Lack of information. What is switching frequency? Are you really operating SiC MOSFET SCTW90N65 with 12V unipolar gate voltage? What was the actual output voltage when transistor failed?
I guess, it's either an overvoltage or overtemperature problem. Did you measure the Vds waveform with a differential probe, or Vd and Vs separately? Also Vgs maximum ratings might be exceeded with unsuitable driver circuit layout.
Do you have a thermal camera to observe the transistor case top temperature?
A layout photo would be interesting.
did the buck diodes fail? most likely is insufficient heatsinking - or volt spikes at turn off - as no snubbers ...!!!!
As a minimum - look at the Vds on the 2 mosfets and the current in the Tx pri at the same time ...
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Oooh - just one more thing - in the photograph - it appears you have no input or o/p caps on the board? is this the case? if so it answers your initial question ...
Hi,
Saturating inductors?
Please give a link to the datasheet.
What capacitors do you use? Are they high frequency, low ESR types? Datasheet?
Klaus
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The PCB layout is far away from being ideal.
Did you follow/check the current loops:
* when FET is ON
* when FET is OFF
Klaus
snubbers on the fets and diodes will definitely help a lot in many regards - esp in reducing RFI getting into your controller
Why limited? The current will rapidly increase.... If they saturates it should limit current flow
What you think about low switching like 20khz. Now it was 40khz
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