Help Building an Inductor

[Bdrt]

Hi everyone,

After dimensioning an inductor for a buck converter, i was researching about how to build it.

I've found a couple of articles/books but none that helped me, due to the high inductor values.

The parameters of the inductor are:
Ipk = 32A
IoutMax = 30A
L = 4,7mH
Fsw = 15kHz

I've found cores suitable for lower values but i cant seem to find for this one.

Does anyone has experience dimensioning/building inductors can give me a few tips about this ?

Thanks,

 

[ysba]

Unitrode seminars are a great reference on practical inductor building.

https://www.ti.com/seclit/ml/slup132/slup132.pdf

 

[Bdrt]

Unitrode seminars are a great reference on practical inductor building.

https://www.ti.com/seclit/ml/slup132/slup132.pdf

Hi,

thanks, I'll try to read that to see if i can find everything i need to build my own =)

Best regards,
Bruno

 

[Velkarn]

is it correct L = 4,7mH? not 4,7 microH?

 

[BradtheRad]

is it correct L = 4,7mH? not 4,7 microH?

Several millihenries is not likely. You would need to switch it at a slow frequency to obtain 32A peak.

 

[smijesh]

Hi

Your previous post we were taking about 1mH or below. Where you got 4.7mH ? it is too large value.

 

[Bdrt]

Hi

Your previous post we were taking about 1mH or below. Where you got 4.7mH ? it is too large value.

From My spreadsheet with the formulas.
Someone told me already they got a very different value but i cant seem to reach it. Dont really know what may be different from my calculation to theirs.

I can post here the spreadsheet if it helps...

Thanks

- - - Updated - - -

Hi

Your previous post we were taking about 1mH or below. Where you got 4.7mH ? it is too large value.

This are the two conditions



The formula from the "Buck Converter design demystified" gets me to this values.

Thanks

 

[FvM]

A standard inductor design procedure would first choose the core material depending on frequency and ripple magnitude, then select the core size according to stored energy 0.5*I²L. Then calculate air gap, wire gauge and number of windings.

15 kHz can be still handled by regular (thin) laminated iron.

 

[smijesh]

Your calculations are correct unless the LIR value




You may not get slandered core for this inductor, so use multiple staked core for this application

 

[Bdrt]

Your calculations are correct unless the LIR value

View attachment 131785


You may not get slandered core for this inductor, so use multiple staked core for this application

Hi,

Thank you for the confirmation . i was starting to doubt myself =)

i used 0,1 LIR because this will be used as a Li Battery charger. i wanted the minimum current ripple possible.

I still dint found any relevant information about the typical requirements for a high voltage Lithium battery charger. Thats why i am assuming that value.

Thank you for your help.