Timeline for Having trouble understanding the stability of following system
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
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| Nov 1 at 23:33 | comment | added | Andy aka | @needbrainscratched which part of my comments and question did you somehow overlook when I suggested you were not revealing something. The "negator in summing node" is a totally crucial element (in that it adds 180 deg or performs signal inversion) that you missed out of your question despite me saying things that should have provoked you into revealing it then, after all of this you downvote me. Do you think that is fair when I'm trying to help you? | |
| Nov 1 at 21:11 | comment | added | Pete W | I think OP understands that part of it. (not my downvote tho!) | |
| Nov 1 at 21:11 | comment | added | needbrainscratched | my plant has a negator in summing node. So -180 degree from my transfer function is getting added in an inverted manner. Total phase around loop must become 360, with gain>1. | |
| Nov 1 at 21:05 | history | edited | Andy aka | CC BY-SA 4.0 | added 461 characters in body |
| Nov 1 at 21:00 | history | edited | Andy aka | CC BY-SA 4.0 | added 461 characters in body |
| Nov 1 at 15:53 | comment | added | Andy aka | And, @needbrainscratched what extra 180 degrees are you talking about in the latter part of your comment? Feedback doesn't imply another inversion unless you have not revealed something in your question. | |
| Nov 1 at 15:52 | comment | added | Andy aka | The loop gain produces 180 degrees at low frequency so, if this is fed back it will be totally stable (unless there is something you are not revealing about the plant i.e. you haven't considered its contribution in the graph in your question) @needbrainscratched | |
| Nov 1 at 15:49 | comment | added | needbrainscratched | I don't mean the -180 due to negative feedback. I mean just the phase contribution from loop gain alone. I understand that an opamps open loop gain is positive, but it will lead to instability if it's phase adds another 180 degree in unity feedback. In my system, the 180 degree phase is coming from the two poles at DC. Wouldn't another 180 degree from feedback make it unstable? | |
| Nov 1 at 15:43 | history | answered | Andy aka | CC BY-SA 4.0 |