smps: AC or pulsed DC fed into transformer?

Mar 15, 2016

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this true?

For example, here, the transistor simply turns on and off, providing pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed high-frequency AC instead of high-frequency pulsed DC (for example, by using an H-bridge to provide a negative voltage across the transformer primary for the second half of each cycle)?

Thanks,

Michael

Mar 15, 2016

On Tuesday, March 15, 2016 at 1:06:49 PM UTC-7, Jim Thompson wrote:

On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this true?

For example, here, the transistor simply turns on and off, providing pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed high-frequency AC instead of high-frequency pulsed DC (for example, by using an H-bridge to provide a negative voltage across the transformer primary for the second half of each cycle)?

Thanks,

Michael

Yes. But flybacks take fewer external parts.

...Jim Thompson

Oh! It's a cost-savings thing, then.

Thanks,

Michael

Mar 15, 2016

On Tuesday, March 15, 2016 at 1:53:20 PM UTC-7, John Larkin wrote:

On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this true?

For example, here, the transistor simply turns on and off, providing pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed high-frequency AC instead of high-frequency pulsed DC (for example, by using an H-bridge to provide a negative voltage across the transformer primary for the second half of each cycle)?

Thanks,

Michael

Really big (like kilowatt) switching supplies are often forward
converters, with symmetric square-wave drive, no DC component, into
the transformer. No DC in the transformer core is more efficient.

http://www.industrial-electronics.com/image/7_33.jpg

http://jugandi.com/ebooks/eXe_Power%20Supplies/Power_Supplies/image150a.png

https://dl.dropboxusercontent.com/u/53724080/Circuits/ESM/ESM_power_B.pdf

There are also some clever resonant designs that run real AC (sine
waves) through the magnetics.

Small, cheap supplies work well with the flyback topology.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Ok, thanks!

Forward Converter... new vocabulary words for today

Michael

Cursitor Doom · Mar 15, 2016

On Tue, 15 Mar 2016 15:16:25 -0700, John Larkin wrote:

On Tue, 15 Mar 2016 14:17:26 -0700 (PDT), mrdarrett@gmail.com wrote:

On Tuesday, March 15, 2016 at 1:53:20 PM UTC-7, John Larkin wrote:
On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is
this true?

For example, here, the transistor simply turns on and off, providing
pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed
high-frequency AC instead of high-frequency pulsed DC (for example,
by using an H-bridge to provide a negative voltage across the
transformer primary for the second half of each cycle)?

Thanks,

Michael

Really big (like kilowatt) switching supplies are often forward
converters, with symmetric square-wave drive, no DC component, into
the transformer. No DC in the transformer core is more efficient.

http://www.industrial-electronics.com/image/7_33.jpg

http://jugandi.com/ebooks/eXe_Power%20Supplies/Power_Supplies/
image150a.png

https://dl.dropboxusercontent.com/u/53724080/Circuits/ESM/
ESM_power_B.pdf

There are also some clever resonant designs that run real AC (sine
waves) through the magnetics.

Small, cheap supplies work well with the flyback topology.

--

John Larkin Highland Technology, Inc picosecond timing
precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Ok, thanks!

Forward Converter... new vocabulary words for today

Michael

A few more

Forward

Flyback

Buck

Boost

Cuk

Sepic

Resonant

Cockroft-Walton

Royer

Baxandall

(there must be more)

There are. Not least many sub-categories of the above!

Helmut Wabnig · Mar 16, 2016

On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this true?

For example, here, the transistor simply turns on and off, providing pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed high-frequency AC instead of high-frequency pulsed DC (for example, by using an H-bridge to provide a negative voltage across the transformer primary for the second half of each cycle)?

Thanks,

Michael

High Frequency chopped DC is equal to High Frequency AC.

I.T. I.S. A.C.

w.

Jim Thompson · Mar 16, 2016

On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this true?

For example, here, the transistor simply turns on and off, providing pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed high-frequency AC instead of high-frequency pulsed DC (for example, by using an H-bridge to provide a negative voltage across the transformer primary for the second half of each cycle)?

Thanks,

Michael

Ian Field · Mar 16, 2016

<mrdarrett@gmail.com> wrote in message
news:9bcd7f2a-6040-4c60-a214-c875e7a135bb@googlegroups.com...

On Tuesday, March 15, 2016 at 1:06:49 PM UTC-7, Jim Thompson wrote:
On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this
true?

For example, here, the transistor simply turns on and off, providing
pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed
high-frequency AC instead of high-frequency pulsed DC (for example, by
using an H-bridge to provide a negative voltage across the transformer
primary for the second half of each cycle)?

Thanks,

Michael

Yes. But flybacks take fewer external parts.

...Jim Thompson

Oh! It's a cost-savings thing, then.

One big motivation is higher frequency allows smaller cheaper reactive
components.

The penalty is running into transistor switching times, ferrite losses and
rectifier Trr.

Not studied this area - but I think semi-resonant SMPSUs are the answer to
that.

If I understand it correctly - they're sort of AC transformer drive instead
of DC pulses.

John Larkin · Mar 16, 2016

On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this true?

For example, here, the transistor simply turns on and off, providing pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed high-frequency AC instead of high-frequency pulsed DC (for example, by using an H-bridge to provide a negative voltage across the transformer primary for the second half of each cycle)?

Thanks,

Michael

Really big (like kilowatt) switching supplies are often forward
converters, with symmetric square-wave drive, no DC component, into
the transformer. No DC in the transformer core is more efficient.

http://www.industrial-electronics.com/image/7_33.jpg

http://jugandi.com/ebooks/eXe_Power%20Supplies/Power_Supplies/image150a.png

https://dl.dropboxusercontent.com/u/53724080/Circuits/ESM/ESM_power_B.pdf

There are also some clever resonant designs that run real AC (sine
waves) through the magnetics.

Small, cheap supplies work well with the flyback topology.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Ian Field · Mar 16, 2016

<mrdarrett@gmail.com> wrote in message
news:8ea32720-d16b-4b01-be4a-2158b8466282@googlegroups.com...

On Tuesday, March 15, 2016 at 1:53:20 PM UTC-7, John Larkin wrote:
On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this
true?

For example, here, the transistor simply turns on and off, providing
pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed
high-frequency AC instead of high-frequency pulsed DC (for example, by
using an H-bridge to provide a negative voltage across the transformer
primary for the second half of each cycle)?

Thanks,

Michael

Really big (like kilowatt) switching supplies are often forward
converters, with symmetric square-wave drive, no DC component, into
the transformer. No DC in the transformer core is more efficient.

http://www.industrial-electronics.com/image/7_33.jpg

http://jugandi.com/ebooks/eXe_Power%20Supplies/Power_Supplies/image150a.png

https://dl.dropboxusercontent.com/u/53724080/Circuits/ESM/ESM_power_B.pdf

There are also some clever resonant designs that run real AC (sine
waves) through the magnetics.

Small, cheap supplies work well with the flyback topology.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Ok, thanks!

Forward Converter... new vocabulary words for today

Forward converters don't have to be as big as the examples JL mentioned.

The early PC/AT psus were often flyback, but forward converters became
pretty much the standard once the ratings got to around 200W.

There's plenty of off the shelf controller chips to chose from and also
plenty of appnotes with example circuits. The SG3524 is just one of many
that springs readily to mind.

The KA7500 is popular in ATX supplies, so there may be a free development
sample gathering dust in the loft. AFAICR: the TL494 is another common
choice.

Those 3 part numbers will find manufacturers that have other similar parts
on offer.

John Larkin · Mar 16, 2016

On Tue, 15 Mar 2016 14:17:26 -0700 (PDT), mrdarrett@gmail.com wrote:

On Tuesday, March 15, 2016 at 1:53:20 PM UTC-7, John Larkin wrote:
On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this true?

For example, here, the transistor simply turns on and off, providing pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed high-frequency AC instead of high-frequency pulsed DC (for example, by using an H-bridge to provide a negative voltage across the transformer primary for the second half of each cycle)?

Thanks,

Michael

Really big (like kilowatt) switching supplies are often forward
converters, with symmetric square-wave drive, no DC component, into
the transformer. No DC in the transformer core is more efficient.

http://www.industrial-electronics.com/image/7_33.jpg

http://jugandi.com/ebooks/eXe_Power%20Supplies/Power_Supplies/image150a.png

https://dl.dropboxusercontent.com/u/53724080/Circuits/ESM/ESM_power_B.pdf

There are also some clever resonant designs that run real AC (sine
waves) through the magnetics.

Small, cheap supplies work well with the flyback topology.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Ok, thanks!

Forward Converter... new vocabulary words for today

Michael

A few more

Forward

Flyback

Buck

Boost

Cuk

Sepic

Resonant

Cockroft-Walton

Royer

Baxandall

(there must be more)

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Phil Hobbs · Mar 16, 2016

On 03/15/2016 06:16 PM, John Larkin wrote:

On Tue, 15 Mar 2016 14:17:26 -0700 (PDT), mrdarrett@gmail.com wrote:

On Tuesday, March 15, 2016 at 1:53:20 PM UTC-7, John Larkin wrote:
On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this true?

For example, here, the transistor simply turns on and off, providing pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed high-frequency AC instead of high-frequency pulsed DC (for example, by using an H-bridge to provide a negative voltage across the transformer primary for the second half of each cycle)?

Thanks,

Michael

Really big (like kilowatt) switching supplies are often forward
converters, with symmetric square-wave drive, no DC component, into
the transformer. No DC in the transformer core is more efficient.

http://www.industrial-electronics.com/image/7_33.jpg

http://jugandi.com/ebooks/eXe_Power%20Supplies/Power_Supplies/image150a.png

https://dl.dropboxusercontent.com/u/53724080/Circuits/ESM/ESM_power_B.pdf

There are also some clever resonant designs that run real AC (sine
waves) through the magnetics.

Small, cheap supplies work well with the flyback topology.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Ok, thanks!

Forward Converter... new vocabulary words for today

Michael

A few more

Forward

Flyback

Buck

Boost

Cuk

Sepic

Resonant

Cockroft-Walton

Royer

Baxandall

(there must be more)

Flybuck

ICL7660-style flying capacitor

Tesla coil

thunderstorm

Cheers

Phil Hobbs

Jasen Betts · Mar 16, 2016

On 2016-03-15, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:
> It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this true?

yes.

> For example, here, the transistor simply turns on and off, providing pulses to the transformer, right?

It's not a transformer... it's an inductor with two windings.

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed
high-frequency AC instead of high-frequency pulsed DC (for example, by
using an H-bridge to provide a negative voltage across the transformer
primary for the second half of each cycle)?

That won't work with a flyback, but with a forwards converter*
it would work, but now you have twice the switch losses.

(*) where the secondary and primary windings conduct simultaneously
eg: Royer.

--
\_(ă)_

Jasen Betts · Mar 16, 2016

On 2016-03-15, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:

On Tuesday, March 15, 2016 at 1:53:20 PM UTC-7, John Larkin wrote:
On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this true?

For example, here, the transistor simply turns on and off, providing pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed high-frequency AC instead of high-frequency pulsed DC (for example, by using an H-bridge to provide a negative voltage across the transformer primary for the second half of each cycle)?

Thanks,

Michael

Really big (like kilowatt) switching supplies are often forward
converters, with symmetric square-wave drive, no DC component, into
the transformer. No DC in the transformer core is more efficient.

http://www.industrial-electronics.com/image/7_33.jpg

http://jugandi.com/ebooks/eXe_Power%20Supplies/Power_Supplies/image150a.png

https://dl.dropboxusercontent.com/u/53724080/Circuits/ESM/ESM_power_B.pdf

There are also some clever resonant designs that run real AC (sine
waves) through the magnetics.

Small, cheap supplies work well with the flyback topology.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Ok, thanks!

Forward Converter... new vocabulary words for today

A good intro to switched mode:

http://www.onsemi.com/pub_link/Collateral/SMPSRM-D.PDF

--
\_(ă)_

Mar 16, 2016

On Wednesday, March 16, 2016 at 1:00:58 AM UTC-7, Jasen Betts wrote:

On 2016-03-15, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:
On Tuesday, March 15, 2016 at 1:53:20 PM UTC-7, John Larkin wrote:
On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this true?

For example, here, the transistor simply turns on and off, providing pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed high-frequency AC instead of high-frequency pulsed DC (for example, by using an H-bridge to provide a negative voltage across the transformer primary for the second half of each cycle)?

Thanks,

Michael

Really big (like kilowatt) switching supplies are often forward
converters, with symmetric square-wave drive, no DC component, into
the transformer. No DC in the transformer core is more efficient.

http://www.industrial-electronics.com/image/7_33.jpg

http://jugandi.com/ebooks/eXe_Power%20Supplies/Power_Supplies/image150a.png

https://dl.dropboxusercontent.com/u/53724080/Circuits/ESM/ESM_power_B.pdf

There are also some clever resonant designs that run real AC (sine
waves) through the magnetics.

Small, cheap supplies work well with the flyback topology.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Ok, thanks!

Forward Converter... new vocabulary words for today

A good intro to switched mode:

http://www.onsemi.com/pub_link/Collateral/SMPSRM-D.PDF

--
\_(ă)_

Ooh thanks!

Michael

Ian Field · Mar 16, 2016

"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
news:ubKdnYuZLqFYCXXLnZ2dnUU7-TOdnZ2d@supernews.com...

On 03/15/2016 06:16 PM, John Larkin wrote:
On Tue, 15 Mar 2016 14:17:26 -0700 (PDT), mrdarrett@gmail.com wrote:

On Tuesday, March 15, 2016 at 1:53:20 PM UTC-7, John Larkin wrote:
On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is
this true?

For example, here, the transistor simply turns on and off, providing
pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed
high-frequency AC instead of high-frequency pulsed DC (for example, by
using an H-bridge to provide a negative voltage across the transformer
primary for the second half of each cycle)?

Thanks,

Michael

Really big (like kilowatt) switching supplies are often forward
converters, with symmetric square-wave drive, no DC component, into
the transformer. No DC in the transformer core is more efficient.

http://www.industrial-electronics.com/image/7_33.jpg

http://jugandi.com/ebooks/eXe_Power%20Supplies/Power_Supplies/image150a.png

https://dl.dropboxusercontent.com/u/53724080/Circuits/ESM/ESM_power_B.pdf

There are also some clever resonant designs that run real AC (sine
waves) through the magnetics.

Small, cheap supplies work well with the flyback topology.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Ok, thanks!

Forward Converter... new vocabulary words for today

Michael

A few more

Forward

Flyback

Buck

Boost

Cuk

Sepic

Resonant

Cockroft-Walton

Royer

Baxandall

(there must be more)

Flybuck

ICL7660-style flying capacitor

Tesla coil

thunderstorm

I'd be interested to see a 6MV supercapacitor and a buck that can bring that
down to national grid type voltages.

Apparently US power companies have for some time been experimenting with EHV
DC distribution lines. Last I heard they were reaching for 1MV in an attempt
to find the tradeoff between corona discharge on EHV DC compared to
capacitive losses on lower voltage AC distribution.

John Larkin · Mar 17, 2016

On Tue, 15 Mar 2016 19:03:33 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 03/15/2016 06:16 PM, John Larkin wrote:
On Tue, 15 Mar 2016 14:17:26 -0700 (PDT), mrdarrett@gmail.com wrote:

On Tuesday, March 15, 2016 at 1:53:20 PM UTC-7, John Larkin wrote:
On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this true?

For example, here, the transistor simply turns on and off, providing pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed high-frequency AC instead of high-frequency pulsed DC (for example, by using an H-bridge to provide a negative voltage across the transformer primary for the second half of each cycle)?

Thanks,

Michael

Really big (like kilowatt) switching supplies are often forward
converters, with symmetric square-wave drive, no DC component, into
the transformer. No DC in the transformer core is more efficient.

http://www.industrial-electronics.com/image/7_33.jpg

http://jugandi.com/ebooks/eXe_Power%20Supplies/Power_Supplies/image150a.png

https://dl.dropboxusercontent.com/u/53724080/Circuits/ESM/ESM_power_B.pdf

There are also some clever resonant designs that run real AC (sine
waves) through the magnetics.

Small, cheap supplies work well with the flyback topology.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Ok, thanks!

Forward Converter... new vocabulary words for today

Michael

A few more

Forward

Flyback

Buck

Boost

Cuk

Sepic

Resonant

Cockroft-Walton

Royer

Baxandall

(there must be more)

Flybuck

ICL7660-style flying capacitor

I think LTC or somebody makes what is basically a flying-inductor
converter.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

szczepan bialek · Mar 18, 2016

"Helmut Wabnig" <hwabnig@.- --- -.dotat> napisal w wiadomosci
news:0iqgeb9fhj643eqvbeti4b8nkmtrc830sb@4ax.com...

On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this
true?

For example, here, the transistor simply turns on and off, providing
pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed
high-frequency AC instead of high-frequency pulsed DC (for example, by
using an H-bridge to provide a negative voltage across the transformer
primary for the second half of each cycle)?

Thanks,

Michael

High Frequency chopped DC is equal to High Frequency AC.

It is true.

I.T. I.S. A.C.

But "Alternating current (AC), is an electric current in which the flow of
electric charge periodically reverses direction, whereas in direct current
(DC, also dc), the flow of electric charge is only in one direction".

So the High Frequency AC which is flowing in a transmising line is not AC
at all. It is the impulsing current.
Do you agree?
S*

szczepan bialek · Mar 18, 2016

<mrdarrett@gmail.com> napisal w wiadomosci
news:41831c05-fc32-4e3f-942c-38ec697932a6@googlegroups.com...

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this
true?

For example, here, the transistor simply turns on and off, providing
pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed
high-frequency AC instead of high-frequency pulsed DC (for example, by
using an H-bridge to provide a negative voltage across the transformer
primary for the second half of each cycle)?

https://en.wikipedia.org/wiki/File:Types_of_current.svg

Your flyback is using the impulsing current.

But the term "impulsing current" was used by Tesla.
Up to now the Tesla name is absent in textbooks about radio.
Do You know that Tesla was "Father of radio":
http://www.tfcbooks.com/tesla/1929-09-22.htm
S(

repurplecirculation · May 17, 2016

On Tuesday, March 15, 2016 at 4:05:16 PM UTC-4, Helmut Wabnig wrote:

On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this true?

For example, here, the transistor simply turns on and off, providing pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed high-frequency AC instead of high-frequency pulsed DC (for example, by using an H-bridge to provide a negative voltage across the transformer primary for the second half of each cycle)?

Thanks,

Michael

High Frequency chopped DC is equal to High Frequency AC.

I.T. I.S. A.C.

w.

I disagree. AC REVERSES polarity (hence the "Alternating" in Alternating Current). Pulsed DC does not.

szczepan bialek · May 18, 2016

"repurplecirculation" <dave@beefydog.com> napisał w wiadomości
news:1e55c872-29ab-44a3-a021-a178a49fc1a8@googlegroups.com...

On Tuesday, March 15, 2016 at 4:05:16 PM UTC-4, Helmut Wabnig wrote:
On Tue, 15 Mar 2016 12:23:29 -0700 (PDT), mrdarrett@gmail.com wrote:

It seems to me that flyback SMPSes use pulsed DC instead of AC. Is this
true?

For example, here, the transistor simply turns on and off, providing
pulses to the transformer, right?

http://www.repairfaq.org/sam/smpsbd.gif

Would SMPSes be more efficient if their transformers were fed
high-frequency AC instead of high-frequency pulsed DC (for example, by
using an H-bridge to provide a negative voltage across the transformer
primary for the second half of each cycle)?

Thanks,

Michael

High Frequency chopped DC is equal to High Frequency AC.

I.T. I.S. A.C.

w.

I disagree. AC REVERSES polarity (hence the "Alternating" in Alternating
Current). Pulsed DC does not.

Sometimes names are not precise.
The High Frequency AC in the radio mast is not symetric AC. So it is
practically the Pulsed DC.
S*

smps: AC or pulsed DC fed into transformer?

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