Final Report

Video Lecture

Video, Slides

Description:

The Final Report Guidelines are the primary reference document for this assignment.

Requirements and Grading:

The Final Report is held to professional standards of language and format and is evaluated by staff in the ECE Editorial Services, who also check theses and dissertations for the department. The report is also evaluated for technical content and organization by the course staff. The Grading Rubrics are available for both English/Formatting and Technical Content , but here are some pointers:

  1. If you didn't click the link above, the Final Report Guidelines should be your first stop.
  2. Use a template to help get the formatting right (Microsoft Word template or LaTeX template).
  3. Since your Final Report is similar in purpose to a thesis, you may find the Thesis Writing Guidelines helpful for style and formatting.
  4. For citations, you may also find the IEEE Citation Reference guide useful.
  5. Please note the maximum number of pages (20) allowed for the final report. This does not include your references or appendices.You will be penalized for going over the maximum number of pages and/or not following the prescribed format.

    6. Submission and Deadlines:

    The Final Report document should be uploaded to My Project on PACE in PDF format by the deadline on the Calendar.

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.