Lately I've been tinkering with an SSTC half-bridge driver. I've ran a couple of tests using relatively low input voltages ~50V and the IGBTS seemed to do fine, there was no noticeable heating at all. When I used rectified mains to power up the circuit it works fine for a few minutes and after that the transistors violently explode.
The gates should be pretty well protected: 15V Zenners, 10k pull down resistors, 10 Ohm resistor to prevent ringing and diode for discharge. The driver IC is an IR 2184.
I am wondering if the culprit for the failure at high voltage might be the lack of a DC blocking cap across the primary thus in the event that both IGBTs are on it shorts the power supply creating huge current. Heat is not a problem, the thermocouple showed them at 50 degrees C right before the explosion.
Any help is greatly appreciated, I don't know what else might be wrong with the circuit and I want to ask for a second opinion before plugging in my last 2 IGBTs. Thank you very much for your time.