15v / 200a Help!

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Hello Everyone !
Please help to find corect value of RC SNUBBER and corect drowning on schematic !

An externally hosted image should be here but it was not working when we last tested it.


Waveform on primar without SNUBBER , this happened when start (0 to 42% duty) !
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Waveform from sg352 and gate IGBT
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at 310vdc without SNUBBER blow :(

thanks for help !
 
the values of RC snubber components are directly related to parasitics in your transformer and layout.
Measure the ringing frequency at mosfets turn-on/off, then choose the resistor snubber value equal to the characteristic impedance given by measured leakage inductance: R=2*pi()*Fringing*Lleakage.
The capacitor value comes immediately: C=1/(2*pi()*Fringing*R).
 
: Hello Luca. There is no beast...yet. Right now it is in the design / testing stage and everything looks very ugly. I didn't have time to draw a pcb so everything is connected with wires at this point. I managed to acheive something good at 30kHz
I increased the frequency to 50kHz and I want to re-calculate the correct values

32Khz ringing 12,82Mhz
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32Khz whit snubber
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32Khz in Power, primar I=3A, U=90v
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Waveform at 50khz whit snubber
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All tests were made at 30v and 100v
 
RC SNUBBER IGBT R=22 C=4,7nF Uin =30v

this values for the snubber is not used for mains powered smps. this may work with 12 pus-pull step-up converters as those used in car audio amps. most of the supplies use 47R at min 5W with 1nF to 2.2 nF cap. at min 1kv.

fa un pcb sau macar pe un breadbord un layout cat mai apropiat de cel real, la cum stau sarmele alea, nu ai cum sa obtii un semnal curat. fa asta pana nu se buleste ceva :hot:
cu ce ai implementat redresarea sincrona din sec. ?

Bafta !!!
 
Hello cnx ! Salut
this snubber work at 285vdc but resistor are hut (~100grade C)
waveform U=285v snubber 4.7nF/1200v , 28R/6w
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U on 28R (R fron snubber)
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BUT!!!NOT WORK on 285v (electrical network)
An externally hosted image should be here but it was not working when we last tested it.
 
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