# LLC converter with internal & external leakage and magnetising inductance terms?

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#### treez

Hello,

We are doing an Half Bridge LLC resonant converter with both internal & external leakage and magnetising inductance terms…(as in the attached diagram).

Please could you confirm the following three equations for this topology?

w0 = 1/ [L(res).Cr] (1)
where:
w0 = upper resonant frequency
L(res) = Lr + Llkp + Llkp//Lm

wp = 1/[L(mag).Cr] (2)
where:
wp = lower resonant frequency
L(mag) = Lm(ext) // (Llkp + Lm)

m ={ [Lm(ext)//(Llkp + Lm] + [Lr + Llkp +(Llkp//Lm)] } / {Lr + Llkp + (Llkp//Lm)}

(3)

This is derived with regard to AN-4151 by fairchildsemi…
https://www.fairchildsemi.com/application-notes/AN/AN-4151.pdf

#### Attachments

• LLC CONVERTER.pdf
205.4 KB · Views: 15

#### treez

Re: LLC converter with internal & external leakage and magnetising inductance terms?

Actually here is the above LLC converter redrawn with the transformer's magnetising inductance more correctly represented.

#### Attachments

• LLC CONVERTER _1.pdf
252.1 KB · Views: 14

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