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Re: [TCML] Gate Drive Waveforms Ringing

Another thing i have noticed is that taking the measurements
differentially or single ended makes a difference. For me, when I
measure the output of the drive electronics or the gdt, if I use a
single scope probe I get ringing just like in your picture, but if I
use two probes and set the scope to 'subract', (differential
meausurement) with the grounds tied together and floating, I get a
nice square wave. I dont quite understand this, as my drive
electronics are isolated from mains ground (different story for the
h-bridge, Im just refering to the control and drive electronics), so
it shouldn't make a difference; maybe its some kind of radiated
common-mode noise?


On 8/19/09, Brian <brianv@xxxxxxxx> wrote:
> Hi Jesse,
> Actually this is an unloaded waveform, there is no primary at this point I
> was only phasing this H-Bridge when I noticed the ringing. I think what I am
> going to try is using magnet wire to wind both primary and secondary on each
> of the GDT and see if this is a leakage inductance problem. Right now I am
> using parallel winding on the primary, 10 turn primary and 20 turn secondary
> on each of the GDT, now I did reduce the number of turns on each of the GDT
> to see if perhaps that was the case, and here is what I found, if I leave
> one of the GDT's at 10 turn primary and the other at 9 or 8 turns, then the
> ringing pretty much goes away, if I reduce both of them the same amount the
> ringing comes back. I can honestly say I have never seen this type of
> problem, I have seen ringing and have always been able to clear it (well
> usually) but this one is just trying my patients.
> Thanks
> Brian
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