Transcript HMS Home Management System

Dennis Kilgore
Zineb Heater
Ryan Jones
Project Motivation

Power bills only give consumers a look at
 Monthly power usage
 Power usage for the entire house

How much power does your home
entertainment system use?

What if you could turn your water heater off
when you don’t need it?
Standby Power

All electronics that are powered by DC power have an AC to DC
converter
 These converters draw power even when they aren’t in use

Entertainment systems consume power when off, cable box, gaming
system, almost every other modern device

Research in leading G8 countries shows that Standby power consumes 8
to 12 percent of a home power bill
 France – 7%
 US – 10%
 Japan – 12%
Goals





A system that measures the power
consumption of various household
appliances
A system that allows the user to shut the
power off any household appliance
A system that monitors the power usage
and display it on an LCD screen
A system that can be accessed wirelessly
A system that will save more energy than it
uses
Project Overview
Build a circuit to measure both the
current and voltage used by an
appliance
 Build the circuit to control the power on
and off an appliance
 Write a program to calculate the power
and transmit it wirelessly
 Display the results on an LCD touch
screen

Requirements and Specifications
Measure currents varying from 0 Amps
to 15 Amps
 Measure voltages up to 120V
 Control the relay and shut the power off
an appliance
 Power measured must be within 10%
error

Block Diagram
Hardware
Current Sensing Methods
Current measuring Shunts
 Current transformers
 Hall Effect current sensors
 Magneto resistive Field sensors

Pros and Cons
Pros
Cons
Price
Shunt
High Accuracy
Heat Dissipation
Moderate
Transformer
Isolation
Large size
Moderate
Magnetic
High Accuracy
Temperature
dependency
Moderate
Hall Effect
Isolation
High Accuracy
High Linearity
Repeatable
operation
Small Output
Voltage
Moderate
Our Decision
AMP25 Hall Effect Linear sensor
 Linearity 1%, Accuracy +/-2%
 25 Amps rating
 -55ºC to +125ºC
 Voltage supply Vs 4.5VDC to 10VDC
 Offset voltage of Vs/2 +/-2%
 Output voltage proportional to Vs

AMP25
Voltage Sensing Methods
Voltage sensor, expensive, configuration
required
 Voltage divider, cheap and easy

Power Measurement

What are we calculating: Real Power (P)
in Watts or Apparent Power (S) in VA?
P=V*I*cos(θ)
S=V*I
Power measurement Error vs. PF
Power Relay
TRIAC switch, expensive, large
 Solid state relay switch, small and
reliable

CX240D5 SSR
Ratings of 5A
 AC or DC control
 Zero-crossing (resistive loads) or
random-fire (inductive loads) output

SFH620A, Optical Isolator
Isolation test voltage, 5300 VRMS
 High collector emitter voltage
 Low saturation voltage
 Fast switching times
 Temperature stable

SFH620A, Optical Isolator
Schematic Layout
Schematic layout
Schematic Layout
Schematic Layout
Schematic Layout
Schematic Layout
PCB layout
Testing
Testing
Output of Vcc/2 when there is no current
 Vcc=4.86 V
 100W@120V
 I=P/V=833mA
 The sensor has an output of 37mV/1A
 Sensor should have an output of
30.821mV for this load
 30.821mV*7 loops = 216mV RMS

Testing
Testing
Testing
Testing
Testing
Testing
Microcontroller

2-3 analog inputs
 High accuracy D/A conversion
2 digital outputs
 1 serial i/o

Microcontroller

Arduino Pro Mini

Small Size: .7 x 1.3 inches

Easily Programmable through FTDI

Development Environment
Accuracy
Accuracy is a major concern
 Any inaccuracy in the measurement
circuit will multiply with microcontroller
inaccuracies.
 Need to measure and confirm accuracy
of the chip.

0
0.1
0.203
0.305
0.407
0.5
0.605
0.702
0.799
0.896
1.007
1.107
1.205
1.308
1.399
1.497
1.607
1.707
1.803
1.9
2.002
2.117
2.204
2.309
2.401
2.501
2.6
2.7
2.798
2.901
2.999
3.1
3.202
3.298
Voltage vs Integer Calculation
1200
1000
800
600
Series1
400
200
0
0
0.1
0.203
0.305
0.407
0.5
0.605
0.702
0.799
0.896
1.007
1.107
1.205
1.308
1.399
1.497
1.607
1.707
1.803
1.9
2.002
2.117
2.204
2.309
2.401
2.501
2.6
2.7
2.798
2.901
2.999
3.1
3.202
3.298
Measured vs Calculated;
Error %
12
10
8
6
Series1
4
2
0
0
0.1
0.203
0.305
0.407
0.5
0.605
0.702
0.799
0.896
1.007
1.107
1.205
1.308
1.399
1.497
1.607
1.707
1.803
1.9
2.002
2.117
2.204
2.309
2.401
2.501
2.6
2.7
2.798
2.901
2.999
3.1
3.202
3.298
Measured vs Calculated;
Error %, correction
12
10
8
6
Nominal
Addition
4
2
0
-2
0
0.1
0.203
0.305
0.407
0.5
0.605
0.702
0.799
0.896
1.007
1.107
1.205
1.308
1.399
1.497
1.607
1.707
1.803
1.9
2.002
2.117
2.204
2.309
2.401
2.501
2.6
2.7
2.798
2.901
2.999
3.1
3.202
3.298
Error Correction
3.5
3
2.5
2
1.5
Series1
1
0.5
0
Microcontroller Programming

Setup

Main Loop

Read Serial Data Function

Print outputs
Setup

Initialize serial communication

Set digital pin 10 to digital output

Set the pin to high
 Turns on the relay
Main Loop

Take Measurements
 Find high and low of the waveform over 1
sec period
 After 1 second, print the values to serial

If switch is off, wait to turn back on
Read Serial

Read the incoming serial data and
decide what to do
 Incoming data will be the on/off command
 Be able to respond immediately to
commands

Microcontroller is always looking for
incoming serial data
Print outputs

Determine the height of the waveform
 Correct for innacuracies
○ Hall effect sensor floats at 1.5 mV(integer of
5) when powered
○ Subtract 1 from the voltage measurement

Print the output as comma separated
values to the serial comm, to be
processed by the screen
 N#,vol,cur,
Wired Communication

Powerline Communication
 No range or attenuation issues
 Requires Bulkier Parts
 Increases size of end unit PCB
 Requires modifications to home circuitry
depending on the house
Wireless Communication

Zigbee
 Mesh Networking
 Excellent range
 Better supports many nodes
 Protocol and parts are a mess
Zigbee -> Xbee

Xbee is not Zigbee
 Xbee is based on the Zigbee stack

It is however a more stable alternative to
Zigbee
AT Command Structure
The Xbee units use AT commands for
control
 This allows direct control of the
addressing, and node address discovery
 Changing the address to a specific node
requires the address to be known

Control Board
Future Designs DK-57VTS-LPC3250

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ARM926EJ-S processor
256KB of Internal SRAM
512MB NAND Flash
Micro SD (up to 16GB)
Ethernet, USB, RS232
Embedded Linux
5V or 3.3V
LCD Touch Screen




5.7” VGA LCD Screen
4 Pin Resistive Touch
1024x768 resolution
18 bit color
User Interface

MiniGUI
 GNUPlot for graphs
 Much of the support is in Japanese

Qt for Embedded Linux
 Qwt for graphs
 More support in English
GUI Mock-Ups
GUI Mock-Ups
GUI Mock-Ups
Software Block Diagram
Integration


Receive data from Xbee
 Process data
 Store data
 Update graphs
Respond to touch
 Navigate Menus
Administrative
120
100
80
60
40
20
0
Research
Parts
Acquisition
Design
Prototype
Test
Budget
Item
#
Unit Cost ($)
Total Cost ($)
Arduino Pro
3
19.00
57.00
Xbee
4
19.00
76.00
PCB
3
20.00
60.00
LCD Screen
1
515.00
515.00
Xbee Adapter
4
11.00
44.00
Hall Effect sensors
4
11.90
47.60
Power Relay
4
13.18
52.72
Resistors, capacitors, etc.
12
Total
863.72
Questions?