Calendar

Week Monday Tuesday Wednesday Thursday Friday
1/16
First class meeting 4:00p - 5:50p ECEB 1002
Initial Web Board Post due 11:59p
1/23
Second class meeting 4:00p - 5:50p ECEB 1002
Laboratory safety training due 11:59p
Early Project Approval due 4:45p
CAD assignment due 11:59p
1/30
Add/Drop Deadline due 11:59p
Third class meeting 4:00p - 5:50p ECEB 1002
Project approval due 11:59p
2/6
First team meetings with TAs 4:00p ECEB 3081
Proposals due 11:59p
Initial Conversation With Machine Shop (required if using the shop) due 4:00p ECEB 1047
Soldering assignment due 4:45p
2/13
2/20
Design Review Sign-up opens
Design Document due 11:59p
Team Contract due 11:59p
2/27
Design Review 8:00a - 6:00p With Instructor and TAs
Design Review
Fliflet: ECEB 2070
Design Review
Mironenko: ECEB 2072
Design Review
Gruev: ECEB 2074
Design Review 8:00a - 4:00p With Instructor and TAs
PCB Board Reviews 4:00p - 6:00p
Design Review
Fliflet: ECEB 2070
Design Review
Mironenko: ECEB 2072
Design Review
Gruev: ECEB 2074
Design Review 8:00a With Instructor and TAs
Design Review Sign-up closes
Design Review
Fliflet: ECEB 2070
Design Review
Mironenko: ECEB 2072
Design Review
Gruev: ECEB 2074
3/6
First Round PCBway Orders (MUST PASS AUDIT BY TODAY) due 4:45p
Teamwork Evaluation I due 11:59p
Last day for revisions to the machine shop due ECEB 1048
3/13
Spring Break
Spring Break
Spring Break
Spring Break
Spring Break
3/20
Second Round PCBway Orders (MUST PASS AUDIT BY TODAY) due 4:45p
3/27
Board Review 4:00p - 6:00p ECEB 3081
Third Round PCBway Orders (MUST PASS AUDIT BY TODAY) 4:45p
Individual progress reports due 11:59p
4/3
Fourth Round PCBWay Orders (MUST PASS AUDIT BY TODAY) 4:45p
4/10
Fifth Round PCBWay Orders (MUST PASS AUDIT BY TODAY) 4:45p
Team Contract Fulfillment due 11:59p
4/17
Mock demo During weekly TA mtg
Mock demo During weekly TA mtg
Mock demo During weekly TA mtg
Mock demo During weekly TA mtg
Mock demo During weekly TA mtg
4/24
Final Demo With Instructor and TAs
Demonstration
Fliflet: ECEB 2070
Demonstration
Mironenko: ECEB 2072
Demonstration
Gruev: ECEB 2074
Final Demo With Instructor and TAs
Demonstration
Fliflet: ECEB 2070
Demonstration
Mironenko: ECEB 2072
Demonstration
Gruev: ECEB 2074
Final Demo With Instructor and TAs
Demonstration
Fliflet: ECEB 2070
Demonstration
Mironenko: ECEB 2072
Demonstration
Gruev: ECEB 2074
Mock Presentation With Comm and ECE TAs
Mock Presentation With Comm and ECE TAs
5/1
Final Presentation With instructor and TAs
Presentation
Fliflet: ECEB 2070
Presentation
Mironenko: ECEB 2072
Presentation
Gruev: ECEB 2074
Final Presentation With Instructor and TAs
Presentation
Fliflet: ECEB 2070
Presentation
Mironenko: ECEB 2072
Presentation
Gruev: ECEB 2074
Final papers due 11:59p
Lab checkout 3:00p - 4:30p With TA
Award Ceremony 4:30p - 5:30p ECEB 1002
Lab Notebook Due due 11:59p

Active Cell Balancing for Solar Vehicle Battery Pack

Tara D'Souza, John Han, Rohan Kamatar

Featured Project

# Problem

Illini Solar Car (ISC) utilizes lithium ion battery packs with 28 series modules of 15 parallel cells each. In order to ensure safe operation, each battery cell must remain in its safe voltage operating range (2.5 - 4.2 V). Currently, all modules charge and discharge simultaneously. If any single module reaches 4.2V while charging, or 2.5V while discharging, the car must stop charging or discharging, respectively. During normal use, it is natural for the modules to become unbalanced. As the pack grows more unbalanced, the capacity of the entire battery pack decreases as it can only charge and discharge to the range of the lowest capacity module. An actively balanced battery box would ensure that we utilize all possible charge during the race, up to 5% more charge based on previous calculations.

# Solution Overview

We will implement active balancing which will redistribute charge in order to fully utilize the capacity of every module. This system will be verified within a test battery box so that it can be incorporated into future solar vehicles.

Solution Components:

- Test Battery Box (Hardware): The test battery box provides an interface to test new battery management circuitry and active balancing.

- Battery Sensors (Hardware): The current battery sensors for ISC do not include hardware necessary for active balancing. The revised PCB will include the active balancing components proposed below while also including voltage and temperature sensing for each cell.

- Active Balancing Circuit (Hardware): The active balancing circuit includes a switching regulator IC, transformers, and the cell voltage monitors.

- BMS Test firmware (Software): The Battery Management System requires new firmware to control and test active balancing.

# Criterion for Success

- Charge can be redistributed from one module to another during discharge and charge, to be demonstrated by collected data of cell voltages over time.

- BMS can control balancing.

- The battery pack should always be kept within safe operating conditions.

- Test battery box provides a safe and usable platform for future tests.