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Registered Member #599
Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624
IamSmooth wrote ...
Kizmo, at your power levels I would suggest liquid cooling. You will loose IGBTs from overheating.
Yeps that is of course another option but i would like to fix the main cause of heating which is switching losses during turn off. And that is of course caused by poor power factor of this type of feedback method.
Registered Member #599
Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624
This whole transformer idea is starting to feel stupid. I cant have more than 5uH of inductance from transformer or this thing will turn into ear wrecking machine. And there is no way i can fit enough windigs on any of my smaller ferrites :(
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
How are you calculating the inductance? It's the leakage inductance, so to a first approximation, it's the inductance of the secondary by itself with the primary and core removed. In practice slightly less, if you wind the primary close to the secondary as I did.
That should be much less than 1uH. To keep a sense of scale, I remember that a 10 inch diameter loop has an inductance of about 600nH.
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
Kizmo wrote ...
IamSmooth wrote ...
Kizmo, at your power levels I would suggest liquid cooling. You will loose IGBTs from overheating.
Yeps that is of course another option but i would like to fix the main cause of heating which is switching losses during turn off. And that is of course caused by poor power factor of this type of feedback method.
Registered Member #599
Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624
IamSmooth wrote ...
Kizmo wrote ...
IamSmooth wrote ...
Kizmo, at your power levels I would suggest liquid cooling. You will loose IGBTs from overheating.
Yeps that is of course another option but i would like to fix the main cause of heating which is switching losses during turn off. And that is of course caused by poor power factor of this type of feedback method.
What is your frequency?
Limited by capacitor between 16 and 32kHz. This first prototype ran at 44kHz and at this frequecy calculated turn-off losses (=hard switching) are almost 800W/transistor.
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OMG Induction Heater
