southern university la aces team excelle experiment (experiment for solar cell efficiency) tannus...
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Southern University Southern University La ACES TeamLa ACES Team
EXCELLE ExperimentEXCELLE Experiment(Experiment For Solar Cell Efficiency)(Experiment For Solar Cell Efficiency)
Tannus Joubert, Kristen Hypolite, Kevin James, Tannus Joubert, Kristen Hypolite, Kevin James, Laquonda Johnson, Michael Johnson, Shanta Laquonda Johnson, Michael Johnson, Shanta
McKinzie, Leslie SanfordMcKinzie, Leslie Sanford
Preliminary Design Review (PDR)Preliminary Design Review (PDR) March 18, 2005March 18, 2005
Mission ObjectivesMission Objectives
Measure the light conversion efficiency Measure the light conversion efficiency Output of an assortment of solar cells Output of an assortment of solar cells
throughout various levels of the atmosphere throughout various levels of the atmosphere Results Results
– conclude whether future La ACES experiments conclude whether future La ACES experiments can be powered by the most efficient solar cells can be powered by the most efficient solar cells found found
SCIENCE GOALSSCIENCE GOALSUnderstandingUnderstanding
Solar Cell Efficiency Solar Cell Efficiency The Solar Spectrum The Solar Spectrum
– Its relation to the silicon solar cell material band Its relation to the silicon solar cell material band gap gap
Energy Energy PhotonsPhotons Wasted HeatWasted Heat
Types of solar cellsTypes of solar cells
MonocrystallineMonocrystalline– Made from pure silicon, most efficient Made from pure silicon, most efficient
(~24 % in the lab), but most expensive (~24 % in the lab), but most expensive since they are difficult to makesince they are difficult to make
Polycrystalline Polycrystalline – Less efficient (18 % in the lab) Less efficient (18 % in the lab)
AmorphousAmorphous– Least efficient (13%), used in watches, Least efficient (13%), used in watches,
calculatorscalculators
Technical GoalsTechnical Goals
Measure the light conversion efficiency that Measure the light conversion efficiency that solar cells solar cells – Research the condition the solar cells can Research the condition the solar cells can
withstand withstand – Find the position that the sun is at the time of Find the position that the sun is at the time of
launch and during launch to maximize the solar launch and during launch to maximize the solar power power
– Deal with the rotation that maybe encountered Deal with the rotation that maybe encountered by the cord being tangled by the cord being tangled
Payload DesignPayload Design
The payload will be surrounded with three The payload will be surrounded with three types of solar cells, so that energy types of solar cells, so that energy conversion efficiencies can be compared.conversion efficiencies can be compared.
DesignSubcategories: DesignSubcategories: SystemSystem ThermalThermal MechanicalMechanical ElectricalElectrical Software design Software design
Principle of OperationsPrinciple of Operations
N-Type
P-Type
_ _ _ _ _ _ _ _ _ _
+ + + + + ++ + + + ++ + + + + + +
Electric Field
Photon Path
I
Load
Power output
+
_
Vo
Possible challengesPossible challenges
Rotation effects- may be dealt with by measuring position Rotation effects- may be dealt with by measuring position of sun with respect to pay load of sun with respect to pay load
Ultra-violet radiation- Will it damage the cells or be Ultra-violet radiation- Will it damage the cells or be beneficial by providing more energy?beneficial by providing more energy?
Pendulum motion of package- will it interfere with our data?Pendulum motion of package- will it interfere with our data?
Launching at dawn – how to maximize sunlight intake due Launching at dawn – how to maximize sunlight intake due to low position of sun? to low position of sun?
System Interface ComponentsSystem Interface Components
Main System: Basic Stamp Processor
Subsystems: Solar cells User Interface Real Time Clock Analog-To-Digital Converter Memory Power System Reset Temperature Sensor
*Real Time Clock provides accurate date and time
Solar cells send the charge
through charge converter for
signal acquisition by
the multiplexer.
ADC converts analog to a readable digital signal
Memory must be
synchronized with the ADC to process the
data.
User interface (Laptop) will be used to upload and
download software and data.
Basic Stamp Processor is used to
control all data acquisition and
processing. Solar Cells
Charge Converter
Analog to Digital Converter
Basic Stamp Processor
Memory
Real TimeClock
System Reset
User Interface
MultiplexerTemperature
Sensor
Power
System Interface ComponentsSystem Interface Components
Electrical DesignElectrical Design
BalloonSat SystemBalloonSat System– 6V at 100mA6V at 100mA– 4 AA Li Batteries4 AA Li Batteries
Charge Controller/ConverterCharge Controller/Converter– Convert current coming from each cell into voltage Convert current coming from each cell into voltage – Convert excess voltage into heat, used to keep inside of Convert excess voltage into heat, used to keep inside of
box warm box warm – Voltage signal/readings to be passed through an 8 Voltage signal/readings to be passed through an 8
channel multiplexer channel multiplexer combine all the signals into one data stream combine all the signals into one data stream
Electrical Design cont’dElectrical Design cont’d
Onboard Temperature Reading Onboard Temperature Reading – Onboard ADC Onboard ADC – Voltage Regular Temperature ReadingVoltage Regular Temperature Reading– Operational AmplifierOperational Amplifier
BASIC STAMPBASIC STAMP– If memory is full Basic Stamp is able to turn itself off If memory is full Basic Stamp is able to turn itself off – Power supply regulator is already built into the circuit Power supply regulator is already built into the circuit
board board – LEDs will be used to confirm operations LEDs will be used to confirm operations
Electronic FlowchartElectronic Flowchart
SOLAR CELLS
CHARGE CONVERTER
MULTIPLEXER
ADC
RTC
BASIC STAMP
MEMORY
Thermal DesignThermal Design
Flying payload to the height of approximately Flying payload to the height of approximately 30km at the temperature of -6030km at the temperature of -60ooC.C.
Location Palestine, Texas.Location Palestine, Texas. Challenge is to design a payload to stay well Challenge is to design a payload to stay well
in the range of the operating condition of the in the range of the operating condition of the electronics.electronics.
Overheating of the solar cellOverheating of the solar cell
Payload Operating at -60 oC
Overheating of the Solar Cells
80oC
Overheating of Electronics
Thermal SchematicThermal Schematic
Solar cells cool by radiation
Mesh
Inner Temp maintained to within 5 - 6oC with induced convection with fan
Electronics generate heat
Air (R)
Solar Cells (R)
Mesh (INS) (C)
Foam Core (C, R)
Inside Payload (R) (CV)
Qcond
Spacer
Air flow (-60oC)
where R- radiation, C-conduction, CV-Convection, and INS – Insulation
RecommendationsRecommendations
Spacer-mesh combination to prevent Spacer-mesh combination to prevent scorching of foam corescorching of foam core
May rely of rotational effects to radiate heat May rely of rotational effects to radiate heat from the boxfrom the box
Test simulation will be done on electronic Test simulation will be done on electronic and payload system to determine possible and payload system to determine possible thermal effectsthermal effects
Mechanical Design Mechanical Design
1. Creating a payload of a low weight, high thermal stability, and a suitable degree impact resistance. Constructing a payload that will withstand such stresses is also a key factor in our design.
2. The method of attaching solar cells to the payload and interfacing them with the rest of the electronics.
3. Preflight worthiness test .
We will focus on :
Mechanical DesignMechanical Design
The box concept for now is simply rectangular payload with which consist of two modules:
1. Inner module
2. Outer module
Mechanical DesignMechanical Design
The functions of the outer module are:The functions of the outer module are:
1. To serve as a primary encase1. To serve as a primary encase for the second module.for the second module.
2. Provide a protective covering 2. Provide a protective covering against acceleration, deceleration,against acceleration, deceleration, shock, and impact.shock, and impact.
3. To provide a surface for the 3. To provide a surface for the
attachment of the solar cellsattachment of the solar cells
and framed mesh.and framed mesh.
4.4. To provide a barrier against theTo provide a barrier against the
cold temperatures experienced by the payload.cold temperatures experienced by the payload.
17 cm
18 cm
15.5 cm
Mechanical DesignMechanical Design
The functions of the inner module are:The functions of the inner module are:
1. To provide a containment for the electronics.
2. To hold the batteries.
3. To serve as a second line of defense against impact, shock and gravitational forces.
4. To help optimize the heat transfer of the payload.
14 cm
15 cm
6 cm
Mechanical Design Mechanical Design
•The solar cells will be mounted on a sheet of mesh framed with Popsicle sticks.
•The removable frame will then be attached to the payload by screwing the frame into half inch non-conducting standoffs that will already be attached to the box.
•By mounting the solar cells on this structure, the heat that will dissipate from the solar cells will be able to flow freely away from the payload.
Back view of framed mesh. Front view of framed mesh.
Non-conducting standoff
Mechanical Design Mechanical Design
Weight Budget of the Pay Load:Weight Budget of the Pay Load:
Weight limit: 500 g
• Balloon Sat:
0.5g x 3 x 4 = 6.00 g
63.55 g
• One monocrysitaline solar cell:
• Batteries: 8.3 x 4 = 33.3 g
• Inter and outer modules: 160 g+ 262.85 g500 g - =
< 237.15 g237.15 g• Frame
• Mesh
• Standoffs
Futuristic Payload DevelopmentFuturistic Payload Development
Charge Converter SystemCharge Converter System Control Solar SystemControl Solar System
– CircuitCircuit Mechanical SystemsMechanical Systems
– ScrewsScrews Thermal Control SystemThermal Control System
– Too Hot???Too Hot??? Finishing SoftwareFinishing Software Build PrototypeBuild Prototype
– Find circuits that work interface with softwareFind circuits that work interface with software
Payload Construction PlanPayload Construction Plan
Electronics- planning, development, and Electronics- planning, development, and implementationimplementation
Mechanical and thermal- Planning, Mechanical and thermal- Planning, development and implementationdevelopment and implementation
Software systemsSoftware systems DocumentationsDocumentations Flight ImplementationFlight Implementation
Electronics Mechanical Thermal Software Integration Flight
BalloonSat
Basic Stamp
ADC Converter
Multiplexer
Sensors
Interfaces
Foam Core
Inner Module
Outer Module
Spacers
Mesh
Solar cells
Electronics
Modules
Solar cells
Mesh
Foam Core
ADC program
Sensors
Basic Stamp
Control
Interfaces
Electronics
Mechanical
Thermal
Software
Interfaces
BalloonSat
Basic Stamp
ADC Converter
Multiplexer
Sensors
Interfaces
Hardware FabricationHardware Fabrication
Solar CellsSolar Cells– Testing Testing – Framework Framework
Charge Converter Circuitry (Separate Boards)Charge Converter Circuitry (Separate Boards)– CircuitryCircuitry– MultiplexerMultiplexer
Box StructureBox Structure– Shock and Thermal TestingShock and Thermal Testing– Drop TestDrop Test
Battery (Power System)Battery (Power System)– LocationLocation– Interfacing to Whatever Needs PowerInterfacing to Whatever Needs Power
Integration PlanIntegration Plan
To test the connections between electronics To test the connections between electronics and software.and software.
Stabilize Power ConnectionStabilize Power Connection
Ensure that the Mechanical structure is able Ensure that the Mechanical structure is able to hold the batteries, boards, and other to hold the batteries, boards, and other system ancillaries.system ancillaries.
Take Thermal Test to ensure that Take Thermal Test to ensure that components are working properly due components are working properly due changes in temperature.changes in temperature.
Software Implementation and Software Implementation and VerificationVerification
The Software designed will calculate and The Software designed will calculate and measure the current and voltage output by measure the current and voltage output by the cells and store the data the cells and store the data
The software will decide from which set of The software will decide from which set of cells the signal is being read, and process cells the signal is being read, and process each accordingly. The software will be used each accordingly. The software will be used to calculate voltage and power produced by to calculate voltage and power produced by the cells as a function of altitude. the cells as a function of altitude.
ADC
Inputs the Data
SolarCell
Identifier
1Not 1
2
Reads the ADC value
Reads the ADC value
Calculates the
Voltage
SolarCell
Identifier
SolarCell
Identifier
3
Stores into Memory
End
Time Stamp
Function
After completion of flight, memory is downloaded to obtain data and for the analysis of results.
TemperatureNot T
Not 2
Reads the ADC value
T
Flight Certification TestingFlight Certification Testing Upon the completion of the total payload, we will start flight certification Upon the completion of the total payload, we will start flight certification
testing. We will do both testing. We will do both temperaturetemperature and and shock testingshock testing. .
Temperature testing of the payloadTemperature testing of the payload : : We will place the payload in a ice chest which will contain dry ice and We will place the payload in a ice chest which will contain dry ice and
run the electronics as if in actual flight. run the electronics as if in actual flight.
Shock Testing of the payload: To test the durability of the payload. We will drop the payload (about To test the durability of the payload. We will drop the payload (about
10ft) to make sure the electronics are safely contained and will good 10ft) to make sure the electronics are safely contained and will good conditions to take post-flight measurementsconditions to take post-flight measurements. .
We will analyze the data for both test and make the necessary We will analyze the data for both test and make the necessary changes needed for a successful flight mission.changes needed for a successful flight mission.
Mission Operations
*Synchronize our Real Time Clock with the Global Positioning System
*Erase all test data before flight
Launch Requirements
*Synchronize RTC with GPS. *Computer to communicate with
the Basic Stamp.
Flight Requirements and Operations
*Flight duration of approximately 4 hours*Reach approximately 100,000 before
falling *Temperatures ranges from -60 to 85
degrees Celsius.*Ascent of balloon is expected to be
smooth*Turbulence is expected during the fall.
Data Acquisition and Analysis Plan
Data to be collected:*Charge from solar cells*Product of current and voltage
will allow us to compute the power output by each cell group.
*Temperature inside the payload*Time stamp generated RTC
*All data will be stored on board using EEPROM memory.
Data needed:GPS system data: Longitude, Latitude, Altitude.This data will be gathered after the flight. The data will then be
correlated to the data collected on the payload.
Organization and ResponsibilitiesOrganization and Responsibilities
La Aces Program Office
Team Leader(T. Joubert)
PayloadDesign
Data Analysis(L. Johnson)
Project Management(T. Joubert)
MechanicalDesign
(L. Sanford )Documentation
ThermalDesign
(M. Johnson)
ElectricalDesign
(S. McKinzie )
Software Design
(T. Joubert )
SystemDesign
(K. James )Calibrations
Parts/Budget Flight Data Analysis
Scheduling(K. Hypolite)
Results
Interface ControlInterface Control
Electronic Interfaces(System) Need to know much voltage is coming in various components.Circuits needs to checked for connections to software and system components
Thermal InterfacesDepends on the mechanical design for cooling of solar cells, temperature inside the box.All electronic components on the payload will need to endure extreme temperature changes
Mechanical InterfacesNeeds to be able supply an adequate amount of space for all components. Materials used in construction depend on thermal testing.To provide a suitable degree of impact resistance.
System DesignNeeds to be able to communicate with all components.
Interface Control
Software Interfaces(Electronic) Needs to know when to read data; how often to read data.
Master ScheduleMaster ScheduleActivity Start Finish
Mission Objectives/Project Management 2/28/2005 3/9/2005
Payload Design 3/2/2005 4/12/2005
Payload Development 3/9/2005 4/12/2005
Payload Construction Plan 3/9/2005 3/9/2005
Master Budget/ PDR 3/10/2005 3/13/2005
Submit Complete PDR 3/17/2005 3/17/2005
Preliminary Design Review 3/18/2005 3/18/2005
Spring Break 3/21/2005 3/29/2005
Submit Complete CDR 4/12/2005 4/12/2005
Critical Design Review 4/15/2005 4/15/2005
Flight Readiness Review
5/23/2005 5/24/2005
Launch Trip 5/22/2005 5/26/2005
Work Break Down ScheduleWork Break Down Schedule
Time ScheduleTime Schedule MilestonesMilestones
BudgetBudgetName Vendor Source Delivery
TimeQty Part No. Price per
quantityPrice
Solar Cells Radio Shack Went tostore
In Stock 6 276-124 10.00 10.0010.00
Multiplexer Digi-Key TBD TBD TBD
Glue TBD TBD
EEPROM Digi-Key Catalog 1 week 1 AT27BV256-12JC-ND
2.32 2.322.32
Batteries RadioShack Went toStore
In Stock 1 4 AA 3.99 3.993.99
Foamcore ACESProgram
In Stock 1
ADC Digi-Key CatalogCatalog TBD TBD
Popsickles Wal-Mart TBD 100 TBD
Standoffs Digi-Key Catalog 1 week 10 1902ck-nd $5.24 5.245.24
Construction Tools
ACESProgram
In Stock
Total So Far $21.55$21.55
RISK MANAGEMENTRISK MANAGEMENTLevels of RiskLevels of Risk
HighHigh
MediumMedium
LowLow
Transfer of ResponsibilityTransfer of Responsibility