M. Hartmann, H. Ertl, J.W. Kolar:
"EMI Filter Design for High Switching Frequency Three-Phase/Level PWM Rectifier Systems";
Talk: Twenty-Fifth Annual IEEE Applied Power Electronics Conference and Exposition, Palm Springs, CA, USA; 02-21-2010 - 02-25-2010; in: "Proceedings of Applied Power Conference and Exposition", (2010), ISBN: 978-1-4244-4782-4; 8 pages.

The actual attenuation characteristic of EMI filters in
practice often differs from theoretical predictions and minor changes
could result in a significant performance improvement. Whereas
the performance of the differential-mode (DM) filter stage usually
can be well predicted, the common-mode (CM) behavior is more
difficult to handle. This is especially true for three-phase PWM
rectifier systems, which show a large high-frequency CM voltage
at the rectifier output. In this work the possible CM noise current
paths of a three-phase/level PWM rectifier are analyzed where
parasitic capacitances to the heat sink and to earth are considered.
Additionally, a concept to significantly reduce CM emissions is
discussed in detail. Based on the proposed models an EMI filter
design for a system with 1MHz switching frequency is shown.
Experimental verification of the designed EMI filter is presented
by impedance and conducted emission (CE) measurements taken
from a 10 kW hardware prototype. Several practical aspects of filter
realization like component arrangement, shielding layers, magnetic
coupling etc. are discussed and verified by measurements.

http://publik.tuwien.ac.at/files/PubDat_186993.pdf