Abstract
This work reports a modeling methodology for the prediction of conducted emissions (CE) in a wide frequency range (up to 100 MHz), which are generated by dc/dc converters and propagate along the power buses of satellites. In particular, the dc/dc converter seen as a source of CE is represented by a behavioral model, whose parameters can be identified by two unit-level experimental procedures performed in controlled test setups. A simplified multiconductor transmission-line (MTL) model is developed to account for the propagation of CE in shielded bundles of twisted-wire pairs used as power cables. The whole power system is represented by the interconnection of the circuit models of dc/dc converters, cables, and Power Conditioning and Distribution Unit (PCDU). By solving the obtained network, frequency spectra of CE can be predicted. Experimental results are reported to substantiate the accuracy of the proposed unit-level dc/dc converter model and the MTL model of cables. Finally, a system-level test setup composed of three dc/dc converters connected to a PCDU is considered, and predicted CE are compared versus experimental measurements.
Highlights
Among several requirements for the verification of Electromagnetic Compatibility (EMC) in the Space sector, those concerning conducted emissions (CE) are aimed at enforcing strict limits to radiofrequency currents flowing in dc power buses in a wide frequency range extending up to 100 MHz [1]
This paper presents a new modeling methodology for the prediction of CE in spacecraft power systems which is more general than [7] since it involves an admittance-matrix representation of the dc/dc converter passive model, and it accounts for the propagation of CE along the power buses
EMC is an important technical field in Space engineering, pursuing the prevention of risks associated with electromagnetic emission or susceptibility, which may lead a mission to failure
Summary
Among several requirements for the verification of Electromagnetic Compatibility (EMC) in the Space sector, those concerning conducted emissions (CE) are aimed at enforcing strict limits to radiofrequency currents flowing in dc power buses in a wide frequency range extending up to 100 MHz [1]. Model parameters have to be inferred by suitable measurements performed at unit level, namely, in a controlled test setup involving only the operation of the dc/dc converter under analysis and leaving any other component of the satellite power bus out of consideration. Where R0 = 50 Ω is the standard S-parameter reference resistance and 12 is the 2 × 2 unit matrix This measurement method was found to be quite accurate, and interpretation of the obtained results for a number of dc/dc converters showed an input admittance dominated by the frequency response of the integrated electromagnetic-interference (EMI) input filter (composed of inductors and capacitors). The average error is mostly lower than 6 dB, which is adequate for practical aims of designers involved in EMC analyses (e.g., estimation of interference levels and definition of EMC requirements for subsystems)
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