Why do my IGBT´s blow

[gunni]

On two occasions I have had a IGBT blow now.

First time I had been driving for a couple of months,
then one time pulling hard out on the motorway running through 2nd, 3rd, then into 4th and duhh.........
no running engine.

I didn´t have my laptop so no problem fixing.

This time I was pulling hard out of a roundabout in 2nd, 3rd, and then 4th and duhh..
I knew what had happened and had my tools so into a garage rolling and swapped to another igbt.
and adjusted the software and off I was. No I had driven this morning at speeds of 90mph+ (4500rpm) for at least solid 40minutes without any issues.
then driving back and only after 20minutes this happened.

What could be causing something like this?
dwell is 3.01ms at 14V and vems sees voltage of about 12.5v according to megatune.
There is only one ignition output in use for 6cylinders.

and I have revved to past 6k on number of occasions and this did not happen ....

[Bat]

Hi,
Check the earths and power feeds to VEMs. What is the voltage measured at the econoseal plugs?
I'm guessing that you have a suitable heatsink for the IGBTs?
Is the feed to the coil fused?
Cheers,
Gavin

[rob@vems.co.uk]

I'm guessing heat and

Try moving the IGBT to the furthest part of the board so that the case would be cooler.

Also check the max current of the IGBT and make sure that you have a decent fuse inline with the coil and control line.

[gunni]

My flyback wire was almost separated yesterday and I cut and fixed it.
Can the fact that the wire was about to snap, meaning that about 5% of it was hanging together
when I touched it it snapped and I had to rewire.

I wish I had a log of what happened exactly when the igbt failed but you know how it is.

the day before I gave it full throttle from 2k in 5th gear to about 4-5k. which took a long while and nothing happened.
it was hotter on that day then yesterday.

Does VEMS automatically lower dwell for higher rpm´s using one coil?

There is something going on , and I want to be able to use any igbt as well, not just one specific one
When I touched the case it wasn´t that hot really

[rob@vems.co.uk]

Its difficult to say really... Have you considered changing the coil?

Rob

[gunni]

Yes.
It´s done more then 200k miles,.
and could be breaking down and taking up to much current.
If I had a picoscope for instance I could check if the
coil is operating right.

I´m going to wasted in the fall anyway.

I was looking in the wiki and came upon some various drivers. Is there a strongest one?

[mattias]

Are you certain that 3 ms is the required dwell to get the coil charged?
What is the size of the fuse ?

[gunni]

I don´t have a fuse.

And 3ms is what I got in a file from you I belive.
Steffan with a M30 engine.

If this is Mattias from Sweden

[mattias]

Install a fuse. Unless you have really good idea for the proper dwell for your coil you're really gambling with the IGBTs. Even then I've seen cases where the IGBTs aren't up to the job, like with the later M30 engine coils in BMW 7-series from the late 80s/early 90s.