secondary transformer windings within a flyback converter

[[email protected]]

hello to all!!! I'd like to know why the secondary windings of
trasformer in a flyback converter can suppress the continuous
conmponent af the PWM signal present in the primary windings? how is
it possible? i can understand it!!

thank you

 

[John Popelish]

hello to all!!! I'd like to know why the secondary windings of
trasformer in a flyback converter can suppress the continuous
conmponent af the PWM signal present in the primary windings? how is
it possible? i can understand it!!

The output rectifier is what suppresses the secondary
current during the "on" time for the primary. The voltage
across all windings is roughly the same (in volts per turn
terms) The primary carries current during the PWM "on"
time, and the secondary and output diode carry current
during the "off" time of the PWM.

 

[Phil Allison]

<[email protected]

hello to all!!! I'd like to know why the secondary windings of
trasformer in a flyback converter can suppress the continuous
conmponent af the PWM signal present in the primary windings? how is
it possible? i can understand it!!

** Did you bother to look up Google or Wiki ??

http://en.wikipedia.org/wiki/Flyback_converter


Maybe the misleading use of the word " transformer " has you foxed.

Its really just an inductor with an additional isolated winding.

Its not like a normal AC power transformer where a DC component in the
primary or secondary would be a bad thing.



....... Phil

 

[Robert Baer]

hello to all!!! I'd like to know why the secondary windings of
trasformer in a flyback converter can suppress the continuous
conmponent af the PWM signal present in the primary windings? how is
it possible? i can understand it!!

thank you

Maybe it has something to do about *current* in the secondary (how
much, and when) as well as overall DC biasing of the core?

 

[Aenima1891]

i'm speak about this primary-side switched mode power supply (SMPS)?
Is there anybody able to explain it to me?

this is the circuit http://i68.photobucket.com/albums/i21/aenima1891/Immagine.jpg

and these are the waveforms http://i68.photobucket.com/albums/i21/aenima1891/Immagine-2.jpg

 

[Winfield]

i'm speak about this primary-side switched mode power
supply (SMPS)? Is there anybody able to explain it to me?

this is the circuit
http://i68.photobucket.com/albums/i21/aenima1891/Immagine.jpg

The circuit shows the parasitic capacitances that can
push flyback switching noise into the output DC ground,
and into the input AC power line, if not dealt with in
some manner. It shows capacitance from the drain of
the flyback MOSFET to its heatsink, and thence to the
input AC-line common. It also shows the capacitance
from the flyback signal at the transformer primary to
the secondary, and hence to the DC output's ground.

and these are the waveforms
http://i68.photobucket.com/albums/i21/aenima1891/Immagine-2.jpg

Perhaps you can explain the charge spikes to us?

 

[legg]

i'm speak about this primary-side switched mode power supply (SMPS)?
Is there anybody able to explain it to me?

this is the circuit http://i68.photobucket.com/albums/i21/aenima1891/Immagine.jpg

and these are the waveforms http://i68.photobucket.com/albums/i21/aenima1891/Immagine-2.jpg

This isn't a flyback converter, and it appears that the schematic is
attempting to review RF emission paths, not converter function.
Expertise in EMC shoulde not be mistaken for experience in practical
power conversion.

When capacitive full wave rectification is employed on a single-ended
circuit, current is entirely dependent on the voltage and turns
ratios. It cannot be controlled through PWM when Vout/Vin < Ns/Np.

RL

 

[Aenima1891]

ok. I 'll explain the circuit using my EMC reference book
http://i68.photobucket.com/albums/i21/aenima1891/Immagine.jpg

The full-wave bridge rectifier rectifies the ac commercial power
waveform and produces a pulsating dc
waveform, which is smoothed by the bulk capacitor CB to provide an
essentially
constant waveform that has the value of the peak commercial voltage
waveform.
This is applied to a transformer that has multiple "taps" or windings
on its secondary.
The Mosfet is a switching element that opens or closes the connection
to the transformer primary. A variable-duty-cycle square-wave waveform
is applied
to the gate of this switching element. Varying the duty cycle of this
waveform
provides regulation of the output voltages of the supply.

<B>I don't understand why there is a pulsating waveform that has
alternating polarity pulses at the secondary!!!!!!!!
How can i have the negative polarity when i have only positive or null
polarity at the primary winding of the transformer?</B>
http://i68.photobucket.com/albums/i21/aenima1891/Immagine-2.jpg

Then the full-wave rectifier rectifies this waveform, which is
smoothed by the
bulk capacitor and filtered by the lowpass filter. Because of the
ability to have multiple
taps on the secondary, numerous dc voltages of different levels can be
obtained.

 

[Phil Allison]

"Aenima1891"


** **** off - you PITA idiot.

ok. I 'll explain the circuit using my EMC reference book...

** Musta been written by Daffy Duck after getting a lobotomy.

Get a * real text " on the damn subject.

Piss head !!




........ Phil

 

[Aenima1891]

"Aenima1891"

** **** off - you PITA idiot.


** Musta been written by Daffy Duck after getting a lobotomy.

Get a * real text " on the damn subject.

Piss head !!

....... Phil

are you crazy?
if you have nothing to do today, don't waste your time insulting
people on internet

 

[Phil Allison]

"Aenima1891"

** GET Fucked - you PITA idiot.

ok. I 'll explain the circuit using my EMC reference book...

** What a load of craaaaaap !!!

Musta been written by Daffy Duck after getting a lobotomy.


Get a * real text " on the damn subject - you ASS.

Now;

Piss off - you fucking dick head !!



....... Phil

 

[legg]

ok. I 'll explain the circuit using my EMC reference book
http://i68.photobucket.com/albums/i21/aenima1891/Immagine.jpg

The full-wave bridge rectifier rectifies the ac commercial power
waveform and produces a pulsating dc
waveform, which is smoothed by the bulk capacitor CB to provide an
essentially
constant waveform that has the value of the peak commercial voltage
waveform.
This is applied to a transformer that has multiple "taps" or windings
on its secondary.
The Mosfet is a switching element that opens or closes the connection
to the transformer primary. A variable-duty-cycle square-wave waveform
is applied
to the gate of this switching element. Varying the duty cycle of this
waveform
provides regulation of the output voltages of the supply.

<B>I don't understand why there is a pulsating waveform that has
alternating polarity pulses at the secondary!!!!!!!!
How can i have the negative polarity when i have only positive or null
polarity at the primary winding of the transformer?</B>
http://i68.photobucket.com/albums/i21/aenima1891/Immagine-2.jpg

Then the full-wave rectifier rectifies this waveform, which is
smoothed by the
bulk capacitor and filtered by the lowpass filter. Because of the
ability to have multiple
taps on the secondary, numerous dc voltages of different levels can be
obtained.

If you want the errors in your reference text, or errors in your
understanding of it, explained, you're going to have to provide access
or reference to the full page that the drawings are on as a bare
minimum.

I've already explained what's wrong with the schematic and why the
error might not be relevant to the author's intended purpose for the
original drawing.

You cannot pwm efficiently, between two voltages or two capacitive
nodes, without an intervening inductive storage element, no matter how
small or imaginary it may be - or what topology is used - period.

You're not likely to take full advantage of strays, in what appear to
be inductorless transfers of energy, until you can recognize where
they are and how normal components work in practical situations.

RL