HMS Home Management System

Dennis KilgoreZineb HeaterRyan Jones

Home Energy Management System

Sponsor: Progress energy

Project MotivationPower bills only give consumers a look atMonthly power usagePower 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 dont need it?

Standby Power All electronics that are powered by DC power have an AC to DC converterThese converters draw power even when they arent 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 billFrance 7%US 10%Japan 12%3GoalsA system that measures the power consumption of various household appliances A system that allows the user to shut the power off any household applianceA system that monitors the power usage and display it on an LCD screenA system that can be accessed wirelesslyA system that will save more energy than it uses

Project Overview Build a circuit to measure both the current and voltage used by an applianceBuild the circuit to control the power on and off an applianceWrite a program to calculate the power and transmit it wirelesslyDisplay the results on an LCD touch screen

Requirements and Specifications Measure currents varying from 0 Amps to 15 AmpsMeasure voltages up to 120VControl the relay and shut the power off an appliancePower measured must be within 10% error

Block Diagram

Hardware

Current Sensing Methods Current measuring ShuntsCurrent transformersHall Effect current sensorsMagneto resistive Field sensorsPros and Cons ProsConsPriceShuntHigh AccuracyHeat DissipationModerateTransformerIsolationLarge sizeModerateMagneticHigh AccuracyTemperature dependencyModerateHall EffectIsolationHigh AccuracyHigh LinearityRepeatable operationSmall Output VoltageModerateOur Decision AMP25 Hall Effect Linear sensorLinearity 1%, Accuracy +/-2%25 Amps rating-55C to +125CVoltage supply Vs 4.5VDC to 10VDCOffset voltage of Vs/2 +/-2%Output voltage proportional to Vs

AMP25

Voltage Sensing Methods Voltage sensor, expensive, configuration requiredVoltage divider, cheap and easyPower Measurement What are we calculating: Real Power (P) in Watts or Apparent Power (S) in VA?

P=V*I*cos()S=V*I

Power measurement Error vs. PF

Power RelayTRIAC switch, expensive, largeSolid state relay switch, small and reliable

CX240D5 SSRRatings of 5AAC or DC controlZero-crossing (resistive loads) or random-fire (inductive loads) output

SFH620A, Optical IsolatorIsolation test voltage, 5300 VRMSHigh collector emitter voltageLow saturation voltageFast switching times Temperature stable

SFH620A, Optical Isolator

Schematic Layout

Schematic layout

Schematic Layout

Schematic Layout

Schematic Layout

Schematic Layout

PCB layout

Testing

TestingOutput of Vcc/2 when there is no currentVcc=4.86 V100W@120VI=P/V=833mAThe sensor has an output of 37mV/1ASensor should have an output of 30.821mV for this load30.821mV*7 loops = 216mV RMSTesting

Testing

Testing

Testing

Testing

Testing

Microcontroller2-3 analog inputsHigh accuracy D/A conversion2 digital outputs1 serial i/o

MicrocontrollerArduino Pro Mini

Small Size: .7 x 1.3 inches

Easily Programmable through FTDI

Development EnvironmentAccuracyAccuracy is a major concern Any inaccuracy in the measurement circuit will multiply with microcontroller inaccuracies.Need to measure and confirm accuracy of the chip.Voltage vs Integer CalculationMeasured vs Calculated; Error %Measured vs Calculated; Error %, correctionError CorrectionMicrocontroller ProgrammingSetup

Main Loop

Read Serial Data Function

Print outputsSetupInitialize serial communication

Set digital pin 10 to digital output

Set the pin to highTurns on the relayMain LoopTake MeasurementsFind high and low of the waveform over 1 sec periodAfter 1 second, print the values to serialIf switch is off, wait to turn back on

Read SerialRead the incoming serial data and decide what to doIncoming data will be the on/off commandBe able to respond immediately to commandsMicrocontroller is always looking for incoming serial dataPrint outputsDetermine the height of the waveformCorrect for innacuraciesHall effect sensor floats at 1.5 mV(integer of 5) when poweredSubtract 1 from the voltage measurementPrint the output as comma separated values to the serial comm, to be processed by the screenN#,vol,cur,

Wired CommunicationPowerline CommunicationNo range or attenuation issuesRequires Bulkier PartsIncreases size of end unit PCBRequires modifications to home circuitry depending on the house

Wireless CommunicationZigbeeMesh NetworkingExcellent rangeBetter supports many nodes

Protocol and parts are a mess

Zigbee -> XbeeXbee is not ZigbeeXbee is based on the Zigbee stackIt is however a more stable alternative to Zigbee

AT Command StructureThe Xbee units use AT commands for controlThis allows direct control of the addressing, and node address discoveryChanging the address to a specific node requires the address to be known

Control BoardFuture Designs DK-57VTS-LPC3250

ARM926EJ-S processor256KB of Internal SRAM512MB NAND FlashMicro SD (up to 16GB)Ethernet, USB, RS232Embedded Linux5V or 3.3V

LCD Touch Screen5.7 VGA LCD Screen4 Pin Resistive Touch1024x768 resolution18 bit color

User InterfaceMiniGUIGNUPlot for graphsMuch of the support is in Japanese

Qt for Embedded LinuxQwt for graphsMore support in English

GUI Mock-Ups

GUI Mock-Ups

GUI Mock-Ups

Software Block Diagram

IntegrationReceive data from XbeeProcess dataStore dataUpdate graphsRespond to touchNavigate Menus

AdministrativeBudgetItem#Unit Cost ($)Total Cost ($)Arduino Pro319.0057.00Xbee419.0076.00PCB320.0060.00LCD Screen1515.00515.00Xbee Adapter411.0044.00Hall Effect sensors411.9047.60Power Relay413.1852.72Resistors, capacitors, etc.12Total863.72Questions?