Satellite Electrical Power Subsystem for Direct-Drive Electrical Propulsion

The interest for the electric propulsion for space applications has been growing more and more over the years. Each manufacturer competes to improve the efficiency and to reduce the mass and the size of its Power Processing Units (PPU). In parallel, new missions require more and more power for the electric propulsion. To answer this quest for efficiency, power, reduced mass and reduced size and to maintain Europe as a leading power in electric propulsion for spacecraft, the European Direct-Drive Architecture (EDDA) project was initiated. The objective was to apply the principle of direct-drive to a spacecraft power architecture to improve the electric propulsion by directly connecting the solar arrays to the thrusters, without any power conversion. New power architectures were defined and analyzed, and a full demonstrator was manufactured and tested to validate the concept [1]. This paper presents the resulting Power Conditioning Unit and its performances. What is the impact of the thruster current oscillations on the main power bus quality ? Is the concept compatible with multiple types of thrusters ? Is it possible to drive multiple thrusters in parallel ? Are the architectures compatible with wide load transients ? What is the impact of the tracking of the Maximum Power Point (MPP) on the bus quality for other users ? The results presented in this paper and obtained by testing various configurations will drive the definition of the next-gen space equipment for the electric propulsion, compatible with direct-drive.