Buck Converter_Inductor RMS current calculation

Prajeesh Kottinadath

Hello,

For calculating the RMS current of inductor in buck converter i have seen the formula Irms = Sqrt (Io^2 + (Iripple)^2 / 12).

Please let me know why 12 is considered?

0 JohnTucker over 7 years ago

Prajeesh,

This is going to be tedious using text. The RMS ripple current for a triangular wave is Sqrt ( ((ILmax^2) + ( ILmin^2) + (ILmax *ILmin)) / 3)).

ILmax = Iout + (Iripple/2)

ILmin = Iout - (Iripple/2)

Substituting and factoring you get:

Irms = sqrt ( 3 * (Io^2) + ((Iripple^2) / 4))

Dividing both terms by 3 gets

Irms = sqrt ( (Io^2) + ((Iripple^2) / 12))

0 Prajeesh Kottinadath over 7 years ago in reply to JohnTucker

Thanks for your reply

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