IGBT Selection

[Halfcorp]

So I'm not new to Tesla Coils, but I am new to SSTC's and more specifically, DRSSTC's.

I have digested a wealth of information on building DRSSTC's online, from Steve Wards original site to oneTesla.com. I have found kaizerpowerelectronics.dk to be a very useful resource so thanks Mads for providing that!  I am planning to use 4 of the IXYS IXYN80N90C3H1 IGBT's in a full bridge configuration with a bus voltage of 340V, a peak primary current of 500A and an Fres of 149 KHz.

Datasheet: https://docs.rs-online.com/c6f1/0900766b812671f6.pdf

I am aware that the datasheet says that 50 KHz is the max switching frequency, but am also aware that for soft switching with low duty cycles the true max frequency is much higher. I have inspected the simple timing information and have followed through with the thermal analysis of power dissipation outlined in Mads guide and have concluded that it can run at about 4 MHz. However, before I sink hundreds of pounds into buying them and since this is my first solid state TC build, I wanted to check if there is anything obvious I have missed that would make these IGBT's unsuitable for my design (or if my calculation of 4 MHz sound incorrect)

Any guidance on this would be much appreciated as I have the rest of the design all specs out and ready to build. Thanks! 

[davekni]

Hopefully others will offer opinions too.  The only hesitation I'd have is on this IGBT's internal reverse diode.  I don't see any surge current rating.  That makes it hard to know how well the diodes can handle primary resonant current after the enable pulses end.  The diodes are also a bit on the slow side.  That's not an issue as long as you have sufficient lead-compensation in your controller.  With lead compensation, the diode commutation is soft - with conduction ending while the associated IGBT is already enabled.  Without lead-compensation, diode conduction is forced off abruptly as the opposite IGBT turns on, making a large VBus current spike.

[Mads Barnkob]

I am glad you found the guides useful

Depending on the price on these IXYS IGBTs, I would recommend getting smaller used bricks like SKM75/100/200 as they will most likely outperform these at the same price and be moire suitable for your 150 kHz coil. SOT-227B / miniBLOCK have disappointed me on their Icm capabilities compared to bricks or the good old 40N60 miniBLOCKS. Looking at its SOA rating (which is square), it is limited to 160A Icm for Ice < Ices, seems like a pretty steep derating, but since you use 300+VDC you can properly use the Icm 340A rating without worry. 

It is a relatively high voltage rated IGBT compared to your planned DC bus, aim for 2/3 of the voltage rating for enough head room, but also so that you do not suffer in current capability, as that tends to be lower on high voltage parts.

I am not too happy about there is no Vce(sat) graph to extrapolate on, as I do not believe the 2.7V for when overdriven, 4V is more likely to be normal.

I would look at 600V parts with higher current and pulse current ratings, as the pulse current ratings are a weak point of the miniBLOCK package that is just a beefed up TO-247 with a larger heat sink, but properly the same amount of silicon inside.

[Hydron]

If you're in the UK, then consider grabbing some of these, is a killer deal for new parts. Maybe a bit slow for 150kHz, but if you're able to lower your Fres then you'll have a lot more options, or you could just try it given it's only 30 quid for 2:

https://www.ebay.co.uk/itm/SKM200GB12V-SEMITRANS-3-VCES-1200-V-IC-200-A/201898900403

(note that I have not bought from this person though, so cannot vouch for them)

[Halfcorp]

Thanks for all the info everyone. I will certainly look into trying to get some of those bigger bricks suggested. 

If you're in the UK, then consider grabbing some of these, is a killer deal for new parts. Maybe a bit slow for 150kHz, but if you're able to lower your Fres then you'll have a lot more options, or you could just try it given it's only 30 quid for 2:

https://www.ebay.co.uk/itm/SKM200GB12V-SEMITRANS-3-VCES-1200-V-IC-200-A/201898900403

(note that I have not bought from this person though, so cannot vouch for them)

I am from the UK and wow are those cheap! Might be worth a try regardless since there's not much to lose cost wise. 

[Hydron]

Let me know if the seller accepts an offer <15 quid. I don't _need_ any, but I have been tempted by them in my watch list for months now!