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

This work investigates the effects of frequency dependent grid impedance on the aggregated emission from multiple converters in the 2-150 kHz frequency range. Field-measured 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.