|
|||||||
| Home | Forums | Rules | Articles | Store | Gallery | Blogs | Register | Donations | FAQ | Calendar | Search | Today's Posts | Mark Forums Read | Search |
  |
|
|
|
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 |
 |
|
|
Thread Tools | Search this Thread |
21st January 2010, 12:34 PM
|
#1 |
|
diyAudio Member
Join Date: Nov 2004
Location: Bucharest
|
Help RC SNUBBER!
Hello, please help me find the correct values of RC snubber!
45% duty cycle, frequency 54khz, without feedback http://img9.imageshack.us/img9/28/farafeedback.jpg 20% duty cycle http://img696.imageshack.us/img696/7017/cufeedback.jpg waveform of the primary and secondary is incorrect. DATA SHEET FOR TRANSFORMER http://img260.imageshack.us/img260/8462/datetehnice.jpg Thanks in advance! |
|
|
21st January 2010, 01:33 PM
|
#2 |
|
diyAudio Member
Join Date: Sep 2005
Location: in Slovenia :)
|
waveforms look ok you know, they are far from bad
|
|
|
|
21st January 2010, 02:24 PM
|
#3 |
|
diyAudio Member
Join Date: Nov 2004
Location: Bucharest
|
power test on direct secondary, without feedback
picture of Vcc and Acc (power in) and wave form of secondary http://img20.imageshack.us/img20/8218/vlcsnap219656.png My feedback dont work! without feedback output voltage = 24.5V My feedback is set to down voltage at 15v, bat dont work, output voltage remains at 24v |
|
|
|
21st January 2010, 02:24 PM
|
#4 |
|
diyAudio Member
Join Date: Oct 2003
Location: Near the sea
|
I agree with luka, waveforms are not that bad, at least within the level of detail that the tiny pictures provide.
I see some brief peaking and ringing on the leading edge of the secondary winding waveform, a RC or RLC snubber can be quite useful there, but the picture has not enough detail to see the frequency of the ringing and the height of the peak. Primary side snubbers don't look like optimum, a 20W resistor is usually wirewound and exhibits too high inductance to be useful. The capacitors across the IGBT don't look like optimum either, although they can make things simpler and allow the transformer gate drive to work without parasitic turn-on. EDIT: Remember to ground SYNC pin. At first glance I don't see a clear reason for feedback not to work, but there is no frequency compensation at all, so if it works, it won't be stable.
__________________
I use to feel like the small child in The Emperor's New Clothes tale 
Last edited by Eva; 21st January 2010 at 02:28 PM. |
|
|
|
21st January 2010, 06:41 PM
|
#5 |
|
diyAudio Member
Join Date: Nov 2004
Location: Bucharest
|
Primary side snubbers R=25ohm, C=8nF
Test is made at 100Vcc without snubber http://img641.imageshack.us/img641/58/21012010918.jpg http://img641.imageshack.us/img641/9249/21012010917.jpg with snubber R=25 C=8nF http://img14.imageshack.us/img14/5230/21012010927.jpg http://img204.imageshack.us/img204/4770/21012010926.jpg waveform on primary whit snubber http://img204.imageshack.us/img204/1651/21012010925.jpg waveform on resistor (25ohm) http://img130.imageshack.us/img130/5697/21012010924.jpg What is your opinion? |
|
|
|
22nd January 2010, 05:32 AM
|
#6 |
|
diyAudio Member
Join Date: Jan 2003
Location: Milwaukee, WI
 
|
What is the inverter current waveform?
Your output filter inductor doesn't seem to be inducting. The transformer waveform should be pulled to zero by the inductor. Were you drawing any current while measuring those waveforms? I suppose the explanation comes from here, http://img260.imageshack.us/img260/8462/datetehnice.jpg where if you indeed followed its recommendation of slightly over 1uH, you won't be seeing continuous output current for along while (>30A?). Try a much heavier load. Snubbers aren't very appropriate for the kind of overshoot you are seeing. That's more of a wiring / stray inductance issue. Or possibly a probe or oscilloscope compensation thing... Rigol isn't exactly vintage Tektronix. Since the peaks aren't blowing transistors, it's no big deal. Tim
__________________
See my Electronics webpage -- the home of Vacuum Tube Drag Racing. The key to being a successful Audiophile: "I reject your reality and substitute my own!" |
|
|
|
22nd January 2010, 09:22 PM
|
#8 |
|
diyAudio Member
Join Date: Nov 2004
Location: Bucharest
|
Last modifications!
Remove capatitors on igbt, primary side snubbers R=25ohm, C=4.7nF schematic driver http://img33.imageshack.us/img33/1682/63788787.jpg Video whit waveform at secondary whit mini-loud YouTube - SMPS Multimeter 1 = V out Multimeter 2 = I in at 300Vcc Multimeter 3 = V in 300Vcc separator transformer 220 to 220 What is your opinion?, Why can not decrease V-out more then 19V? Last edited by mgm2000ro; 22nd January 2010 at 09:51 PM. |
|
|
|
22nd January 2010, 10:14 PM
|
#9 |
|
diyAudio Member
Join Date: Sep 2005
Location: in Slovenia :)
|
best thing I can think of is to check the voltage on input pin and what ever the other is for reference
|
|
|
|
23rd January 2010, 05:47 AM
|
#10 |
|
diyAudio Member
Join Date: Jan 2003
Location: Milwaukee, WI
|
Did you apply a load yet?
__________________
See my Electronics webpage -- the home of Vacuum Tube Drag Racing. The key to being a successful Audiophile: "I reject your reality and substitute my own!" |
|
|
|
| Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | |
| Thread Tools | Search this Thread |
|
|
Similar Threads
|
||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| Snubber AND non-snubber ? | jimbo1968 | Chip Amps | 10 | 6th December 2005 07:49 AM |
| Power Supply Designing using LM317, RC-snubber | okina | Power Supplies | 4 | 12th September 2005 02:17 AM |
| RE: RC-19 or RC-30 | chungtat | Tubes / Valves | 6 | 6th August 2005 03:51 AM |
| Help calculating RC values for rectifier snubber | Eric | Pass Labs | 2 | 31st January 2003 06:57 PM |
| New To Site? | Need Help? |
| Page generated in 0.10692 seconds (84.99% PHP - 15.01% MySQL) with 11 queries |
