help with converter waveforms
help with converter waveforms
(OP)
We have measured quite high levels of even current harmonics in the input to our VSI npc drive system (24 pulse, obtain by two 12 pulse transformers shift by 7.5deg with respect to one another). Attached are the 6 pulse current waveforms on the secondary side of one of those transformers. Does someone have guidance, or otherwise an online reference, with assisting to interpret the converter waveforms and what we could further investigate to find out source of such harmonics. All references I find with harmonics is related to the characteristic harmonics that are expected in such systems, e.g. 5th, 7th, 11th, 13th etc but no guidance or information on waveforms found in practise that might not represent the textbook.
thanks.
thanks.






RE: help with converter waveforms
RE: help with converter waveforms
Here is a class I took at University of Idaho that is still online that might help.
http://www.ece.uidaho.edu/ee/power/ECE528/
Here are the two text that went with the class. An old pdf of the Dugan book can be found online and I think if you have an IEEE membership you have access to it, too.
Primary Text: Electrical Power Systems Quality, Third Edition by Dugan, McGranaghan, Santoso,
and Beaty. (McGraw-Hill, 2012, ISBN 978-0-07-176155-0). (Abbreviated PSQ in class)
Secondary Text: Fundamentals of Electric Power Quality by Surya Santoso. Available at
Amazon.com (Abbreviated FPQ in class) Note: the ISBN number of the latest edition is:
978-1440491023. This is the Winter 2010 edition. The 2009 edition is also acceptable
RE: help with converter waveforms
" We are all here on earth to help others; what on earth the others are here for I don't know.
" -- W. H. Auden
RE: help with converter waveforms
Typically a single rectifier fails but it's very obvious in the patterns with pulses missing.
RE: help with converter waveforms
HH: Thank you for the course link, from first glance it looks like good reference material
RE: help with converter waveforms
What did the other one look like?
Are the rectifiers in series or parallel?
RE: help with converter waveforms
the rectifiers are in series.
we were using flexible rogowski coils for current measurements. could that result in a false interpretation of zero offset?
RE: help with converter waveforms
RE: help with converter waveforms
RE: help with converter waveforms
RE: help with converter waveforms
I'm wondering if this is could lead to other issues in the driven mechanical system? (Electric propulsion application), we have other issues such as cavitation. I've been reading up on torque pulsations and wonder if these measurements show our system is unheathy?
https://www.researchgate.net/profile/Vaclav_Kus2/p...