Power System Design and Performance for Low Earth Orbit Spacecraft

On the September 26, 2016, Algeria's enhanced micro-satellite Alsat-1B was launched into a 680-km low Earth orbit onboard a PSLV-C35 rocket from Sriharikota near the metropolis of Chennai (South India). The spacecraft was designed, manufactured, and launched as an 18-month long technology transfer program between the Algerian Space Agency (ASAL), Algeria and Surrey Satellite Technology Limited (SSTL), U.K. This article describes the design and in-orbit performance of the power system and the design of the Alsat-1B high-efficiency solar power system used to charge AEA Battery System Ltd and Société des Accumulateurs Fixes et de Traction Lithium-ion batteries. The solar power system described in this article is deployed on many satellites including Alsat-1b, which was launched from a heritage SSTL power system. It was implemented with a conventional pulsewidth modulator (PWM) duty cycle ratio control method to design and build a solar battery charger. Maximum power point tracking (MPPT) was used to maximize the output power, irrespective of the temperature of the solar arrays and irradiation conditions. The simulation results achieved by using Orcad/Pspice programs are in good agreement with the experimental results. These results demonstrate the reliability and validity of the implemented MPPT technique. The battery charger prototype was tested and the results obtained provided conclusions on the conditions of permanent control on the battery charger.