Aggregated EMI Prediction in 2-150 kHz using Black Box Model of Power Converters

This work investigates the effects of frequencydependent grid impedance on the aggregated emission from
multiple converters in the 2-150 kHz frequency range. Fieldmeasured grid impedances, as well as normative reference
impedances used in the 2-150 kHz range, are considered. Indeed,
a suitable model based on a black box modelling approach is
proposed to predict emissions. Results show that the aggregated
emission from multiple converters is significantly influenced by
the grid-to-converter impedance ratio. Additionally, the
reference impedances used to represent the grid in the 2-150 kHz
range, such as IEC61000-4-7 and CISPR 16-1-2 artificial mains
networks (AMNs), are found to overestimate the grid voltage and
underestimate current compared to the actual grid impedance.
Furthermore, with an increasing number of converters connected
to the grid, only a fraction of the individual converter current
propagates to the grid. This dependence is determined by the
converter-to-grid impedance ratio, while the remaining current
circulates among the converters