KUMU A’O CUBESAT Amy Blas. Background 2 What is CubeSat? 10x10x10 centimeter cube Launched in...
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Transcript of KUMU A’O CUBESAT Amy Blas. Background 2 What is CubeSat? 10x10x10 centimeter cube Launched in...
KUMU A’O CUBESAT
Amy Blas
Background2
What is CubeSat?
10x10x10 centimeter cube Launched in lower earth orbit (LEO) The project started last semester. 13 members Objective is to be the first CubeSat in
space from Hawaii
Proposed Mission4
To be Hawaii’s first developed, tested, launched, and operated CubeSat successfully placed into orbit
CubeSatellite System
5
•Brain•Digestive•Ears and Mouth•Bones•Skin and Blood•Eyes and appendages
•Command and Data Handling•Electrical Power•Telecommunications•Structure•Thermal•Attitude Control and Determination
Recap of CDR
Was working on PCB Realized that Proto-typing is more
important Started Prototyping
What have we been working on now? We have been prototyping all of our
chips Finding values of circuit parts Putting the circuit together Getting Results
Block Diagram of EPS8
Solar Cells
Step Up Converter
Battery Charger
C&DH
Battery Gauge and
Sensors
Battery Pack
DC-DC Converter
and Switching
Mechanisms
Electronic Components
Block Diagram of EPS9
Solar Cells
Step Up Converter
Battery Charger
C&DH
Battery Gauge and
Sensors
Battery Pack
DC-DC Converter
and Switching
Mechanisms
Electronic Components
Solar Cells10
High efficiency n/p design (28°C, AM0)
-BOL: 26.8% min. average efficiency @ maximum power
(26.5% @ load voltage)
-EOL: 22.5% min. average efficiency @ maximum power
(22.3% @ load voltage), Integral bypass diode protection Transparent insertion into existing
systems
Spectro Lab’s Improved Triple Junction (ITJ) 26.8% efficiency Solar Cells
11
Solar Cells
•1 Set = 2 Series Cells•Six Sets in parallel•12 cell configuration
•Each cell is 4 x 7 cm•2.32 V per cell•Jload min avg= 16.10 mA/cm²
•4.64 V and 450.8 mA per cell (After adjustments)
Bypass Diode
Blocking Diode (prevent
power drain)
10 cm10 cm
Current Sensor
10 cm
Step-up Converter – MAX1771
12
2 to 16.5V Input Voltage Range
90% Efficient for low load currents
Output current range of 30mA to 2A
Preset 12 V or adjustable output voltage
Set by input voltage of charger
Solar cell design
Used 3 MAX 1771 Chips Simulate solar cell input 6 V output
Component Value R1 = 10 K Ω R2 = 30 kΩ
3.3 V DC Input
6 V output
SchottkyDiodes
6 V DC Output
Data Values
Input Theoretical
Chip1 Chip 2 Chip 3 Placement
Notes
3 V 6 V 6.254 V
6.306 V 2.844 V B4 diode 1
3 V 6 V 6.741 V
6.504 V 3.271 V Aft Diode 2
3.30 V 6 V 6.254 V
6.316 V 3.013 V B4 Diode 3
3.30 V 6 V 6.67 V 6.467 V 2.994 V Aft Diode
3.00 V 6 V 7.00 V
3.30V 6 V 7.13 VNote 1 : All values of our resistor parts were the same Note 2 : Realized something was wrong in Chip 1 and 3; no diode voltage diode.Note 3: Debugging and changed out capacitors.
Problems – MAX 1771
Part Values Mosfet Rsense
Same value, Different Brand Capacitors Inductors
Exact circuit – incorrect values
Block Diagram of EPS17
Solar Cells
Step Up Converter
Battery Charger
C&DH
Battery Gauge and
Sensors
Battery Pack
DC-DC Converter
and Switching
Mechanisms
Electronic Components
Battery Charger – MAX1898
Simple circuit design 4.5 to 12V input
range Programmable
charge current Output voltage of
4.1V Internal current
sense resistor Programmable safety
timer
Proto-typing
Using equation and looking at the battery specifications for 1.4Amps charging rate Rset = 1K
Used a different battery to test Old PDA Lithium Ion BatteryInput Theorize
d Voltage
Theorized Current
Output Voltage
Shunted Voltage6.4Ω
Output Current
5 V 4.1 V 1.4A 4.12 V 3.714 V 624mA
6.5 V 4.1 V 1.4 A 4.123 V 3.717 V 650 mA
What we learned
Battery Reset Need to hook up pin to micro controller Hard reset
The charger works!!!!
Block Diagram of EPS
Solar Cells
Step Up Converter
Battery Charger
C&DH
Battery Gauge and
Sensors
Battery Pack
DC-DC Converter
and Switching
Mechanisms
Electronic Components
DC-DC converters22
Load Load Load
DC-DC converters23
Load Load Load
DC-DC step-down converter24
MAX1921(step-down) Up to 90% efficiency 2 to 5.5V input range Fixed 3.3V output
voltage Guaranteed 400 mA
output current Up to 1.2MHz switching
frequency Operating temperature
range of -40 to +85°C
Problems and Solutions
Data sheet mix ups Schematic and given values Equations
Components Electrolytic, ceramic, or tantalum Resistor Values
Guess and check R1= 360K
Data
Input Theoretical
Output Shunt 6.4Ω Output Current
4.0 V 3.3 V 3.28 V 3.001 V 469mA
4.70 V 3.338 V 2.83 V 442mA
5.0 V 3.337 V 3.269 V (10Ω) 327mA
Input Resistor Values
Output
5.0 V
200 K 2.6 V
300 K 3.04 V
400 K 3.480 V
360 K 3.337 V
DC-DC converters27
Load Load Load
Step-up Converter – MAX1771
28
2 to 16.5V Input Voltage Range
90% Efficient for low load currents
Output current range of 30mA to 2A
Preset 12 V or adjustable output voltageo Set by input voltage of
charger External resistors can be used
to set the output voltage Operating Temperatures
= - 40oC to +85oC
DC-DC converters29
Load Load Load
DC-DC Step-up converters
MAX1703(step-up) Fixed 5V output voltage Up to 95% efficiency 0.7 to 5.5V input Range Up to 1.5A output Operating temperature
range of -40 to +85°C
Problems
Incorrect parts Similar but not exact
Soldering
Detailed Schematic32
Actual Circuit
Overall
Problems Components Soldering
Solutions Order exact parts PCB for certain chips
QUESTIONS????!!!!!