Development of spacecraft solar array electrical performance simulation system

Abstract

The spacecraft electrical power system (EPS) employs photovoltaic array (PVA) to supply power to platform and user loads. Thus, it is important to predict power production capability of PVA for spacecraft mission planning and certification of on-orbit flight operating. The PVA performance is primarily determined by irradiation level, temperature, and solar array shadowing. To provide an accurate and flexible method for analyzing spacecraft PVA performance, the author developed spacecraft Solar Array Electrical Performance Simulation system (SAEPS). The SAEPS was consisted of 5 modules: simulation setting module, orbit mechanics module, geometric model control module, shadow analysis module, power supply capability analysis module. The current vs. voltage (I-V) model of photovoltaic (PV) cell under on-orbit irradiation intensity, temperature and shadow was built. The model of PV string, which is composed of PV cells, bypass diodes and block diodes, is built. Output current of PVA is obtained by summing all strings output currents at predefined bus voltage. Simulation was performed for a typical spacecraft in this paper. Results show this method is applicable to arbitrary illumination levels, temperatures and shadow patterns, and accuracy improved 20% compared to traditional method.