Hey you all, i am new with IGBTs and I really doubt what they mean by 1200V and
Hey you all, i am new with IGBTs and I really doubt what they mean by 1200V and
60A by that tiny device.I have worked with thyristors all my life and IGBT looks so small. It works fine for upto 40V ,but blows whenever I want to goto Real 440V. I seem to have taken all the care,but how do you design lead connection for 20A in such a small device? How do you cool it? It just blasts whenever I put it on full 440V,the score is rising,any suggestions?
not PWM it? full on saturation !
IGBTs will not tolerate any overvoltage, so if switching an inductive load, clamp the collector somehow - this automatically occurs for a half-bridge, (assuming the igbt has an associated antiparallel diode, which most if not all do) as long as the inductance is kept small enough that L*dI/dt + Vdc < 1200V.
a piss-weak gatedrive is another great way to blow up an igbt - miller capacitance can make your igbt do the exact opposite of what you want. likewise ensure that gate inductance is very low.
and finally, you have to be able to suck out the heat.
I've happily used 600A 1200V IGBTs at 900A on a 950Vdc bus, with no problems at all - including operating into a dead short (fat wide strap bolted across one IGBT), by doing nothing more than following the aforementioned points.
Cheers Terry
i am using a parallel resonant load circuit,in a bridge ,feeding constant current through a large inductor.my problem is a small short circuit i have to create to change over current from one arm to other.as you mentioned if i dont give this overlap a large over voltage would occur.I think i am having problem in deciding this short circuit time,because a thyrister would switch off naturally,whereas in this case i have to decide the on off signal.
I don't think anyone's mentioned that you shouldn't reverse bias these parts either. Your thyristors simply self commutate; IGBTs can go kaboom.
While the intended overlap may prevent overvoltage due to coupled energy, it won't protect against uncoupled leakage terms - so you'll still likely need something there to catch overshoot. It's hard to tell without looking at even a crude diagram.
RL
Are you turning BOTH igbts on at the same time on one side? If so then thats your problem, at full gate drive voltage you have about 5uS before destruction. If you reduce the gate drive voltage to the minimum necessary for conduction you can extend the safe time to around 50uS. These are typical numbers it's very device dependent check your data sheet.
Have something to add? Share your thoughts — no account required.
Ask the community — no account required