Switched mode power supplies

Magura · 2nd January 2004, 10:18 PM

Whats the current status on SMPS ?

During the last couple of weeks ive read a few comments like "no big deal" and "ive made several that works fine".

I need a lot of power, like 40A 12 to 30V.

Anybody made something like that that actually works?

AND with a reasonable reliability and expected life to it???

Circlotron you mentioned that SMPS is a nogo no matter what, since i know theyre part of your profession, id like to have a short explanation why it is so.

Magura

Sch3mat1c · 3rd January 2004, 01:31 AM

All I've heard is that they are noisy as all hell but nobody's yet given me a reason why this noise can't be filtered, so go for it. I've tried a little work with flyback supplies and have had up to 10W output, I need a larger "spring"...

Tim

Magura · 3rd January 2004, 01:34 AM

well...monster size inductors are is the smallest problem. I havnt got much clue about the rest, and at 40A this is dangerous i guess

Magura

Tony Salsich · 3rd January 2004, 01:46 AM

I did an off-line, 30V/1kw supply for a customer. It was a 200khz, full bridge forward converter. Full bridge is a bit complicated, but the transformer was so small. I used a small PQ transformer with a center-tapped foil secondary. The primary was wound with triple insulated wire - great for meeting safety requirements. Rubadue, Furukawa and others make this kind of wire.

Magura · 3rd January 2004, 01:51 AM

Sounds interesting, got schematics for it?

How big is such a thing?....expensive??....reliable??

Magura

Tony Salsich · 3rd January 2004, 01:58 AM

I can get it to you in a few days. Yes, a bit expensive. It was part of a much bigger system: 1kW PFC front end, four independent full bridge outputs (for driving thermo-electric coolers). Basically a big pain in the ***, but also a great learning exerience. Each pice of the system was pretty straight forward, but making them all play together on one board was tough. It did meet class B conducted emissions though.

Magura · 3rd January 2004, 02:00 AM

what is the expected life of such a monster?

Magura

Tony Salsich · 3rd January 2004, 02:01 AM

I don't know what should 'wear out'. Should last years.

jackinnj · 3rd January 2004, 02:11 AM

Quote:

Originally posted by Sch3mat1c
All I've heard is that they are noisy as all hell but nobody's yet given me a reason why this noise can't be filtered, so go for it. I've tried a little work with flyback supplies and have had up to 10W output, I need a larger "spring"...
Tim

as you filter a square wave, eventually you get a pretty good sine wave but then you reduce efficiency -- this is how I use a PIC as a low distortion oscillator --

take a look at Application Note 70 on Linear Tech's website -- they have the noise down to where it can be used in hydrophones, medical applications, etc. You can order the parts from Linear directly, they have a low noise gate driver using the same slew-control technology.

Magura · 3rd January 2004, 02:12 AM

How about getting +30-0- -30V, is that possible in a reasonable way?

How about an option to regulate the output voltage, lets say from 12V to 30V ?

Magura

2nd January 2004, 10:18 PM	#1
Magura diyAudio Member Join Date: Oct 2003 Location: Denmark, Viborg	Switched mode power supplies Whats the current status on SMPS ? During the last couple of weeks ive read a few comments like "no big deal" and "ive made several that works fine". I need a lot of power, like 40A 12 to 30V. Anybody made something like that that actually works? AND with a reasonable reliability and expected life to it??? Circlotron you mentioned that SMPS is a nogo no matter what, since i know theyre part of your profession, id like to have a short explanation why it is so. Magura __________________ Everything is possible....to do the impossible just takes a little while longer. www.class-a-labs.com

3rd January 2004, 01:31 AM	#2
Sch3mat1c diyAudio Member Join Date: Jan 2003 Location: Milwaukee, WI	All I've heard is that they are noisy as all hell but nobody's yet given me a reason why this noise can't be filtered, so go for it. I've tried a little work with flyback supplies and have had up to 10W output, I need a larger "spring"... Tim __________________ Seven Transistor Labs, LLC Projects and Resources / Electronic Design and Consultation

3rd January 2004, 01:34 AM	#3
Magura diyAudio Member Join Date: Oct 2003 Location: Denmark, Viborg	well...monster size inductors are is the smallest problem. I havnt got much clue about the rest, and at 40A this is dangerous i guess Magura __________________ Everything is possible....to do the impossible just takes a little while longer. www.class-a-labs.com

3rd January 2004, 01:51 AM	#5
Magura diyAudio Member Join Date: Oct 2003 Location: Denmark, Viborg	Sounds interesting, got schematics for it? How big is such a thing?....expensive??....reliable?? Magura __________________ Everything is possible....to do the impossible just takes a little while longer. www.class-a-labs.com

3rd January 2004, 02:00 AM	#7
Magura diyAudio Member Join Date: Oct 2003 Location: Denmark, Viborg	what is the expected life of such a monster? Magura __________________ Everything is possible....to do the impossible just takes a little while longer. www.class-a-labs.com


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3rd January 2004, 01:46 AM	#4
Tony Salsich diyAudio Member Join Date: Dec 2003 Location: Cold country (Wisconsin)	I did an off-line, 30V/1kw supply for a customer. It was a 200khz, full bridge forward converter. Full bridge is a bit complicated, but the transformer was so small. I used a small PQ transformer with a center-tapped foil secondary. The primary was wound with triple insulated wire - great for meeting safety requirements. Rubadue, Furukawa and others make this kind of wire.

3rd January 2004, 01:58 AM	#6
Tony Salsich diyAudio Member Join Date: Dec 2003 Location: Cold country (Wisconsin)	I can get it to you in a few days. Yes, a bit expensive. It was part of a much bigger system: 1kW PFC front end, four independent full bridge outputs (for driving thermo-electric coolers). Basically a big pain in the ***, but also a great learning exerience. Each pice of the system was pretty straight forward, but making them all play together on one board was tough. It did meet class B conducted emissions though.

3rd January 2004, 02:01 AM	#8
Tony Salsich diyAudio Member Join Date: Dec 2003 Location: Cold country (Wisconsin)	I don't know what should 'wear out'. Should last years.

3rd January 2004, 02:12 AM	#10
Magura diyAudio Member Join Date: Oct 2003 Location: Denmark, Viborg	How about getting +30-0- -30V, is that possible in a reasonable way? How about an option to regulate the output voltage, lets say from 12V to 30V ? Magura __________________ Everything is possible....to do the impossible just takes a little while longer. www.class-a-labs.com

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