Hi there,

I am currently working on a half bridge solid state tesla coil. I have built a class e sstc but I am having trouble with this one. Things seem to be going wrong at the gate pin of my mosfets for the half bridge. Lots of heat on mosfets and no spark at output. At the moment, I have a signal generator attached to the feedback antenna to give a 606kHz (~resonant frequency of the secondary coil + topload) signal.

Lots of ringing at MOSFET gate. I originally had 6.8ohm resistors, but I replaced them with higher value to suppress ringing but not much changed.

Also Faze lead should be phase lead. Idk what I was thinking

 

C1 is capacitance between L1 "hat" and grounded aluminum foil pad.
Frequency of HV is 625 kHz.
Note: Source V3 is not grounded!

 

Lots of ringing at MOSFET gate. I originally had 6.8ohm resistors, but I replaced them with higher value to suppress ringing but not much changed.

Do not keep increasing the resistor blindly. The correct value depends on the MOSFET, gate driver, GDT, wiring inductance, gate capacitance, and switching current.

https://toshiba.semicon-storage.com...e-series-gate-resistor-affect-the-mosfet.html
https://commongnd.org/articles/sstc/the-gate-loop-is-an-rlc

 

Hi there,

I am currently working on a half bridge solid state tesla coil. I have built a class e sstc but I am having trouble with this one. Things seem to be going wrong at the gate pin of my mosfets for the half bridge. Lots of heat on mosfets and no spark at output. At the moment, I have a signal generator attached to the feedback antenna to give a 606kHz (~resonant frequency of the secondary coil + topload) signal.

Lots of ringing at MOSFET gate. I originally had 6.8ohm resistors, but I replaced them with higher value to suppress ringing but not much changed.

Also Faze lead should be phase lead. Idk what I was thinking

Please show us the actual circuit!!
It is quite likely that the output of the signal generator is not adequate. THAT has been my frequent experience. Most of the Tesla coil projects that I have seen that did not work suffered from not nearly enough feedback, so that they did not oscillate. The coupling between the drive coil and the feedback coil must not only be adequate, it must also be the correect phase relationship. THAT is often a serious challenge.

And now, a lot later, it is clear that the drive is not nearly adequate.
IN ADDITION, you need to actually have the circuit oscillate. Driving it close to resonance will not work. THAT means you need an adequate feedback winding on your coil setup. AND an adequate drive coil, with adequate coupling to the high voltage coil.
The circuit that works will look a lot like a power inverter for a big mobile radio transmitter power supply, except for the transformer.
ALSO, understand that there needs to be good power coupling between the drive winding and the feedback winding, and then that high voltage coil. AN they DO NEED to resonate at the same frequency.