IGBT Output Spikes
Graham Armitage, Thu May 12 2016, 09:52PMAfter destroying an IGBT brick I am trying to phase tune the new one so it doesn't happen again and getting a strange result. I can eliminate the spikes on the half bridge output, but only on one side. I am using a CM300-24H half bridge brick with the UD2.7c driver and 5.1ohm gate resistor. To scope this I have an isolation transformer and running it at low power (bus voltage of about 100v) Probe grounds on the negative bus, one probe on G2 and one probe on E1C2 (output). The photo shows what is happening. Top trace is the Gate voltage and bottom is the output voltage. There is a slight overshoot on one side of the gate signal which may be causing the large rise on the output, but the spike is really large. I can't seem to get either to disappear with tuning. Would love some suggestions. Thanks
Re: IGBT Output Spikes
Mads Barnkob, Fri May 13 2016, 04:36AM
You can find an explanation on the large switching spikes at low voltage testing here:
Mads Barnkob, Fri May 13 2016, 04:36AM
You can find an explanation on the large switching spikes at low voltage testing here:
Re: IGBT Output Spikes
Graham Armitage, Fri May 13 2016, 12:13PM
Thanks Mads. Good thread. I am still not understanding why it's only happening on one side. Wondering if one of the GE reverse diodes (2 x 1N5934BG) is failing and not clamping the gate voltage appropriately??
Graham Armitage, Fri May 13 2016, 12:13PM
Thanks Mads. Good thread. I am still not understanding why it's only happening on one side. Wondering if one of the GE reverse diodes (2 x 1N5934BG) is failing and not clamping the gate voltage appropriately??
Re: IGBT Output Spikes
loneoceans, Sat May 14 2016, 12:45AM
Have you read this page in detail? - It should answer many of your questions on using the UD2, likewise many of the questions on the other linked thread. 
loneoceans, Sat May 14 2016, 12:45AM
Graham Armitage wrote ...
Thanks Mads. Good thread. I am still not understanding why it's only happening on one side. Wondering if one of the GE reverse diodes (2 x 1N5934BG) is failing and not clamping the gate voltage appropriately??
Thanks Mads. Good thread. I am still not understanding why it's only happening on one side. Wondering if one of the GE reverse diodes (2 x 1N5934BG) is failing and not clamping the gate voltage appropriately??
Have you read this page in detail? -
It should answer many of your questions on using the UD2, likewise many of the questions on the other linked thread. Re: IGBT Output Spikes
Proud Mary, Sat May 14 2016, 10:17AM
How about some transils?
Proud Mary, Sat May 14 2016, 10:17AM
How about some transils?
Re: IGBT Output Spikes
Graham Armitage, Sat May 14 2016, 12:03PM
That page is a permanent bookmark :) Super helpful info. I found what could be the problem. One of the diodes across the gate resistor was dead and shorting out the resistor. Probably what blew the IGBT in the first place. Was sure I checked it but I guess I missed. Would explain why I was seeing weird behavior on one side only. Thanks for the help.
Graham Armitage, Sat May 14 2016, 12:03PM
loneoceans wrote ...
Have you read this page in detail? - It should answer many of your questions on using the UD2, likewise many of the questions on the other linked thread.
Have you read this page in detail? -
It should answer many of your questions on using the UD2, likewise many of the questions on the other linked thread. That page is a permanent bookmark :) Super helpful info. I found what could be the problem. One of the diodes across the gate resistor was dead and shorting out the resistor. Probably what blew the IGBT in the first place. Was sure I checked it but I guess I missed. Would explain why I was seeing weird behavior on one side only. Thanks for the help.
Re: IGBT Output Spikes
Mads Barnkob, Sun May 15 2016, 05:12AM
Generally it is a good idea to disassemble everything on the secondary side of the GDT to check it after IGBT failures. I have often seen gate resistor take damage.
Mads Barnkob, Sun May 15 2016, 05:12AM
Generally it is a good idea to disassemble everything on the secondary side of the GDT to check it after IGBT failures. I have often seen gate resistor take damage.
Re: IGBT Output Spikes
Graham Armitage, Tue May 17 2016, 04:04AM
Yup - lesson learned. Will definitely check there next time - hopefully not too often! Well, both coils up and running again. Was able to phase tune nicely. Thanks again for the help.
Graham Armitage, Tue May 17 2016, 04:04AM
Yup - lesson learned. Will definitely check there next time - hopefully not too often! Well, both coils up and running again. Was able to phase tune nicely. Thanks again for the help.
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