SISG IGBT Opinion: Single IGBT vs. Paralleled B-Grade Dies

Daniel Kramnik, Thu Mar 26 2015, 03:25AM

I'm looking to replace a rotary gap on my ~3kW SGTC with a series stack of SIDAC-triggered IGBTs per Terry Fritz's design. The peak expected primary current in my design is roughly 800A, which is close to the upper limit of the TO247-based trigger boards I've seen (I'd really rather not move to bricks because my power source is a 14.4kV potential transformer that I'd prefer not to replace).

For reference, here's a picture of the system that gives you an idea of its size:



Since I haven't been able to find anything much better in a TO247 package than the IRGPS60B120KDP used in the original design, I'm planning on sticking with that device. The issue is that they are roughly $15 on Digikey and Arrow right now, but can be purchased on eBay from China for $4 or less. I've been advised that these are likely B-grade dies that won't perform as well as the real thing, so my question is has anyone here used the Chinese version with success? Two paralleled Chinese IGBTs is cheaper than a single device off of Digikey, even if you include the cost of the heatsink, so it seems like I might be able to get away with B-grade dies, and even get a more reliable/expandable system in the event that they don't turn out to be tremendously sketchy.

eBay link:

Digikey link: