Boost converter using stw33n60m2.

[vasudev]

Hi, I am designing a boost converter based on stw33n60m2, its 2.5kW 420Vout and 250Vin 5 amp Iout. the diode I am using is SIC schottky diode(very less reverse recovary). The issue is that I am facing mosfet failue at around 450v VDS (I dont observe too much overshoots). gate drive voltage is 14Vgs and I am using split resistor for turn on(4.7ohm) and turn off (2.2ohm) .I have made turn on slower and turn off faster. The mosfet just fails even at light load. I have taken care to see that inductor wont saturate. Any help is appreciated. 

[AScha.3 · Accepted solution]

hi, --- just my biggest PFC is about 1kW , 360V out.

but i killed no mosfet ! 🙂

what i did : keep the dv/dt rise at the mosfet under his destruction limit !

so at first : check with (fast)DSO the rise time here ! your mosfet will kill itself at > 50V/ns ,

thats why it dies even at low load, if you make it switching faster....maybe a snubber can help.

i used even for my 1kW design a mosfet with 100V/ns  and checked the speed is not higher...

[vasudev]

yaa, I forgot mosfets have parasitic BJT in it. I am young and learning