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ClydeSpace Electronic Power System Yashraj Khaitan Space Sciences Laboratory University of California, Berkeley. ClydeSpace EPS Agenda. AGENDA Requirements Overview Alternatives Features Testing. Overview. 3 Battery Charge Regulators (BCRs) on 6 solar array sections
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ClydeSpace Electronic Power System Yashraj Khaitan Space Sciences Laboratory University of California, Berkeley
ClydeSpace EPS Agenda AGENDA Requirements Overview Alternatives Features Testing
Overview • 3 Battery Charge Regulators (BCRs) on 6 solar array sections • Independent operation even without battery backup • Maximum Power Point Tracking
Alternatives • BCRs could have been designed using switch mode regulator ICs at a much lower cost • Efficiencies could have increased by conducting MPPT for each solar array
Features • BCR uses Single Ended Primary Inductor Converter (SEPIC) for high efficiency • power conversion • 5V and 3.3V regulators use BUCK converters at 90% efficiency • Over-current protection switches to protect CUBESAT circuitry • Telemetry and Telecommands interface via I2C digital interface • 0.1W system quiescent power consumption • Peak Power Tracking using the CubeSat EPS Peak Power Tracker • Mass = 80g • The 32 ADC channels on the board can be used to track the temperature, current • and voltage of all solar arrays, buses, and the batteries.
Testing and Precautions • The conversion efficiency of the BCRs can be tested by interfacing to a solar panel, USB connector or a 8V current limited power supply • Shorting the batteries to ground while they are connected to the EPS instantly fries the board • The charging source should be connected to the batteries only after closing the pull pin connection, else at least one BCR is damaged • Each battery pack is composed of 2 Lithium Ion cells. Batteries should be stored within a voltage rating of 6.4V to 7.6V at -4F to 68F and charged periodically to prevent permanent damage
Development Plans • Test the board and verify charging efficiencies • Familiarize with the board’s firmware to collect working data on performance of batteries, buses, and solar panels • Test over-current protection circuitry • Test EPS output under a variety of illumination conditions to ensure that worse case 3W output is achieved even under longest shadow conditions