Low Earth Orbit Nano Satellite Electrical Power System Design

The following text shows the requirements for LEO satellite’s EPS design, namely the initial mission assessment, the available power budget, the filtering components sizing, the finalized circuit design and the expected efficiency for optimal operation point. One early assessment was the reliability of the photovoltaic array system in terms of how the cells should be laid out: whether in parallel, series, or hybrid assembly. Once the source voltage at maximum solar exposure was determined, voltage converters were chosen considering each desired rail voltage. Care was taken for the implementation of Li-ion batteries, choosing to place a buck regulator at their input, to guarantee that they were never exposed to disruptive voltages. Afterwards, each of the system’s components was chosen from existing online catalogues, taking into account efficiency, cost and size, in that order. Lastly, efficiency assessment of the system was done, not only to have a good idea of how the system will perform, but mostly because one of the initial design steps in switched regulators is setting a target minimum efficiency, and one must make sure this initial value was not overshot.