Methodology for PPU
Each of the two partners TAS-B and ASP will develop LEO power processing units. For the PPUs a strong use of COTS components is foreseen. PPU designs from previous projects will be continued to be further optimized (mainly for cost) and interfaces will be harmonized among the different system units. Also, a transfer of functions from real electronic parts into the firmware of digital control elements reusing already existing resources in the controller circuits shall be considered, leading to a further reduction of parts.
In these designs, measures are implemented to avoid tuning steps and rather to set programmable parameters. Also, the PPU level testing shall be simplified by avoiding non-testable hidden functions as easily exist in software failure handling branches for rare conditions. Finally, qualification units are built or made available and tested to reach TRL 6.
Each of the two partners TAS-B and ASP will develop LEO power processing units. For the PPUs a strong use of COTS components is foreseen. PPU designs from previous projects will be continued to be further optimized (mainly for cost) and interfaces will be harmonized among the different system units. Also, a transfer of functions from real electronic parts into the firmware of digital control...
LEO Power Processing Units
ASP directly implements the flight representative design and builds an EQM for qualification representative of the flight units. Accordingly, for this strategy, flight representative parts have to be procured for all line items.
In case of COTS parts (as planned) this usually includes the batch testing of critical line items, and may be time-consuming and significant in effort. The advantage of this strategy is, that directly after EQM qualification, flight units can be manufactured and delivered to final customers, allowing a rapid market entry.
The Design of the PPU will be directly optimized for high production rates, implementing techniques like SMT component and planar transformers.
TAS-B proposes a coupling test with a PPU EM tested to TRL 6 as output of the H2020 project.
In order to provide confidence to the potential customer and secure the development, it’s important to perform as quickly as possible the coupling test of a fit form and function representative PPU with the thruster. Manufacturing a PPU EQM instead of a PPU EM would bring longer delay due to the manufacturing and inspection processes required for EQM. Furthermore, the electrical test and the potential investigations and reworks are quicker to implement on EM than on EQM.
From previous experiences, TAS-B is convinced that early coupling test with PPU EM are more valuable. In the frame of PPU Mk3 development, the formal coupling tests performed with PPU EQM have fully confirmed the previous coupling tests performed with PPU Mk3 DM which was fully fit form and function representative.
