Highway to DRSSTC

[Laci]

After two months,I found a problem of the driver.No wonder that the mosfet driver circuit was always working,but with the mosfet output stage not.I used WIMA MKS-4 1uF decoupling capacitors for the mosfet drivers,but 10uF tantalum or no decoupling capacitors for the mosfets.Maybe after Afrotechmods last video about capacitors gave me the idea to think about them.Just scoped the 24V going into the mosfets and it was terrible,with large high frequency ripples.2x1uF MKS-4 seems to keep the voltage pretty stable,but far away from the driver's 2x10uF.
Here is a gate waveform of the full bridge IGBT inverter.It's not the best,but a lot better than before.I tested the driver as SSTC at 20V and 55V,but it is drawing too much current,so no more voltage.The inverter should be rebuilded,because of the poor perfboard design.Has anybody got an idea how to make it?
The driver is also too complicated,antenna feedback,additional breadboard connections and a GDT for the 4xIRFZ44 mosfet output stage,because I do not have P channel mosfets and they drive the IGBTs through the other GDT

[Mads Barnkob]

There is a huge difference between MKP and tantalum capacitors in a decoupling job, tantalum capacitors should never be used for this, I think we have discussed this long ago when you first asked about DRSSTC drivers. Tantalum are great for energy storage/decoupling on IC supply rails, but never for power switching circuits DC blocking.