Rasat Leo Satellite Power System Design and Operation

Abstract

This paper presents the power system design and operation of RASAT micro satellite. The design of the power system reflects the need for autonomous operation, independent of all other systems, and therefore should require no intervention from the ground station in the event of an anomaly arising on the spacecraft. Autonomy is obtained by having dual redundant and multiple systems. There is a dedicated Battery Charge Regulator (BCR) for each of the four body mounted solar arrays and two identical, cold redundant Power Conditioning Modules (PCMs) with autonomous switching to ensure that a regulated 5 V line is always available to the subsystems. The hardware is also designed to adapt to environmental changes. The most obvious example of this is the BCR 's ability to monitor the temperature of its respective solar panels and the battery. The BCR is able to estimate the Maximum Power Point of the solar panels using the array temperature as a parameter. The battery charge rate is also controlled by the BCR, which taper charges the battery once the End of Charge (EoC) voltage is reached. The battery temperature measurement is also required because of temperature dependence of the EoC voltage.