This repository contains the Public Domain files of the Radio Amateur Satellite Corporation (AMSAT) Fox-1 satellite Maximum Power Point Tracker. This is a PCBA flying on the Fox-1 series of 1U cubesats which optimizes the power extracted from the six solar panels on the spacecraft using analog computing.

The Fox-1 Maximum Power Point Tracker utilizes analog computing to track the solar panel voltage which generates the maximum amount of power from solar cells. It implements what is essentially a "temperature-based set-point constant voltage algorithm" MPPT. Since the solar cells are well-known, this design uses op-amps to compute the predicted voltage which will produce maximum power as fast as the analog bandwidth of the components used will allow it. Analog MPPT was chosen for it's "stateless" design due to radiation tolerance concerns of microcontrollers.

Revision 1.2 boards are Revision 1 PCB's with BOM modifications necessary for correct operation. This included stacking some capacitors ontop of feedback resistors in the RTD circuit for stability. Revision 1 PCB's are green soldermask in color. Revision 2 PCB's were created to adress these issues better and properly mount all parts with correct footprints and adress some other manufacturing needs. These boards are use a blue soldermask and the design files for the Rev 2.1 boards have been uploaded to this Github repository.

READ THE FOX-1 MPPT TECHNICAL OVERVIEW TO UNDERSTAND THE PROJECT!

This project began as a Rochester Institue of Technology Multi-disciplinary Senior Design (MSD) project during the 2012-2013 school year. Originally the P13271 AMSAT-MPPT project which successfully delivered a proof-of-concept MPPT intended for a 3U cubesat, the design was continued and modified for use on the smaller Fox-1 satellites which are 1U in size.

The original RIT team to create this MPPT included

• Bryce Salmi, KB1LQC
• Brenton Salmi, KB1LQD
• Ian MacKenzi, KB3OCF
• Daniel Corriero

Work was performed over two years between 2013 and 2015 by Bryce Salmi and Brenton Salmi to bring the design to flight status from the P13271 project as seen here.

The Revision 1.2 and Revision 2.1 Maximum Power Point Trackers are currently slated to fly on several launches to Low Earth Orbit with more launches being sought after. These flights are accurate as of 9/3/2016.

Two MPPTs will fly aboard two cubesats on the same launch. These satellites are Fox-1Cliff and Fox-1D which are being sent up on the Spaceflight SHERPA payload on a SpaceX Falcon 9.

One MPPT will be flying on the Fox-1B cubesat set to launch aboard a ULA Delta II rocket.

One MPPT will be flying on the Fox-1E cubesat set to launch aboard a Virgin Galactic Launcher One in December, 2017.

All hardware files are located in the Hardware/Rev2_1 directory. They consist of Kicad EDA files which were developed using Kicad Build: 2013-07-07 BZR 4022 which is the July 2013 stable version of the EDA tool (Windows). Also placed into the hardware directory are the project output files. These are the files which were used to order the PCBs and present an easy to use view of the design (PDF, Excel, Gerber, etc).

Notable Documents

• MPPT Schematic PDF Export
• MPPT BOM
• MPPT Extra Components BOM
• Addition parts for the solar panels necessary for the MPPT to work
• MPPT KiCad project file
• KB1LQC KiCad schematic symbol library
• KB1LQC KiCad PCBNew footprint library
• MPPT PCB Fabrication Files
• MPPT PCBA Assembly Files

The documents folder contains support documents necessary to describe the design intentions and analysis of the MPPT.

Notable Documents

• Fox-1 MPPT Technical Overview
• Fox-1 Satellite Solar Panel Calculations
• Fox-1 Solar Panel Telemetry Scaling
• Scaling telemetry downlinked from satellite over RF into Celcius from RTD circuit

The images directory contains a select set of high-quality stock images showing the Rev 2 MPPT very clearly. Not much more needed to say about this 🚀