secondary transformer windings within a flyback converter

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.

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

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

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

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

and these are the waveforms

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.

Perhaps you can explain the charge spikes to us?

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

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

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.

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?

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.

"Aenima1891"

** Fuck 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

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