Demystifying differential and common mode currents

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Johannes Illenberger, Bernd Deutschmann
TU Graz

Poster-Abstract

For a systematic filter design for filters in supply lines (for both mains voltage and DC voltage), it can be very helpful to be able to distinguish and quantify the components of differential mode and common mode voltage and/or current. When performing measurements for conducted emissions most of the CISPR 16-1-2 line impedance simulation networks (LISN) for AC mains voltages do not provide 2 outputs for simultaneous measurement of the noise (EMI interference) voltage on phase and neutral. An alternative measurement method is shown, the results compared and application examples presented.