@bson: that looks voltage only, as I said that isn't a problem, voltage and current at the same time is harder. Also, changing the load from very inductive to a very capacitive load can change dramatically the conditions. While switching from CC to CV or back, for a load change like a short circuit getting in and out, avoiding overshoot and keeping a fast response is hard, and if you want to add remote voltage sensing you are facing a harder and harder problem. All those should be specs of a reliable lab psu and that's what I'm struggling with, not just a stable voltage or current regulator for a particular load.
I've made a dummy load and then improve it in simulations so a second itteration should be good enough. They are very similar but dealing with PSRR, line regulation and swapping the voltage feedback to regulate the voltage in the load not in the supply makes the device as it is not a straight forward conversion.
I haven't touch it in a while, when I get some time I might as I do want to build one but rock solid and being able to adapt the design for different power levels and precission would be nice, once you get one scaling might be fine if it's carefully designed.
JS