TRIO-CINEMA 1 UCB, 2/08/2010 ClydeSpace Electronic Power System Yashraj Khaitan Space Sciences Laboratory University of California, Berkeley

TRIO-CINEMA 2 UCB, 2/08/2010 ClydeSpace EPS Agenda AGENDA Requirements Overview Alternatives Features Testing

TRIO-CINEMA 3 UCB, 2/08/2010

TRIO-CINEMA 4 UCB, 2/08/2010 Overview 3 Battery Charge Regulators (BCRs) on 6 solar array sections Independent operation even without battery backup Maximum Power Point Tracking

TRIO-CINEMA 5 UCB, 2/08/2010 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

TRIO-CINEMA 6 UCB, 2/08/2010 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.

TRIO-CINEMA 7 UCB, 2/08/2010 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 -4  F to 68  F and charged periodically to prevent permanent damage

TRIO-CINEMA 8 UCB, 2/08/2010 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

TRIO-CINEMA 9 UCB, 2/08/2010 Thank you