The document summarizes the electrical power systems for the mule and sensor nodes of the Boston University Nanosat-8 mission. It describes the components used, including solar panels, batteries, and power control boards. It lists the requirements for each subsystem and notes which have been verified so far through testing. These tests are then described in further detail, including simulations of expected power generation and functional tests of voltage regulation and load switching. Remaining tests are outlined to fully verify all requirements before launch.
3. 3
Subsystem Requirements
Mule
• Provide loads with regulated power at 3.3, 5, and 12 V
Sensor Nodes
• Provide loads with regulated power at 3.3, 5, and ±6 V
Both
• Switch off and on power loads when prompted by C&DH
• Power monitor for duration of primary mission
• Meet NSTS 1700.7B, NSTS/ISS 18798 Rev B, and NASA Technical Memorandum 102179 electrical safety
requirements
• Designed for EMC and EMI for LV susceptibility and range radiation environments
• Operate autonomously unless overridden by ground command
• Do not consume more power per orbit than the solar panels can generate
Solar Panels
• Solar cells must operate within manufacturer efficiency rating and provide sufficient battery charging power
for the duration of the mission
4. 4
Status of Requirements
Varified Requirements
Solar Panels
• operate within manufacturer efficiency and power budgets are power
positive for mule and sensor node
Sensor Nodes
• EPS power buses of 3.3, 5 and 12V buses are reporting proper
voltage outputs
Mule
• EPS communicates to Arduino micro-controller and reports proper voltage
outputs across the designated 3.3, 5, and 12V buses.
• Capable of accurately monitoring power usage
• Operates autonomously
5. Status of Requirements
Requirements to be Verified
Mule
• EPS can be overridden if necessary
• Switch on & off loads through C&DH
• Confirmation of EMC & EMI compliance
Sensor Nodes
• (Courtney, fill in requirements for Nodes)
5
6. 6
Analysis Performed
Solar Panels
• Tested actual efficiency of cells and modeled power generation in-
orbit, comparing it to the power budgets.
• MATLAB model for in-orbit power generation; Sensor Node PCB
assembled and tested on roof with multimeter (current/voltage
measurements)
• In-orbit model predicts 2 Wh/orbit and 16.68 Wh/orbit for Nodes
and Mule, respectively. Panel testing indicates efficiency of
25.43%. Blocking diodes are being added to ensure proper power
generation.
7. Analysis Performed
Mule
• Health and Status information coming out of CS-XUEPS2-60 were tested for a match to
the actual values desired.
• EPS connected to Arduino Uno and 30 Wh Li-Po battery from ClydeSpace. I2C DATA
and Clock (Pins A4, A5) of Arudino connected to corresponding pin-outs of EPS
(H1.41, H1.43). Resistors placed in pins H2.25, H2.27, H2.51 (5V, 3.3V, 12V) and
ground to simulate Mule components. Voltmeter and Ammeter checked outputs at each
Bus; BCR out pins were connected to Dummy Load & resistors to measure EPS
voltage & current response.
• Voltage from solar panels to BCR out pins dropped to 7.8V (Spec sheet: 8.2V); Current
sent through BCR out to Dummy Load was 49mA (54mA expected); 3V, 5V, and 12V
were read by the voltmeter for H2.27, H2.25, & H2.51, respectively. ALL OF THESE
VALUES MATCHED THE REPLY BY THE CLYDESPACE EPS.
7
8. Analysis Performed
Sensor Node
• (Courtney, fill in tests done on EPS [how the tests prove the RVM
requirements, what tests were performed, how the tests were
performed, results, effect of results on design]) Use multiple
slides if you need them.
8
9. 9
Subsytem Testing Statuses
Sensor Nodes
• (Courtney, fill in the integrated hardware tests performed on the EPS)
Mule
• CS-XUEPS-60 read proper voltage levels back through I2C to C&DH
• EPS reads proper current measurements to C&DH Arduino
• Connected to 30 Wh battery and operated autonomously
10. 10
Future Steps
Sensor Nodes
• (Courtney, fill in what other tests we need to do to have checked all RVM requirements)
Solar panels
• Test board in vacuum environment with ideal irradiation exposure.
Mule
• Integrate remainder of stack (AD&C, radio, etc.) to the EPS to check full operation
functionality (override control, switch on/off loads)
• Run DITL test for confirmation of mission success (EMC & EMI check, electrical safety
check)
