coupled inductors together application

Dear All
Hi
Thank you for your time .
I know about coupled inductors ( two inductor in a core ) ( my mean isn't transformer i'm very familiar with transformers .)
But i was wondering , what will be the application of two inductor in a core ( my mean isn't differential inductors )
Thanks in advance
Goldsmith ;-)

Do you mean common mode chokes.

Common-mode choke coils are useful in a wide range of prevention
of electromagnetic interference (EMI) and radio frequency interference (RFI)
from power supply lines and for prevention of malfunctioning of electronic equipment.
They pass differential currents (equal but opposite), while blocking common-mode currents.

Common Mode Choke Theory for our Custom Built Coils
**broken link removed**

Dear KaK
Hi
Thank you very much for your reply . but as i mentioned , i'm not referring to the differential coils ( to remove EMI ) ( i'm familiar with them ) but my mean , is : if we wind some coils on one core ( in mode that is not common mode ) where will be the application ? ( i have read this things in circuit books , but i couldn't find any application for that until now )
If you guide me , i'll be happy and grateful .
Best Regards
Goldsmith

---------- Post added at 13:00 ---------- Previous post was at 12:56 ----------

By the way , about page :**broken link removed** what is that nylon that wounded around the inductor ? is that mylar ?
Thanks again
Goldsmith

my mean isn't transformer

Click to expand...

Generally speaking, transformers are coupled inductors, too. It's the coupling coefficient respectively ratio of main to leakage inductance and different core material that distinguishes different "coupled inductor" flavours.

Two inductors in a core most likely have coupling coefficients > 0.7 and surely show some transformer properties.

goldsmith said:

Dear All HiThank you for your time .I know about coupled inductors ( two inductor in a core ) ( my mean isn't transformer i'm very familiar with transformers .) But i was wondering , what will be the application of two inductor in a core ( my mean isn't differential inductors ) Thanks in advance Goldsmith ;-)

Click to expand...

Any time you have more than one coil on an inductor, you have a transformer. They may be used differently then a standard AC transformer, but they still perform transformer functions. Some applications that use the transformer inductance as part of the circuit function are flyback transformers and coupled inductor converters such as Sepic and Cuk.

Dear" FvM and dear crutschow "
Thank you for your replies . but as i know at transformer we gave a voltage across the primary and we will get this voltage across the secondary , but at coupled inductor , both of inductors can have currents , ( however with different frequencies ) and we will have inductive effect ( from each other together ) . am i right ?
In the other hand , if we can consider those are transformers too , why we can't see the same relations for them ? ( why we can't use from equations of transformers for them ?) ( my mean is i didn't see at some textbooks that i have seen , they used from the equations of transformer for coupled coils , or perhaps my text books aren't correct ? ) now i'm a bit confused , if you clarify me , i'll be happy and grateful .
Thanks in advance
Goldsmith

This component is not transformer, still has two or more coils in a core.

http://en.wikipedia.org/wiki/Magnetic_amplifier

Magnetic Amplifiers principles and applications
free E-book 110 pages
http://www.tubebooks.org/Books/mag_amp.pdf

Magnetic amplifier in switching power supply
http://www.ti.com/lit/ml/slup129/slup129.pdf

All coupled inductor coils will exhibit transformer coupling between the coils. That's why they are call "coupled". Any current change is one coil, as caused by a voltage across that coil, will be reflected by a voltage in the other coil(s) proportional to the relative turns ratios.

The difference in the equations is that coupled coils use the inductance of the coil as part of the circuit operation. In standard AC transformers the inductance is only used to determine the value of the magnetizing current, and does not enter into the normal transformer equations otherwise.