EMC Filter Design Part 4: Differential Mode EMC Filter Design Down to Component Level

This video explains in detail how to design a differential mode filter and how to eliminate component values that violate our stability and other criterion. We will also teach how to use an Impedance Paper as a fantastic graphical tool to help us quickly calculate our components. For further information on Biricha's EMC filter design workshop please visit: www.biricha.com/emc
Please note: From 1:55 onwards, when Ali draws the impedance graph, the capacitance and inductance should decrease as frequency increases. However, all the printed impedance plots are correct.

[@BeesKneesBenjamin]

I wish my lecturers were even half as good in explaining than you are... This content is absolutely amazing

[@rajarshisarkar9767]

Simplicity is the beauty of understanding! Very nice Sir!

[@thunderbolt854]

Your explanation and this method for calculation is crystal clear having followed previous parts of the series. Thank you for putting such content out.

[@TheLordsForce]

Dude, FANTASTIC series!!!

[@ggppdk]

Very well explained, thanks, just a comment here (at the beginning of video) the plots of capacitors impedance is in reverse order It should be (left to right) 100nf, then 10nf, then 1nf. The capacitor with higher capacitance out of the 3 capacitors has 100nf aka it should have the smallest impedance graph, aka placed at leftmost. The printed graph at about 3:40 has it correct way

[@keerthithallam9678]

Hi sir, Thank you for the video. Could you please share the link for the impedance paper?

[@ivanmaksimovic9219]

dam this series is good, really helpful

[@melvinegberts2347]

really great content

[@kundurujanareddy449]

dear sir, thanks for this video. In my design 115V, 3Phase, 400Hz supply is used, In this MIL-CE101 Got failed at 1.2KHz onwards( It is Harmonics of the Fundamental Frequency) at the Amplitude of 10db more than the my limit line. I want one filter Circuit for getting passed my design, please suggest the Inductor and capacitor values.

[@ramagirikuna1586]

Thanku sir❤

[@mtomaschewski]

Why do we not learn this at the University? Amazing!

[@brucetouzel6484]

maybe you would learn this at a electronics trade school ?

[@sakismicro]

Great video!! Just how we define the cut off frequency to 7.5KHz on the differential? Should be the same with the common filter?

[@korkutkutaymetin1581]

Thanks for the video series but there is only one thing that ı do not understand. I am designing my own emc filter for my ac-dc power supply. I do not know Fcutoff and L-C. Can you help me please. (By the way my power supply works on 47to63 hz is that my Fcutoff ?)

[@deathblowhere]

Hey guys! Could you please re-upload the impedance paper? The provided link is not working any more.. Thanks! Phil.

[@sinavosouq8536]

مرسی استاد

[@TB-jl9fr]

Notice this for the first time, but are you at a german company?

[@sentient1640]

how did you determine that Z = sqrt(L/C) ?

[@Coolgiy67]

That is output impedance of a single stage lowpass filter

[@eunicechen1315]

X = 1/(jwC) , why is the function graph is linear, but not inverse proportion graph?

[@ricardoabreu4030]

Because it is a log scale graph.

[@TeacherBrunoOneil]

Is it okay if I ask some basic questions that are haunting me ? For instance, you’re using examples of high frequency cutout but I usually see this filter in switching mode power supply and the main usually uses 60 or 50 hz. But in one of your videos , you mentioned the need of the emi filters because of the harmonics and noises produced by the switching ( pwm and transistors ). You haven’t explained how you got the the cutout frequency. We usually know the frequency of the pwm ic used in the power supply, which are usually very high ones. I guess to answer the question of which cutoff frequency we should use has to do with the pwm ci ( that’s for filters in psu ) but I can’t come up with an answer on my own. I’m still studying circuit analysis. If I were designing an audio filter , it would be easy to set a cutoff frequency. But it’s for power supplies. Another point to consider is the amplitude of the signal. The capacitors working voltages discharging time does not influence on the filter ? I wonder. I see that you didn’t mention about the capacitor’s voltage but obvious if the line is 110vrms , the capacitor will have to be at least more than that. How much more ? I’ve seen 250v capacitors in psu.

[@jaydeepsejpal1427]

cutt off frequ. will b your switching freq, or max harmonic that you measure or which harmonic component you want to suppress.

[@TB-jl9fr]

@@jaydeepsejpal1427 Like for example you have to fullfill requirements of the 40th harmonics of your SMPS and your switching frequency ist about 100kHz. Then your cut-off frequency is the 40th harmonic of 100kHz. EMI filter surpress noise (aka surge currents and so on..) from the line (X-Components) but also noise from the switching supply itself (Y-Component).

[@jesusguerra7639]

Thank very much for this great videos. There is a small mistake when the impedance paper is drawn because the capacitance/inductance increases over the X axis (should decrease). Anyway, this is clear with the next impedance paper shown

[@Mrstev3]

big thanks for your video

[@homemade83]

it seems to be easy than usual 👏

[@stockdam]

Can you elaborate on the criteria used to decide on the filter cutoff frequency.

[@TeacherBrunoOneil]

I wonder the same. He said nothing about that.

[@xinpengyang-dz5rt]

Maybe 1/100-1/10 switching frequncy

[@enesog]

Why is Zo = sqrt(L/C) ?

[@ricardoabreu4030]

This also puzzles me. Zo = sqrt(L/C) is a well known result from transmission lines (where L and C stand for distributed inductance and capacitance), but I cannot find relation of this with a low passa filter.

[@tsaneesh]

How to calculate the cutoff frequency?

[@enesog]

LC-Filter has following impedance Z: Z = 0 + j*(wL - (1/(wC) ) The cutoff frequency occures when Real part {Re(Z)} = {Im(Z)} so {Re(Z)} = 0 and {Im(Z)} = wL - (1/(wC) than you have the Equation: 0 = wL - (1/(wC) wich leads to: w = 1/sqrt(LC) with: w = 2*pi*fc ----> fc = 1/(2*pi*sqrt(LC))

[@sakismicro]

@@enesog L anc C are the differential componets ? Correct?