Transcript High Efficiency Hyperspectral Imager

Wireless Power Measurement
System
Group 2
Manuel Rodriguez
Frank Ladolcetta
Amir Shahnami
Alex Demos
Project Description
Meter that will measure the power
consumption of household appliances
 Meter information will be sent wirelessly to
an LCD display
 Display the approximate daily and
accumulated power consumption of the
appliance being monitored
 Capacity to turn appliances on and off
directly from the head unit

Project Motivation
Keep track of energy usage in order to
use less energy and spend less money
 Prevent surprising power bills at the end
of the month
 Corroborate energy savings of “energy
efficient devices”
 Make a system that is user friendly
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Project Overview
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Design a circuit that measures current and
voltage
Create program to calculate power
Program the wireless transceivers to
communicate with each other and transmit
the sensor information
Design a circuit to display information on
LCD
Create program to display information
Project Specifications
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No more than 10% accuracy error
Keep cost as low as possible
Wireless transmission should be no less
than 30 feet
Measure current up to 7A
Measure voltage on a 120V wall outlet
Block Diagram of System
Wall Outlet
Relay
Voltage Measurement
Current Measurement
Microcontroller
Wireless transmission
Microcontroller
Display
Meter Overview
Build Requirements
Meter circuit design should be safe
and reliable
 Design a circuit that is both cost
effective and efficient
 Build a meter circuit that draws a
low amount of power

Power measuring methods
• Voltage measurement using a voltage divider
• Current measurement using a current sensing
resistor
• A pair of optoisolator to isolate and amplify the
signal
Powering the circuit
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The circuit is powered using 2 transformers that each go
through a full wave rectifier and finally through a 5 volt
voltage regulator.
A transformerless circuit was tested but it was not as
reliable as the circuit with the transformer.
Voltage measurement
Voltage will be measured directly
from the house wiring
 A voltage divider is used to bring
down the voltage to a level usable by
the optoisolators
 Filters are added to eliminate high
frequency noise in the circuit

Current measurement
Current sensing resistor will be installed
in the neutral side of the outlet wiring to
measure voltage drop
 A hall effect sensor was considered but it
is too expensive
 A current transformer was considered
but it is a less accurate method and more
expensive

Component specifications
2 resistors; a 2Mohm and a 1kohm
with a 5% tolerance and a power
rating of 1/4 watt
 A .025 ohm current sensing resistor
with 1% tolerance and rated at 3W
 12A, 240V relay
 Avago Technologies HCPL-7520
linear optoisolator

Main Unit & LCD
Diagram of device
LCD display requirements
One row to list the information to identify what is
displayed on the screen.
 Three rows of data pertaining to three separate
sensor devices.
 Must have a traversable menu to view up to 50
different sensors.
 Must display power consumption data in terms of
dollars spent.
 Simple character display method.
 LED backlight for nighttime use.
 Low power consumption. (< 3W typical)
 Low price. (<$50)
 Readily available.

LCD Specs & Technical Data
• 4 lines x 40 characters
• 2 - HD44780 equivalent
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microcontrollers
190mm x 54mm x13.6mm
18 - 2.54mm pins (14
Logic, 3 Supply, 1 NC)
Requires a 5.0V Power
Supply
11 Built-in instructions
5V, 1.2mA typical for LCD
(.006W)
5V, 360mA typical for
Backlight (1.8W)
NHD-0440AZ-FL-YBW
Reprinted with permission of Newhaven Display International
Push Buttons/ Switches
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We require four tactile (pushto-make) pushbuttons on the
front of device.
Two of these buttons will be
used for movement within the
LCD menu.
One pushbutton will
disconnect supplied power to
selected appliance.
One pushbutton will allow the
user to enter the menu.
We also require a Single
pole, single throw switch on
the side of the device to
control the LED backlight.
Pushbutton Examples
Reprinted under creative commons 3.0 license
SPST Example
Reprinted with access from public domain
Instruction List
Instructions
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To operate, the device has 2
separate internal microcontrollers
to display to the LCD.
A specific instruction must be
selected by the main
microcontroller and sent to the
eight data pins.
When the instruction is sent, the
device must be enabled on the
selected microcontroller (E1 or E2)
to have the device complete the
instruction.
If characters are to be displayed,
the RS pin must be set on and the
device will output the selected
character to the specified location
designated by the set address
command
Reprinted with permission of Newhaven Display International
Coding
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The Arduino microcontroller
uses C programming
language, and provides
libraries for use with their
product.
The code will start off with an
initialization section for initial
powering up of device.
The device will then display
the data every minute from
the MC in a line by line
fashion to ensure all sensors
are updated.
Separate functions will be
called for cursor movement,
menu setup, and sensor
power down.
Coding example (Turning device on)
Int main(void)
{
lcd_top.setCursor(0,0);
lcd_bottom.setCursor(0,0);
lcd_top.print("Please enter days in cycle.");
lcd_top.setCursor(0,1);
lcd_top.print("Use Up to go left");
lcd_bottom.print("Menu to advance:");
lcd_bottom.setCursor(0,1);
delay(1500);
}
Microcontroller Design
Microcontroller
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One single type of microprocessor for both
applications
Both applications use ATMega168 with a
preloaded bootloader.
Programmed with a USB to serial adapter.
6 analog input pins
14 digital input/output pins
1.8 to 5.5 volt operating voltage
Programmed with Arduino software v. 0018
using C/C++
Each pin draws up to 0.22W (from 40mA),
VCC draws up to 0.275W (from 50mA)
Reprinted with permissions from Sparkfun
Main Unit Programming
• Initialize the LCD display to properly display all information
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needed
Enter a setup prompt for the price per kWh and be able to
re-enter this setup at any time
Dynamically allocate ID numbers to each individual sensors
Communicate to a specific sensor once an ID has been
established.
Sends information as floats to ensure both accurate values as
well as smaller information size
Updates LCD information as information from sensors are
received
Able to store a running total of money spent regardless of
device status
Sensor Unit Programming
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Requests an ID from the main unit.
• Constantly measures both voltage and current and averages
power over 15 seconds.
• Sends both an ID as well as power to the main unit to ensure
individual device recognition
• Sends information as floats to ensure both accurate values as
well as smaller information size
Main Unit Schematic
• Powered by AC to
5V DC converters
not shown
• Pull down resistors
to prevent button
inputs from floating
high.
• Pull down resistors
to the XBee header
Sensor Schematic
• Receives 2
separate power
supplies through
AC to 5V DC
converters.
•Pull down
resistors to the
XBee header.
•Status LED and
relay are
controlled directly
from the
microcontroller.
•7A fuse added to
the circuit.
Wireless Communication
XBee Specs
•We looked at four pieces of
technology for this project:
Zigbee, Bluetooth, WiFi, and
XBee
•Xbee Series 1
•$19.00 per unit.
•The range was good enough
for the group having a max
range of 100ft (30m)
•24.38mm x 27.61mm
XBee Specs
Transmission rate of 250kbps
It is an RF transceiver and it runs
at 2.4 GHz, which is the norm for
this kind of device.
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Voltage range from 2.8 to 3.4V.
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The current:
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when receiving data it is
50mA,
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while transmitting
information, the current is
flowing at 45mA
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while it is in power-down
mode it runs below 10µA.
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XBee Adapter
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$10/kit
Connects to
microcontroller
Cord connects to
computer to
program the chip
Programming of XBee
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Using the AT command mode with X-CTU
program is how the XBee chip will be
programmed.
• AT commands deal with all things from setting
the sleep mode to resetting the chip.
• The command below is a sample command that
will display the lower 32 bits of the address.
Programming of XBee (cont.)
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For the XBees to communicate to each
other, the following need to match with the
parenthesis being what we are using:
– the Personal Access Network (234)
– the BAUD rate (9600)
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We set up an Association network, which is
like a peer-to-peer network with one device
being the head unit.
Block Diagram of XBee
Example of how data is
received from one device
and then sent to another
Testing
Testing Procedure
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The device will be tested against a commercial Kill-A-Watt
power monitor, which is rated at 99.8% accuracy.
We tested the various levels of power consumption using a
light bulb rig with 4 bulbs in parallel.
Then, each power consumption level will be tested in
comparison with level displayed on the Kill-A-Watt power
monitor and will be graphed for an accurate comparison.
Accuracy Results
450
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250
Power Meter
Kill-A-Watt
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150
100
50
0
Timeline, Budget and
Completion Summary
Timeline
Our timeline for Senior Design was based on bimonthly goals, however due to unforeseen
consequences our timeline changed slightly.
April 30th: Complete Research & Documentation
May 31st: Have a good understanding of all aspects concerning the
project
June 1st: Begin testing parts, working for an accurate and quality
design
July 8th: All parts tested and working
July 9th: Order PCB
July 19th: Begin attaching parts to PCB
July 24th: Have all parts put together
July 30th: All parts tested and working which gives us a week
prepare for the final presentation
Workload
Senior Design 1
Senior Design 2
LCD Design
5
Microcontroller
2
Wireless
8
Power Supply
16
Power Measurement
190
Documentation
180
15
PCB Design
5
Troubleshooting/Soldering
50
Project Boxes
25
Coding
60
TOTAL
180
376
Work Distribution
LCD Design
Frank Manny
Alex
X
X
Microcontroller
X
Wireless
X
Power Supply
X
Power Measurement
X
X
Documentation
X
X
PCB Design
Project Boxes
Coding
Amir
X
X
X
X
X
X
X
X
Approximate Budget
Item
Spent ($)
LCD Design
$ 85.00
Microcontroller
$ 400.00
Wireless
$ 270.00
Power Supply
$ 60.00
Power Measurement
$ 150.00
Documentation
$ 15.00
PCB Design
$ 60.00
Project Boxes
$ 30.00
RLC
$ 85.00
Hardware
$ 100.00
TOTAL
$ 1255.00
Completion Summary
Design
Parts Acquisition
Software
Prototyping / Testing
Presentation
0
10
20
30
40
50
60
70
80
90
100
Questions?