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Em 11/08/2014 07:45, Dorian Black via Tesla escreveu:
Hi,
I've noticed all my IGBT Vce on-voltages (and many I saw online) have a slope-nature, going from some significant voltage at turn-on down to a minimum at the end of the half-cycle. I find this hard to explain as with zero-current switching that is the point where current is a minimum and should hence yield a minimum Vce.
Here's a link to an image on 4hv forums that shows this:
http://4hv.org/e107_files/public/1383943659_599_FT144747_aaa.jpg
It's necessary to see exactly how this waveform was measured to comment.
Verify if there is something, a current transformer with excessive
impedance for example, between the oscilloscope and the driver output.
In a high-power setup even interference in the oscilloscope probes
(induced voltage in series) may happen, and a large current may flow
through the ground connection of the oscilloscope, affecting the mesurement.
