What is Nyquist Criteria ?
What is Nyquist Criteria ?
Nyquist Stability Criterion Definition
The Nyquist stability criterion is defined as a graphical technique used in control engineering to determine the stability of a dynamical system.
Application of Nyquist Criterion
It applies to open-loop systems and can handle transfer functions with singularities, unlike Bode plots.
Criterion Formula
Z = number of roots of 1+G(s)H(s) in right-hand side (RHS) of s-plane (It is also called zeros of characteristics equation)
N = number of encirclement of critical point 1+j0 in the clockwise direction
P = number of poles of open loop transfer function (OLTF) [i.e. G(s)H(s)] in RHS of s-plane.
Examples of Nyquist Criterion
Different open-loop transfer functions demonstrate stable, unstable, and marginally stable systems using Nyquist plots.
Matlab Examples
Matlab code helps plot Nyquist diagrams to analyze the stability of various systems.
