Why all the plots from my program originate from (0,0).

I am building a state-space feedback controller for a single phase bipolar inverter by using MATLAB Simulink.

I want to extact the angle of the output voltage as part of the control strategy. However, I found out all the voltage plots originate from (0,0). In such a case, how to tell the phase difference and which voltage is the reference?

I attempted to use code "Angle(V)" and FFT function block. It either give me 0 degree or 180 degrees.

I have also tried to use "phasor solver", however, my IGBT switches are not compatible with this mode.

Anybody has experience of extracting phase anlge of a voltage in MATLAB Simulink? I really appreciate any suggestions and it is urgent.

[Lei]

Guys please give me some help

[Jan]

The term "urgent" is an anti-pattern in this forum. It reduces the chance to get an answer by 73%. On the other hand your problem concerns Simulink, but you did neither specify this in the Tags nor in the Prodcuts nor in the title. I have the impression that Simulink users are not active in this foum frequently, and without a corresponding hint it is unlikely that their attention is caught.

Therefore I suggest to brush-up the question, remove the "urgent" and the meaningless answer, which is only a BUMP.

[Azzi Abdelmalek]

when you said phase voltage, compared to what? when do you consider that the phase is zero?, is your signal sinusoidal?

[Lei]

Thanks for replying. I am not too sure if Simulink automatically find the reference. I also managed to do exactly the same controller in PSCAD and I didnot specifically define a reference.

If I have to define a reference, does anyone know how to define a reference?

Thanks guys again

[Daniel Shub]

Lei, please do not add meaningless bumps. Further, if you insist on bumps, don't add them as answers since this reduces the likelihood of people looking at the question (since it is already answered).

Answer 1

[Babak]

The reason that usually simulink generated plots (out of scope) start from (0,0) is that the initial conditions of the Simulink blocks are set to zero.

In my opinion you should check the initial conditions of the source blocks you migt have.

[Lei]

How should I check the initial condition?

[Babak]

first find out what source blocks you are using in your Simulink model (like step, clock, time, input, ramp,... ) then double click on those blocks that are placed in your simulink model file. For each block a GUI opens up. The GUI includes information on how to set up the parameters corresponding to those blocks. source blocks usually have a parameter to be set up which is their initial condition

Answer 2

[K E]

If your question is "how do I change the display on my scope", this blog post may help. But I likely misunderstand what you are asking for help on.