In the lecture for Ripple Analysis in the Power electronics curriculum and reference under PWM converters, Alex Hanson derives the ripple for the output capacitor in a buck converter, using the charge stored in the capacitor due to the AC current from the inductor.
He shows that Q+ = 1/2 (T/2 )(delta-i_subL_pp/2) = T/8*delta-i_subLpp.
He then substitutes (1-D)*Vout/L for delta-i_subLpp. However, I think delta-i_subLpp should equal (1-D)*Vout*T/L, such that the resulting charge on the capacitor should be:
Q+= (T^2)/8*Vout(1-D)/L.
I'm looking for clarification of this derivation -- is there an error in the lecture, or is my understanding of what delta-i_subLpp is incorrect?
Thank you,
Jorge
