How to simulate data from txt correctly?

I'm stuck with an investigation project and I don't have experience in this situations with matlab.

I have to simulate a corrent impulse loading the data from a txt.

The txt has 2 columns, one for time, and the other for intensity.

To import this data to two variables in the workspace and plot them is easy, but the nightmare comes when I want to simulate this data.

I use the block 'from workspace' to load the two variables into simulink, but what is shown in the scope block has no sense.

I think the problem may be with 'time step' or how the time is interpreted, but as far as I have tested it I don’t get any change.

The finality of loading this data and get to simulate it properly, is to see how movs(metal oxide varistors) behaves, so next to the from workspace block I will put some inductors, resistances and the varistor block from simulink with voltage and current sensors.

I have to say that I don't use to ask for help and I look for answers by myself, but now this is getting me in trouble.

Thank you in advance/Gracias

Answer 1

[Mathieu NOE]

hello

I tried to reproduce your problem , but got the right output , not what you show... hope the attached files can help you

I simply created a column oriented array with time in first col and signal in second col

then the simulink model has fixed time stamps (fixed solver , step = dt as declared in m file), no zero crossing detetction, no interpolation...

% some dummy data 
Fs = 1e6;  % 1 MHz
dt = 1/Fs ;
t1 = (-10:290)*dt; % 100 microS of data
It1 = zeros(size(t1));
It1(20:end) = exp(10000*(-t1(1:end-19)+t1(1)));

plot(t1,It1);

% prepare data for simulink to Workspace block
% For matrix formats, each row of the matrix has a time stamp in the first column
% and a vector containing the corresponding data sample in the subsequent column(s).
t_start = t1(1); % put that in simulation simulation start time
t_end = t1(end); % put that in simulation simulation stop time
simin = [t1(:) It1(:)]; % (:) this makes sure the data are column oriented 

[Jose Manuel Velasco Sanchez]

Thank you!

Adding what you said make it work

Finally I added this part of the code:

Fs = 1e6;
dt = 1/Fs ;
t_start = t1(1);
t_end = t1(end);

I would like to understant why it needed this changes, for example why the variable Fs and dt.

I modified this line of code to be able to use all the data, but, I saw that erasing this line it still worked the same way, is this line to simulate just this period of time?

t1 = (-10:2000)*dt; 

The next line gave me error at the beginnig, later it worked fine:

simin = [t1(:) It1(:)]; % (:) this makes sure the data are column oriented 

[Mathieu NOE]

Glad it works fine now !

[Jose Manuel Velasco Sanchez]

@Mathieu NOE When I ran it at home it worked me, today I tried it in the laboratory with Matlab online and it don't worked anymore.

Is there a big difference using Matlab in a web browser?

[Mathieu NOE]

%% hello - seems to be running fine even on line ! 

% some dummy data 
Fs = 1e6;  % 1 MHz
dt = 1/Fs ;
t1 = (-10:290)*dt; % 100 microS of data
It1 = zeros(size(t1));
It1(20:end) = exp(10000*(-t1(1:end-19)+t1(1)));
plot(t1,It1);

% prepare data for simulink to Workspace block
% For matrix formats, each row of the matrix has a time stamp in the first column
% and a vector containing the corresponding data sample in the subsequent column(s).
t_start = t1(1); % put that in simulation simulation start time
t_end = t1(end); % put that in simulation simulation stop time
simin = [t1(:) It1(:)]; % (:) this makes sure the data are column oriented 

[Jose Manuel Velasco Sanchez]

I will investigate it more, thank you!!