square wave gerneration from harmonics and fundamental

[DaraOL]

Hi

I am completly new to Labview and strugling with the following problem. Sorry if it is a bit basic for this forum but any help would be great.

I am looking to construct an aproximation for a square wave by summing a fundamental and three harmonics. Thr fundamental freq is 1600 and amplitude is 1v

I am woking out the freq and amp of the harmonics by

freq (4/pi) * (1/3 * V),     (4/pi) * (1/5 * V),     (4/pi) * (1/7 * V) 

amp (4/pi) * (3 * freq),    (4/pi) * (5 * freq),    (4/pi) * (5 * freq)

I am then subing in the values to the two block diagram attached but neither seem to work.

I am looking for a square wave but just getting errors.

Any help would be great

Thanks

D

[altenbach]

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@DaraOL wrote:

I am then subing in the values to the two block diagram attached but neither seem to work.

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Please attach the actual VI instead of pictures. We cannot debug pictures.

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@DaraOL wrote:

I am looking for a square wave but just getting errors.

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If you are getting errors, it typically helps if you tell us the exact error message.

[altenbach]

As a first step, you should make your code scalable. The core computations of all harmonics is the same and only two numbers change, and they can be calculated from the [i] of the harmonic. I don't know why your right code has a component with zero freqeuncy and amplitude. Can you explain? Of course your left code is useless to tell what you are doing, because all configurations are hidden.

Here's a quick draft how to calculate and sum the harmonics for a square wave with an adjustable number of harmonics. You can probably adapt it to your problem.

 

[Sachindian]

Hello Altenbach

I am trying to do a similar stuff. But in my case i have custom Amplitude and phase for each harmonic.

I have Written the code in a block for your reference. Its a custom signal generated from an inverted plant. Feedforward control. The reference signal is a triangular signal

ref -> G(inverse) -> u-> G(plant)-> y (output)

I am generating the signal u offline by fitting a polynomial on the plant freqency response and using the coefficents of polynomials to calculate amplitude and phase of the system at each harmonic and generating the input u to the plant by summing the harmonics.

I am not getting the output. Could you please suggest what is the problem with the code.

Regards

Sachin

[altenbach]

Autoscale your graphs on the right. Wire a TRUE to the reset terminal of the "sine waveforrm" generators.