I am trying to make a voltage generator. I used an inverter and it is controlled by a PWM signal. I used a LCL filter to filter the output signal since it is rich in harmonics but in the choice inductance I found a problem, it is necessary that this inductance is of value 3.9 mH, supports a current of 3A and only 2 pins, the problem is that all the inductances that I find them with 4 pins my question is there a problem for me if I use this type of inductor and in the common mode branch are there any undesirable effects on the current or the characteristics of the inductor?

inductance datasheet:https://eu.mouser.com/datasheet/2/400/b82725s2-1527604.pdf enter image description here

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here is the electrical schema: here is the simulation:

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    \$\begingroup\$ You forgot to link to the inductor data sheet. Not all 3.9 mH inductors are equal and it's likely that those that you chose are not suitable for common terminal configurations because there cores will heavily saturate. \$\endgroup\$ – Andy aka May 14 at 12:11
  • \$\begingroup\$ inductance datasheet:eu.mouser.com/datasheet/2/400/b82725s2-1527604.pdf \$\endgroup\$ – odd May 14 at 12:22
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    \$\begingroup\$ That's a common mode choke you are using in a differential mode fashion. It will saturate immediately. Also, it's unknown what you are trying to filter out in the first place. Try it with a similator first. What does your PWM circuit look like? \$\endgroup\$ – winny May 14 at 12:24
  • \$\begingroup\$ here I am changing my question \$\endgroup\$ – odd May 14 at 13:19

As Andy aka and winny have pointed out using common mode chokes in this application is not suitable.

As common mode chokes are used normally the core material needs to handle only the difference of magentic fields created by current going one way in the upper coil and the other way in the lower coil. Only if this current difference (may be some 10mA) is too large the core material will be saturated.

I.e. even if the common mode choke is rated for 3 A, it will be almost useless if too much current (some 10mA; much less than 3A) is going the same direction through both sub-coils (or only through one of them).

  • \$\begingroup\$ so what is the type of inductor that should be used in this situation? \$\endgroup\$ – odd May 14 at 13:49
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    \$\begingroup\$ If you pick one that has only 2 (instead of 4) terminals you can be sure that it is not a common mode choke; and of course it needs to be rated for the current and frequency in your application. It might be quite large and expensive... \$\endgroup\$ – Curd May 14 at 13:52
  • \$\begingroup\$ I can not find one that has only 2 with a value of 3.9 mH. \$\endgroup\$ – odd May 14 at 14:17
  • \$\begingroup\$ Maybe you find some inductors originally made for audio applications, that are suitable for your purpose. That's what I've found: falconacoustics.co.uk/… \$\endgroup\$ – Curd May 14 at 14:36

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