×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Nyquist Plot & stability

Nyquist Plot & stability

Nyquist Plot & stability

(OP)
Can any one explain how Nyquist plot is assosciated with predicting Stability of a system

RE: Nyquist Plot & stability

If you have a system with transfer function H(s) and negative feedback loop with function G(s), then overall system is
H(s)/[1+G(s)H(s)].

As can be seen from the equation, the system will blow up when the product G(s)H(s) approaches -1.  If you plot trajectory on the nyquist plot you can see how close it comes to the -1 point. Gain margin is how far below |1| the gain was when angle passed through 180. Phase margin is how much ahead of 180 was the phase when gain decreased through the magnitude |1| circle. Same info can be gained from Bode plot.  There's lot's more that can be said....

RE: Nyquist Plot & stability

(OP)
Thanks pete,

Further, will u be able to qoute some websites/ URL's for reference

regards,

kashyap

RE: Nyquist Plot & stability

My favorite search engine is dogpile.com.
It gives you back results from a large number of other search engines.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources