# How calculate the transfert function of boost converter with input capacitor?

the Boost converter figure is like this

• Hi, it is always nicer to add a few sentences with "please'' and "thank you", especially when posting for the first time. Check out this link cbasso.pagesperso-orange.fr/Downloads/PPTs/… and apply the technique for the boost converter. The input capacitor plays no role as long as the source impedance is close to 0 ohms: $V_{in}$ is always considered constant in small-signal analysis except when you insert a front-end filter. – Verbal Kint Dec 22 '18 at 12:28
• @VerbalKint, "please" and "thank you" aren't required here. But a few sentences saying what solution OP already tried and why the results aren't satisfactory would be helpful. – The Photon Dec 22 '18 at 17:21
• @The Photon, I am probably too old fashioned to believe these simple words still have a meaning when you start a discussion in a forum. No problem with me. – Verbal Kint Dec 23 '18 at 8:49
• @VerbalKint thank you Sir for your explanation It's the first time that I ask in a discussion.I 'm working in controlling a photovoltaic system and I have a lot of difficulty with the boost converter so I asked quickly. thank you Sir again. – Asma Dec 23 '18 at 17:45
• Hi Asma, hey, no big deal! : ) Please check my other APEC seminars in the given page (2013 and 2014). I describe the PWM Switch model introduced by V. Vorpérian in 1990 and it is the best tool to study switching converters small-signal responses. It is, in my opinion, simpler to manipulate than state-space averaging technique or SSA. Besides, it predicts that the three basic dc-dc converters remain heavily damped second-order systems when operated in the discontinuous conduction mode or DCM what SSA originally failed to demonstrate. Happy Holiday Season! – Verbal Kint Dec 23 '18 at 18:05