S3R Stability Margins and Design Guidelines
Christophe Delepaut · 1977
Since its introduction in the seventies, the S3R (Sequential Switching Shunt Regulator) concept for regulated bus has been successfully applied on many spacecraft. A number of publications have been dedicated to it leaving however open the issue of the stability margins. The present paper is dedicated to these features. It is shown that the sizing of the S3R commutation thresholds as originally proposed provides a phase margin of about 60° and a gain margin above 10 dB. The stability analysis also encompasses the possible resonance between the SA parasitic capacitance and the harness inductance, and highlights the additional sizing provision to be made to make it fully sustainable. Accordingly, exhaustive guidelines for S3R design are provided.