Posts Tagged ‘a system’

Difference between Poles and Zeros of a Control System

April 22nd, 2014 | 1 Comment | Posted in Electrical distribution
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In the previous article, Nasir discussed transfer function of control system. Now check the last but one article of his tutorial: Difference between Poles and Zeros of a Control System…


The input-output explanation of system is elementally the spreadsheet of all possible input-output pairs. Like for linear system, spreadsheet can be described by single input single output pair, e.g. the impulse response or the step response.

Transfer function is function of complex variables. The transfer function can be obtained by simple algebraic jugglery of differential equations that illustrates the system. Transfer function can represent higher order systems also, even infinite dimensionless systems which regulates on partial differential equations.

The frequencies for which the values of denominator and nominator become zero in a transfer function are called Poles and Zeros. Poles and Zeros analyze the performance of a system and check the stability. The values of Poles and Zeros control the working of a system. Usually the numbers of Poles and Zeros are equal in a system and in some cases number of Poles is greater.

Definition of Poles

Poles are the roots of the denominator of a transfer function. Let us take a simple transfer function as an example:

Where, N(s) and D(s) are simple polynomials.

Where, N(s) and D(s) are simple polynomials


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