PID controllers are tuned on the frequency response of the closed-loop...
Frequency Response of Closed-Loop System
The frequency response of a control system is the measurement of the system's response to a sinusoidal input signal at varying frequencies. It is an essential tool for analyzing the stability and performance of the closed-loop system.
A PID controller is a popular type of feedback controller that uses three terms: proportional, integral, and derivative, to control the system's output. It is necessary to tune the PID controller's parameters to achieve the desired performance and stability.
Tuning a PID Controller
There are various methods for tuning a PID controller, but the most common method is to use the frequency response of the closed-loop system. The following are the steps involved in tuning a PID controller:
1. Determine the Open-Loop Gain
The open-loop gain is the gain of the system when the feedback loop is opened. It is necessary to determine the open-loop gain of the system at the frequency corresponding to the marginal stability. The marginal stability is the frequency at which the system is just stable or unstable.
2. Calculate the Phase Margin
The phase margin is the amount of phase lag that the system can tolerate before becoming unstable. It is necessary to calculate the phase margin of the system at the frequency corresponding to the marginal stability.
3. Adjust the PID Parameters
The proportional, integral, and derivative parameters of the PID controller are adjusted based on the open-loop gain and phase margin. The proportional parameter is adjusted to achieve the desired response amplitude, the integral parameter is adjusted to eliminate the steady-state error, and the derivative parameter is adjusted to reduce the overshoot and settling time.
Why Option A is Correct?
The option A is correct because the open-loop gain corresponding to marginal stability is the most critical parameter for tuning a PID controller. The open-loop gain determines the system's gain margin, which is the amount of gain that the system can tolerate before becoming unstable. The gain margin is directly related to the stability and performance of the system. Therefore, tuning the PID controller based on the open-loop gain corresponding to marginal stability is the most effective method for achieving the desired performance and stability.
PID controllers are tuned on the frequency response of the closed-loop...
PID controller:
PID stands for Proportional, Integral, and Derivative.
It is used to increase the stability and accuracy of the system.
The PID controller's circuit diagram is shown below:Tuning methods: Some of the tuning methods are mentioned below
- Trial and Error method.
- Process reaction curve technique
- Ziegler-Nicholas method.
Process reaction curve:
- It is an open-loop tuning technique.
- It produces a response when a step input is applied to the system.
- Initially, we have to apply some control output to the system manually and have to record the response curve.
The PID controllers are tuned by using the open-loop gain corresponding to marginal stability.
Important points:
- PID controller acts as a Band rejection filter.
- It reduces rise time and increases the Bandwidth.
- It decreases peak overshoot and increases the damping ratio.
- It works like the Lag-Lead compensator.
To make sure you are not studying endlessly, EduRev has designed Electrical Engineering (EE) study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in Electrical Engineering (EE).