Can Voltage dependent capacitance be modeled in Simscape?

Can a voltage dependent capacitance be represented directly using capacitor or any other in built block in Simscape model? Or it has to be modelled in terms of equations using Simulink ?

Answer 1

[Vasco Lenzi]

Hi Amruta

If you have Simscape Electrical, you can use the Variable Capacitor that accepts C as a Simscape Physical Signal.

You can measure voltage over the capacitor and apply some transformation/lookup table to feed in into the C signal:

edit: changed image with one that would simulate. Please remember to adjust the Units in the PS Look-up table block!

Please stay within "Simscape World" and use Simscape Physical Signals (brown Simulink-like blocks) to deal with Physical Signals insad of going into Simulink. This will make the simulation more stable.

If you don't have Simscape Electrical, you can build your own Simscape based component block using Simscape Language:

[Ali Zahid]

@Vasco Lenzi can you please diagnoze this error, i am facing the same issue.

[Vasco Lenzi]

@Ali Zahid I can reproduce above error, if I keep the lookup table unitless. And that's the problem, as reported by the error diagnostic: "3) query values and table data have the commensurate units;"

If I change from unitless ('1') to the right SI units V and F, then it works fine:

[Ali Zahid]

@Vasco Lenzi I set the units to SI but then i get the following error

[Ali Zahid]

I figured out that i need to add an electrical reference and then a solver configuration to the block diagram and then it works.

Thank you for the help

[Vasco Lenzi]

you are right, the first screenshot was just a sketch to illustrate the concept but would not simulate. I'm editing and adding a better model image for context.