Simulink cannot solve the algebraic loop

Hi I try to simulate a regenerative brake system for an electric vehicle. I recive the following error: Simulink cannot solve the algebraic loop containing 'RGB/DCDC/Solver Configuration/EVAL_KEY/OUTPUT_1_0' at time 144.14439749058252 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. To rule out solver convergence as the cause of this error, either a) switch to TrustRegion-based algorithm using set_param('RGB','AlgebraicLoopSolver','TrustRegion') b) reducing the ode23t solver RelTol parameter so that the solver takes smaller time steps.

Actually I did the second recommendation for reduceding the step size but it doesnt work. About the first one I dont know how should I apply it. Please help me to solve the problem.

Regards

Answer 1

[ag]

Hi Maryam,

Algebraic loops occur when an input port with direct feedthrough is driven by the output of the same block, either directly, or by a feedback path through other blocks which have direct feedthrough. I kindly suggest you to check if the model contains any such loops.

In most of the cases the solution is to model the system so that the loop is no longer present. In some cases, adding a small delay (Either discrete delay block or continuous memory block) to the system at its highest level might remove the loop.

For a better understanding of Algebraic loops and how can they be solved, I kindly suggest you to go through the following MATLAB answers post: https://www.mathworks.com/matlabcentral/answers/95310-what-are-algebraic-loops-in-simulink-and-how-do-i-solve-them

Hope this helps!