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EMI filter for Conducted Emission

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bharathi_dasan

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power line emi filters design

can anyone suggest me how to design EMI filter for CE?... i already tried with inductive filter (input is 3phase 5wire system).. i cud see the improvement but still it fails to meet standard... so pls can u peeps suggest how to go with L-C filter?... i am new to this design area so help out pls.... the problematic areas are 150kHz to 1MHz and 2 to 4MHz....
 

wichayen

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common mode choke conducted emissions

I don't understand your question.
Are you designing only EMI filter ? or You are designing AC power line filter circuit.
 

bkr eddy

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conducted emission filter

you can try one filter for each line and also different values of filters.
 

bharathi_dasan

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conducted emission emi filter

yes i am designing emi filter only...
 

george1

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filtering conducted emission

Are u designing SMPS?
 

fguihot

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filter conducted emission

Hi !!!

You said your input are 3 phases 5 wires. It's a star configuration, with neutral and shielding.
First, you should try a LC star filter. I mean, a L on each phase, and a C between phase and neutral.
If your 3 phases are not exactly balanced, there should be a return current in the neutral wire, which is not filtered by the LC filters. If you can, you should use a triangle configuration...
There could be also a return current in the ground. Since you try to eliminate the conducted Emission, you should try to connect the shielding at only one end, the one of lowest impedance. If you fear common mode voltage, you could connect the other end with a impedance (R, or LC...)
This kind of problem is quite difficult to solve, it depend on the connections. You should try several configuration.... Good luck!!!
Hope it will help you !!!
 

som_raparty

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hi
you can try using combination of differential filters and common mode filters
just try putting diferential filtrs on all the three lines and neutral
common mode choke on each line with neutral
you can laso try by adding come capacitors after differential chokes
if you need in detail abt selection of common mode and differential
can mail me

bye
somanadh
 

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