Howtosignalprocessing
- Why stability is a major concern in closed loop control system?
- What is the stability requirement for a closed loop system?
- What condition assures stability of a closed loop control system?
- How the stability of the system is affected by increasing the loop gain?
Why stability is a major concern in closed loop control system?
Closed-Loop Stability
Ensuring the stability of the closed-loop is the first and foremost control system design objective. Even though the physical plant, G(s), may be stable, the presence of feedback can cause the closed-loop system to become unstable, as in the case of higher order plant models.
What is the stability requirement for a closed loop system?
A closed loop system is stable when all its eigenvalues have positive real part. Incidentally, poles of are same as zeros of . This means for stability, number of zeros of in the right half of the complex plane must be zero.
What condition assures stability of a closed loop control system?
The open loop control system is absolutely stable if all the poles of the open loop transfer function present in left half of 's' plane. Similarly, the closed loop control system is absolutely stable if all the poles of the closed loop transfer function present in the left half of the 's' plane.
How the stability of the system is affected by increasing the loop gain?
As the loop gain increases the error decreases, thus large loop gains are attractive for minimizing errors. Large loop gains also decrease stability, thus, there is always a tradeoff between error and stability.
