How to change the transfer function variable in simulink during simulation time

Hi,

I have a Simulink model, where I need to change the transfer function coefficient during simulation run time. For example the TF is (1/1+sRC). Here R and C values need to change during run time. How to do that? Problem here is that the R value is calculated with the load current, that is (output voltage)/(load current). So I know the load current variation by calculating the R values. If anyone knows how to change the TF coefficient during runtime please help me. Thanks in advance.

Answer 1

[Paul]

Hi Swasthik,

If I understand correctly, the R and C values are changing dynamically. Just use blocks (integrators, subtraction, product, etc.) to implement the first order differential equation explicitly. The Transfer Function block is intended to be used with fixed parameters.

[Swasthik Baje Shankarakrishna Bhat]

Hi Paul, Thanks for the reply. I didn't understand properly. Let me explain again, for example, I have a transfer function 1/(sRC+1) at the output of some system. Where i need to check the system behaviour for different load conditions. How can I do that? Can you elaborate with some examples. I am sorry to trouble you. Thanks in advance.

[Sam Chak]

Hi @Swasthik Baje Shankarakrishna Bhat

What @Paul meant is probably that the transfer function

can be expressed in the 1st-order Differential equation form:

.

If R is a function of the state , then using the Integrator block and some fundamental blocks, you can construct the signal flow according to this Integral equation:

.

[Swasthik Baje Shankarakrishna Bhat]

Thank you so much paul and sam. It worked. Sorry for the late reply. Regards, Swasthik

[Sam Chak]

You're welcome @Swasthik Baje Shankarakrishna Bhat. Don't forget to "click-Accept" @Paul's Answer.