05-09-2012, 11:29 AM
Transfer function of d.c machine
Transfer function.ppt (Size: 1.42 MB / Downloads: 60)
Concept Of Transfer function:
In any system ,first the system parameters are designed and their values are selected as per the requirements.
The input is selected next to see the performance of the design system.
Effect of system parameters = output
Input
Mathematically such a function explaining the effect of system parameters on input to produce output is called Transfer function.
Advantages:
Individual analysis of various components is possible by the transfer function approach.
As it uses a Laplace's approach, it converts time domain equations to simple algebraic equation.
It suggests operational method of expressing equations which relate output to input.
Once transfer function is known, output response for any type of reference input can be calculated.
Disadvantages:
Only applicable to Linear Time Invariant system.
It does not provide any information concerning the physical structure of the system. i.e. whether it is mechanical or electrical cannot be judged.
Effects arising due to initial conditions are totally neglected.
Procedure to determine the transfer function of a system:
Write down the time domain equations for the system by introducing different variables in the system.
Take the Laplace transform of the system equation assuming all initial conditions to be zero.
Identify the system input and output variables.
Eliminating the introduced variables, get the resultant equation in terms of input and output variables.
Take the ratio of Laplace transform of output variable to Laplace transform of input variable to get the transfer function model of the system.