High Voltage Forum

Tesla coils => Dual Resonant Solid State Tesla coils (DRSSTC) => Topic started by: Spuriosity_ on June 16, 2018, 06:20:26 PM

Title: IGBT selection - TO-247 or minibrick?
Post by: Spuriosity_ on June 16, 2018, 06:20:26 PM
I'm currently in the early stages of designing my first DRSSTC, and am at the tricky point of deciding which IGBTs to order. I've noticed that there is a significant price disparity between the TO-247 packaged IGBTs, like https://au.mouser.com/ProductDetail/IXYS/IXGH48N60A3D1 (https://au.mouser.com/ProductDetail/IXYS/IXGH48N60A3D1) versus modules like https://www.arrow.com/en/products/ixgn200n60b3/ixys (https://www.arrow.com/en/products/ixgn200n60b3/ixys). Reading the datasheets reveals that the current rating for the TO-247 units drops off dramatically with temperature compared to 200n60 module.

Could I get around this by attaching large heat sinks, or should I bite the bullet and get some proper bricks?

The secondary has already been wound (and used successfully on a simple SGTC) - its resonant frequency is 174 kHz, with a 360mm diameter toroid atop a 50 100 mm diameter, 460mm long 1300 turn secondary. Ideally I'd like to have >40cm sparks, but I'm not exactly sure what ball park I need my primary circuitry in to achieve this.

EDIT: 1am brain wrote down the secondary radius rather than diameter. Whoops.
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: TDAF on June 16, 2018, 06:28:20 PM
If you wanna buy a brick I suggest you go all in and buy something like a Cm200 or a Cm300

I don't think there's much of an advantage to be gained with these so-called "mini-bricks"
Instead, I suggest you parallel up two full bridges of TO-247 IGBTs like FGH60N60 or FGA60N65

With a good heatsink and some fans to blow air on it, I think you'll be all set ;)

If you're going the bricks route more power to you
I can't really give you any advice on that since I am a brick n00b myself :P
But others on the forums can give you a plenty
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: Hydron on June 16, 2018, 10:12:08 PM
TDAF is correct about the "mini-brick" - price/performance ratio isn't great.

At 174kHz a CMx00 full size brick might be a bit slow, so I'd lean towards using two parallel TO-247 bridges as suggested.

I am also assuming that you mean 500mm LONG secondary, rather than diameter :

If you give some more info about the SGTC setup then you may be able to get some advice on which bits are suitable for the DRSSTC version - e.g. the primary circuit (MMC + coil) may be OK for DRSSTC use, which would drop the costs of building significantly.
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: oneKone on June 17, 2018, 01:59:48 AM
Welcome to the forum.

I can understand where TDAF and Hydron are coming from with the price/performance of mini-bricks, but i like them. they are neat to setup in a fullbridge/halfbridge configuration and they are more robust than a T0-247 package (in my limited experience)

Whats the frequency with the topload on?   Fabrício Franzoli uses a CM75BU-12H on his smaller drsstc that have a frequency of 150kHz and has an ocd limit of 350A. Its a fullbrifge brick and if i'm remembering correctly he buys them from aliexpress.   
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: profdc9 on June 17, 2018, 06:07:55 AM
Another data point.

I am using a full bridge of 8 FGN60N60SMD IGBTs, each with 2 IGBTs in parallel.    I only run at 250 A, because I use pulse skip mode to lower the peak current.  With about 2 kW in I can get perhaps 100 to 120 cm sparks.  All of the videos I made were using this system and so far it seems very robust and capable probably of handling more power than my current circuit can provide.

 [ Invalid Attachment ]

The gerbers for this board are available in the DRSSTC PCB pack if you want to make you own.  The hardest part is making a heatsink, which I made from an aluminium L-channel with heatsink pads in between the TO-247 packages and the heatsinks.  The transistors don't get that hot though, warm to the touch, but not hot.  I blow on the bridge with a fan.

You can easily get two TO-247 for the price of a minibrick, so I think this is a good solution, the only disadvantages being that swapping out dead transistors is harder, and you have to make a custom heatsink, or modify one to be mounted on the back of a pair of transistors.

Dan

Title: Re: IGBT selection - TO-247 or minibrick?
Post by: TDAF on June 17, 2018, 01:06:30 PM


You can easily get two TO-247 for the price of a minibrick, so I think this is a good solution, the only disadvantages being that swapping out dead transistors is harder, and you have to make a custom heatsink, or modify one to be mounted on the back of a pair of transistors.

Dan

About the custom heatsinks
One can easily use the standard 70mm cpu heatsinks available at almost every computer repair ship for cheap
If one is lucky you can get some with huuuuge thermal masses

Also, mounting fans to these isnt a problem
These are what I use for my DRSSTC and SSTCs
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: Mads Barnkob on June 18, 2018, 01:53:12 PM
I have blown up much more TO-247 parts than minibricks, but that was also at a time with simpler drivers, higher current and short on-times. Most minibricks will not tolerate much above 500Apulsed anyway, that is about the safe limit of their increased thermal mass.

60N60 was also expensive when I built my DRSSTC1, I just spend a shitload of buying 30 at once, that was not cheap, came directly from digikey with import taxes ;(

TO-247 needs to have service put into the design, it sucks to build something compact and the IGBTs blow up and then you realize its impossible to change them! That was easier with minibricks/bricks as its all screws, no soldering.
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: Hydron on June 18, 2018, 04:07:44 PM
Woah, just realised that the brick linked in the first post doesn't have a diode built in. This is something you MUST have either in a co-pack device or separately next to the IGBT. The linked mini-brick is also pretty slow - you might find some of the full-sized bricks have similar speeds and are available used for cheaper than the mini-bricks.

One of the main advantages of bricks (both mini and full-size) is the lack of need for insulation when mounting them to a heatsink. This is a pain in the ass for TO-247s etc as it can add significantly to the thermal resistance (e.g. the headline spec of 0.25 K/W for a FGA60N65SMD isn't much worse than a mini-brick, but you'll need to add quite a bit to this if you use a sil-pad insulator). There are ways around this, such as using an intermediate larger-area copper heat-spreader before a much bigger sil-pad, or a separate heatsink for every IGBT (I have done this), but it's not as easy as mounting a brick.

This probably doesn't help a lot (still a choice to make), but I'd look for a different mini-brick than what you linked if you're leaning that way!
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: Spuriosity_ on June 21, 2018, 04:19:06 PM
Thanks for the advice. I'm leaning away from the linked brick IGBT.

The existing coil's primary circuit is an unholy hybrid of an 4-turn speaker-wire cylindrical winding and an 8-turn 8mm copper pipe conical winding - (originally I was planning on using the copper pipe only, but it had insufficient inductance that I improvised around). I'm aware of the issues in using this - including, but not limited to, induction heating of the central part and the general power losses that tend to happen in stranded wire - so I was planning on reworking the whole thing anyway.

SGTC MMC: One series string of 16x Kemet R76TR34704030J 470nF 1.6kV to form a 29.3 nF @ 25.6kV capacitor bank.

What kind of IGBT configuration would be most suitable for this size of coil? I'm currently leaning towards a doubled full-bridge made out of 8 FGA60N65SMD's (around $50 AUD on Mouser) as opposed to two CM300 units which would set me back upwards of $300 AUD. I know the latter is probably a better investment for long-term performance, but I'm willing to risk some silicon shrapnel.
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: Hydron on June 21, 2018, 07:01:55 PM
Sounds like you have a reasonable base to work with - the MMC caps sound ideal for DRSSTC work and you may even be able to use the nicer tubing part of your primary. I'd maybe look at reworking the MMC for lower voltage rating/higher capacitance (along with fewer turns on the primary - this is what might save your existing one) so that you can get the impedance down a bit and drive a bit more current into it with the IGBT bridge.

As for IGBTs, 8*TO-247s sounds like a very reasonable solution for the size of coil you are looking at (50mm dia. secondary) - you may even find that the doubled bridge is unnecessary (though for an extra $25 only is probably worth it). I would not be looking at CM300s for this size or frequency of DRSSTC (that's what I'm using for a 160mm dia. coil!).

Personally I'd have a go getting what you have working with some cheap IGBTs and a DRSSTC controller - if you find you need to improve some aspects of the system (e.g. bigger secondary diameter or better primary coil) then you haven't spent much, have learned a lot and also will have some parts to re-use on an improved version. The MMC especially should be usable (with some re-configuration) for a larger DRSSTC (larger secondary diameter at least - sounds like the current one is pretty long and skinny).
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: Teravolt on June 21, 2018, 09:00:40 PM
so I found this and ordered them

https://es.aliexpress.com/item/DRSSTC-QCWDRSSTC-and-tube-full-bridge-empty-plate/32813310913.html?spm=a219c.search0204.0.0.5c0b302d2gubwd

or

https://es.aliexpress.com/item/QCWDRSSTC-full-bridge-and-full-bridge-PCB-empty-board/32820655877.html?spm=a219c.search0204.0.0.5c0b302dNOmLfA

and they look nice

I found these ones ebay and they are affordable. one of the members have a thread about his tesla hear  using one of these bricks

https://www.ebay.com/itm/igbt-transistor-Semikron-SKM-400GB-123D-400A-1200V-BRAND-NEW/292553916274?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l2649
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: oneKone on June 22, 2018, 04:12:56 AM
If you want the boards faster you could get the board profdc9 linked/designed and get it made from jlc-pcb. I think it would be about $24 aud but you'll have it by next Friday to Aus. (Based from when I've ordered from them, with shipping to Perth)
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: profdc9 on June 22, 2018, 09:44:27 AM
As a bonus, if you get several of the boards made (for example, getting a UD2.9, interrupter, and a bridge board) made at the same time, each additional board is only $5 and the shipping charges don't increase that much as well.  So you can have PCBs made for all of the various parts of the coil at once.

And if you act now in the next 15 minutes, we'll throw in a free pocket fisherman or egg scrambler.  Your choice!  Ok so maybe not.

Dan
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: TDAF on June 22, 2018, 11:03:01 AM
To show you the power of egg scramblertm we sawed a boat in half!
All jokes apart
Jlcpcb works like a charm
Only qualm I have is the exorbitant shipping
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: Spuriosity_ on September 12, 2018, 04:58:28 AM
I've found some alternate IGBTs that seem to do a better job for roughly the same amount:
https://au.mouser.com/datasheet/2/205/DS100526A(IXXH40N65B4)-595301.pdf (https://au.mouser.com/datasheet/2/205/DS100526A(IXXH40N65B4)-595301.pdf)
I'm looking at getting these for their low on resistance and higher pulse current rating compared to the FGA60N60s linked above,
https://www.fairchildsemi.com/datasheets/FG/FGA60N65SMD.pdf (https://www.fairchildsemi.com/datasheets/FG/FGA60N65SMD.pdf)

Can anyone advise on which one to go for?
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: Hydron on September 12, 2018, 08:11:12 AM
The igbt portion of the ixys part looks ok from a quick glance (higher thermal resistance than a 60N60 but overall suitable), but I'm not seeing a diode in the package - you'd need to add an external one to use these.
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: Garyf on September 18, 2018, 05:51:35 PM
I've been away from the Forum and my workbench for awhile, but I occasionally check aliexpress for more powerful TO-247s.  The IXXH100N60b3 came to my attention recently with an Icm of 480 amps.  But no diode. 
So would a unidirectional TVS diode work?  For example 5KP5.0A is good for a 550 amp pulse, 1ps response time.

The rating is for a single pulse, and it's usefulness for freewheeling service is not clear to me.
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: erdal on September 24, 2018, 08:19:17 PM
I found interesting IGBT brick in our locale store.

FUJI 2MBI1400VXB-170E-50. 1700 volt 1400 amp. half bridge (2800 amp 1 ms)

price is 797.86490 USD. for rich man's giant DRSSTC :))

Title: Re: IGBT selection - TO-247 or minibrick?
Post by: Mads Barnkob on September 25, 2018, 06:46:52 AM
I found interesting IGBT brick in our locale store.

FUJI 2MBI1400VXB-170E-50. 1700 volt 1400 amp. half bridge (2800 amp 1 ms)

price is 797.86490 USD. for rich man's giant DRSSTC :))

A good old traction drive IGBT brick, a hell of a long one as well, but looking at those gate charge specifications there is no doubt that these will never run faster than 10-12 kHz as their switching times are 2-3 times higher than a CM600 brick.

Price is of coursealso right out of the question, you can get good 2nd hand IGBT bricks on ebay for much less :)
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: erdal on September 28, 2018, 07:15:33 PM
I found this at aliexpress. What about price and reliability?

CM200DU-24F
https://tr.aliexpress.com/item/SKIIP82AC12IT1/1879726663.html?spm=a2g0s.13010208.99999999.259.37ca3c00pHRXmo
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: setkiki on October 25, 2019, 04:33:12 AM
I found this on allicdata, how is the price and price?

https://www.allicdata.com/product/discrete-semiconductor-products/transistors-igbts-modules/cm200du-12f/4889150.html (https://www.allicdata.com/product/discrete-semiconductor-products/transistors-igbts-modules/cm200du-12f/4889150.html)
Title: Re: IGBT selection - TO-247 or minibrick?
Post by: Weston on October 28, 2019, 03:35:17 AM
I believe both the CM200DU-12F and the CM200DU-24F have a built in current limiting circuit which limits IGBT pulse current to ~2x the rated current provided in the datasheet, making them not a very good fit for DRSSTC use.

http://www.ohm.com.tr/doc/Mitsubishi-Electric---F---Series-IGBT-Modules.pdf

http://kaizerpowerelectronics.dk/teslacoils/cm600du-24fa-igbt-removal-of-rtc-over-current-protection/
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