Consider a closed-loop control system with unity negative feedback an...
Given closed loop control system is shown below,
Nyquist plot of G(s) is shown below,
Given, G(s) has no poles in the right half of s – plane i.e. P = 0 .
Modified closed loop control system is shown below,
Modified open loop transfer function is KG(s)
K = 2 (given)
The Nyquist plot for K = 2 is,
Number of anticlockwise encirclement about critical point (-1+ j0)
N = -2
Number of right hand poles of open loop transfer function P = 0 .
Nyquist stability criteria is given by,
N = P- Z (A.C.W.)
-2 = 0 - Z
Z = 2
Hence, the number of closed loop poles in the right half of complex plane is 2.
Hence, the correct option is (C).