P18262: Battery Health Management System
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Problem Definition

Table of Contents

Project Summary

The RIT Electric Vehicle Team (EVT) designs and races performance electric vehicles to demonstrate the viability of electric drivetrains. We plan to begin working on an entirely new electric motorcycle, referred to as REV 2, beginning in the fall of 2017. One of the major challenges presented by this design is a substantially increased battery voltage over our existing drivetrain. The current battery management system is insufficient, in terms of measurement capabilities and dimensions, to satisfy the needs of this new motorcycle. Our goal is to design a new battery management system that is capable of an increased cell measurement count, while decreasing the overall footprint of the design.

A battery management system (BMS) is a crucial component in the design of an electric vehicle drivetrain. The safe charging and discharging of a lithium ion cell is only possible within a specific voltage range. Large lithium ion battery packs might have substantially different thermal characteristics at various locations in the pack, contributing to slightly different discharge rates between cells. The primary purpose of the battery management system is to ensure that the individual cell voltages and SOC throughout the pack remain close enough to one another such that no single cell is outside of its nominal voltage range. Secondary to that, a BMS is also capable of providing valuable information detailing the cell temperatures, overall state of charge, and alerting the drivetrain to any critically unsafe conditions.

Project Goals and Key Deliverables

Goal

The goal of this project is to create a system that properly manages the batteries of the race motorcycle while in race conditions. Functionality includes reading cell voltages, getting accurate temperature readings and collecting data to provide the team with valuable feedback following the race.

For an updated project description, click on the following link for the PRP

Customer Requirements (Needs)

Our first customer interview was done on September 1st, 2017. The notes from the meeting can be found here.

The following have been recognized as core requirements from the customer of the battery management system. Issues and their solutions that have arisen in previous iterations of the battery management system have been added as requirements.

Customer Requirements, revised 9/25/17

Customer Requirements, revised 9/25/17

Engineering Requirements

The following list of requirements has been created based on the customer requirements to include more technical information of the project.

The complete spreadsheet containing all the requirements information can be found here.

Engineering Requirements, revised 9/25/17

Engineering Requirements, revised 9/25/17

House of Quality

The chart below shows the correlation between Customer and Engineering Requirements, known as the House of Quality (HOQ). The actual spreadsheet can be found here.

House of Quality, revised 9/13/17

House of Quality, revised 9/13/17

Constraints

  1. Must be a compact and lightweight design
  2. Actively balances batteries
  3. Monitor temperatures of cells
  4. Remain in budget of $800
  5. Must be completed in time for EVT's bike testing (~March 1)

Design Review Materials

Presentation Link

After the design review the feedback will be placed in here.

Three Week Plan for Next Phase

As a team we plan on having our processor picked out, our BMS architecture picked out, and the documentation completed that outlines our design selection and reasoning. There will be a time wide meeting to ensure we all have a similar knowledge of the design choices.

Steve Titus - 3 Week Plan

Ben Stewart - 3 Week Plan

Will McCaffrey - 3 Week Plan

Murali Prasad - 3 Week Plan

Jacob Allison - 3 Week Plan

Greg Malanga - 3 Week Plan


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