Design Document Check

updated Fa 2020

Description

The Design Document Check (DDC) is intended to aid your team as it prepares its Design Document. The DDC focuses narrowly upon providing feedback on the preparation of historically problematic Design Document elements. If these elements fall short during your Design Review the following week, precious time is lost.

What are the course staff looking for? i) Evidence that the overall idea of the design is sound; ii) A check of a small subset of required components indicates that the project is on the right track.

Below is a checklist of things to have ready for the design document check. Refer to the design document page and grading rubric for a full description of each item.
  1. Introduction
    1. Start with a brief summary (30 sec) or elevator pitch following this template:

      I will build ___A___ (my core product) for ___B___ (my core customer: the person who pays my company or uses the product).

      My customer has a problem ___C___ (describe the problem your customer has)

      My product solves my customer’s problem by ___D___ (how do you solve the problem?)

    2. Be expected to explain further what the problem is, what’s your idea to solve it, and why your idea is novel.
  2. Visual Aid
  3. High-level Requirements
    1. HL requirements are derived from the problem you are trying to solve (put yourself into the customer's shoes). HL requirements should be the essential features that your customers/users really care about. These features distinguish your product from others (e.g. ones available in the market or previous 445 designs). Be abstract (no tech details, you may come up with different design due to other constraints but still solve this problem), quantifiable (no words like continuously, accurately, etc), and unambiguous. HL&RV slides(P.5) has a good example.
    2. We will look at your HL requirements and check if they are what your customers/users really care about. Be prepared to defend your requirements, so that when you get challenged, you can give a well thought out explanation.
  4. Block Diagram
    1. Block Diagram slides
    2. We will check whether this design appears to solve your problem. 
    3. We will check if formatting is clear (lines, legends, etc). Extra caution is needed as students often make mistakes here (but you shouldn't!).
  5. Requirements & Verification Tables
    1. HL&RV slides: from P. 1-17
    2. Block Module Requirements: Break down your HL requirements into block level requirements. These are the requirements in the RV table (they are not the specs of the parts you have chosen).
    3. Verification: A step-by-step approach allows another 445 student to test if the BL requirement is satisfied. This is like an instruction for your module's unit test (with some surrounding dummy modules, a.k.a, mock object(s)
    4. We will review one piece of it. Show us an important one.
  6. Plots
  7. Circuit Schematics
  8. Tolerance Analysis
    1. Identify an important part that you need to perform some quantitative analysis on. This part should have quantitative values critical to the design and require you do calculations and make trade-offs in order to achieve your best design.
    2. Common mistake: Many students do calculations for tangential parts to pad the space.
  9. Safety & Ethics
  10. Citations

During the DDC, your team will have 5-8 minutes to present an example of each of these elements. Expect to share the 30-minute DDC session with two other design teams. Come prepared to learn from their work - both the good and bad.

Your task is to prepare and upload the above elements in a single PDF document to the course website. During your DDC session, you will present directly from your submission, which will be projected for all to see.

The focus of the DDC is not on the details of your design but rather on the details of your formatting; the design of your project will be covered in-depth during the Design Review. Organize your submission in accordance with the Design Document guidance and the example Design Document.

The course staff will focus on providing feedback on the format of your sample DDC elements - the very limited available time will not afford detailed feedback on your design. Please go to office hours for further guidance.

Requirements and Grading

Upload your DDC submission to your project page on PACE (i.e. ECE 445 web board) before arriving at your DDC session.

As in your Design Document, number pages after the title page in your DDC submission.

Any material obtained from websites, books, journal articles, or other sources not originally generated by the project team must be appropriately attributed with properly cited sources in a standardized style such as IEEE, ACM, APA, or MLA.

The course staff at the DDC will assign individual grades to each student based on:

Submission and Deadlines

Sign-up for the Design Document Check on the ECE 445 course website - specifically at the Sign up for Team Presentation item on the PACE tab. Sign-up will open the Monday one week prior to the DDCs.

Upload your DDC submission (.pdf format) to the ECE 445 course website before your DDC session - specifically at the My Project item on the PACE tab.

While you will not complete peer reviews during the DDC, you are expected to actively contribute to the discussion.

Tech must-know and FAQ for design

Here is the link of "Tech must-know and FAQ for design" which is accessible after logging into g.illinois.edu.

Over semesters, ECE445 course staff have encountered repeated mistakes from students. The document above is designed to provide students with the essential knowledge needed in order to have a good design. Spending 5 min reading it might save you 15 hours later. Also, there might be some quiz questions in your DDC or Design Review. Please help us improve this document. We value your feedback!

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.