Close loop boost chopper

Hello,

I am trying to design a boost chopper.
It works in open loop but in close loop it doesn’t. Even though I change the duty cycle, the output voltage is equal to the input voltage.
Input voltage is 16V and output 24V
Unfortunatly , I am a new user so I can not upload the file.
Do someone can help me to create a close loop? Currently, I use a voltage probe from my charge, I sum it with a voltage ref. After the sum I use a PI then it goes to a comparator. It is compare with a square wave voltage and after the comparator there is a on off switch controller which goes to the MOSFET

Thank you very much
Guillaume

buck_boost_Mod16V_v3.psimsch (61.5 KB)

I ve attached the file, if someone wants to have a look
Thank you
Guillaume