CUBESAT SPACECRAFT ELECTRICAL POWER SYSTEM

Team Members Project Members Aleck Wright – Input Power Regulation Matt Churchman – Output Power Regulation Ricky Flores – Solar Array Simulator Sponsor Craig Kief Mentor Sam Monaco

Description Create a module that will maximize the power acquired from the CubeSat’s solar arrays Energy Efficiency Eclipsed Orbit Peak Power Tracking Mounting Configuration Illumination Level Temperature Electrical Load Orbital Spin

Description Cont. Input regulators have embedded PPT algorithms Supervised and augmented with uC Microcontroller Bypass Control Command and Data Handling Solar Array Simulator Testing

EPS Block Diagram Solar Array Input Relay Unregulated Battery Voltage BCR 1 BCR 2 BCR 3 CTRL BOOST LT Switching Regulator 3.3V LT Switching Regulator 5V LT Linear Regulator 10V BOOST

Project Goals Why design a new EPS? Extend the operational lifespan of current cube satellites Reduce dependencies on overseas manufacturers, i.e. Clyde Space Support and Implement on Trailblazer II Marketable What are the functional aspect goals? “Plug-and-Replace” User-friendly GUI for SAS, fully documented Good Telemetry Data

Input Power Regulators What do the input regulators do? The input regulators take in power from the solar arrays and with the help of the PIC microcontroller keep the voltages within their specified ranges What do we do with that power? The power will be sent through the output regulators to the external modules on the CubeSat. The external modules require 3.3V, 5.0V, and 12.0V What happens in the case of a fault? In the case of a fault each of the three input regulators will be equipped with a bypass relay maintain input power from the SAS. Team Member Responsible: Aleck Wright

Output Power Regulation Team Member Responsible: Matt Churchman Output Voltage Requirements 3.3V, 5V, and 12V Modularity & TB II Raw Battery Voltage Bypass Specifics LT Switching Regulators (3.3V & 5V) LT Linear Regulator (10V to 12V + Feedback)

SAS SYSTEM Team Member Responsible: Ricky Flores What is a SAS ? Can overheating of CubeSat occur? How can we overcome this problem? What circuit are we using for this design?

SAS Schematic

What does the previous circuit uses: a bank of diodes current amplifiers What needs to be done: Modify previous design and make it programmable How are we planning on doing this? We will replace the current amp gain resistor with a voltage controlled resistor and drive it with a uc DAC. We will add a significant amount of diodes to this circuit Why turn them on/off? Short out diodes as needed. Transistors in parallel or relays? Description

GUI Expectations

Familiarization with a variety of new software: Arduino Visual Basic LTspice Studying the SAS model Arduino Mega 2560 is currently working with Visual Studio We have started writing the code for the SAS GUI. Progress

About our Sponsors Eng. Sam Monaco Mentor in the journey through power Helped us with the Project scope clarification Planner and Coordinator Task Manager Craig J. Kief, COSMIAC Deputy Director Sponsor for this project Financial resources provider Gatekeeper Mutual Roles Progress monitoring Participate actively and visibly through our project Team Leaders

Why is this a good senior design project? This project presents a real world engineering design problem It applies many of the skills that we have acquired in the undergraduate program as well as the Engineering Design Process We will be working as a part of a design team, facing challenges together We will be using engineering tools such as LTSPICE, Eagle, and Arduino programming

Major Milestones SAS GUI has to model IV curve of Solar Arrays GUI fully functional Input & Output Power Regulator: Final LTSPICE circuit. Export into Eagle to procure prototype PCB Build prototype EPS on PCB breadboard Test, upgrade, and finalize PCB Microcontroller Develop optimum code for integrating input/output and SAS. Integration and Testing of all 3 parts working together

Deliverables Prototype breadboard of input/output regulators. Functional Solar Array simulator GUI used to test the input/output regulator prototype. Printed board for SAS. Finalized input/output regulator printed circuit board (PCB). Documentation for input/output PCB and SAS GUI Fully Optimized Microntroller for managing input/output regulators Final presentation/poster board.

Challenges & Concerns Input/Output Regulator Junction to case heat must be taken into account Operational temperatures between approximately -40◦ C and 85◦ C. Component options, i.e. what will be the best choice for regulators etc. 12v exceeds regulator rating. It must be compensated with a feedback loop. SAS GUI Graph for GUI must reflect actual power changes on the input regulator Incorporation of transistors and voltage controlled resistor in SAS circuit. Microcontroller Intense testing for optimal results

Upcoming Tasks Input/Output Regulators Continue improvement of the existing LTSPICE circuits, simulating, etc. Work towards a schematic capture in Eagle to get closer to a PCB design and fabrication SAS Keep working on SAS circuit and SAS GUI Visual Basic code. Fully implemented for input/output regulator testing.

Questions? ¿Preguntas?