Understanding operation of the following circuit adapation of a buck converter

Hello all!

Basically, I need help with understanding the operation of this buck converter adaption which goal is to behave as a constant dc current regulator.

It would be convient to disregard capacitor and inductor values at this point as I am only looking forward to understanding what happens when the switch (IGBT) is open and closed.

If additional info is required to provide a better insight regarding the matter, please let me know to provide.

Thanks if any could provide any insight.

Regards,

Carmen S.