AC-model of Integrated Boost-Flyback converter
I'm not completely sure what the you want to achieve here. The only usefull thing I can think of that can simulate on an SMPS using an AC analysis is the (linearized) transfer of the regulation loop. So you could perform a stablilty analysis for example, make a bode-plot of the loopgain and phase.

I see that you have an NMOS in your circuit. I hope you realize that you cannot simulate the behavior of that NMOS as it is working in an SMPS with an AC analysis !

There are also diodes there, I hope you understand that diodes are linearized in an AC analysis. This means they do not recitify in an AC analysis.

I think what you are looking for is the TRAN(sient) simulation which is a time simulation. In 9999 out of 10000 cases designers use a transient analysis for evaluating an SMPS.

An AC analysis can only be used on a derivative model of the SMPS, which you have to make yourself as the SMPS is working as a large signal circuit. For most large signal circuits an AC analysis is completely useless unless you make your own model and evaluate a linear behavior like loopgain etc.

Note that the AC analysis is a small signal analysis, it is for amplifiers etc.