Convert Continous Integrators to Discrete Integrators

I'm trying to convert the integrators in this simulink model of induction motor from continuous integrators to discrete integrators.

After replacing integrators with discrete-time integrator block I obtained this error, "Derivative of state '1' in block 'XYZ/Integrator' at time 0.018500000000000003 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)"

I have to run this model at 1e-3s sample time, the sample time shouldn´t be reduced any further. I tried implementing Trapezoidal Integrators and Euler, but the error does not dissapear.

Answer 1

[Joel Van Sickel]

Hello Nishant,

most induction machines and controllers will need a time step significantly faster than 1e-3 to simulate correctly. However, for your case, maybe that is enough. It is important to use the correct solver for this type of simulation. I have provided some general guidance blow, but if you would like more specific help, please feel free to share your model file.

Place low pass filters on the sensors going to your closed loop controller

use ode23tb if using specialized power systems or simulink based models

use ode23t if using simscape

check for algebraic loop warnings

turn your tolerances up OR

switch to a fixed step solver on your powergui/solver configuration block or in your simulink model.

Also, please see the extensive induction motor models and control examples: https://www.mathworks.com/help/physmod/sps/powersys/ref/asynchronousmachine.html

Regards,

Joel