@OwenD We're doing a university WAAM research project, where there is some variation in settings during the print, and unfortunately we got no say in welder choice, so we're stuck with what we've got. For the most part the goal involves modifying the power supply, so our current welder gets the job done. Unfortunately I have not yet been able to find any welders that are able to do what we need them to do either. Apologies for being vague, there are details of the design I can't post on here.
Good find on the current sensor, I've been trying to look for hall effect sensors but I think I need to work on my googling!
I hadn't considered the signal noise yet. The noise is going to make it quite difficult to control, but I'll cross that bridge when I get to it with some kind of filtering. It will be easier to design once I see a waveform on a screen.
Why do you say unless welding quite large pieces? Is that in relation to the welding current? or the duty cycle of the welder?