Influence of the bus regulation on telecommunication spacecraft power system and distribution

The power systems and the electrical distribution of geosynchronous telecommunication spacecraft are evaluated through 13 examples. Results show that the reduction of the bus voltage range is a determinant factor to improve the electrical and mass performances of the power system. For actual power levels, improvements = 25% for solar array mass and 7.6% for the complete power system mass, while the electrical efficiency increases by 13.8% in sunlight and 12.7% in eclipse. A 50 V regulated bus provides 6.76% efficiency improvement, considering only switching components, distribution constitutes 7%. For converter mass, analysis shows that the bulky components of pulse width modulation units are affected by an increase of 70% to 110% depending on sampling frequency when the input voltage is submitted to a variation from 26.5 to 42.5 V. Absence of regulation of the distributed voltage implies an oversizing of the solar array of 25%, to avoid lock up conditions.