Offline full-bridge SMPS....need help - Page 73 - diyAudio
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Old 6th December 2007, 09:42 PM   #721
luka is offline luka  Slovenia
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Hi

Last one, you will see +60 and -60 labels on schema, you can get any voltage you want, just trafo must be corrected
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Old 6th December 2007, 10:21 PM   #722
chas1 is offline chas1  Dominican Republic
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Default spec's for supply

It would help if you would specify the power needed for your intended load and what is the intened use as well as input voltage and output voltage and current. +/- 85 volt @ 10 amps requires over 2kW input power and you should consider a full bridge.

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Old 8th December 2007, 08:12 AM   #723
Krisfr is offline Krisfr  United States
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Quote:
Originally posted by luka
Hi

Last one, you will see +60 and -60 labels on schema, you can get any voltage you want, just trafo must be corrected
I really appreciate your response....

I am going to go for a 250 to 350 per channel power amp, something like a Leach or similar. I have built a 700 watt but that is another story. I just want to get my feet wet, but not drown now that I have the time in my semi-retirement.

I have started a spreadsheet for the SMPS portion of this project. It is for everyone to see and share if so desired.

I will leave it open for now, but if it get trashed for any reason I will restrict access.

take a look at: http://spreadsheets.google.com/ccc?k...VNhx9eKQ&hl=en


Enjoy thanks for sharing your time and talent. I will do the same with what little I have...
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Old 8th December 2007, 08:13 AM   #724
Krisfr is offline Krisfr  United States
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Default Re: spec's for supply

Quote:
Originally posted by chas1
It would help if you would specify the power needed for your intended load and what is the intened use as well as input voltage and output voltage and current. +/- 85 volt @ 10 amps requires over 2kW input power and you should consider a full bridge.

chas1
Thanks Chas

Would you point me to the schematic that shows the full and the half bridge, I am totally lost on this part.

I have built some small SMPS in my day, but nothing with the power of this design...

Thanks for your help....
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Old 8th December 2007, 10:11 AM   #725
chas1 is offline chas1  Dominican Republic
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Default full bridge & halfbridge schematic

If you go to the URL below and click on Power Supply Schematic you will find a FB design, the complete construction details,parts lists and PCB.

This supply was designed to power the Audio Amp K6 and is an excellent design and will work out of the box as for HB in this thread you will find a schematic of my design which is good up to a kW and should power the Leach amp or Leach supperamp which if I remember require about +/- 40 volts @5 amp

chas1

http://www.a-and-t-labs.com/K6_Sw_Amp/index.htm
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Old 8th December 2007, 12:26 PM   #726
Krisfr is offline Krisfr  United States
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Default Re: full bridge & halfbridge schematic

Quote:
Originally posted by chas1
If you go to the URL below and click on Power Supply Schematic you will find a FB design, the complete construction details,parts lists and PCB.

This supply was designed to power the Audio Amp K6 and is an excellent design and will work out of the box as for HB in this thread you will find a schematic of my design which is good up to a kW and should power the Leach amp or Leach supperamp which if I remember require about +/- 40 volts @5 amp

chas1

http://www.a-and-t-labs.com/K6_Sw_Amp/index.htm
Why didn't just say so in the first place.....

I am so impressed with your hard and very good work. Now if I can just get the boss to approve the funds for the fun to be had to bring it to life. She will I think.

But the K6 will keep me busy for a year or two.

Thanks for the information.
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Old 9th December 2007, 11:18 AM   #727
chas1 is offline chas1  Dominican Republic
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Default Amplifiers

I don't want to mislead anyone, the K6 amp along with the smps was designed by Reinhard Metz and Myzil Boyce, I have constructed the power supply and it functions well. I did not build the K6 as I use my own amp design and have since designed and constructed a halfbridge power supply that powers it. In doing so I have studied many designs,appnotes and purchased some excellent books on the subject and I also purchased a book by Christophe Basso titled Switchmode Power Supply Spice Cookbook which enabled me to simulate using spice various parts of the smps and the complete supply itself along with a quick way to design the feedback and close the loop. A good read, should be on your reading list.

chas1
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Old 9th December 2007, 12:27 PM   #728
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chas1,
howdy, i was looking for your half bridge circuit, is it posted on here somewhere?

how did you decide what decoupling capacitor to use? sizing for current, that is.

thanks
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Old 9th December 2007, 02:15 PM   #729
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Default Re: Re: full bridge & halfbridge schematic

http://www.a-and-t-labs.com/K6_Sw_Am...atic/k6pwr.pdf

This is a voltage mode full-bridge correct? How do you keep the transformer from walking up bh curve? I do not see a series primary cap.
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Old 9th December 2007, 02:59 PM   #730
chas1 is offline chas1  Dominican Republic
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Default series cap for xfmr

jamesrnz

If you have this book "High frequency Switching Power Supplies"
go to page 31 . The full explanation is there, if you don't here it is

Thanks to George Chryssis:

The coupling cap along with the output filter inductor form a resonant circuit whose frequency is:

fr = 1 /6.28 *sqrt(LR*C)

where fr = resonant frequency in kHz
C= coupling cap in uF
LR = reflected filter inductance

reflected inductance is LR = (Np/Ns)^2 * L
where Np/Ns is turns ratio and L is output inductance(uH)

Then C = 1/(4*3.14^2*Fr^2*(Np/Ns)^2*L)

This is how its calculated in this book. As for my self I don't use it and I don't have any problem because the two resistors across the input caps balance the center if you use two 2.5u to 10u caps in parallel depending on load current. this point stays around 160 volts in my halfbridge. Refer to my schematic. You might have to adjust the value for input ripple at low line for if it is to large it will interfere with the regulation. A good value is .1u to 2uf, you can get these caps from an old PC power supply and parallel them if more capacitance is needed.
chas1
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