Questions about the bridge, the rectifier module keeps getting blown up.

[BoltyTheDoge]

Hello, for the past few months I've been building a solid state Tesla coil, I have been using for the most part LoneOceans SSTC2 circuit, now, he used 120v instead of my 240v, so I couldn't use the original design, so, thanks to this forum, i came up with this:



Now, most of it works, even the Arduino code works, but the bridge section (highlighted), doesn't, it's not that I turn it on and nothing happens, it blows up the Rectifier module, something is shorting, and my soldering is exactly as the diagram. I'm hopeless, I tried everything, is there something obvious that I'm missing?

Thanks in advance!

[Max]

I can only spot one thing in the schematic but I’d assume it’s a drawing error: the left contact of the primary is not connected to the IGBT modules (the red dot is missing where both wires cross). Furthermore you have connected one

Have you tested the circuit at lower voltage or checked some signals (especially the gates) with the scope?

Often enough pictures of the setup help finding potential issues, too.


Regards,
Max

[johnf]

Its a big ask to charge a 1000uf cap in the first half cycle of the mains 100's of amps will be flowing from the mains.
a big NTC in series to the bridge on the AC side should soft start it for you or a relay that is powered from the dc buss that shorts out a series resistor

[BoltyTheDoge]

So, i did a test with only the cap in series, and it charged it just fast and okay, nothing blew up. So there's no need for a soft start, I guess I'll just do a new board in case I missed something. Bad thing I don't really have any FBR lefts haha.

Thanks!

[davekni]

Test at low voltage first before applying 220VAC.  Then for initial 220V testing, connect an incandescent light bulb in series with the AC line power.

If you have an oscilloscope, check gate waveforms with low or no power to the FETs.  If you do not have access to a scope, testing will be harder.  Still start at low voltage and then with a light bulb in series with line power.

[Mads Barnkob]

The phasing of the GDT to IGBT gates are not marked with a dot, are you sure you are driving your half-bridge legs opposite of each other? If you follow that drawing, you are turning on both IGBTs at the same time.

[BoltyTheDoge]

The phasing of the GDT to IGBT gates are not marked with a dot, are you sure you are driving your half-bridge legs opposite of each other? If you follow that drawing, you are turning on both IGBTs at the same time.

Yeah, they're connected, there's a dot missing. Still, I'm pretty sure it was a soldering error, I'll just have to rebuild it, thanks!

[klugesmith]

>>Yeah, they're connected, there's a dot missing. Still, I'm pretty sure it was a soldering error, I'll just have to rebuild it, thanks!

It's not missing dots where crossing wires connect.
It's missing dots that indicate winding polarity. A GDT schematic is incomplete and ambiguous without them.

[BoltyTheDoge]

>>Yeah, they're connected, there's a dot missing. Still, I'm pretty sure it was a soldering error, I'll just have to rebuild it, thanks!

It's not missing dots where crossing wires connect.
It's missing dots that indicate winding polarity. A GDT schematic is incomplete and ambiguous without them.

Good to know, but I wasn't referring to my IGBTs blowing up, my board shorted on startup instantly, to it must have been a soldering mistake or something along those lines, I'll be building a new board today so, thanks! Let's hope it doesn't blow up now.