The paper introduces a straightforward procedure for estimating the electrical parameters of a simple, but reasonably accurate, two-branches model of a supercapacitor (SC). The equivalent electrical circuit model includes the voltage and frequency dependence on the SC's capacitance, neglecting the selfdischarge phenomenon, so it is mainly devoted to short and mid-term simulations suitable for most industrial applications. The estimation procedure of the electrical parameters starts by analysing the experimental data achieved by a common constant-current discharge test. Such data are used to build a fitting function which is compared with the analytical solution and numerical approximations for the SC's voltage evolution. Thus, initial estimated values of the electrical parameters are obtained through simple relations and are optimised by implementing the least squares method. The procedure is validated after an easy and fast extraction of the optimal parameters of the two-branches model of an SC. Several tests involving a commercial SC have been carried out in Simulink and the results have been compared against experimental data. A good accuracy of the two-branches model in a wide range of constant-current charging/discharging cycles is reported.
This paper describes a novel methodology to improve the preliminary design and efficiency analysis of the satellite’s electrical power subsystem. Several studies have addressed this issue by proposing a solar array sizing method based on the use of fixed efficiency paths during sunlight and eclipse periods. Indeed, these studies restrict the use of the battery for eclipse periods, and thus the solar array is sized to support the peak power loads on its own. To the authors’ knowledge, no one has so far deeply and jointly analyzed the influence of the power profile demand, the use of the battery during sunlight periods, and the architecture on the efficiency paths to size the electrical power subsystem. This work offers a methodology that takes into account these variables to better estimate the global efficiency of the electrical power subsystem and, consequently, to refine the first design iterations of a satellite. This methodology is particularized for the most common architectures based on power and voltage bus regulation, although it can be implemented in more complex architectures. A case study involving a real space mission, the UPMSat-2 (a 50 kg satellite launched in September 2020), is conducted to test this methodology.
This paper presents a new, accurate, and fast methodology, remote sensing satellites coverage analysis (RSS-CA), for determining 6 the coverage area of Earth observation satellites in concurrent design facilities (CDFs) devoted to space mission analysis. The Earth observation 7 areas of interest are discretized by grid points and the coverage surface is computed from the intersection between the grid and the satellite 8 viewing geometry. This geometry is modeled for off-nadir pointing conical and rectangular field of view (FOV) sensors and considering a 9 perfectly spherical Earth. To test the RSS-CA methodology the MARTINLARA mission analysis was selected as a case study. This mission 10 analysis was carried out at the CDF of the Instituto de Microgravedad "Ignacio Da Riva" (IDR/UPM Institute). The results were compared 11 to the ones obtained with the well-known AGI System Tool Kit (STK) software. The high accuracy of the results shows that the developed 12 methodology (RSS-CA) can simply and effectively be applied in CDFs designed for space mission analysis, representing the possibility of a 13 more open and user-friendly environment in relation to other commercial tools.
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