EV Battery Pack: Building 1 KW Battery Pack Using Active Battery Management System

Project Title

EV Battery Pack: Building 1 KW Battery Pack Using Active Battery Management System

Project Area of Specialization Electrical/Electronic EngineeringProject Summary

The Battery Management System (BMS) is an amalgamate of hardware and software systems which is generally a required part of any high voltage battery pack.

Our Active Cell Balancing Battery Management System (BMS) is a lithium-ion battery management system that is specifically designed to meet the tough requirements of protecting and managing batteries with automotive-grade quality.

In a battery pack, small differences between the cells tend to be magnified with each charge or discharge cycle and weaker cells are overstressed during charging, causing them to become even weaker until they eventually fail and cause a premature failure of the whole battery.

Our Active Cell Balancing BMS equalizes the charge on all the cells in the chain, thus extending the battery life. The charging system must have the proper charging method for the appropriate battery type and overcharge protection to prevent battery damage. One of the prime functions of this system is to provide the necessary monitoring and control to protect the cells from situations outside of normal operating conditions.

A complete BMS with the following features will be offered to extend cycle life:

1. Overcharge & Discharge Protection
2. Thermal Management
3. Intelligent Active Cell Balancing
4. Real-time Health Monitoring
5. Advanced Prediction Algorithms

Project Objectives

The objective of this FYP is develop a BMS for EVs with focus on power optimization, cell balancing and thermal management for safe and efficient functioning of the battery packs. BMS shall include, as key components, front end electronic circuits to interact with the battery pack, micro-computer (such as Arduino) for control, information processing and communication to a computer/mobile and subsequent clouding. A GUI has to be developed at the computer/mobile (PC or a laptop) to display the battery health and status in real time and administer the whole process.

Project Implementation Method

:This is the overview of our project:

It consists of following main components:

1. Flyback Converter
2. Battery Pack
3. Controller

The fly back converter block contains:

The flyback converter is basically used to prevent short circuit during active cell balancing of two cells.

The battery pack contains:

Zoomed version:

This shows the 13 cells in series which are joined together through a MOSFET array in such a way that each cell can be charged by the other and vice versa.

The controller contains:

Here, the SOCs of cells are given and the controller decides which cell to charge and whom to discharge by solving an optimization problem.

Benefits of the Project

Both active and passive cell balancing are effective ways to improve system health by monitoring and matching the SoC of each cell. Active cell balancing redistributes charge during the charging and discharging cycle, unlike passive cell balancing, which simply dissipates charge during the charge cycle. Thus active cell balancing increases system run-time and can increase the charging efficiency. Active balancing requires a more complex, larger footprint solution but prevents the loss of charge.

Other benefits include:

1. Ensure that the battery is in good working order.
2. Battery health is continuously monitored to avoid an explosion.
3. Extends the battery’s life expectancy.
4. Display the battery level.

Technical Details of Final Deliverable

Battery Pack: Capacity: 500Wh, Configuration: 13S, 4P, Battery Pack Voltage= 3.7*13= 48.1V, Can power 250W load for 2 hours.

Each cell provides 3.7 V. In series voltage gets multiplied so 3.7*13=48V. Whereas the Ah are calculated in parallel: 2.6*4=10.4Ah. Can give 5.2A (to a 250W load=5.2*48) in 2 hours if discharged at 0.5C( discharging at 1300mAH). Mostly 48V motors are used including Jolta motorcycles.

Current & Voltage Sensor: 15 of these PCBs are used, ACS712 for Current Measurement, Opto-isolator used for Isolation, Operational Amplifier – LM358. Its circuit is as follows:

Flyback Converter:

For deploying the algorithm of Active Cell Balancing TI Delfino Board is used:

The whole project is simulated below( each componenet has furhter subdivisions in it):

Final Deliverable of the Project HW/SW integrated systemCore Industry Energy Other Industries Others Core Technology Clean TechOther Technologies Shared EconomySustainable Development Goals Affordable and Clean Energy, Sustainable Cities and Communities, Life on LandRequired Resources

Item Name	Type	No. of Units	Per Unit Cost (in Rs)	Total (in Rs)
			Total in (Rs)	64500
PCBs from China	Equipment	20	500	10000
TI Delfino Board	Equipment	1	15000	15000
ESP32	Equipment	2	1000	2000
Breadboard	Equipment	4	250	1000
Li-Ion 18650 Cells	Equipment	52	200	10400
!6 Channel Relay boards	Equipment	3	1200	3600
4 Channel Relay Board	Equipment	1	400	400
ACS712	Equipment	5	300	1500
Decoder IC	Equipment	2	300	600
Li-Ion Battery Charger from China	Equipment	1	10000	10000
Arduino Uno for PWM	Equipment	1	1500	1500
Resistors/ Capacitors	Equipment	25	20	500
Battery Pack Covering	Equipment	1	1000	1000
Soldering Equipment	Equipment	1	2000	2000
Petrol Used Druing Equipment Procurement	Miscellaneous	1	5000	5000