Finding the peak of a sinusoidal voltage using only Simulink Blocks (No Matlab Function Block)

Hi there!

I have a simulink model where I am measuring the line voltages. I need to find the peak of the line voltages over the first 10 cycles for example. So I will have a varaible named "peak_voltage" which should have a value of 0 when the simulation time did not reach 10 cycles, and a value of the peak line voltage afterwards.

I have achieved this using piece of code within a "Matlab Function Block" where I use a persistent variable that gets updated each cycle with the value of the current line voltage when it is on the positive slop of the line signal. But I need to achieve this by only using Simulink Blocks! Any ideas would be appreciated. Thanks

Answer 1

[Sam Chak]

Hi @HASSAN ABDELGABIR

Isn't the MATLAB Function block part of the Simulink block families that grants you the greater potential to achieve what you want in a more convenient way? It is also possible to create a Custom Simulink block to strictly execute the tasks that you specify. You can refer to the following tutorial for detailed instructions:

https://www.mathworks.com/help/simulink/ug/tutorial-creating-a-custom-block.html

[HASSAN ABDELGABIR]

Hi @Sam Chak! Thanks for your comment! I need to avoid using the MATLAB Function (and Cusyom Block) and only using regular Math Operation and Ports & Subsystems blocks for some integration purposes with an exisitng model. I was thinking more into how to achieve this with "MAX" block and "If" & "if Action" blocks and maybe similar blocks.

I think if there is a way to implement and replicate the behavior of the persistent variable in simulink with basic blocks (without scripting), this would be easy to do!

[Sam Chak]

No worries, @HASSAN ABDELGABIR. However, what specifically hinders you from enhancing your efficiency by utilizing the MATLAB Function and Custom Blocks? Have you experimented with the Max block?

[HASSAN ABDELGABIR]

Yes I was able to achieve it using Max block and if block in Simulink. The key was to use the Data Store Memory block to replicate the behavior of persistent variables.

Thank you