Choosing MOSFET Push Pull Converter

[azadfalah]

Hello friends
Please guide me to choose MOSFET correctly in push pull converter
convertor input voltage = 43v max
Max current = 24A
Ferq= 50hz
43V to 230V

I use two IRF3205 for each Line
But the IRF3205 over heating , but if i change input voltage from 43V to 30V no have any over heating and all things is ok.

What the minimum voltage vds for this For For this issue

Thank ,

 

[KlausST]

Hi,

Without seeing your circuit it's about impossible to give good assistance.

So we need to guess:
From what you describe I rather think the (saturating) inductor is the problem, not the Mosfet.

Klaus

 

[azadfalah]

thanks for your response
This is A Classic push pull circuit
No load current is7A

 

[dick_freebird]

Core volt-seconds (w/ winding count) ought to say if
you are saturating. If saturating at 43V, good luck
surviving 230.... The xfmr datasheet, or calcs?

The two-horned transformer imposes 2X VIN (plus
ringing) on the FET drain that's headed "off". Your
IRF3205 is only a 55V FET. So not surprising that
above 30V you are "testing the avalanche ruggedness"
rather than testing circuit operation.