In-orbit performance of Lockheed Martin's Electrical Power Subsystem for A2100 communication satellites

Abstract

This paper describes, in detail, the Electrical Power Subsystem (EPS) for Lockheed Martin's A2100 family of satellites, its evolutionary technology advancement, and its performance based on twelve spacecraft presently in orbit, four ready for launch, and at least six in production. The rapidly growing telecommunications satellite market prompted the development of the A2100 series of satellites, beginning in 1992 at (then) General Electric Astro facilities in East Windsor, New Jersey. Development continued through acquisition by Martin Marietta and Lockheed Martin, culminating in procurement of the first A2100 satellite by GE Americom, and its successful launch in September, 1996. Initial development focused on three satellite classes (A2100-A, B and C) supporting payload power levels of 1500 to 5000 watts. The demand for more powerful satellite to increase the revenue-to-launch cost ratio resulted in stretching the A2100-A to A2100-AX, capable of accommodating payload power levels up to 12000 watts. The EPS, which represented 25 to 30 % of the satellite bus mass and cost, was a significant area of emphasis in A2100 initial development and enhancement. This modular EPS features a tightly regulated 70 volt dc power bus and includes a high-efficiency Power Regulation Unit (PRU), 4 to 10 panel dual wing solar arrays based on a variety of solar cells from standard Silicon to multijunction Gallium-Arsenide, Nickel Hydrogen batteries of various cell string lengths and capacities, fused power distribution, and EPS management software (which makes the EPS operation and battery state of charge management autonomous without the need for ground intervention). The A2100 EPS, as a part of the overall A2100 system, continues to evolve, to take advantage of on-going advances in battery, solar cell and power electronics, providing enhancements that will permit more customer value in future satellites.