ProUST – a “Guardian Angel” for Satellites - Protection Unit for Satellite Testing

A nightmare scenario during assembling and testing a satellite is that it could be damaged due to malfunction or operational error and lead to mission delay and exploding costs. This risk especially occurs at the power subsystem such as solar array interfaces or onboard battery.

Siemens’ Power Special Check-Out Equipment (SCOE) product line contains a proven dedicated safety system, which reacts within microseconds to any anomaly and shuts off power.

Due to rising power demand in spacecraft and related test equipment the protection unit was designated for an upgrade. It had to address several severe requirements at the same time: higher voltages, higher currents, more channels, more flexibility, smaller size (factor 10), and, of course, lower cost.

New features were added such as smart diagnostic capabilities for documentation and quick analysis of events (effectively a 60- channel scope).

The essential challenge to the engineers was stretching electronics to the limit without taking a risk in reliability and trustworthiness.

The investigative approach explored multiple technology trends:

• State-of-the-art platform FPGAs for complex custom digital logic, including a powerful microprocessor for embedded software:
• Isolated sigma-delta modulators for miniaturisation of analogue measurement
• Leading-edge Power-MOSFETs allow fast reaction and dense packing
• The technology mix comprises the best available reed and safety relays
• All devices get connected by sophisticated PCB technology capable to combine high currents with fine-pitch ICs

Efficient manufacturing and thorough testability can not be traded-off and were a focus of research.

Even the mechanical side needed innovative solutions.

Fit into a flat 19” “pizzabox” format, the power dissipation must correspond to a tailored thermal management. An additional constraint are the extreme vibrations during operation at the launchpad, which require a robust construction.

A milled aluminium base plate acting both as housing and heat sink, a steel cover with redundant radial fans mounted to it and a transparent front panel compose the rugged box, which is made of only a handful of ingeniously shaped parts.

One subtle detail tells the expert how extraordinary the result is: 138 independent voltage domains on a single PCB set a new record – far above any consumer electronics you can buy. A key customer initially assessed the product concept as a “dream”. In the follow-up project GPSCOE (Generic Power SCOE) in the frame of the ESA GSTP programme, this dream has become true.

Coordinator

Siemens Communication, Media and Technology, Space - Alfred Fuchs

Siemens Communication, Media and Technology, Space
Alfred Fuchs
Siemensstraße 90
A-1210 Vienna
Tel.: +43 (0)51707 - 34113
E-mail: alfred.fuchs@siemens.com
Web: www.siemens.at/space