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Old 19th June 2005, 11:04 PM   #11
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Location: Slovakia (middle of Europe :-))
Default pics

Here are some more
http://www.anonym555.kgb.cz/amp.rar

You can see the final look of the amplifier, its inside, and a SMPS schematic (this is not very accurate now, there is other kind of PFC-PWM synchronisation and there are these three modifications I mentoined). I also attached a photo of a burned 18Sound 1000W AES bass speaker, just for fun
That is caused by that class-T switching beasts. Maybe I did something wrong, maybe their algoritm is bad... who knows. But speaker's diaphragm was not damaged, so most likely there are some nasty DC peaks or something...
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Old 21st June 2005, 12:06 AM   #12
Eva is offline Eva  Spain
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Such a SMPS must not be left unfiltered. A common mode filter should be placed at the mains input. In order to build the required common mode choke just wrap two symmetrical windings across a high permeability ferrite toroid. Use as many turns as possible. See the picture for more details:

Click the image to open in full size.
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Old 2nd September 2005, 07:36 AM   #13
Pierre is offline Pierre  France
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What an impressive SMPS, Disney_SK!
Are you willing to share the schematics with us? I am also in my way of building a half-bridge SMPS, somewhat smaller, however (around 800W).
I also use a SG3525, but it's in the primary side because I use mains + hv regulator for startup, so I really need an optocoupler. However, I am experiencing basic problems with voltage mode control, so having a peek at your controller (feedback, decoupling, compensation...) could help me a lot.
Also, what power devices are you using, IGBT's or Mosfets? Eva has provided some very good advices to me about that and now I am not completely sure about my first approach: mosfets ;-)

Thanks in advance!
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Old 2nd September 2005, 09:31 PM   #14
rinox is offline rinox  Italy
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I totally agree with Mr. Eva... you can't connect such a monster directly to mains without any kind of filter.
For a quick and dirty solution, you can try to take a pair of yellow toroid (from a normal PC psu) and give some turns of copper (at least 2mm diam., then with a scope measure the noise, and try to oppose the fases.
Hope you'll be able to understan what I mean.... my english is so bad
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Old 2nd September 2005, 11:26 PM   #15
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Quote:
Originally posted by Pierre
What an impressive SMPS, Disney_SK!
Are you willing to share the schematics with us? I am also in my way of building a half-bridge SMPS, somewhat smaller, however (around 800W).
I also use a SG3525, but it's in the primary side because I use mains + hv regulator for startup, so I really need an optocoupler. However, I am experiencing basic problems with voltage mode control, so having a peek at your controller (feedback, decoupling, compensation...) could help me a lot.
Also, what power devices are you using, IGBT's or Mosfets? Eva has provided some very good advices to me about that and now I am not completely sure about my first approach: mosfets ;-)

Thanks in advance!
Of course I can provide the schematics, I already did... but as I see that server has some problems, so I will try to provide the content at http://www.djsonic.sk/amp.rar
I am currently using MOSFETs, but maybe I will move to IGBTs because of their capability to withstand longer current peaks... they do not explode so nasty as mosfets ;-)


Quote:
Originally posted by rinox
I totally agree with Mr. Eva... you can't connect such a monster directly to mains without any kind of filter.
For a quick and dirty solution, you can try to take a pair of yellow toroid (from a normal PC psu) and give some turns of copper (at least 2mm diam., then with a scope measure the noise, and try to oppose the fases.
Hope you'll be able to understan what I mean.... my english is so bad

I understand. EPCOS 10A off-the-shelf mains filter came few days ago and looks forward to be mounted in
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Old 3rd September 2005, 03:03 AM   #16
alabpro is offline alabpro  Thailand
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out- .no feedback you sure working
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Old 8th September 2005, 06:14 AM   #17
Pierre is offline Pierre  France
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I have just been having a look at your schematics...

Do they reflect the changes you have done to the control circuitry so it is estable? I don't think so, because it doesn't show the 560pF from COMP to GND, nor the suggested 22pF from OSC_OUT to GND but it shows the original values you said.
Did you finally include the modifications in your prototype and, if so, did they improve something?

It doesn't show the snubber, as well. Did you measure the primary waveform before and after putting it? Did that waveform improve or did you added it "just in case"?

Best regards,
Pierre
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Old 8th September 2005, 07:05 AM   #18
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Quote:
Originally posted by Pierre
I have just been having a look at your schematics...

Do they reflect the changes you have done to the control circuitry so it is estable? I don't think so, because it doesn't show the 560pF from COMP to GND, nor the suggested 22pF from OSC_OUT to GND but it shows the original values you said.
Did you finally include the modifications in your prototype and, if so, did they improve something?

It doesn't show the snubber, as well. Did you measure the primary waveform before and after putting it? Did that waveform improve or did you added it "just in case"?

Best regards,
Pierre

You're right, this is the original schematic. I have no schematic but I did the changes discussed.
Added snubber consists of 100R/2W resistor and 100pF capacitor. I did not ever measure primary waveforms (too high voltage for me )

I did not add that 22pF to OSC_OUT, but I have made other modifications which I have explained in another topic
(sorry but i don't remember them right now but they were made in accordance to http://www.djsonic.sk/car_supply.gif)
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Old 8th September 2005, 07:14 AM   #19
Pierre is offline Pierre  France
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Following your post, you have replaced the resistor from INV_IN to COMP and now it is 10k, with no capacitor in parallel, and you have also added 10nF from COMP to GND. That's all?
But that doesn't match with the schematics of the 12V supply you have posted, right?
Sorry, I only want to have the point clear to start experimenting.
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Old 8th September 2005, 07:31 AM   #20
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Quote:
Originally posted by Pierre
Following your post, you have replaced the resistor from INV_IN to COMP and now it is 10k, with no capacitor in parallel, and you have also added 10nF from COMP to GND. That's all?
But that doesn't match with the schematics of the 12V supply you have posted, right?
Sorry, I only want to have the point clear to start experimenting.

Well, I have unmounted the control PCB and chcecked it especially for you

now I don't remember which pin is "comp" and so on, so>
560pF and 10nF in parallel from pin at the edge to ground
10k resistor from pin at the edge to the one next to it.

I know this specification is a bit weird... but you know, summertime... people have other interests than smps
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