SSTC MOSFET over heating?

The following images shows my SSTC work, it is based on steve wards mini SSTC. But the problem is that the MOSFETs seem to heat up in like 3-4 sec of running. Input voltage is 220v AC(rectified and filtered later using a SMPS line filter).

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See my Instructable

for some of the reasons, but there are two other fundamental reasons you can look at right now - one, is the FET being turned on hard and fast, and two, where are your heatsinks ?

and turned off just as fast. Losses occur at both the leading AND trailing edges...


iceng3 years ago

I think I see your heatsinks in the second to last pic,

Are you using heatsink thermal transfer grease

to pass the FET heat to the Al ??

Otherwise the heatsink does not work

Oh yeah ,I see them now.