How can I create a variable resistor for use in SimPowerSystems?
Show older comments
I would like to model a variable resistor for use in SimPowerSystems.
Accepted Answer
MathWorks Support Team
on 14 Oct 2022
Edited: MathWorks Support Team
on 14 Oct 2022
2 votes
Simscape, released in R2007a, contains a block called "Variable Resistor":
If you do not have access to Simscape, the attached model shows an example on how to achieve this. This model should also work in most previous versions. Note that the model contains an algebraic loop, but Simulink is able to resolve it and the simulation runs fine with correct results.
In this example model "ControlledResistor_mod_7b.slx", we are directly modifying the current going through the resistor. In a physical sense, this is exactly what a variable resistor does. It limits the amount of electrons going through it by limiting the current. A singularity at R = 0 should never happen because 0 is not a physical resistor value. It should be variable between A and B wherein A,B > 0.
For modelling in SimPowerSystems, one should think in physical terms rather than in mathematical terms. In this model, the approach of computing the voltage that you want the resistor to hold and forcing the appropriate current (I = U/R) through it with a source is taken since it is the practical method in physical terms as opposed to computing the current and forcing the corresponding voltage.
"ControlledResistor_mod_7b.slx" can be modified to "VoltageControlledResistor.slx" for cases when one needs to model a voltage-controlled variable resistor. You can modify the voltage measured across a resistor ("R_var" in the example) as desired in the function block so the resistance is a function of voltage.
More Answers (1)
Sriram Narayanan
on 13 Jan 2015
0 votes
Please right-click the attachment and select "Save Link As" and then you should be able to save the attachment and open the model in Simulink.
1 Comment
Sriram Narayanan
on 13 Jan 2015
The models have been updated to SLX format, so, you should now be able to download the attachments without any issues.
Categories
Find more on Electrical Sensors in Help Center and File Exchange
on 29 Feb 2012
on 14 Oct 2022
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
