Nonlinear solver: failed to converge, residual norm too large.... Here is the set of components with unconverged equations

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Pablo Gonzalez 2019-3-21

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https://ww2.mathworks.cn/matlabcentral/answers/451556-nonlinear-solver-failed-to-converge-residual-norm-too-large-here-is-the-set-of-components-wi

回答： Karanjot 2023-9-29

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Hi!

I've disinged a simscape componet which represents an electrical componet that reproduce the folloving beahviour

, where v is the voltage i the current and k a constant with units

. I develop the following .ssc document

component ducComp
  nodes
    p = foundation.electrical.electrical; % +:left
    n = foundation.electrical.electrical; % -:right
  end
  variables
    i = { 0, 'A' };     % Current
    v = { 0, 'V' };     % Voltage
  end
  parameters
    K = { 1, 'V/(A^2)' };  % k value
  end
  branches
    i : p.i -> n.i;
  end
  equations
    assert(K>=0);
    v == ((i^2)*K);
    v == p.v - n.v;
    
  end
  end

So, the problem is that when I increase the value of my K, the simulation give the following error:

Nonlinear solver: failed to converge, residual norm too large.
Here is the set of components with unconverged equations

I tried to reduce my time step and to increase the Consistency tolerance but the problem persists... I do not know what could be the problem, so if anyone can help me I will be very grateful.

Thanks for you time

Pd: Using matlab 2018b

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Answer 1

Karanjot 2023-9-29

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https://ww2.mathworks.cn/matlabcentral/answers/451556-nonlinear-solver-failed-to-converge-residual-norm-too-large-here-is-the-set-of-components-wi#answer_1321829

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Hi Pablo,

I understand that want to debug the following error in your Simulink model:

Nonlinear solver: failed to converge, residual norm too large.

Please provide the complete model & files associated with this error. This error is often encountered when a model is too ideal and exhibits sudden transitions, hence, the solver fails to converge. In such cases, the solver performs transient initialization.

I recommend the following changes to help resolve the error:

Reduce the maximum time step to see if a smaller time step helps the simulation converge.
Increase the consistency tolerance in the solver configuration block.
Consider adjusting component parameters such as ‘Open resistance’ or ‘Closed Conductance’ that make the model more realistic and less ideal.
Refine the model Review the model for errors, inconsistencies, or incorrect assumptions. Simplify the model by removing unnecessary components or subsystems.

To learn more about troubleshooting simulation errors & transient initialization, please refer to the below documentation:

https://www.mathworks.com/help/simscape/ug/troubleshooting-simulation-errors.html

https://www.mathworks.com/help/simscape/ug/how-simscape-simulation-works.html?searchHighlight=bql2kkl-2.html&s_tid=srchtitle_bql2kkl-2.html_1#bqoxlpd-1

I hope this helps!