharma Arta Kusuma; Making the case for Passive
Balancing of battery lithium polymer using shunt
resistor circuit method. AIP conference proceedings
21st July 2016
BIOGRAPHIES
Tejaswini S
Assistant Professor
Department of Electronics and
Communication Engineering
VidyaVardhaka College of
Engineering Mysore
Subhash Kumar N
Engineering Mysore
Surakshitha P
Engineering Mysore
Swarna K R
Engineering Mysore
Varshitha H M
Engineering Mysore

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