Impedance calculation from instantaneous voltage and current signals

I would like to calculate the circuit impedance from measured instantaneous voltage and current signals.

Z = Voltage divided by Current = V/I

z = u(t)/i(t)

I would expect some constant value calculated from instantaneous voltage and current, and unfortunately I am getting some "mismatched" value of impedance - how to correctly calculate impedance under Simulink?

Answer 1

[Vaibhav]

Hi Peter

It is my understanding that you are facing issue of "mismatched" value of impedance for a circuit in Simulink.

Mismatched value of impedance could be due to several reasons such as incorrect scaling of the signals, incorrect units, or incorrect wiring.

Below are the troubleshooting steps that can be considered to resolve it:

1. Please make sure that the voltage and current signals are correctly scaled and have the proper units.
2. Ensure the voltage and current signals are properly aligned in time.
3. Utilize the "Divide" block in Simulink to divide the instantaneous voltage signal u(t) by the instantaneous current signal i(t).
4. Verify that the output of the "Divide" block is appropriately scaled and has the correct units.

You can refer to the following MathWorks documentation link to know more about "Divide" block:

https://www.mathworks.com/help/simulink/slref/divide.html?searchHighlight=divide%20simulink&s_tid=srchtitle_support_results_1_divide%20simulink

Hope this helps!