Massive igbt's - Page 1
Forum section: electronics / projects

author: VoidsWarranties
author_rank: Contributor
timestamp: December 21, 2016, 07:45:20 pm
content: I found this massive igbt rated at 600a and 1200v for 30$. My question is if this is too good to be true and how simple it would be to run around 4.5Kw DC through it at around 24v. Would it be able to handle this load? It would be powering an arc used for welding.Sent from my iPhone using Tapatalk

author: mk_
author_rank: Regular Contributor
timestamp: December 21, 2016, 07:55:39 pm
content: Quote from: VoidsWarranties on December 21, 2016, 07:45:20 pm200A are not really something this IGBT would be afraid about.... as long as youswitch really fast (keep the switching time unter 100nS, which requires a powerfull gatedriver),keep the whole stuff cool (there is Uce-sat. Multiplied with your weldingcurrent you got the wattage which has to be taken off the IGBT)andtake care when switching of because of L sitting in every cable....and while experimentung - wear protection glasses and earprotecting. The boom could be loud and shrappnels could have high speed if something blows up (and it will...)have funmichael

author: wraper
author_rank: Unknown
timestamp: December 21, 2016, 08:53:32 pm
content: IGBT is not a part for low voltages, they excel at very high voltages where MOSFETS cannot work. Using it at 24V would be highly inefficient because of the voltage drop. You should expect about 280W power dissipation on it. Better go with MOSFETS, will be much more efficient, you will easily achieve less than fifth of that power dissipation.EDIT: also you can easily connect MOSFETS in parallel without worrying much about uneven current distribution, Connecting IGBTs in parallel is not that easy and have serious downsides.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 22, 2016, 12:17:53 am
content: No. You'll drop about 20% of your total supply voltage in the transistor Vce(sat)!Tim

author: mmagin
author_rank: Frequent Contributor
timestamp: December 22, 2016, 03:45:57 am
content: I am not that experienced with this sort of thing, but the warning to "take care when switching of because of L sitting in every cable" is right!But anyway, you can get the IXFN360N10T from Digikey for just $21 (USD). I just took a look for the cheapest thing that can handle twice the voltage and current you're considering and which comes in a SOT-227 package, you at least have a decent hope of losing the 92 watts dissipated in it. You will need a serious gate driver tooThe datasheet says nothing about safe operating area, so I assume linear operation is right out.(Yes, I've been looking for an excuse to play with parts like this sometime.)

author: Jeroen3
author_rank: Super Contributor
timestamp: December 22, 2016, 09:06:31 am
content: Quote from: mmagin on December 22, 2016, 03:45:57 amThat is because it's not one IGBT. It's an array. Youhave touse them either all on, or all off. Halfway would mean half of them being on, instant firework.And when they blow, they can releasetoxicberyllium-oxide, which is the ceramic used as insulated thermal interface.With these things you also have to use a decent gate driver. If they break, it's often the fault of the driver being too slow. Or there are severe voltage peaks returning from whatever it's driving (the cable L's), but you should notice since the varistors will then also be vaporized.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 22, 2016, 09:22:27 am
content: Well... BeO isn't used in any but the fanciest semiconductors. It may've never been used at all with industrial IGBTs? I don't know.DBC (direct bonded copper) with AlNO ceramic insulator is the most common today.Anyway, the base doesn't crack when the dies explode. The enclosure likely will, but that's only a plastic shrapnel hazard (and that, only if you have enough energy storage, or supply power, to cause an arc flash blowout).Tim

author: max_torque
author_rank: Super Contributor
timestamp: December 22, 2016, 11:37:22 am
content: I always smile a bit when people say "i've got this massive transistor, i'm going to make a huge power supply" or what ever!Having the component does not a practical system make. For some reason, i guess perhaps because there are no moving parts in an electronic power switch, people think you just wire these things up and off you go!For example, if i gave you the piston our of a Formula one engine, could you build the 800hp engine to use that piston. No, no you couldn't because that one piston is just a tiny part of the entire, extremely finely tuned and ultra high performance system.It's the same with having an IGBT. It's just a dumb IGBT, to make it work, you need all the finely tuned supporting systems, gate drivers, power supplies, heat sinks, snubbers, dclink caps etc. Then you need to ensure you are operating the IGBT at a suitable set of conditions, in terms of switching times, deadtime, di/dt etc etc. Then there is the further issue, telling what went wrong when it, almost inevitably, does. The reason a commercial high power switching device (VFD,DC/DC, Inverter etc) cost a lot of money is NOT because of the parts within those devices. It's because a lot of very clever people spent a lot of time and money getting them to work properly. An Igbt, when operated correctly can carry a LOT of power in a tiny volume, so when it goes pear-shaped, they is generally not a lot left to tell you what actually went wrong. Then finally, do you have the necessary instrumentation to be able to monitor the actual state of the IGBT, to work out if you are operating it correctly. High voltage, low capacitance differential probes, high speed zero flux current sensors, multichannel oscilloscope etc tecPower electronics is NOT a beginner subject, sorry! (if you have deep pockets, are willing to learn, and accept that things will not work the first, second, or probably 10th time then yes, you can DIY it, assuming you also understand an mitigate the risks as necessary)

author: Jeroen3
author_rank: Super Contributor
timestamp: December 22, 2016, 11:43:16 am
content: Yes. The price of the igbt is small compared to the hours of development you'd have to put in.