Final Video Presentation

1. Project Description

This project is to build a simple, cheap, variable power supply for students to build and use for any application. It will be variable from 0V-25V at 10A and will be a simple surface mount design. Initially, it will have basic functionality. The basic design of our switch-mode power supply consists of three main parts. The power supply will convert single phase AC power from the wall via a full wave bridge rectifier or a step down transformer to DC. We will then install a DC-DC Converter to allow us to control our voltage via micro-controller. Once we have this operational we will build a current limiting circuit to keep the power supply within the 10A range. Depending on the cost and heating requirements we will attach heat sinks to our hard components and, or install a forced cooling system. If the consumer wishes, they may add on a number of improvements at an increased cost. This includes LCDs, LEDs, and better micro-controllers for the purpose of a software interface via USB. The outcome is a power supply that caters to student’s budgets or increased functionality. This power supply needs to be created at a level such that students would be able to look at the architecture, and be able to understand how this power supply works. Also, this project design must be able to fit the needs of anyone requiring a power supply, and therefore must be designed for multiple environments. This means we must account for temperature changes and be able to provide adequate cooling for hot environments if needed. Overall, this power supply will be top of the line, with optimal performance, yet still within our budget to produce a high performance power supply.

Project Requirements

Medium Power Transformer/Bridge Rectifier: The variable switch power supply will have a step down transformer from the wall, that is rectified with a full wave rectifier, which will contain med/high power components.

DC-DC Converter: The full wave bridge rectifier will run from the transformer to a DC-DC converter that will regulate the output voltage via the duty ratio.

Driver: The DC-DC converter will be run via a driver controlled by our micro-controller. The driver will control the switching frequency of the mosfets and the duty ratio. This driver will have a delay built in to protect from having both mosfets on at the same time.

Over Current Protection: There will be a current sensor connected on the output of the DC-DC converter that is fed back to the micro-controller. This will allow us to limit the current to 10 amps.

PCB Board: The board will help with encapsulation, will make external component removal and attachment much easier and will help increase our cooling capabilities and reduce our overall EMP emitted due to shorter connections.

Cooling System: We will either add heat sinks based off of expected ambient temperature and chip temperature and, or built a forced cooling system. Which is better known as a fan circuit.

Micro-Controller: This is the brain of our project. We will most likely use the At-mega 128 board for testing and this will allow us to tell the power supply when to turn the driver on and off. It will also display Voltages and currents to a LED display and will control over current problems via software.

On/Off Light: This light will be a simple LED that will light up when power is supplied to the transformer.

Over Current Light: This will be a simple LED that will light up when the current sensor sends a signal/voltage to the micro-processor saying we are pulling more than 10 amps.

Interface: We will have a programmable user interface via the micro-controller using the programming language C. This will allow us to upgrade our project quicker and easily.

2 Needs Identification and Background Research
3 System Requirements and Desired Features
4 Design Solutions
5 Top Level Block Design
5.1 Transformer and Bridge Rectifier
5.2 DC-DC converter
5.3 Power Mosfet Driver
5.4 Current Sensor
5.5 Enclosure
5.6 Encoders
5.7 Code
5.8 LED Display
5.9 Voltage Sensor
5.10 MicroController
5.11 IC Power
5.12 IC Power Transformer
5.13 Cooling System
6 Testing
7 Project Timeline
8 System Test Evidence
9 Budget
10 Exposition Material

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Group Members:

From Left to Right: M. Thomas, M. Miller, G. Condrea
(Profile)Condrea, Gabriel - (E-Mail)->Gabe.condrea@gmail.com
(Profile)Miller, Matthew - (E-Mail)->Millerm3@onid.orst.edu
(Profile)Thomas, Matthew - (E-Mail)->BaDdAcK@gmail.com

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Mentor(s):
School of Engineering: Don Heer

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References:
Switch Mode Power Supply
Over Voltage/Current Protection