I found this:
http://www.kpsec.freeuk.com/components/ic.htm#logic
seems like 4000 series IC gates can use 3-15volts which is perfect for me. I don't really want to have to regulate the voltage and complicate things even more.
Wow!
Did you read this?
Now my IGBTs are 54amp 400w rated, can I just wire 3 or 4 in parallel to drive more amps?
The general answer is no, however sometimes you need to do this, so there are ways around it.
Here is a technical explanation, and
here is a practical one. (They also happen to be the top 2 google hits for "IGBT in parallel" so you're lucky I didn't give you a
LMGTFY link)
Note that if you have 4 IGBTs sharing 125A, the second recommends you use a 160 milliohm 1% resistor in series with the emitter of each device. It would have to be rated at about 10 watts. Not sure where you're going to find them on the shelf anywhere...
I also read that IGBTs can handle up to 10 times more amps for a short amount of time so maybe even one will handle my 125amp, I'll put a heat sink on it if need be.
No, I would not recommend this. (I recommend you read
this) And you're already going to have a pretty large heatsink on those IGBTs. In fact, you're going to want to have all of them on a large heatsink to keep their temperature close to equal.
You've omitted telling us what IGBT you have, so I'm assuming it's
this one.
You're looking at a saturation voltage of near 4.2V max at the upper end of the temperature range. So assuming 35A through each one, that's a power dissipation of 147 Watts (for each device), or 588 W in total. You'll need a MASSIVE heatsink unless the load is only on for brief periods.
If the load is switched frequently, things get worse because the power dissipated during switching can be many times greater than the steady state loss.
Of course there's thermal inertia involved too, so if this is only used once every 10 seconds to discharge a capacitor in a few microseconds, then your heatsinking requirements will be far less. The device I've found has a pulsed current limit of 160A, so pulses of 125A *may* be OK. The question becomes -- how do you determine that the current is 125A?
Hey guys I decided on a nor gate cd4077, just wondering: can OUTPUTs on this quad gate be connected together to make a stronger signal? Say drive one IGBT with 4 outputs form the gate?
Bwahahhahahahahha. NO! You need a proper gate driver or your IGBT will dissapear in a puff of smoke. You may beed several amps of gate current to turn the device on quickly and the milliamps you'll get from a logic gate (even multiplied by some small number) won't cut it.
Read
this for an explanation. It's pretty technical, but it does provide a link to an online calculator.
