Dear all,
I have a problem with matlab simulink file that i have built. I use some lookup tables inside the program. These tables contain two dimensional data; two inputs for the table with one output.
I almost get this error:
"An error occurred while running the simulation and the simulation was terminated. Simulink cannot solve the algebraic loop at time 1.34454 using the LineSearch-based algorithm due to one of the following reasons: the model is ill-defined i.e., the system equations do not have a solution; or the nonlinear equation solver failed to converge due to numerical issues. "
I tried to solve it by using initial conditions. However, the program can be solved for a while then the problem occurs again.
I have to try an other initial conditions and so on.
It is a kind of try and error and this is very lossless for the time.
Can someone help me by an advice?
Regards
Mohamed
From the error message, there is an algebraic loop in the model. The problem with the model you use. You have to break this loop with a unit delay or memory block
check the same by changing the solver. it may fix the error.
Thanks for your reply.I have already done that solution. Unfortunately, still the error occurs.
From the error message, there is an algebraic loop in the model. The problem with the model you use. You have to break this loop with a unit delay or memory block
Check also if you have a division in your model and avoid to divide by zero.
I have faced this error number of times, and as Prof. Ayman has stated this occurs if there is an algebraic loop in the model and the best solution is to implement a unit delay in any of the feedback loops you may have.
an alternative solution is to select very small max step size - down to milli seconds. This slows down the simulation but works with some models and not with every model. It worked for me with a full vehicle simulation model, where i could not afford to have the unit delay in the feedback loop for PID controllers.
Thanks Gopal for your answer.
I have tried the previous tips. And it is working with a small time step in addition to adding a delay in the feed back.
Personally, when I meet such problem, I try to add z^-1 in my feedback loops, or change to small fixed time step in configuration. These usually work.
Dear Prof,
My self also receive this erroe msg "Derivative of state '1' in block LFC_Single_Area_3PID/Governer' at time 41.399398820911323 is not finite. The simulation will be stopped. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances)".
how I overcome this error running simulation without error.
You have to break this loop with a unit delay or memory block Jagatheesan Kaliannan
Dear Pror.
Thank you so much for your response.
Still I get same error for simulink model. How I rectify this error?
Matlab is a calculator you need to check first whether your model has possible solution or not. Most of then times singularity problem comes when system is ill conditioned (which means inverse of matrix does not exist ) and system gets stuck in a loop.
Hi med nabil.. I am facing the same problem during simulation when used look up table. In same cases i got rid of this stuck by making an offset(too smal value) of one or both look up table inputs so that to avoid dividing by zero or non difined value
I hope that could help
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