[SOLVED] Mysterious MOSFET failures

[Orson Cart]

Wouldnt having a gate resistor of 220R slow down switching enough to get the fets inefficient, and hot? I thought the whole point of MOSFETS is to switch them as fast as possible. I have often seen diodes in reverse across the gate resistor. I don't understand this. I thought the point of the gate resistor is to limit the gate-charge current to something the IR2110 can handle (2A). If you have a diode there, what keeps the IR2110 from frying once it pulls the gate low, and the current bypasses the gate resistor?

220 ohm will limit the true turn on time to ~ 300-500nS enough to test whether turn on induced dv/dt is the root cause of your issues. (noise in the hall sensors)
The mosfet gate is capacitive so for turn off (& on) there is a pulse of current, not a DC level, so a back diode (1A schottky 4oV) gives the lowest turn off time without DC current sin the 2110 or buffer, but yes a buffer on the 2110 gives a MUCH better gate drive, esp for large fets or igbt's.
If your control circuits are RFI sensitive, you will have to make them better or go to a higher value turn on resistor will slightly increased heat sinking...
The fact that you know a very little about mosfet gates makes me think there will be a few more problems that you will have trouble over-coming in the development of your product... e.g. emc...