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what do you think of these bricks?

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LAN_403

Reaching

Tue Aug 01 2006, 10:36AM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

a few days ago i came across a bunch of 9 igbt bricks from fuji 1MBI400F-060
datasheet:

i got them very cheap for around 5$ for one and the ratings are very good, 600volt 400A continious and 800A peak and relatively fast though, gate capacitance of around 22nF.. so now i wanted to build a real monster drsstc out of them and wanted to know what do you guys think ? what is the best way to drive these bricks, i wanted to use a fullbridge running of +30 - 15volts with a 1:1 gdt for each igbt, should work ? the secondary frequency of the coil will be around 60-80khz .so what do you think?

teravolt

Wed Aug 02 2006, 03:07AM

Registered Member #195 Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111

they will work. go to Steve Ward's web site and find the link for Richie Burrnet's link for the theory and any of the senior members links for more stuff. just read. thats how I figured it out

Marko

Wed Aug 02 2006, 12:30PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

I think he just wanted to pimp out some of his loved bricks

The datasheet you put there didn't work for me tough, this is from catalog

gate capacitance seems to be 38nf, and switching times

0.8
0.6
1.5
1.0

microseconds, probably could be used on lowest frequency you can manage to do (40, 50kHz).

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Wed Aug 02 2006, 03:46PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

not micro seconds, y seconds ,, and 40khz seems very low though, i tested one of them okay up to 120khz, with 140khz the current draw increases and the squarewave is distorted but under 100khz everything is perfect , and that was with a single 9A gate driver ic on 12 volt, the quality of the signal will be much better on a drive fullbridge at -15 + 30volt (already build one for my old bricks)

Steve Ward

Wed Aug 02 2006, 06:31PM

Registered Member #146 Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055

Its hard to really know for sure what the switching rate is, it depends on the load characteristics. But, i think the *delay* times are the most crucial thing, and cant really be fixed. In your case, you will probably need a way to generate a little deadtime, so that you dont get shoot-through. I also would suggest operating at 40khz or even *less*. I run considerably faster devices at 40khz, and the delays are very significant, meaning i have to switch about 1/6th of the peak primary current, or about 250A in my case. With slower bricks, the problem just gets worse and worse. When you hard switch more current, you have to deal with larger, more energetic voltage spikes.

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Wed Aug 02 2006, 08:25PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

mhh, why so pessimistic? you build a drsstc with bricks, many other people done it and i already build a sstc with some older bricks and with a much higher frequency than 40khz. okay, itÂ´ll be a big drsstc but i definately cant get it down to 40khz, and to tune the primary circuit to 40khz when the secondary fres is around 60khz (which is in a possible level) is senseless.. and really, voltage spikes can be a problem, but with some surpressor diodes and big decoupling caps that shouldnt be a problem, delay is the problem, but can it be really dangerous to 800A peak Bricks,okay, when the delay is too long it can result in shoot through but i tested one igbt up to 140 khz and below 100khz i get a perfect signal even with a load, so i dont think itÂ´ll be that tricky to build a good fullbridge out of them for frequencies of around 60-80khz .. iÂ´ve build several drsstcs and never had any problems with the delay times even when i ran 100khz igbts with around 300khz (with my mini drsstc5)
okay, first tests will show what i can make with these bricks, i can make failures, they were cheap and i have 9 of them

Steve Ward

Wed Aug 02 2006, 08:42PM

Registered Member #146 Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055

I agree, i am being a bit pessimistic.

and really, voltage spikes can be a problem, but with some surpressor diodes and big decoupling caps that shouldnt be a problem,

But if the inductance leading to the diodes and decoupling caps is too great (>50nH), the spikes will still be present. This is the headache ive been going through when working with these older bricks, they have too much internal inductance, which means they are meant to be switched sloooooowly to prevent huge voltage spikes from developing across the CE junction. Its a whole new beast compared to the new, very fast, very low inductance IGBTs, in which case, you can usually exceed the ratings with little worry.

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Thu Aug 03 2006, 03:35PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

hehe, just got 2 other bricks from ebay dirt cheap for around 5$ for both, they are halfbridge modules rated at 1200 volts 210A continous and 420A pulsed, and are much faster than the other big fuji igbts, maybe good for a "smaller" drsstc with a voltage doubler,and with only 11nF gate capacitance, means you can run a fullbridge of them with normal gdts and 2 pairs of driver ics at around 100khz

. heres the datasheet

hehe, i like those cheap outgoing auctions

Steve Ward

Thu Aug 03 2006, 05:05PM

Registered Member #146 Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055

maybe good for a "smaller" drsstc with a voltage doubler

Those IGBTs are actually capable of processing slightly more power than the 600V 400A bricks. I bet they could do 10 foot sparks in a full bridge.

HV Enthusiast

Thu Aug 03 2006, 06:46PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Just keep in mind, size doesn't mean everything. You don't need big bricks to get big arcs. Just for comparison, I have a DRSSTC running with a half-bridge of small D2Pak Surface Mount IGBTs (which cost about $4.00 each), putting out over 50" worth of arc.

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