I'm an electronics newbie and I need some help/advice with a project.
So basically I need to make a sort of programmable power supply module (or at least that's what I think I gotta do). I got a DC Power Supply that outputs a voltage of 48V, and a maximum current of 20A, and I'm using it to charge a battery that can take up to 50.4V and 33A. The problem with this power supply is that it doesn't limit the current when connected to a load that can take more than 20A, meaning it can easily surpass that maximum current value and "blow up" (don't know the term in english) the fuses of the power source.
So, I need to make a circuit that takes in the 48V from the power supply, and outputs those same 48V, but with a limited current, to a maximum of 20A. I also need the limit of the current to be regulated, using a potentiometer, and also some displays with the output voltage and current.
What I'm having trouble with is what should I use to limit the current. So far I've looked into simple current limiters and 'constant' current sources using BJTs or MOS-FETs, but I don't think they would work for this case.
Thank you for reading. Do you have any suggestions? Let me know if you need some more information.
EDIT: What I'm struggling with is just the part related to limiting the current. The displays and stuff isn't an issue. So far the type of solutions I've been looking into is really simple stuff. The most simple one is a constant current source using 2 MOS-FETs.
Someone gave me an explanation as to why this wouldn't work, I had to connect the positive terminal of the battery to VDD and the negative terminal to Vo, meaning the voltage wouldn't be set by the power supply, and the current would vary substantially. That added to the fact the the power supplied would be almost 1kW, makes this solution not viable.
Another one is using is some BJT's, to make what is called an "active current source". I've been told this wouldn't work, but didn't really get an explanation as to why.
Can someone explain why this last one wouldn't work?