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Does anyone knows about those equations?

Question asked by pappas.constanti.001 on Oct 22, 2012

Dear All,

I am studding the application note AN2794 entitle “1KW dual stage DC-AC converter based on the STP160N75F3”.

At page 11 the equation for the filter inductor  is Lmin>=(N1/N2)*Vin-Vout*(TonMax/ΔΙ)

From the prevous equations we have N1/N2=19

Vin=24, Vout=350, TonMax=5us , ΔΙ=15%. Ιout=0,43 so

(19*24-350)*5*10^-06/0,43=1,23mH but the result which refer to file is 1,109mH. How that occurs?

Another strange point is the ΔtonMax. How that calculated?

Thanks in advance for your time.

Best regards to all