zero crossing detection -simulink

hi,

How can we know if zero crossing is actually required for a block or not.If not how accurately we can decide it and eliminate from the paramters.

My simulation file is too slow, and i doubt if its beause of zero crossing detection enable with most blocks

Thanks in Advance

Answer 1

[Prabhan Purwar]

Hi,

A variable-step solver dynamically adjusts the time step size, causing it to increase when a variable is changing slowly and to decrease when the variable changes rapidly. Zero-crossing is used to accurately locate a discontinuity without resorting to excessively small-time steps.

Following is an example illustrating, exactly when to enable and disable zero-crossing in a system to maintain a balance between required run-time and accuracy of the output.

• Simulink model

In the above model, zero-crossing is enabled for Integrator,Hit-Crossing and Hit-Crossing 1 blocks.

In order to find the no of zero crossings in the model make use of debugger as shown.

• https://www.mathworks.com/help/simulink/ug/using-the-debuggers-graphical-user-interface.html(How to open debugger)

• From the debugger results, we can infer that there is no zero-crossing detected for the Integrator block, while zero-crossing is prominent for Hit Crossing and Hit Crossing 1 block. Thus, it is advisable to disable zero-crossing for integrator block to speed up the simulation.

Alternatively, you can make use of Zero-crossing block to count the number of zero-crossings and enable zero-crossing accordingly.

Please refer the following link for further information

• https://www.mathworks.com/help/simulink/ug/using-the-debuggers-graphical-user-interface.html
• https://www.mathworks.com/help/simulink/ug/zero-crossing-detection.html