Need help Linearizing a Simulink Model?

Hello,

I need help linearizing a non-linear switching variable frequency variable voltage power supply in order to implement the controls.

So far i have tried operating points, linmod, dlinmod, tfestimate, frestimate but no luck. My results always show zero response for step or bode plots. State space results show an A matrix but zero for B,C,and D. Any more suggestions I can try? Are some simulink models not able to linearize? (This model includes digital logic and flip-flops etc.) However, the overall relationship is a setpoint sinusoidal voltage to an output voltage, SO I believe there should be a way to find this relationship.

Please help!

[Arkadiy Turevskiy]

Some models will linearize to zero, when they have things like switching (pwm type) or conditionally enabled subsystems.

frestimate should be able to help in this case. Would you be willing to e-mail your model so I could take a look at it?

[Erman Korkut]

Frestimate usually takes a couple of tries to come up with the right input signal parameter values such as amplitudes, sample times and frequency values. It is always helpful to look at your simulation results using frest.simView command. You can check this demo on how to use frestimate and frest.simView to inspect the estimation/simulation results:

http://www.mathworks.com/products/simcontrol/demos.html?file=/products/demos/shipping/slcontrol/scdenginepad.html

Another tool that might be helpful to you is system identification toolbox.

As Arkadiy mentioned, I would be happy to look at your model if you can send it.

Answer 1

[Laura Proctor]

Posting the comment from Erman Korkut as a solution:

Frestimate usually takes a couple of tries to come up with the right input signal parameter values such as amplitudes, sample times and frequency values. It is always helpful to look at your simulation results using frest.simView command. You can check this demo on how to use frestimate and frest.simView to inspect the estimation/simulation results:

http://www.mathworks.com/products/simcontrol/examples.html?file=/products/demos/shipping/slcontrol/scdenginepad.html

Another tool that might be helpful to you is system identification toolbox.

As Arkadiy mentioned, I would be happy to look at your model if you can send it.