I am interested in understanding better how the regulation for a buck converter works, I don't understand it now and havn't found litterature really explaining it so far, so I am asking you here.
The topology would be a buck converter, with a fixed switching frequency fs, an inductor L, a capacitor L and an output impedance of Rout. The duty cycle is D. There would be two regulating loops, one for voltage and one inner loop for current control. I added a figure to explain these loops (idea)
Now the thing is, up until now I actually thought that in dc/dc converters like the buck you have a fixed input voltage, want a certain output voltage and then set D accordingly to Vout = D * Vin.
What is wished for here is to also have a possibility for current regulation to limit the current to a maximum value for example. But I really do not understand how you can regulate both independently. For me there is Vout/Vin = D = Iin/Iout, and therefore if you want to limit the current you actually change the output-to-input voltage ratio. Could someone explain?
Second question (possibly the same, but a particular case): if such a converter is tested, it would be possible to connect input and output and to let a regulated current flow while supplying the losses from a (low) power source. Here's a schematic:
I know it works, but not how since I did not understand the current control. I guess you set a Uin =/= Uout and then a current (limited by the regulation, and not by the very low impedance path) flows? Could someone please explain this?
Any help would be greatly appreciated!