Why my transfer function is irresponsive?

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Subarna Giri
Subarna Giri on 18 Apr 2018
Commented: Subarna Giri on 19 Apr 2018
Hi, Everyone I have a problem with transfer function application in closed loop buck-boost converter. My transfer function for that converter has higher order in numerator than denominator which is not accepted by the Simulink block. I removed higher order term from the numerator still the transfer function is not responding to the circuit. here is the screenshot of circuit. how to correct the problems. Please advised me. thank you.
Robert U
Robert U on 19 Apr 2018
Hello Subarna Giri:
The Simulink version you used is newer than mine.
1.) Just applying the transfer function with more zeros than poles means that there is differential behaviour. In real systems there must be a time delay since future values cannot be known. Ergo, the system function has to have at least as much poles as zeros.
2.) Just creating the system function did not cause any troubles in simulink and performed same as expected from step-function. The system response to fast changes in signal is quite slow. You have to check whether response time of your controller fits the fastest relevant change of your system.
Kind regards,

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Answers (1)

Subarna Giri
Subarna Giri on 18 Apr 2018
Thank you for your kind response. Here is my Simulink model and the screen shot of transfer function. I must use this transfer function. This model has been designed for 12Volt constant output with 5A load. My design is correct in matlab command bode plot but I could not run the model in simulink with there desired parameter. Please help me kindly to solve this problem. Thank you, again. Have a great day.
Regards, Subarna


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