Extracting Power from circuit [Simulink]

As for introduction,I had a simple circuit where it consists of a voltage supply, couple of resistors, inductors and capacitors either in series or in parallel. How it is possible to get the "Power Input and the Output" of the circuit? Basically Power = [Voltage x Current] I'd used the Current measurement as well as the voltage measurement blocks, but that it just for measuring. I need the power signal being extracted. Any possible answers? Thanks in advance.

Answer 1

[Rick Rosson]

I do not understand why the Current and Voltage Measurement blocks will not allow you to accomplish what you need. If you measure the current flowing through a branch, and the voltage across the same branch, you can take the two resulting signals (in the Simulink domain) and multiply one by the other to compute electrical power. You can then attach the output of the multiplier to a Simulink scope and see how the power varies with time.

Does that work?

HTH.

Rick

[Jason Lee]

Greetings Rick,

Yes, multiplying one by another using "Product block diagram" gives you the Power but it is just the numerical values. From your answer, yes, i had managed to connect it to a scope and see the change of power to the respect of time. But, what i need is to fed the power into my Fuzzy Logic Controller(FLC) inputs. FLC does not recognize it when i use this method. FLC wants a signal, not a numerical values.

Regards,

Jason Lee.

[Arnaud Miege]

A signal is made of numerical values... Is your FLC a Simulink block? Just feed it the power you compute from your SimPowerSystems model.

[Jason Lee]

Yes, FLC is a block from Fuzzy Logic Toolbox.

It shows the error of "Input data dependency violation due to action subsystems. See Subsystem Examples in the Simulink library for valid and invalid examples of action subsystems".

Should i fed the voltage and current into a subsystem where it consists of those multiplication of V and I, FLC block, all inside that one subsystem?

Since the error for me looks like i am doing something wrong and that can be solved using subsystems. Agree?

[Arnaud Miege]

It sounds like you are using an if..action subsystem incorrectly, which is where the problem lies. Could you upload your model to a filesharing site?

http://www.mathworks.co.uk/matlabcentral/answers/7924-where-can-i-upload-images-and-files-for-use-on-matlab-answers

[Jason Lee]

Hi Arnaud.

I am sorry for the inactive status of mine.

But i had just figured out the solution which is,

By placing a unit delay block diagram just before the 2 inputs of my FLC block diagram solves the problem.

But i am yet to know the reason on why i should do this.