output voltage fourier transform of a SPWM 3 phase inverter

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sooyassine1

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Hi,
I'm designing a sinusoidal PWM 3 phase inverter, i need to analyze the output voltage in order to know about harmonics magnitudes for different frequencies. I calculated the fourier transform of the output simple voltage (manually) , but probably i didn't found the correct result.
I need some documents on this topic
 
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Can you give more details on your pwm please method of switching,freq,etc

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Can you give more details on your pwm please method of switching,freq,etc
 

it s a sinusoidal PWM with a switching frequency fpwm=6000Hz and the grid frequency is 50H, this PWM is made by the intesection between a reference signal (sinusoidal with f=50Hz) and a carrier triangular signal (Fpwm=6000Hz)
 

How did you sample the data? Can you post the data here?

Most digital oscilloscopes will have a built in FFT math function which should make this easy.

If you did the calculation manually, then it might be a problem with window size, windowing, aliasing, etc.
 

I can not use an oscilloscope, i m still in the conception stage! I can know about my signal's FFT by simulation on PSIM. but i need to master that theoretically because i need to program my output line voltage on MATLAB.
 

Well if you're just simulating, then it should be a matter of getting the raw data and dumping it into matlab, then doing an FFT. Or you could build the simulation entirely in matlab. Try to make sure that either the duration of the sampled data is an exact integer multiple of your fundamental period, otherwise you'll end up with an incorrect result (or you'll have to apply aggressive windowing).

One quick tip: using a dual slope (triangular) ramp waveform will give lower distortion than using a single slope (sawtooth) ramp.
 

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