Simulink Integrator Error when Fixed-step size increased

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Viewed 2012

I downloaded a Simulink model, which I would like to run with a high fixed-step size, because I am more interested in speed than accuracy.

ode3: Works until Fixed-step size 3

Everything over Fixed-step size 4 leads to error. (Other solvers like ode8 lead to an error with other fixed-step sizes.)

This is the error message: Derivative of state '1' in block 'example_HeatPump/HeatPump/HeatPump_basic/model cold side/Integrator' at time 16.0 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) This is the block where the error occurs

Is there any way to solve this error?

simulink matlab
1 Answers

Just to add to the reason why the model can't handle larger step sizes. For too large step sizes there can be situations during simulations that one or multiple modelling constraints cannot be satisfied, which leads to such an error. So there can be some constraints in your model, which you do not know of, that lead to this.

Just to give an example, if you have a closed loop linkage system for a multibody system, the constraints are the hinges in the model which link the bodies. For too large step sizes the location of the hinge (which links body 1 & 2) in body 1 and the location of the same hinge in body 2 may not coincide at some point during simulation. For small (numerical) errors, there are ways to cope with this. Larger errors lead to problems.

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