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????!!!!!