Learning Forum

[ranjanpal999]

Hi,

I have simulated a 3-Phase Induction motor in MAXWELL.

On performing FFT (Fast Fourier Transform) over the current data for the interval (5 s-20 s), I can observe peaks at fundamental frequency of 50Hz and its odd harmonics.

However, in an actual experimental data, peaks can also be observed at even harmonics i.e. 100 Hz, 200 Hz,..

Why is that, I am not able to observe the even harmonics in MAXWELL simulations.

Can somebody please let me know where am I going wrong ?

[icellb1]

Hi,nMay I ask how you perform FFT in maxwell? It'll be great if you can share screenshots of your settings.nAlso, could you expand your current waveform(your left picture) to show what a period look like?nAlso, did you FFT on the exact same data in maxwell and in experiment for comparison? For example, the simulated current data may not be the same as your experiment measured current data.n

[ranjanpal999]

Hi icellb1nI have first exported the current data into a csv file.nThen, we need to select the time duration in which we wish to perform FFT.nFFT codes can be written in Python/MATALB as per your feasibility.nThe simulated current data and experimental measured data are almost similar.nFor experimental data, I performed FFT on 15 seconds of data. Likewise, I performed an FFT on simulated MAXWELL data.nHowever, even harmonics are not visible in MAXWELL. I suspect that there is some settings which needs to be enabled in MAXWELL.nFor example to see triplen harmonics we need to disable the Y connection: /forum/discussion/12765/current-data-of-transient-anlysis-in-maxwell-for-3-phase-induction-motor#latestn

[icellb1]

Hi,nWe have to ensure the current data are exactly the same to get the same harmonics. There isn't special FFT operations in maxwell as long as integer number of periods are in the selected time interval to perform FFT. The settings you mentioned is to get simulation results closer to real life experiment results, it's not for letting maxwell perform better FFT. There could be many reasons that the simulation result is not exactly the same as measured/real life result.n

[ranjanpal999]

Hi icellb1,nYou have got me correct that I wish to have simulation results closer to real life experimental results.nIs it possible for us to change some settings in MAXWELL and get the even harmonics ?n