TRIBHUVAN UNIVERSITY� INSTITUTE OF ENGINEERING� PASHCHIMANCHAL CAMPUS, POKHARA

TEAM HORSEPOWER

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Members

Anil Kumar Yadav (PAS075BEL004)

Nikee Thakur (PAS075BEL026)

Rahul Kumar Jha (PAS075BEL030)

Sumina Neupane (PAS075BEL041)

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Battery Management System (BMS) in Electric Cycles

INTRODUCTION

• EVs use an electric motor, battery, and charger instead of a traditional engine tank, and gasoline pump due to global climate change and rising crude oil prices.
• Lithium-ion batteries are a suitable choice due to their high specific energy, energy density, open circuit voltage, and low self-discharge.

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�BATTERY MANAGEMENT SYSTEM

• The battery management system (BMS) plays an important role in preserving battery life and improving EV performance. 
• The BMS performs tasks such as measuring voltage, current, and temperature, determining state of charge and health, and controlling and monitoring charge/discharge characteristics of battery.

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Any electronic system that manages a rechargeable battery by protecting the battery from operating outside its safe operating area

FUNCTION OF BATTERY MANAGEMENT SYSTEM

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• Battery Monitoring: The BMS will continuously check the voltage, temperature, and charge of the battery.
• Battery protection: The BMS will put preventative measures in place to stop the battery from being overcharged or over discharged.
• Battery Communication: To provide real-time information on the battery's performance and health, the BMS will communicate with the vehicle's control system.
• Battery management: To ensure the battery's durability and efficiency, the BMS will regulate how it is charged and discharged.
• Battery Safety: The BMS will put safety precautions in place to stop any unexpected failures and guarantee the safety of the vehicle and its occupants.

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BMS CYCLE�

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1. Battery Monitoring

2. Battery Protection

3. Battery Balancing

4. Battery Management Algorithms

5. Data Logging

6. Communication with external devices

System constantly monitors the battery's voltage, current, temperature, and state of charge (SOC) & this data is used to determine the battery's health, capacity, and overall performance.

activated if necessary to prevent overcharging, over discharging, overheating, or short-circuiting.

Performed to ensure that all cells in the battery pack are operating at similar voltages. Battery Charging Control is used to ensure that the battery is charged safely and efficiently.

used to perform functions such as state of charge estimation, voltage and current monitoring, and protection circuit activation

used to analyze the battery's performance over time and identify potential problems.

Battery chargers, Voltage regulators & other Control Systems used to provide information on battery performance & protection status

Various methods to estimate the state of charge.

Method 1. Coulomb counting SOC estimation

Method 2. Fuzzy logic SOC estimation

Method 3. Impedance spectroscopy SOC estimation

Method 4. Kalman filtering SOC estimation

Method 5. Open circuit voltage SOC estimation method

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OBJECTIVES�

• To monitor and control the battery's state of charge, temperature, and voltage.
• To provide real-time information on the battery's health and performance.
• To prevent overcharging and over-discharging of the battery.
• To ensure the safety of the battery and the vehicle.
• To prolong the battery's life and maximize its efficiency.

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Why Implementation of BMS in Electric cycles instead of Electric Cars in Nepal ?

• Lack of infrastructure,
• high initial costs,
• limited access to technology and expertise,
• lack of government support,
• power supply issues and
• lack of incentives and regulations could hinder the adoption of electric vehicles in Nepal.

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Advantages of Manufacturing Electric Cycles with BMS in Nepal

The advantage of manufacturing electric cycles with battery management systems (BMS) in Nepal is

• improved battery performance,
• enhanced safety,
• better range,
• increased user confidence,
• better resale value,
• improved battery lifecycle,
• lower operating costs for users.

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BMS Implementation

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The master and slaves, star topology, organize cells into blocks or modules with one slave managing each module.

The master monitors the current and integrates it over time to calculate the net Coulomb flow. The master controls the main battery isolation contactor(s) initiating battery protection in response to data from the main current sensor or voltage and temperature data from the slaves.

The master also provides the system communications.

BMS Control Diagram

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Voltage sensor(IC)

Specification

BMS DESIGN

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Current Sensor

Specification

ACS712ELCTR-20A-T:  Current Sensor

• AC/DC Current
• 5V
• 8-Pin SOIC N T/R

Package: SOIC-8

Mfr. Part#: ACS712ELCTR-20A-T

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Temperature Sensor (IC)

Specification

Operation range:-40⁰ – 125⁰c

Operating voltage:1.9-3.6v

Low power consumption

Model: TH06C

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Microcontroller

Model : AT-Mega 2560

Used for controlling the logic

Keil Software used to program 8085

Design of protection circuit

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The purpose of the protection circuit is to disconnect the power lines between the battery and the load using a 30 Ampere relay and fuse as shown in Figure .

Fuse is useful for preventing component damage when a sudden overcurrent occurs.

Relay on the other hand is used because it decides the path mechanically to prevent overvoltage, undervoltage, overheat, overcurrent conditions. Relay is activated through AT-Mega 2560 pin digital based on information from voltage sensors, current sensors and temperature sensors.

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Software development

The software development has been done using C-language (Arduino IDE). The sequence of operational instructions has been uploaded into the ATmega 2560 microcontroller.

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Economic Analysis and Basic Datas

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Electric Cycles in Nepal

Here are some examples of electric cycles that are available in Nepal:

1. Yadea Electric Bike: A popular brand of electric bikes that are known for their stylish designs and high-performance electric motors.
2. SOHO Electric Bike: Another popular brand of electric bikes in Nepal that offers a range of electric bikes, including e-mountain bikes and e-city bikes.
3. Ampere Electric Bike: A well-known brand of electric bikes in Nepal that offers a variety of electric bike models for different purposes, including commuting, leisure riding, and off-road riding.
4. Bafang Electric Bike: A Chinese brand of electric bikes that are known for their high-quality components and affordable prices.
5. Lectro Electric Bike: An Indian brand of electric bikes that are popular in Nepal for their stylish designs and reliable performance.

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CONCLUSIONS�

In conclusion, the Battery Management System is a crucial component in electric cycles that plays a vital role in ensuring the battery's safety, performance, and efficiency.

By continuously monitoring the battery, controlling the charging and discharge cycles, protecting the battery from hazardous conditions, and providing real-time information to the user.

The BMS helps to extend the life of the battery and improve the performance of the electric cycle. It is very important that the BMS should be well maintained with battery reliability and safety

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References

1. H.J. Bergveld, Battery Management Systems Design by Modeling, 2001, ISBN 9074445-51-9
2. D. Bell, “A battery management system,” Master’s thesis, School Eng., Univ. Queensland, St. Lucia, Australia, 2000.
3. Sandeep Dhameja, Electric Vehicle Battery Systems, 2002, ISBN 0-7506-9916-7.
4. K. Shimitzu, N. Shirai, and M. Nihei, “On-board battery management system with SOC indicator,” in Proc. Int. Electric Vehicle Symp., vol. 2, 1996, pp. 99–104.
5. Ng, K.S.; Moo, C.S.; Chen, Y.P.; Hsieh, Y.C. Enhanced coulomb counting method for estimating state-of-charge and state-of-health of lithium-ion batteries. Appl. Energy 2009, 86,1506–1511.

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