Drive/gate resistor on IGBT

[jeffmarsh750]

Want to try this IGBT ( http://www.digikey.com/product-detail/e ... ND/1923117 ) as an ignition driver and was wondering If anyone thought I would need a 1k or 330 ohm resistor to drive the gate ? Or is it not needed with the MS3 pro3.

Any thoughts on adding a 1m ohm resistor as a pull down to switch off faster ?

Thanks

[dontz125]

Looking at the datasheet, it has in integral 100 Ohm gate resistor as well as a 10k-30k gate-emitter pull-down resistor. Sounds to me like you could install it as-is, with no extra parts.

[jeffmarsh750]

Thanks, That's what I was thinking and if I wanted a lower output current I could add a 1k to 330 ohm resistor to the gate.

[dontz125]

That's not how an IGBT works; output current is controlled by input voltage, like with a MOSFET. You'd have to use a voltage divider to reduce the Vge, and that could get silly, fast.

Limit your primary coil throughput with dwell, not gate resistors ...

[racingmini_mtl]

All the specs in the datasheet are given with a 1k gate resistor. I would use that.

Jean

[slow_hemi6]

Yeah I looked at the data sheet and fairchilds test rig had a 1k gate resistor with a 5v logic input. Should tell you something IMO. Turn on voltage is only about 2-2.5v or above.

[jeffmarsh750]

I want the maximum current without any safety features. If it fails, I would prefer a fail to zero. 100.00 to build an hi perf box is cheap compared to lifted heads and split blocks with 3 piece cranks. These drivers actual are rated up to 8 volts gate charge. All their tests sheets and some specs are rated with 5v input and 1k resistor. The lowest volts used in their graphs is 3.7v which limits the current at 35 amps, and has a slower rise time. 8volts gets it done quick and provides 50+ amps. I will test and report back. Our testing with the quad spark box and IGN-1a coils has been quite successful so far and we would like a margin of safety.

[slow_hemi6]

The coil will melt down well before 35A let alone 50A so this should be a very strong driver if supplied by a sensibly rated fuse.

[jsmcortina]

What coils are you using that need 50A ?

James

[jeffmarsh750]

At this point I don't have 50 amp coils but will possibly need something like that with the nitro Harley. With the NOS and turbo bikes what we need is ignition boxes that don't mis-fire at high rpm and high boost or with a 250 shot on a 250hp motor. They probably won't even pull 25 amps but it will be good to know we can run maximum dwell, high voltage, and high rpm in waste spark. When we tested a few different setups it went like this. All tests normally aspirated at this point. All tests run up to 11500rpm and they see 13500rpm at the track. All tests were with over 15volts.
1) we tested Dyna ignition and carbs.Waste spark. Made 243hp no mis fires.
All tests below with the same carbs and jetting and timing.
2) tested MS3pro with carbs, used the Quad Spark and blue .5ohm coils (Dyna blue, same as above)at 3ms dwell and 1ms spark duration.Waste spark. Made 245hp
3) At 4.5ms of dwell it mis fired at 10500rpm.
3) Tested GM LS2 (non heat sink coils) Sequential mode. Mis fired at 3.5ms dwell at 8500rpm. turned dwell to 3ms and made 238hp. Turned dwell up to 4.5 and it misfired at 8000rpm but we pulled through it and it mis fired again at 10500 but made 241hp
4) Installed 4 IGN-1A coils in sequential at 3ms dwell and made 243hp. Turned them up to 6ms dwell and it mis-fired at 8500 we shut it off. Turned dwell back to 4ms and it made 244hp again.
Bottom line is with this high of voltage and the dwell turned up a bit we get mis fires. Sure we can keep the dwell around 3ms, or we can use a 13 volt battery but we would prefer to have a margine of safety. If a NOS bike mis-fires it can lift the head off the block. Just as an 8-1 wheel makes no more power than a traditional 1 magnet/1 sensor waste spark trigger. A 36-1 makes no difference either just adds complexity and more crank trigger problems and lost sync. All MS3pro tests above used a VR crank sensor with 8-1 wheel and when in sequential mode used a Hall sensor on the cam. We actually made more power with waste spark by 2hp. That could have been because that was done 4 days earlier but the baro and temps were the same.
We will build a new module for waste spark and test with the blue coils again. Find the limits and turn it down to an acceptable level.