MV Drive Significant Harmonics

[sky2020]

What are the significant harmonics of a multilevel VFD? If we have 5 stages per phase and 300Hz carrier frequency, I assume the carrier will generate at 2*5*300 = 3000Hz. What are other significant harmonics? 2000Hz and 4000Hz? and why?

 

[jraef]

In order of most to least significant, 5th, 7th, 11th, then the rest above that are individually insignificant but can end up cumulatively noticeable.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[electricuwe]

Please indicate if you are talking about line side harmonics or output side harmonics. Usually with this kind of drive neither is causing major issues, if the transformer is designed properly and the modulation is implemented well. Look of publications on "casacaded cell inverter" or the publications from former Robicon (now part of Siemens) who invented these inverters many years ago. As the main patents have expired many years ago there are now a lot of companies selling similar designs.