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Need a up-to-date refresher, Mosfets and IGBTs

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Killa-X

Wed Nov 08 2017, 06:42AM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
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Posts: 1039

I'm just curious, Has much changed since 2012, in terms of whats considered the 'oh everyone runs those!' mosfets and IGBTs?

Years ago in 2012 I remember everyone was using IRFP460s for SSTC's and then for small DRSSTCs everyone was using 40N60s

Is this still true today? Or are there more newer, faster, 'defaults' everyone tends to go towards? I ask this because I still have a bit of secondaries laying around. I wouldnt mind giving them some life, especially the little secondaries. However, I dont want to go out and shove in the mosfets I ran back in 2012, and find out now in 2017 everyone loves ______ which run soooo much cooler and more effecient. Having a 3D printer now and everything, I feel it would be fun to build one again. Just lightly dusting back into things, I got other hobbies keeping me busy and taking my money away...

Plasma

Thu Nov 09 2017, 03:36AM

Registered Member #61406 Joined: Thu Jan 05 2017, 11:31PM
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Posts: 268

Based on special 2.5kv 100amp continues is about 50,you can get 4.5kv igbt, it has made large bounds

loneoceans

Sat Nov 18 2017, 05:33PM

Registered Member #4098 Joined: Fri Sept 16 2011, 09:26PM
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Posts: 236

May I recommend checking out the FGH60N60SMD or FGA60N65SMD from Fairchild/Onsemi. They are not particularly new but as far as I am aware of, represent the best balance of cost with performance. There are more exotic parts such as the 75A eqv. from Fairchild (but has no mounting hole), and the IXXX line from IXYS (but very expensive), and better looking IGBTs on paper (but much smaller dies).

While some people have pushed these TO-247 IGBTs to 300Apk in DRSSTC mode, I prefer to try to keep within datasheet ratings these days and have paralleled bridges or devices. They have positive tempco and if you design correctly it should be no problem. The 60N65s look like they have exactly the same die but with a slightly different TO-3P package. I no longer use mini-Bloc transistors since they're simply too expensive and not worth the $/performance IMHO. Regardless, would still appreciate any new suggestions!

Killa-X

Mon Nov 20 2017, 03:12AM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039

loneoceans wrote ...

May I recommend checking out the FGH60N60SMD or FGA60N65SMD from Fairchild/Onsemi. They are not particularly new but as far as I am aware of, represent the best balance of cost with performance. There are more exotic parts such as the 75A eqv. from Fairchild (but has no mounting hole), and the IXXX line from IXYS (but very expensive), and better looking IGBTs on paper (but much smaller dies).

Thanks for the info, I may look into such. I just have a handful of secondaries around and it would be nice to put some of them to use. Mostly SSTC in mind, still got a secondary I planned for DRSSTC, since the 7ft tower was taking up too much room. And eventually, one day, i had hopes to do a QCW since I got a lot of ferrite cores and such yeaaars ago and never made anything with them.. it was back when i was talking with Eric, and he recommended me a coil size...cores..etc. so..one day! Heh

paulj

Mon Nov 20 2017, 05:36AM

Registered Member #59353 Joined: Sun Apr 17 2016, 02:08PM
Location: France
Posts: 84

Hello,

there is a Brazilian who uses modules
CM75BU-12H,

the kit one tesla use fga60n65smd, it's a cool kit.

Hydron

Tue Nov 21 2017, 08:53AM

Registered Member #30656 Joined: Tue Jul 30 2013, 02:40AM
Location: UK
Posts: 208

I have just ordered a bunch of FGA60N65SMDs myself after quite a lot of comparison and evaluation.

I had the following wish list when picking IGBTs:
- Reasonable Qg to make driving at 350kHz for 10-15ms at a time not too difficult
- Fast, with low Eoff (will be some hard switching - OFF only - in QCW)
- Cheap (am running multiple parallel bridges, so needed a few!)
- Low Rjc to keep die temperature swing down

After hours of searching I ended up back where I started - overall the standard choice of 60N65s(/60N60s) were the best option, and are well tested. Second pick was the FGY75N60SMD, with the following pros/cons compared to the 60N6x parts:

Cons:
- about 50% more expensive
- more Qg (though not excessive)
- slightly higher Eoff per amp, though significantly lower fall time, so a little dubious about how much difference there really is here
- no mounting hole for those who need this (am using clips so I don't care)
- no 650V rated option, only 600V (though I suspect the 600 vs 650 is mostly packaging related, and can likely be disregarded)

Pros:
- no mounting hole to reduce heatsink contact area
- lower Rjc thermal impedance, especially for the co-pack diode (which has less than half of the 60N65 value). Diode is only important if using freewheeling or phase shift QCW
- maybe easier to find?

I was very close to getting the 75N60s, mainly due to the thermal impedance stuff, as I plan to use the freewheeling diode quite a bit for phase shift QCW modulation. In the end the 60N65 seemed likely to be good enough, and if I have issues then there's still an upgrade path!

As a heads up, stock seems to be a bit scarce of some of these parts - Mouser had the best price on the 60N65s so I bought from them, but they only have 11 left now and a 1 YEAR lead time on more!

loneoceans

Tue Nov 21 2017, 09:41PM

Registered Member #4098 Joined: Fri Sept 16 2011, 09:26PM
Location:
Posts: 236

Hydron that's the 75A part I was talking about but without mounting hole. The 60N65s are good. I've used them in hard switch QCW and they work very well. It's really a matter of which I can purchase cheaper (vs 60N60). A side note, do check arrow.com. A while back I bought a whole rail of them for very cheap but it seems like prices have gone up a little. Also another note for Hydron - you can consider driving the IGBT gates at a lower voltage to reduce gate drive. E.g. use +-12V by winding paralleled secondaries for your GDTs. Works great esp with paralleled bridges for 60A operation per IGBT.

Hydron

Tue Nov 21 2017, 11:16PM

Registered Member #30656 Joined: Tue Jul 30 2013, 02:40AM
Location: UK
Posts: 208

Thanks for the confirmation about the choice, and the suggestions.

Arrow wasn't an option, but I've just looked again and could have saved ~10% (after taking into account shipping) by buying from Avnet Europe. Good to know for next time, and the pain of finding out wasn't to bad - these are well priced parts!

As for gate charge/voltage, I was already planning on running at 18V rather than 24, but upon re-reading the datasheets I probably should drop it further to 15V or so (to give a bit more margin for supply droop than 12V would). I'm using the braid/core of RG-174 as primary/secondary windings to give very low leakage L, so would need to drop the primary voltage rather than changing turns ratio to get a lower voltage.

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