Hi,
Looks like the inductor could use some back emf clamping. It's a boost converter with no load in one operational mode
The actual circuit has TVS diodes across the power NMOS, amp, but not across the inductor because it was physically impractical without really long lead wires. Otherwise, yeah, the circuit would have blown from voltage spikes long ago.
Schematic in post #12; why a power amp to drive a Gate? Why +50 volts and -24 volts to drive the gate. If the load is removed the mosfet dies. Quickly removing the current kills the fet. The power driver is hot because of oscillation. Two amps?
The -24V could have been a lot less but was the most convenient supply I had and is just there to provide a little negative supply since I needed to work close to 0V but the LTC6090 is not a rail-to-rail op amp.
50V is what was required to produce the necessary slopes to produce the current waveforms we wanted in the inductor. THe LTC6090 is powered off 50V so it can accept the worst case current sense voltage even though it never actually outputs that during normal operation, resulting in a volt of voltage drop across it, which I think was the reason it overheated.
The power NMOS was a IXYS IXTN200N10L2
https://ixapps.ixys.com/DataSheet/DS100238(IXTN200N10L2).pdf
The power-amp was an Apex PB58:
https://www.apexanalog.com/resources/products/pb58u.pdf
Now that I type this out, I realize some details were left out. The actual setup has six power NMOSs in parallel which I forgot to put into the simulation schematic above. I need to add that.
Note that in all this, there were TWO versions of the circuit. The schematic shown in is the SECOND version (but omits the six parallel power NMOSs which the actual circuit has).
The first circuit is essentially the same thing, but without the power-amp in the output path of the LTC6090 wired as a unity buffer, and with four LTC6090s in parallel. This circuit was less finicky than the one containing the power-amp but suffered from the LTC6090s overheating. The second circuit with the power-amp (aka the schematic above) did not overheat but was even more finicky.
You mention oscillations. Are you referring to oscillations due to instability? Or just the regular oscillating nature of the signals coming from our source signal? Because whenever the LTC6090s circuits died due to heat it was stable (or maybe only marginal stable, since as I previously mentioned, there was a lot of noise riding on the waveform. It almost looked like it wasn't noise but was the control loop visibly fighting to keep the circuit under control). This "noise" was present in both versions of the circuit.