Comprehensive design and control methodology for DC-powered satellite electrical subsystem based on PV and battery

The design of electrical power subsystem of a satellite is challenging since it involves many components and depends on multiple parameters including mission duration, satellite orbit, eclipse times and etc. In contrast to the existing mission specific designs, we propose a generalized and comprehensive method to design and size key EPS elements: PV array and battery, which are integral for mission success. For battery, the proposed design incorporates battery cell characteristics, round trip efficiency, degradation, eclipse load profile and operating modes. The proposed design of PV array takes into account orbit inclination and altitude. In addition, structure and geometry of PV array are also considered and used for irradiance forecasting. Reliability, power margins and power fraction for summer solstice are also factored in the design. For the planning and development of operational strategy, parameter limits are determined for depth of discharge, initial state-of-charge, final state-of-charge and end-of-charge voltage of the battery. The controller design is also presented for the EPS. The effectiveness of the proposed design methodology is verified by a case study of Mysat-1, an imaging nanosatellite developed and launched by Khalifa University.