oops!! - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 21st September 2006, 02:00 AM   #11
diyAudio Member
 
ifrythings's Avatar
 
Join Date: Oct 2005
Quote:
Originally posted by poobah

Ever seen a wookiee on fire?



Got pictures or a movie
  Reply With Quote
Old 21st September 2006, 05:03 PM   #12
Danko is offline Danko  Hungary
diyAudio Member
 
Join Date: Apr 2004
Location: Hungary
Hi!
Finally, back from school....

Here are 2 pictures from the prototype, as Eva asked :-)

http://sziget.mine.nu/~danko/aramkor...t/dscn0465.jpg
http://sziget.mine.nu/~danko/aramkor...t/dscn0453.jpg

The actual state is not exactly that, on the picture. I removed the 0.01 Ohm SMD resistors from the PCB, and moved to a separate small PCB. (not that, wich exploded)
This is on picture 0465. There is some calculation, on the desk


poobah! I gonna lower the inductor value. I haven't thought the inductor....

I have a small problem with dead time. If there is no dead time, that is a problem. Cross conduction, and smoke, and other bad things happen... If there IS dead time, then there is a short time, where none of the MOSFETs are conducting, so the inductor's stored energy can cause a voltage spike on the MOSFETs. The inductor is about 9-10nH. Can this inductor cause such high voltage spike, that can kill a 100V MOSFET? How can I avoid this spike?

JensRasmussen!

I had to use 2 paralelled MOSFETs, becouse I only had "just" 80A types.
__________________
Best regards, Danko
  Reply With Quote
Old 21st September 2006, 05:10 PM   #13
poobah is offline poobah  United States
diyAudio Member
 
poobah's Avatar
 
Join Date: Nov 2005
Danko,

If you are sure you have no deadtime, that is the first place to work...

During your dead time, the inductor will draw its current from the body diode in the lower FET, this should not cause a large spike. But, the body diode of a Low-voltage FET is not the best thing either.

Check your calculations for peak inductor current. If your inductor saturates; it becomes a short circuit.



P.S. 9nH does not sound right. What is your Fs, Vi, Vo, and Po?

  Reply With Quote
Old 21st September 2006, 05:16 PM   #14
diyAudio Member
 
ifrythings's Avatar
 
Join Date: Oct 2005
I believe a snubber across the mosfets will suppress any large voltage spikes that the deadtime will cause.
  Reply With Quote
Old 21st September 2006, 05:21 PM   #15
luka is offline luka  Slovenia
diyAudio Member
 
luka's Avatar
 
Join Date: Sep 2005
Location: in Slovenia :)
Send a message via Skype™ to luka
Can I see your schema, please?

Would it be OK if I would use ONLY uperside mosfet and diode?
  Reply With Quote
Old 21st September 2006, 05:24 PM   #16
poobah is offline poobah  United States
diyAudio Member
 
poobah's Avatar
 
Join Date: Nov 2005
Yes... but you must replace the lower Fet with a good switching diode.

  Reply With Quote
Old 21st September 2006, 05:56 PM   #17
Danko is offline Danko  Hungary
diyAudio Member
 
Join Date: Apr 2004
Location: Hungary
Yes, schematic is coming soon. I just have to make it "human readable" format. It's quite messy....

poobah:
Fs=222kHz
Vi= 50V DC , from a 1.5kVA toroid
Vo=2.5V-15V
Io= /max/ 70A

7 turns on the inductor, and 70A /neglecting the dI/ through the inductor is 490 Amper*turns. The core, I'm using, the max. Amp*turns is about 7-800.
It should not saturate....

About dead-time.... I placed on the PCB R-C 's, but I think they caused too small dead-time.

luka: I have only ~20A diodes, and I had to paralelled many of them, to achieve safe operation. Oh, and the power loss would be almost double.
__________________
Best regards, Danko
  Reply With Quote
Old 21st September 2006, 06:23 PM   #18
luka is offline luka  Slovenia
diyAudio Member
 
luka's Avatar
 
Join Date: Sep 2005
Location: in Slovenia :)
Send a message via Skype™ to luka
I will use diode RURG8060 and my freq. is 50kHz, input voltage is 45DCv from 2kw trafo, I aim at 13.8v at 70A to charge several car baterys.
  Reply With Quote
Old 21st September 2006, 06:25 PM   #19
luka is offline luka  Slovenia
diyAudio Member
 
luka's Avatar
 
Join Date: Sep 2005
Location: in Slovenia :)
Send a message via Skype™ to luka
How big are those spikes? I intende to use 100v mofets to.
  Reply With Quote
Old 21st September 2006, 06:26 PM   #20
Danko is offline Danko  Hungary
diyAudio Member
 
Join Date: Apr 2004
Location: Hungary
The schematic:
http://sziget.mine.nu/~danko/aramkor...-06_201024.png

some notes:

The "voltage" line somes from the output. On the output there's a pot.meter, the "voltage" line is connected to it's wiper.
The "current" comes from a rail-to-rail ( Texas TLC2272 ) op.amp. The current shunt's voltage is amplied by the op.amp.
the circled R-C parts are makeing the dead-time. But... There's is a mistake, I think. One R-C slows down the turn-ON, the other slows down the turn-OFF.

The feedback around the TL494 isn't final.
__________________
Best regards, Danko
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Oops..i removed leds from amp circuit board cliffy Parts 5 5th January 2008 03:52 PM
Oops! Now what? cytokine Subwoofers 17 31st August 2005 12:33 PM
Oops.. May have fried my M-audio SuperDAC 2496 motherone Digital Source 3 11th March 2005 09:09 PM
Blew my first Chip ..Oops Help not doing it again? Adam M. Chip Amps 13 6th September 2004 03:08 PM
Oops squashed my smoothing caps!! Beggar Parts 1 6th September 2003 09:43 AM


New To Site? Need Help?

All times are GMT. The time now is 03:15 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2