EE 477 Final Report

Purdue ECE Senior Design Semester Report
Course Number and Title
Semester / Year
Team Number
Project Title
ECE 477 Digital Systems Senior Design Project
Spring 2006
Profs. Meyer, Johnson, and Nyenhuis
Maximum Power Point Tracker
Senior Design Students – Team Composition
Area(s) of Expertise
Utilized in Project
Eric Aasen
Atandra Burman
Daniel Kisslinger da Silva
Sriharsha Vangapaty
Graduation Date
May 2006
May 2006
May 2006
May 2006
Project Description: Provide a brief (two or more page) technical description of the design
project, as outlined below:
(a) Summary of the project, including customer, purpose, specifications, and a summary of the
The maximum power point tracker (MPPT) unit implements a digital control system that
controls an existing power board that is on the Purdue Solar Racing car. This unit communicates
with other remaining MPPT units in the car as well as solar car’s telemetry system and driver
interface unit. The MPPT unit’s purpose is to use the solar array in the solar car as its input and
measures its current and voltage levels and using these input parameters, it locates an optimum
“power point” along the current versus voltage curve that produces the most power and using
special logic it controls the external DC/DC converter through a PWM signal to charge the
batteries in the solar car.
The design replaces an existing board. It retains all the functionalities of the existing
board while including additional interfacing, lower power consumption, and more software
functionality all while maintaining a reasonable cost. The MPPT board is 4.25mm x 4.75mm x
2.00mm and weighs an approximate 0.250kg – 0.300kg including the packaging.
The approach to this project was to build a new design from an existing MPPT design.
The new board is able to implement more functions than its predecessor. More software
implementation is also present in the new board.
(b) Description of how the project built upon the knowledge and skills acquired in earlier ECE
The MPPT project greatly enhanced the knowledge and skills acquired through various ECE
coursework taken up previously. This being an embedded systems design class provided us the
opportunity to gain first hand experience in the programming and interfacing of the
microprocessor and its peripherals. This project involved designing the analog for the MPPT unit
using knowledge of various active filter designs, existing power supply models, analog scaling
techniques, knowledge of bypass capacitors, op amps, diodes, BJTs and voltage division circuits.
A fairly decent knowledge of microprocessor programming and usage of various microprocessor
related modules such as ATD, PWM and SPI were useful for this project. The schematic capture
was designed using previous knowledge of Design Entry CIS and PCB layout was finished using
knowledge of Layout Plus. Further, knowledge of communication protocols such as uart enabled
in structuring the debug mode for this project. In summary a wide area of electrical and computer
engineering knowledge achieved from the various classes in our undergraduate classes greatly
helped us successfully design our project.
(c) Description of what new technical knowledge and skills, if any, were acquired in doing the
The senior design project being an embedded systems project provides us a fairly large
knowledge base for microprocessor programming and interfacing. In the course of this project
we had an opportunity to learn to use various new tools. We learnt to use the MPLAB-PICDEM
in circuit debugger for debugging C code written to program the PIC18F2680. We spent
considerable amount of time researching and implementing the CAN protocol to enable sending
and receiving CAN messages over the CAN network so as to communicate and service requests
from the telemetry system and the driver interface unit. Besides this we also acquired knowledge
about the individual component in our design by consistently referring to the extensive
datasheets for these devices.
(d) Description of how the engineering design process was incorporated into the project.
Reference must be made to the following fundamental steps of the design process:
establishment of objectives and criteria, analysis, synthesis, construction, testing, and
First, the project objectives were clearly established as well as the success criteria. With
those objectives in mind, the components to be used in the design were chosen. The design
was done in order to achieve the project’s objectives. The parts used were the parts
previously chosen to best meet the set objectives. After schematics were finalized, the
design layout was created. Afterwards, the PCB was produced following the layout. The
components were mounted to the PCB. The board was tested to make sure all components
behave as designed. Software was installed at the same time and tested along with hardware.
Once hardware and software were fully integrated, the PSSCs were demonstrated.
(e) Summary of how realistic design constraints were incorporated into the project
(consideration of most of the following is required: economic, environmental, ethical,
health & safety, social, political, sustainability, and manufacturability constraints).
(f) The project did not face significant economic constraints, because the boards will be
produced in small numbers, i.e. only 8 of these boards will produced for the Purdue Solar
Racing. Components that did not contain lead were always preferred when it did not impose
significant cost increase. Safety features were added to both hardware and software, i.e. over
voltage protection. Temperature sensor along with fan avoids board to become hot,
increasing its lifetime.
(g) Description of the multidisciplinary nature of the project.
Electrical Engineering knowledge was extensively used to design the project. Many
considerations regarding power consumption, heat dissipation and parts’ size were
considered when choosing components in the project. Computer Engineering knowledge
was used to create an algorithm to find the maximum power point as well as for the interface
with the communication protocols and the microcontroller used in the project. Technical
English was used to write all homeworks, presentations, and final report.
(h) Description of project deliverables.
Packaging – design of a packaging used by board.
Schematic – design of hardware.
PCB Layout – design of project’s PCB layout.
Parts List – list of all parts used in the board.
FMECA Worksheet – analysis of critical failures.
Software – all software used in the project.
Project Poster – poster advertising project.
User Manual – user manual for project.
Final Report – report containing all documentation related to project.