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Re: [TCML] Gate Drive Waveforms Ringing



I did measure the frequency of the ringing and it is right around 11MHz so I
think just adding the RC snubber across the DC rails will ultimately take
that out. I completely forgot to add that when I did the assembly. And also
the ringing on the Gate drives is still a mystery to me as I did not have
that when I ran the coil the first time however it did eventually show up. I
thought maybe a bad solder connection somewhere as this is only a prototype
unit right now and the boards are home made with out any solder mask on the
boards and they can be a pain to solder sometimes. You know the interesting
thing is I had this coil running and sparking until I turned the voltage up
and then it just stopped, that is when I checked the signals again and found
the ringing on the gate drives which was not there before. However I am sure
the ringing was on the output of the H-Bridge considering I did not have any
AC bypass circuit in place and that is probably why it took out one of the
IGBT's trying to switch 11 MHz at an increased current is probably not good
for them. So I will add that and then look at the wave forms again see what
it looks like and if all is good then I will fire it up again and hopefully
have a nice running coil.


Thank again for the input 




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