Modular MRU (main bus regulator unit) for application in geo telecommunication satellites

This paper describes the architecture and the performances of a Main Bus Regulator Unit (MRU) specifically conceived for application in GEO telecommunication satellites three-axis stabilised. The design of the unit is driven by the need to optimise the performances w.r.t. the cost figure. The cost minimisation is the most important design parameter when it is addressed to a commercial market like the telecommunication satellites one. In order to get easy adaptability to the Spacecraft (S/C) payloads and eclipse power requirements, the MRU is based on a modular design with the goal to minimise the overall mass, power dissipation, Assembly Integration and Test (AIT) activities time and to have high reliability an autonomy in-orbit. According to the above features and also to electrical and mechanical performances, specific power regulation and control modules have been designed and developed. The performances of each type of module and of a 3KW MRU Engineering Qualification Model (EQM) (presently under qualification for SICRAL programme) are presented in detail.