Which of these statements is correct about proportional plus deri
A. It decreases the stability of the system
B. It has high sensitivity
C. It improves the steady-state accuracy
D. The derivative constant is expressed in units of hours
Please scroll down to see the correct answer and solution guide.
Right Answer is: B
SOLUTION
Proportional + Derivate:
The additive combination of proportional & Derivative control is known as P-D control.
The overall transfer function for a PD controller is given by:
\({G_C}\left( s \right) = \frac{{U\left( s \right)}}{{E\left( s \right)}} = {K_P} + s{K_D}\)
PD controller is nothing but a differentiator (or) a High Pass Filter.
The frequency of noise is very high.
So this high pass filter will allow noise into the system which results in noise amplification.
Effects of Proportional Derivative (PD) controllers:
- Decreases the type of the system by one
- Reduces the rise time and settling time
- It has high sensitivity.
- Rise time and settling time decreases and Bandwidth increases
- The speed of response is increased i.e. the transient response is improved
- Improves gain margin, phase margin, and resonant peak
- Increases the input noise
- Improves the stability
Effects of Proportional Integral (PI) controllers:
- Increases the type of the system by one
- Rise time and settling time increases and Bandwidth decreases
- The speed of response decreased i.e. transient response becomes slower
- Decreases the steady-state error and steady-state response is improved
- Decreases the stability
