[![Quarter Bridge][1]][1]I am in the process of building a low frequency (that is, transformer based) pure sine wave power inverter; 24 VDC to 120/240 60 Hz AC. The schematic I've attached is for one quarter of the entire bridge; all the other quadrants are identical.  Progress so far has been to implement SPWM from an Arduino Nano, driving a pair of IRF21844 half bridge MOSFET drivers. Those drivers subsequently drive TLP351 opto gate drivers. There is independent 12 V isolated power supplies to each high side quadrant and the two low side quadrants share a power supply.

The TLP351 output passes through a 4.7 ohm gate resistor that is in parallel with a reverse biased Schottky diode. Each FET has a 22 kohm gate-source resistor. The FETs themselves are IRF3905 with two per quadrant. All of this works pretty good to drive resistive loads or even brushed AC motors, but even small induction motors blow the FETs. I've managed to alleviate this somewhat by putting 15 V zener diodes from source-to-gate, but even then, if I rapidly switch the motor, I'll occasionally blow some FETs.

I've got the parts on hand to make some RC snubbers between the drain-source of each FET, but haven't done that yet. I was relying/hoping the FET body diode would suffice, but I don't think it is.

My question is, assume parts count wasn't an issue, how would you make the ultimate bulletproof H-bridge. Keeping the driving components the same, what would you add to the H-bridge to make it the best possible bridge?

Edit to describe logic drive:

I've added a schematic to the OP. I'll try to address your points, @bobflux. The 24 V is from four 215 AH 6 V lead acid deep cycle batteries charged by a 435 watt solar panel. So no automotive shenanigans. I am using isolated drivers because I want the FET board as electrically isolated from the driver board as possible. The driver design is pretty much a done deal. There is a bootstrap diode and cap available and originally that is how I started. But I found out pretty quickly that one small misstep with a scope or meter probe, or even just regular testing that blows a FET will also kill the IRF21844s and maybe even the Arduino Nano. So I now use isolated gate drive supplies and TLP351 opto drivers. The IRF21844s still handle the dead time and they have a shutdown pin that will eventually be used with a CT and hardware amplifier for rapid shutdown. I haven't put any of that to use YET because I am still working the bridge bugs out. 


  [1]: https://i.sstatic.net/X0PXo.png