A generic, customizable, fault tolerant load protection system for Small Satellites

Small Satellites having modular system design can be best modified to suit different mission profiles and scientific objectives. This paper describes the design and functioning of the Load Protection System developed in the Electronic Power System (EPS) of Swayam Satellite, which is a 1-U class picosatellite. The Load Protection (LP) system serves multiple functionalities in the EPS and hence is the heart of the analog intelligence of the EPS. It fits into the system constraints of space, size and mass implicit to any 1-U cubesatellite. The LP system has been optimized, tested and tailor made for catering to the power demands of individual modules of the satellite. The system handles all possible voltage and current contingencies that may arise during the course of operation of the satellite and has a built in triple redundant mechanism for taking corrective actions. A specially designed logical interface has been introduced to grant the On-Board Computer (OC) and the Terminal Node Controller (TNC) a central control in selectively switching the electronic modules of the satellite. Each module has been characterized for their current and voltage profiles and the power limits have been set accordingly. Satellites in the Low Earth Orbit (LEO) frequently suffer from Single Event Latchups (SEL), and radiation hardened electronics can prove to be prohibitively expensive for small mission profiles. Power cycling can be an effective and viable option for damage control and recovery of the modules from SELs. The LP System efficiently resolves such SELs and offers a low cost, multi-functional design for an EPS. Information regarding the recurring faults gets logged into the Health Monitoring Data of the satellite, so that future missions can be designed accordingly by considering these factors. The LP System in the EPS of Swayam Satellite is a generic platform for developing an intelligent, analog fault correction scheme with appropriate redundancies that cater to small sate- lite mission profiles.