EMI Filter Design in SMPS

Thread Starter

mishra87

Joined Jan 17, 2016
645
Black box calculation for EMI filter design for AC to DC Converter in SMPS.
Please suggest me application note for step by step design calculation.
 

Janis59

Joined Aug 21, 2017
1,057
RE: <<There's no cookbook for EMI design. What EMI limits do you need to meet?>>

Second sentence, I think, has answer rather chrestomatic. American standarts, European standarts, and russian standarts are rather the same if not identical in this meaning. I have not convinced there are any standarts for this in China, but if they export anything to EU or US, it ought to comply too. So the answer is rather trivial.

Now about first sentence, being not very much accurate, as the plethora of different detalisation articles been published and are available at herr majesty internet. At least my collection on this topic counts near hundred different methodics (partially conflicting between each other :).

So, the first question must be done is do those is 1-phase or 3-phase system. Other question must be done how large capacitance must be observed by serviced machinery differential mode noise and how much of sinphase mode noise. Then, pardon for brutality, must be examined, how physically far the system will work off the grid understation and who may claim on You if the standard will be passed rather poor.

Then my experience with all this sh*. You may calculate how much You want, but anyway the system sizing will be determined by components You really are able to purchase. The circuitry itself one may find in zillion places at Google, it has no variations, generally. But the nominals.... there You CANT do too much, but is damn easy to do too poor. Just experiment with those result of the work, measure it.
My understanding says that in second stage You MAY use even the slow electrotechnical steel core, but in first stage even the most fastest powder ferrite cores will be just just but below the hopes. So use the best You may find, as the noise is really going up to many tens if not hundreds of MHz.
The usual complication is that network voltages You work is 538 Volts (when net is 380V), so the 600V capacitors are just on the edge, so they need to have an appropriate temperature marking, and appropriate reactive power class to not explode.

But You may create it how good You want, anyway the result will be at least 2 to 3 fold worser as calculations shows. :)
 
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Thread Starter

mishra87

Joined Jan 17, 2016
645
Thank you all for your response.

Pls. find below limit as per CISPER-22
upload_2018-5-16_18-34-9.png


Now how do we calculate EMI filter value to meet the standard !!!

Cx1=??
Cx2=??
Cy1=??
Cy2=??
Comon mode choke = ??

My intention is to have black box calculation before component testing.
As a beginner how one can understand EMC ????
 

Thread Starter

mishra87

Joined Jan 17, 2016
645
RE: <<There's no cookbook for EMI design. What EMI limits do you need to meet?>>

Second sentence, I think, has answer rather chrestomatic. American standarts, European standarts, and russian standarts are rather the same if not identical in this meaning. I have not convinced there are any standarts for this in China, but if they export anything to EU or US, it ought to comply too. So the answer is rather trivial.

Now about first sentence, being not very much accurate, as the plethora of different detalisation articles been published and are available at herr majesty internet. At least my collection on this topic counts near hundred different methodics (partially conflicting between each other :).

So, the first question must be done is do those is 1-phase or 3-phase system. Other question must be done how large capacitance must be observed by serviced machinery differential mode noise and how much of sinphase mode noise. Then, pardon for brutality, must be examined, how physically far the system will work off the grid understation and who may claim on You if the standard will be passed rather poor.

Then my experience with all this sh*. You may calculate how much You want, but anyway the system sizing will be determined by components You really are able to purchase. The circuitry itself one may find in zillion places at Google, it has no variations, generally. But the nominals.... there You CANT do too much, but is damn easy to do too poor. Just experiment with those result of the work, measure it.
My understanding says that in second stage You MAY use even the slow electrotechnical steel core, but in first stage even the most fastest powder ferrite cores will be just just but below the hopes. So use the best You may find, as the noise is really going up to many tens if not hundreds of MHz.
The usual complication is that network voltages You work is 538 Volts, so the 600V capacitors are just on the edge, so they need to have an appropriate temperature marking, and appropriate reactive power class no not explode.

But You may create it how good You want, anyway the result will be at least 2 to 3 fold worser as calculations shows. :)
Thank you so much for your reply !!

could you share me some application note on EMI design .
 

Thread Starter

mishra87

Joined Jan 17, 2016
645
Thank you so much for your response !!!

I am only interested in single phase SMPS design. !!!

Janis59 !!!
That is what I wanted. There is step by step procedure which one can easily understand.

Atleast I will be having now basic understanding of EMI design.

My intention to write post to this group is I will get more comments with multiple people but nowadays only a few active member who reply the quaries.
 

Thread Starter

mishra87

Joined Jan 17, 2016
645
After reading lots of paper on EMI Filter design I am still unable to design EMI Filter.
Could anybody in the group explain me a bit more theoretically.

Let's take a example.

Input -

Vin= 90-265VAC
Pout= 6W
Fsw= 150KHz
Efficiency = 80%
Std = CISPR 22

Now could anybody explain me how to design EMI(pie) filter for this to attenuate CM and DM noise.

A step by step procedure would be appriciated.

Thanks to all !!!
 

Thread Starter

mishra87

Joined Jan 17, 2016
645
Further to post no #9

Specifications are given.
Could anyone explain me a bit about -
1. How to calculate corner frequency for CM and DM noise if CISPR 22 say frequency range is 150 KHz to 30 MHz for CE and is that the same filter used for RE.
2. How to calculate Lcm(common mode) and Ldm(differential mode) choke
3. How to calculate X and Y capacitor.

Thanks !!!
 
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