How to linearize a switching model of buck-boost converter?

I have a buck-boost converter (switching model) and I want to linearize my converter around some steady state operating condition. I know how to get analytically derive the transfer function of the model but I want to verify my transfer function (or characteristics) with what I get from linearization function. I know PLECS has perturbation and response small signal blocks and then you can do impulse response to get bode plots. How to get the linearized model of my converter and thus obtain any kind of plots like bode? I am attaching the switching and average model of my buck-boost converter. Any help and clues are much appreciated.

Thanks Puneet

Answer 1

[Rakesh Chavan]

Hi,

You can use the Linear Analysis tool for linearizing your model. Some examples and documentation for the same can be found at the following link: http://www.mathworks.com/discovery/linearization.html

You can set the operating points as needed as well as observe the responses in terms of Bode plots. You may also want to look at the following link for Frequency Response Estimation Using Simulation-Based Techniques: http://www.mathworks.com/help/slcontrol/examples/frequency-response-estimation-using-simulation-based-techniques.html

Hope this helps.

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Regards

Rakesh

[Puneet]

Thanks for response. I have already looked at both of these examples. The frequency response estimation technique that has been demonstrated in your link 2 runs my computer out of memory after an hour or two. Also I found out that I can get the transfer function from the average model easily than Switching model. I still don't know how to get the transfer function for the switching model though (still searching for it). Meanwhile I have one more question on linearization:

When you click "Linearize At" it asks to give a vector [0 1], also there is an option for "Taking Snapshot" and to "Trim Model" which opens a variable dialog box. What is the difference between all three techniques? Can anyone help?

[Rushi Jariwala]

Hi Puneet. Can you share how you did frequency response estimation for the averaged model? Is it the same as described in the 2nd link?

Answer 2

[Sathish Lakshmanan]

HI I am also searching for Linearization of Switching models. I have AC supply , Input Filter, Vienna rectifier(PFC correction) and DC-Dc Resonant converter in my model. To derive the transfer function fot this whole model looks complicated. If somebody can help me how to derive the transfer function directly from the Simscape Model. I will derive the transfer function for each model and finally combine the model.

Thanks in Advance

[Arkadeep Deb]

Hello, did you manage to solve the problem? I am having the same problem as mentioned above. Can you please help me?