Solver was unable to reduce the step size without violating the minimum step size value

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Hamed Majeed
Hamed Majeed 2021 年 11 月 29 日
コメント済み: Steve Miller 2021 年 12 月 2 日
  • Solver was unable to reduce the step size without violating the minimum step size value of 1.17684e-19 for 1 consecutive times at time 3.31252e-05. This usually may be caused by violating algebraic constraints in the differential-algebraic system or by the high stiffness of the system. Try tightening the error tolerances, and/or the tolerances for computing consistent conditions. If the problem persists, please check the system or increase the solver Number of consecutive min stepsviolation parameter.
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Steve Miller
Steve Miller 2021 年 12 月 2 日
Attached is the model saved in R2020b.
--Steve

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採用された回答

Steve Miller
Steve Miller 2021 年 12 月 1 日
I examined your model. The diagnostic clearly points to the heat exchanger components. If you eliminate them from the loop, the model simulates extremely fast. I have attached a model with those components eliminated (see attached Upload_mathworks_sm.slx).
You need to look at the parameterization of the heat exchangers.
--Steve

その他の回答 (1 件)

Walter Roberson
Walter Roberson 2021 年 11 月 29 日
you probably have an algebraic loop. Algebraic loops are mostly caused by having feedback processes through a sequence of steps that do not take any time. The error is not typically in the fact that the feedback exists, but rather in the fact that no processing time was associated with the sequence, so mathematically you get into situations similar to "x must equal x+1" (which is is only possible for infinite x in that example.)

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