Department of Electrical and Computer Engineering CDR Presentation Thursday February 28, 2013...

Department of Electrical and Computer Engineering

CDR PresentationThursday February 28, 2013

Reviewed by: Prof. Bardin & Prof. Gao

Paulo Leal, Kevin Okiah, Chris Finn & Tim Mirabito

2Department of Electrical and Computer Engineering

Outline

MDR Recap CDR Goals/Progress Design Choices FPR Goals Demos Cost Breakdown Questions?


Project Recap

Project GoalGive people a means to monitor and control the

electrical devices within their households. Motivation• Energy conservation has a significant social &

economic impact. • It is hard to conserve energy because • Limited quantitative data• Limited social awareness• Limited residential control


MDR Recap: Block Diagram


MDR Recap: Communication Flow


Tim’s MDR Review

At MDR I had reverse engineered the critical components of the P4400 Kill-a-Watt device.

From this process, circuit schematics for each subsystem of the device were generated.

In addition, a proprietary design for a transformerless power supply was created, simulated and laid out on a PCB.• The specifications of were designed to match the power

requirements for our components.


Tim’s Proposed CDR Goals

Prototype modified “Tweet-a-Watt” for real-time data

Complete proprietary design of watt meter subsystems

Integrate relay and XBee layouts into proprietary design

Complete schematic and PCB layouts for a fully functioning system


Initial Power Supply Design

Initial PCB layout for the transformer less power supply design schematic with a 15V and 50mA output.


Design Revision: Power Supply

Initial design for a transformerless power supply presented efficiency & fail safe challenges.• Conversion Efficiency of

~10%

Opted instead for a commercial power supply in a fail safe configuration.

CUI Series VSK-S1 Model 5U


Design Revision: Power Supply


Design Choice: Relay Circuit

The simulation results for the XBEE trigger showing relay control


Design Choice: Current & Voltage Sense

Utilization of the INA128P instrumentation amplifier from Texas Instruments was chosen due to the design being specifically

applicable to our objective and high CMRR of 130dB.


Current & Voltage Sense Subsystem

Circuit schematic and simulation output from the implemented design show the voltage values

corresponding to current and voltage readings being sent to the XBEE.


Paulo’s Goals/Progress

Build Tweet a Watt Networking Circuit• Setup XBee Network• Transmit data wirelessly from model A to B• Control Switching Mechanism

Relay Circuit• Design & Test


Overview - Design Choice: Tweet a Watt


Overview - Design Choice: XBee Wireless Radios

XBee Series 1• Indoor Range: 100ft.• RF Data Rate: 250Kbps• Frequency: 2.4 GHz• AES encryption• Analog to Digital converter


Overview – Previous Design Choice: Relay CKT

PowerSwitch Tail for 110-120vac • Provide single pole switching at 20 amps • 5300vrms isolation• Driving voltage as little as 3vdc @ 3ma

• Cost: $18.50


New Design – Relay Circuit

Outlet Switching Circuit• Relay – 220V @ 20A • NPN transistor controls coil current (80mA)• R1 pulls the trigger pin to ground so if

anything goes haywire the relay will remain in the safe (Off)

• Diode – protects power supply and nearby parts

• Cost: $5


Christopher’s CDR Goals/Progress

Parse XBee input Allow connection from user interface to database

• Over internet via port forwarding

Relay circuit control• Integrated with user interface buttons

Security• SSL for apache server• User account database/login system• AES XBee communication encryption


Quick Review of Design Choices

Raspberry Pi• 700 MHz ARM computer• Runs custom Debian Linux

• Utilize Linux packages

LAMP Server Python

• Serial communication to/from XBee• Data processing• Database interactions• Raspberry Pi GPIO control


Security

Generated Self-Signed SSL Certificate• Has to be manually trusted by browser to suppress

warnings

Login system• Table of user/md5(password) combos• PHP sessions

XBee 128bit AES encryption


Data Flow: Outlet Data


Data Flow: Relay Control


Additional Design Notes

Physical Storage Requirements• Trade off between accuracy & storage size• Past Year

• Minute intervals => 4.2MB per outlet per year• >1 Year

• Fifteen Min. intervals => 280KB per outlet per year• Total per outlet = 4.2MB + 4*280KB = 5.3MB• Est. Household Total (5 yr, 100 outlets) = ~0.5GB


Kevin’s MDR Recap /CDR Goals Developed a Basic user interface prototype

that is functional across all operating system

NetworkInterface


Kevin’s MDR Recap /CDR Goals Continued

Plotting functionalityFLOT AwesomeChartJS

Demonstrated plotting data by successfully querying the databaseUser Interaction with the system was LimitedFunction to receive and send relay SignalDevelop a function to assimilate new devices to the system


PROGRESS

Programing LanguagesHTML5 CSSJavaScriptPHPJQUERY


Progress continued

Main Functions• Real-time data• Account summary• Usage History• Your Energy Cost• Devices


Demos!


FPR Group Goals

Chris• Multi-room integration (via HomePlug)• User defined storage intervals• Downloadable ZIPs of table data• Optimize data calculations• Code revisions

• Clean up & optimize Tim

• Professor review of preliminary PCB layout for manufacture.• Implementation of scalability functions:

• Multiple 120V Outlets• 240V Outlet Interface• Increased Sampling Rate

Paulo• Expand Wireless Network to multiple rooms• Finalize Integration Process within blocks• Design a safe and minimized final enclosure

Kevin• Seamless assimilation of new devices to the PowerPi system• Expand my plotting functionality to accommodate more than one device/ outlet.• Improve user interaction by giving users more control over the system


Full Circuit Schematic


XBee Explorer

Using the current design of the XBee Explorer as a foundation, the final implementation of the watt meter PCB will have a subsystem

with pin out headers for easy upgradability.


Full Circuit PCB Layout

PCB layout done via Cadsoft’s EAGLE Top & Bottom

Layered with copper grounding.

Part outlines established via silk screening.

Board Size: 119mm x 105mm


PCB Fabrication

PCB fabrication can be done at many companies; some of the ones I’ve looked at:• Custom Circuit Boards, LLC. in AZ• E-Teknet, Inc. in AZ• PCB Solutions LLC in NV• Fineline Circuits & Technology, Inc. in CA• PCB FAB EXPRESS in CA

The cost to fabricate a single board will cost $60-$100 dependent on board layering, and size.

The turn around time varies from 3 to 10 days.


Cost Breakdown

QTY UOM Unit Price Description Total

1 1 $35.00 Raspberry PI Model B $35.00

3 1 $19.49 P3 International P4400 Kill A Watt Electricity Usage Monitor $58.47

1 1 $49.99 Actiontec PWR511K01 500 Mbps HomePlug HD Power line Wall Plug Network Adapter

$49.99

1 1 $3.95 Jumper Wires Premium 6“ M/F Pack of 10 $3.95

1 1 $3.95 Jumper Wires Premium 6" F/F Pack of 10 $3.95

3 1 $3.00 T9A Series Relay $9.00

2 1 $19.00 XBee Series 1 XB24-AWI-001 $38.00

5 1 $21.00 Prototype PCB $105.00

5 1 $11.01 VSK-S1 Power Supply $55.05

Total $358.41


Questions

Department of Electrical and Computer Engineering CDR Presentation Thursday February 28, 2013...

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