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jyanof · 07-02-2009, 05:15 AM

hey guys, thanks for the kind words! feelin like we're getting close...

i've been working on this constant current stuff most of the day today and it's kinda thrown me for a loop. (pun intended?)

first, i had to have -5V and +5v on the current sensor in order to get it to work - Paul, you didn't run into this problem? i'm using the 50A tamura current sensor...

then, i spent a ton of time playing with control algorithms. having PWM increment if the current was too high or too low caused the current to oscillate. there was ~400hz sine wave when I put the scope across the current sensor output.

next I tried a PD loop, but that caused some weird things to happen. very noisy current signal, bouncing around a lot between two values.

i tried a few other things, but it seems just basic low value
proportional control works best.

it still does some weird things at certain current settings. like, makes noise and the control loop goes a little unstable.

i'll play with it more tomorrow...

07-02-2009, 05:15 AM	#128 (permalink)
jyanof Joe Join Date: Feb 2009 Location: phx Posts: 260 Thanks: 0 Thanked 48 Times in 38 Posts	hey guys, thanks for the kind words! feelin like we're getting close... i've been working on this constant current stuff most of the day today and it's kinda thrown me for a loop. (pun intended?) first, i had to have -5V and +5v on the current sensor in order to get it to work - Paul, you didn't run into this problem? i'm using the 50A tamura current sensor... then, i spent a ton of time playing with control algorithms. having PWM increment if the current was too high or too low caused the current to oscillate. there was ~400hz sine wave when I put the scope across the current sensor output. next I tried a PD loop, but that caused some weird things to happen. very noisy current signal, bouncing around a lot between two values. i tried a few other things, but it seems just basic low value proportional control works best. it still does some weird things at certain current settings. like, makes noise and the control loop goes a little unstable. i'll play with it more tomorrow...