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Non Finite Derivative for Integrator Block

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Mathis Sterling Allen
Mathis Sterling Allen on 31 Aug 2020
Commented: Fangjun Jiang on 4 Sep 2020
My model is receiving the following error:
I have deduced that the source of the error is coming from the following subsystem, but I cannot figure out what is causing the issue.
SMO SubSystem:

  3 Comments

Mathis Sterling Allen
Mathis Sterling Allen on 1 Sep 2020
I’m willing to provide more information if necessary.
Fangjun Jiang
Fangjun Jiang on 1 Sep 2020
"Subsystem" block is not shown. Attach the whole model and data if possible.

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Answers (1)

Fangjun Jiang
Fangjun Jiang on 1 Sep 2020
Most often this is caused by the ideal Derivative block. You have three in the model, two of them are in series.
  1. Comment out all three Derivative blocks, simulation runs. But of course, your model is not in its original intent anymore.
  2. Use three approximated derivattives (for example, transfer function s/(0.01*s+1) to replace the three ideal Derivative blocks, simulation runs. This is what you should do.

  2 Comments

Mathis Sterling Allen
Mathis Sterling Allen on 4 Sep 2020
That change didn’t help solve the problem.
Fangjun Jiang
Fangjun Jiang on 4 Sep 2020
In R2019b, the model runs without error after replacing the three Derivative blocks with s/(0.01s+1).
It won't be the same as the ideal Derivative block but having two ideal Derivative blocks connected in series is problematic.

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