Stable gain nyquist plot

1. How do you know if a Nyquist plot is stable?
2. What is the gain at the origin of the Nyquist plot?
3. How do you interpret a Nyquist plot?
4. What is gain margin in Nyquist?

How do you know if a Nyquist plot is stable?

The greater the gain margin, the more stable the system. If the gain margin is zero, the system is marginally stable. (Note: the text also shows that the Nyquist plot crosses the real axis when the Nyquist path is going through the point s=j3.

What is the gain at the origin of the Nyquist plot?

The frequency at which the Nyquist plot is having the magnitude of one is known as the gain cross over frequency. It is denoted by ωgc. The stability of the control system based on the relation between phase cross over frequency and gain cross over frequency is listed below.

How do you interpret a Nyquist plot?

With a Nyquist plot, you can simply observe the distance between (–1, 0) and the point at which the curve crosses the negative real axis. More distance between these two points corresponds to a larger gain margin and, consequently, to a circuit that is more reliably stable.

What is gain margin in Nyquist?

The gain margin is the factor by which the gain must be multiplied at the phase crossover to have the value 1. The phase crossover occurs at 0.010 Hz and so the gain margin is 1.00/0.45 = 2.22. The phase margin is the number of degrees by which the phase angle is smaller than −180° at the gain crossover.