Problems with generating closed loop bode plot for a dc-dc converter

Hi,

I want to generate a closed loop bode plot for a dc-dc buck converter but having issues with it. I am able to successfully generate the open loop bode plot of input to output as well as the bode plot of the compensator. However, when I am trying to generate closed loop bode plot, it is giving me a blank plot.

(Note: I am using simscape electrical and have a PWM block in my dc-dc converter)

Any help would be appreciated.

Thanks,

Shardul

Answer 1

[Vasco Lenzi]

Hi Shardul

What workflow are you using to generate the open-liip response?

I would take a look at the Frequency Estimator Block (it requires R2019a and Simulink Control Design)

https://www.mathworks.com/help/slcontrol/ug/frequencyresponseestimator.html

In this example we show how to use it with System Identification to generate a frequency plot for the closed loop system:

https://www.mathworks.com/help/slcontrol/ug/online-estimation-of-frequency-responses-of-nonlinear-plant.html

This should do the trick even for a DCDC converter which cannot be linearized because of the switching nature of the PWM.

Hope this helps

Vasco