FreeLists / si-list / [SI-LIST] Conducted Emissions and SMPSs help needed

[Erin.McPhalen@xxxxxxxxxxxxxxxxxxxxxxxxx]

Hi
Wondering if any of the Guru's out their might be able to provide some 
advice on how to proceed on a problem I am having with a switch mode power 
supply.

The power supply is a 3 Phase supply (L1,L2,L3,N, Gnd) operates from 
90Volts to 300 Volts AC.   Currently, it has a very low margin at 200 kHz 
for CISPR 22 Class B conducted levels.   The mains filter consists of 5 mH 
inductors and the standard capacitor values for L-GND and phase to phase 
(4n7 and 47n respectively).   All my efforts have reduced  everything over 
400 kHz considerably but has not budged the two spikes at 200 kHz and 300 
kHz.  Using a splitter(0deg and 180deg) and two LISNs, the source of the 
conducted emissions is common mode.

Any ideas on how to reduce this low frequency conducted emissions would be 
greatly appreciated.

Erin



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