15v / 200a Help!

mgm2000ro · 2nd May 2009, 10:07 AM

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

Waveform on primar without SNUBBER , this happened when start (0 to 42% duty) !

Waveform from sg352 and gate IGBT

at 310vdc without SNUBBER blow

thanks for help !

EWorkshop1708 · 2nd May 2009, 12:27 PM

That looks like a beast of an SMPS! I'm not sure of your snubber values, but that thing looks setup for serious power!

star882 · 2nd May 2009, 01:39 PM

There is a mistake in the design. 6A input will not be enough to get 200A output at the input and output voltages.

mgm2000ro · 2nd May 2009, 01:47 PM

thanks for help !
I will change !

The problem is RC SNUBBER value!

mflorin · 3rd May 2009, 07:01 AM

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).

mgm2000ro · 3rd May 2009, 09:27 AM

Multumesc!
thanks for help Florin !

luka · 3rd May 2009, 10:13 AM

Any pictures of this beast? Trafo, did you build it or what?

mgm2000ro · 3rd May 2009, 07:24 PM

: 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

32Khz whit snubber

32Khz in Power, primar I=3A, U=90v

Waveform at 50khz whit snubber

All tests were made at 30v and 100v

luka · 3rd May 2009, 07:43 PM

more dead time on second, I think it was 32kHz picture. slope should go all the way up..

mgm2000ro · 3rd May 2009, 08:00 PM

Now I'm playing with 52khz

RC SNUBBER IGBT R=22 C=4,7nF Uin =30v

what is your opinion?

2nd May 2009, 10:07 AM	#1
mgm2000ro diyAudio Member Join Date: Nov 2004 Location: Bucharest	15v / 200a Help! Hello Everyone ! Please help to find corect value of RC SNUBBER and corect drowning on schematic ! Waveform on primar without SNUBBER , this happened when start (0 to 42% duty) ! Waveform from sg352 and gate IGBT at 310vdc without SNUBBER blow thanks for help !

2nd May 2009, 12:27 PM	#2
EWorkshop1708 diyAudio Member Join Date: Nov 2004 Location: Florida	That looks like a beast of an SMPS! I'm not sure of your snubber values, but that thing looks setup for serious power! __________________ You can call me Mad Professor, building crazy experiments in my Electronics Workshop

2nd May 2009, 01:39 PM	#3
star882 diyAudio Member Join Date: Mar 2007	There is a mistake in the design. 6A input will not be enough to get 200A output at the input and output voltages. __________________ "Fully on MOSFET = closed switch, Fully off MOSFET = open switch, Half on MOSFET = poor imitation of Tiffany Yep." - also applies to IGBTs!

3rd May 2009, 10:13 AM	#7
luka diyAudio Member Join Date: Sep 2005 Location: in Slovenia :)	Any pictures of this beast? Trafo, did you build it or what? __________________ home page @ http://www.classdaudio.co.cc @ 24/7 all year long I FEEL SLOVENIA

3rd May 2009, 07:43 PM	#9
luka diyAudio Member Join Date: Sep 2005 Location: in Slovenia :)	more dead time on second, I think it was 32kHz picture. slope should go all the way up.. __________________ home page @ http://www.classdaudio.co.cc @ 24/7 all year long I FEEL SLOVENIA


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2nd May 2009, 01:47 PM	#4
mgm2000ro diyAudio Member Join Date: Nov 2004 Location: Bucharest	thanks for help ! I will change ! The problem is RC SNUBBER value!

3rd May 2009, 07:01 AM	#5
mflorin diyAudio Member Join Date: Jun 2005 Location: IASI	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=2pi()FringingLleakage. The capacitor value comes immediately: C=1/(2pi()FringingR).

3rd May 2009, 09:27 AM	#6
mgm2000ro diyAudio Member Join Date: Nov 2004 Location: Bucharest	Multumesc! thanks for help Florin !

3rd May 2009, 07:24 PM	#8
mgm2000ro diyAudio Member Join Date: Nov 2004 Location: Bucharest	: 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 32Khz whit snubber 32Khz in Power, primar I=3A, U=90v Waveform at 50khz whit snubber All tests were made at 30v and 100v

3rd May 2009, 08:00 PM	#10
mgm2000ro diyAudio Member Join Date: Nov 2004 Location: Bucharest	Now I'm playing with 52khz RC SNUBBER IGBT R=22 C=4,7nF Uin =30v what is your opinion?

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