Maybe method 3 here: https://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/mmc-tank-capacitor/

I've seen identical failures on my bridge. I can't see a way that a PCB failure would cause the IGBT to fail. When the PCB fails it becomes an open circuit and prevents further current from flowing. When the IGBT fails however they normal fail short circuit. In this case there's nothing to stop very high currents flowing which will destroy the PCB.

As for your high repetition rate question, higher BPS means higher duty cycle (assuming you maintain the same on time). This results in the IGBTs heating up more. From here multiple things can go wrong. You could exceed the ability of the part to transfer the energy to the heatsink causing failure. The other thing that changes when you heat up the IGBT is the turn on and more importantly turn off delay increase. This can cause your zero current switching to be further from ideal causing more heating and can ultimately result in shoot through which at elevated temperatures especially, tends to be fatal for the IGBTs.

GrantV,

I also designed a H-bridge based on "80mm" version of loneoceans, in your final product, how much copper oz you used?

He was asking about frequency response to 20 khz which is at the upper limit of human hearing. This implies an expectation of high fidelity sound from a Tesla coil. If this is indeed the case I informed him that his expectation was unrealistic and why. I rarely use CDs but even though they are "old skool" as you say, they are still the highest fidelity form of music playback technology available to the average consumer. If the idea of an optical disc bothers you does FLAC technology with flash drive storage comport with your vision of modern high fidelity playback? If not, then what? Either CD or FLAC technology provides the same sound quality.

I don't know and you don't  know what his expectation of sound quality is from a Tesla coil. It all sounds perfectly on-topic to me.

The yellow wire is wound 31 times around the core plus one loop around the other core with 32 turns of  red wire. The two red wires go to in input of the bridge of the 2.7c. Or in my case my test bridge and a 50uf cap and 5 ohm burden. The wire going through the yellow has 200 amps at 60 hz flowing. At 200 amps I am getting 11 mv across the 5 ohm burden. Got to be doing something stupid, this is not hard. Thank you and hope you spot something in picture.

There's little reason to keep the inrush as low as 10A. Uncontrolled inrush is usually in the thousands of amps, if you limit the inrush to the high tens to low hundreds of amps, you should be fine. If you want to be conservative, a B-characteristic circuit breaker will handle minimum 3 times nominal current for a few seconds, so you could start with 40 amps for example. And since we're talking about seconds time-scale rather than microseconds, you can use the RMS voltage to calculate the current. This gives a minimum of 6 ohms, so 10 would be fine. Many breakers will be C- or D- characteristic, and the time to charge the capacitor will be in the low milliseconds, so you could likely get away with 4.7 or even 3.3 ohms as well, but if you can get a 10 ohm NTC with the right energy and voltage rating you should be good.