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This paper addresses the problem of system stability of the NASA EOS satellite power system. A potential stability problem exists without a clear specification of the payload input impedance characteristic. Design guidelines are established for the control of the power system and the individual subcomponents to help insure stability with an unknown complex load. A testbed of the EOS power system is employed to verify the analysis.

Analyses and designs of a peak-power-tracking system using microprocessor control are performed. Large-signal stability and dynamics of the system for various modes of operation are analyzed based on qualitative graphical representations of DC load lines at various interfaces of the system. Small-signal stability around the equilibrium points is also analyzed. Predictions from the analyses are verified by experimental results.

The design of a solar array simulator for use in the NASA EOS power system testbed is presented. The simulator accurately simulates the complete DC and AC characteristics of a high voltage array over illumination and temperature. The simulator is suitable for testing both a DET and PPT power system.

The multi-module, multi-phase (MMMP) charger is compared to a single-module (SM) charger to identify potential performance improvements. The advantages of the MMMP charger are documented. This paper then details the design of the MMMP battery charger. The battery charger was developed as part of the NASA EOS Space Platform Testbed Project.

The hardware and software design of a Nickel-Hydrogen (Ni-H2) Battery Simulator (BS) with application to the NASA Earth Observation System (EOS) satellite is presented. The battery simulator is developed as a part of a complete testbed for the EOS satellite power system. The battery simulator involves both hardware and software components. The hardware component includes the capability of sourcing and sinking current at a constant programmable voltage. The software component includes the capability of monitoring the battery's Ampere-hours (Ah) and programming the battery voltage according to an empirical model of the nickel-hydrogen battery stored in a computer.