How can I dynamically change a value of resistance during SimPowerSystems simulation?

I'm modelling an uncontrolled three phase rectifier and with the vary the load on the DC bus during simulation but changing the declared variable does not affect the simulation.

I'm using the branch RCL block.

I've tried changing the parameter in the mask to allow it to be tunable but this has not worked, any suggestions?

Answer 1

[Ryan G]

You want to use the variable resistor from the base Simscape Eletrical library. You can connect this up to your SimPowersystems model using simpowersystems interface elements

[Diarmaid]

This solution requires the Simscape toolbox, which I have but will not have on the end machine I will be running this simulation on, so if I could figure out how to do this with SimPowerSystems it would be better!

I just don't understand how since I have selected the resistance as a tunable parameter in the block mask that it won't change during the simulation, is this a feature of simpowersystems itself?

[Ryan G]

What version of MATLAB are you using? SimPowersystems is dependent on Simscape in newer versions.

You could also measure the voltage/amplitude and use ohm's law to implement it via Simulink instead. This can cause some issues if the resistor loop causes an algebraic loop, but sometimes the solver can workaround it. In simscape this is resolved with Physical Signals, not sure about simpowersystems.

You can also see this solution which may help.

[Diarmaid]

I'm running 2012b but the computer this will eventually be used on will have 2010a or b, so it won't have simscape as part of the simpowersystems pack.

This was what I was thinking of doing, using a controlled current source to create a varaible resistor. I'll give it a go. Thanks!