Simulink SimPowerSystems Breaker - Tunable on resistance, Ron

Hello,

I am using a simpowersystems breaker block in Simulink and loading the simulation model I created onto a Real-Time target.

I would like to adjust the value of the on resistance (Ron) between simulation runs without rebuilding the model on the target.

This parameter is not marked as tunable, so is there a way around this?

Perhaps there is a way to make a copy of the model and modify this aspect, or is there a better way to work with non-tunable parameters to allow this functionality to occur with commands like target.setparam or other techniques to allow model parameters adjustments between runs without rebuilding?

Thanks in advance.

Answer 1

[Sebastian Castro]

You may need to make your own "variable resistor" component which accepts resistance values from an input port. Then, you could feed that resistance value in through a Constant block, which is definitely tunable.

The way you would make it is by implementing "V = IR" using Simulink blocks. You could use a Voltage Sensor to measure the voltage, multiply it by a value R, and then apply the resulting current back into SimPowerSystems using Current Sources.

You could then connect this in series with the breaker block, and configure the breaker block to have negligible resistance (or zero if it allows it).

- Sebastian

[McSpark]

I used a current source, voltage sensor, function block to ensure no zero division (u+(u==0)*eps) with the constant of desired resistance.

I found I had to add a parallel 1000 ohm resistor with current source to get it to function as well.

I also used the Simulink example power_nonlinearresistor and linearised it and that works also.

Thanks

[Sebastian Castro]

That looks like the right way to go -- and good find on the power_nonlinearresistor example. Exactly what I had in mind!

That extra resistor you had to add is expected. Even the regular SimPowerSystems Breaker block has a "Snubber resistance Rs" parameter, which is explained in the documentation:

A series Rs-Cs snubber circuit is included in the model. It can be connected to the circuit breaker. If the Breaker block happens to be in series with an inductive circuit, an open circuit or a current source, you must use a snubber.

- Sebastian