Mainly there are two type of control systems, one is positive feedback control system and another one is negative feedback control system a feedback is very important in control system it gives idea to a system engineer about the overall performance of a control system.
Negative feedback control system:
In negative feedback control system the output of system is subtracted from the input before again it introduce to the system, in such a system output of system is increases in denominator of a output equation so it decreases overall output of a system.
Negative Feedback Equation.
H= CH.
Input to the system.
E= R-CH.
Output of a Equation.
C= [(R-CH)]G.
C= GR-GCH.
Adjusting the terms.
C+GCH= GR.
Taking the C Common.
C(1+GH)= GR.
When we adjust the terms.
C/R = G/(1+GH).
Positive Feedback Control System:
In positive feedback control system, the output is feedback to a system with positive value and overall gain of a system increase, while the output equation denominator is decrease and the gain of a system increase.
Positive Feedback Equation.
H= CH.
Input to the system.
E= R+CH.
Output of a Equation.
C= [(R+CH)]G.
C= GR+GCH.
Adjusting the terms.
C-GCH= GR.
Taking the C Common.
C(1-GH)= GR.
When we adjust the terms.
C/R = G/(1-GH).
Transfer Function of Control System:
Transfer function of a control system is a ratio of laplace transform of output to the Laplace transform of input.
Transfer Function= L.T of Output / L.t of Input.
Simply convert equation of negative feedback and positive feedback to the S-domin of laplace transform.
Transfer Function for negative feedback:
C(s)/R(s)= G(s)/(1+G(s)H(s)).
Transfer Function for positive feedback:
C(s)/R(s)= G(s)/(1-G(s)H(s)).
Conclusion:
In this article we are explaining about feedback and type of feedback, then we explain about the transfer function and uses of transfer function and expression of transfer function in negative and positive feedback control system.
FAQ:
Q.1 What is transfer Function?
Ans. Transfer function is a ratio of output to the input of laplace transform and it's use to convert signal in S-domin.
Q 2 Why transfer function is use?
Ans. Transfer function is use to convert time domain signal to its corresponding s-domin signal.
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