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I really need your help on this. I am designing an inductor which is rated for 50 A and 350 Vrms for 85 kHz. I want to get 3 inductance value from one inductor so I decided to tap between the points or to use switch to get the required inductance.

I just want to know if my assumptions are right.

I considered ETD 59 core. Let's say I make 5 turns to get 14 uH and solder both the ends to the bobbin pin (lets consider pin 1 to 2). Again I make 3 turns on the second layer (I start from the side where 1st layer winding ends) I solder both the sides (pin 3 to 4).

Now, if I connect between:

  • 1 and 2 I am supposed to get 14 uH (5 turns).
  • 3 and 4 I am supposed to get 5 uH (3 turns).

If I short 2 and 3 and measure between 1 and 4 I am suppose to get 36 uH (8 turns) which makes it in series, I just calculated using ferroxcube tool for respective turns and assumed it would give the same.

Here my questions are:

  1. Can I use switches and jumpers between the windings as I said and get the mentioned inductance value?
  2. If there is a space on the first layer after making 5 turns, can I start with the same layer to make 3 turns? Does mutual inductance come into play in this case?
  3. If it's right which way is better to do either making 3 turns in 2nd layer or in the same layer?

PS: Here I am doing tunable network where I am reducing the total size of the circuit by doing 3 inductance value in a single inductor.

I would really appreciate if anyone can tell me what to do with this. I can give you more information on this if you need it. Thank you in advance. Waiting for your valuable answers.

winny
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Manjesh Gowda
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    Link to the data sheet of the core set and material and state what gap you are considering and how you calculated that gap to arrive at an \$A_L\$ of 0.56 uH. Link to the ferroxcube tool too. I think you will be running too close into saturation to make this an effective design. – Andy aka Dec 01 '20 at 16:05
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    Hello, datasheet http://ferroxcube.home.pl/prod/assets/etd59.pdf I did wrong in ferrox cube tool.. it was supposed to be 25uH max from ETD 59. I just wanted to know if my method works which is getting 3 values from one inductor.. And also which core would you recommend for the given specification? lets say I want to get Maximum of 20uH and min of 8uH or 4uH..I do not want to loose any inductance at 40A...Please recommend me any cores which is from ferroxcube or TDK – Manjesh Gowda Dec 01 '20 at 19:47
  • This isn't a product recommendation site - just in case you didn't know. See also my other questions in the comment above. – Andy aka Dec 01 '20 at 19:53
  • I beg your pardon.. U could mention any core size for the specification..Sorry for mentioning. I just wanted to know which core size suit this. – Manjesh Gowda Dec 01 '20 at 19:55
  • I beg your pardon... Are you requesting that I design this inductor for you? – Andy aka Dec 01 '20 at 19:57
  • Haha..Not at all...Atleast let me know if i can proceed in the way i mentioned in the post..Thank you – Manjesh Gowda Dec 01 '20 at 20:00
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    Your thoughts about how the windings interact are correct but you will need to gap those ferrite but I suspect you might have already considered this. – Andy aka Dec 01 '20 at 21:15
  • You mean the Air gap? Yes I have considered it.. Can I also make turns for my second inductance value on the first layer? if there is space? – Manjesh Gowda Dec 02 '20 at 08:11
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    I can't tell you that. Get a bobbin and try it is my advise or try and calculate it from the bobbin dimensions. – Andy aka Dec 02 '20 at 09:32

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