MATLAB: One to one mapping between bode plot and transfer function

Control System Toolboxtf and bode plot mapping

Is it possible that Bode plot can have multiple transfer functions in S domain or there is always one to one mapping between perticular bode plot and transfer function… Actually I have to design filter and I have its bode plot. I have derived corresponding transfer function .But it is of order 5 and I want to have transfer function with lower order. So is it possible to have lower order filter with same bode plot response

Best Answer

Leaving aside the theoretical part of the question, you can use command tfest from System Identification Toolbox to identify a transfer function of specified order from frequency domain data.

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MATLAB: If i have poles and zeros of a transfer function, how to obtain this transfer function ??

transfer_function = tf( zpk(ListOfZeros, ListOfPoles, ListOfGains))

MATLAB: Bode Diagram

You need to use bodeoptions command and set PhaseWrapping to on. Here is an example showing how to do it:

>>s=tf('s'); %define Laplace variable

>>freq=logspace(-1,2,1000); %define frequency vector

>>sys=1/(s^3+2*s^2+3*s+1); %some tf with phase <-180

>>bode(sys,freq) %phase is not within -180:180

>>p=bodeoptions

>>p.PhaseWrapping='on'

>>bode(sys,freq,p) %phase is wrapped inside -180:180

HTH, Arkadiy

Best Answer

Related Solutions

MATLAB: If i have poles and zeros of a transfer function, how to obtain this transfer function ??

MATLAB: Bode Diagram

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