SMPS Noise

[ChocoHolic]

Yes, I mean ...

I mean. NO. Not across drain gate.

And take care to run your smps from an isolation transformer !
Last but not least: Take care & survive! You are playing with a lethal weapon.

 

[microsim444]

SMPS

Hi,


I will post the voltages, but I need is an explanation why the mosfets die quickly.

do I need to put Zener diodes at each secondary output?

Running the supply at 170VAC , will make it survive.

But at 220VAC , problems starts.


And please note that I know exactly what I am doing.

 

[megajocke]

I see two immediate problems with the K6 supply:
No DC blocking cap.

Gate resistors are probably too large (for turnoff) and IRFP450 have huuge Csrss, probably causing shoot-through. You should probably add a diode (or even better a suitable transistor circuit) in parallell with the gate resistors to help discharge the gate and keep the transistors off. Turn-on probably needs to be pretty slow though.

 

[microsim444]

Diode

megajocke

Can you advice the place of the DC blocking capacitor?

and the direction of the diodes in parallel with the resistors? and the value of the resistor?