Popped my first pair of IRFP460's

[Zipdox]

Give me a list of things that could've gone wrong?

[Weston]

You are going to need to provide a lot more information than that, such as what are you using for a driver and the power level. Do you have an oscilloscope?

At a fundamental level MOSFETs really only fail due to gate oxide breakdown or overheating (excessive DS voltage causes avalanche which gets converted to heat). Many issues can cause these two things though.

Common possible issues:

You are just running too much power through the MOSFETs with insufficient cooling
The driver is not optimally tracking the resonator frequency, leading to excessive switching loss
The driver is completely loosing track of the resonator frequency and driving the bridge with too high / low a frequency, causing large losses
Overvoltage on the gate due GDT ringing
Shoot-through on the bridge due to GDT resistor values and mismatched turn on / turn off speeds, leading to current/voltage spikes and excessive power dissipation
Bad bridge layout leading to excessive switching loss


Also, I don't think its directly related to the current issue, but is that strike rail type thing a fully connected circle? If so it's acting as a shorted turn. You want to have a gap on it.

[Zipdox]

You are going to need to provide a lot more information than that, such as what are you using for a driver and the power level. Do you have an oscilloscope?

At a fundamental level MOSFETs really only fail due to gate oxide breakdown or overheating (excessive DS voltage causes avalanche which gets converted to heat). Many issues can cause these two things though.

Common possible issues:

You are just running too much power through the MOSFETs with insufficient cooling
The driver is not optimally tracking the resonator frequency, leading to excessive switching loss
The driver is completely loosing track of the resonator frequency and driving the bridge with too high / low a frequency, causing large losses
Overvoltage on the gate due GDT ringing
Shoot-through on the bridge due to GDT resistor values and mismatched turn on / turn off speeds, leading to current/voltage spikes and excessive power dissipation
Bad bridge layout leading to excessive switching loss


Also, I don't think its directly related to the current issue, but is that strike rail type thing a fully connected circle? If so it's acting as a shorted turn. You want to have a gap on it.

I probably need to get a variac instead of running it first time on 320VDC. It popped once and the breaker tripped when I sent a signal with the interrupter.

[ritaismyconscience]

Can you send the waveform on the gates (unplugged, of course). That might solve GDT problems
Also check if your interrupter is working.

[Mads Barnkob]

I concur with Weston. You are on the brink of breaking forum rules with such a short, non-informative and asking straight for instructions post.

I will give you the chance to add more information, as you do have a coil built by yourself, that you want to troubleshoot on.

So please go ahead and supply all design details, detail pictures, numbers, calculations, how you ran it at time of failure etc.

Else the thread is subject to be closed.

[Zipdox]

The circuit is the Kaizer SSTC 3 with current transformer feedback from the secondary.