How to get coil back EMF apply forward to same load as additional higher volts?

[russwr]

1.5MH coil has back EMF higher voltage during the half wave off time. How can this be forced forward as in addition to first pulse forward?

[Classic]

Have a look at this man yt channel https://youtu.be/08aAPKzbaew

[Verpies]

1.5MH coil has back EMF higher voltage during the half wave off time. How can this be forced forward as in addition to first pulse forward?

EMF is a voltage, "Forward" typically refers to the direction of electric current.  Me thinks you are conflating these two concepts in your question and you are forgetting that the direction of current in the coil does not reverse during the "half wave off time" - actually,  during the "off time", the current decays but keeps flowing forward in same direction as it had during the "on time" ...when an external power supply was energizing the coil.

This article might help you understand it further.

P.S.
Did you mean 1.5mH coil ?  A 1.5MH is an inductance that is billion times larger.

[Allcanadian]

A good example is a boost converter as shown below...

When the switch is closed the electrons flow from the (-) terminal, through the switch, through the coil then back to the (+) terminal.

When the switch is open the electrons flow from the coil to the (+) then (-) terminal, through the cap and resistor then through the diode back to the coil.

Note that if the current did not remain in the forward direction when the switch was opened it could not flow through the diode. So the direction of the diode proves the discharge current direction remains forward just as before.

AC

[Classic]

Electrons don't flow anywhere, they just transmit the signal when we are speaking about electricity. Let's bring up to date the science and avoid old and wrong wording. Also electricity doesn't flow anywhere because it is everywhere surrounding everything. When we short + and - we obtain an effect which manifest itself according with materials and their geometry. If we start to look at it from this perspective we might get a different level of knowledge and understanding what and how to use for different purposes. Where frequency and resonance bring their fair share.

[forest]

I need  your advice especially from someone experienced in flyback converters. Will that attached simplified converter work ?

[partzman]

I need  your advice especially from someone experienced in flyback converters. Will that attached simplified converter work ?

Yes, if the transformer has the correct dot polarity.  For example, place a dot near the drain of Q1 on the primary, and place a dot on the secondary near the anode of D2.  Do not expect OU from this circuit IMO.

Regards,
Pm

[forest]

Yes, if the transformer has the correct dot polarity.  For example, place a dot near the drain of Q1 on the primary, and place a dot on the secondary near the anode of D2.  Do not expect OU from this circuit IMO.

Regards,
Pm

Sorry, I was non precise. I want diode to conduct only when current is flowing in primary circuit while bloking current on flyback on primary. Is diode position correct for this to happen?

[Verpies]

I want diode to conduct only when current is flowing in primary circuit while bloking current on flyback on primary. Is diode position correct for this to happen?

Impossible to answer without the dots in the schematic.
See: Dot convention.

[forest]

Impossible to answer without the dots in the schematic.
See: Dot convention.

L1 and L2 are in the same direction in fact it is wound using two wires together . I simply wonder if we could catch both induction current from secondary and flyback from primary

[Verpies]

I don't thinks so, the current in the primary does not reverse direction when the primary circuit is interrupted.  Even if there is a diode there.

[forest]

I mean this : when current flow in primary there is produced current in secondary, when current in primary is interrupted there is flyback current in primary. To me it's like having 2 times more energy as suggested by this topic

[Verpies]

I mean this : when current flow in primary there is produced current in secondary, when current in primary is interrupted there is flyback current in primary. To me it's like having 2 times more energy as suggested by this topic

No, in a "flyback transformer" the primary and secondary currents do not flow at the same time.  This makes the name "transformer" a misnomer.

When the current in the primary is interrupted, then the current in the secondary (flowing through the diode and load) takes over the job of maintaining the flux built up in its core.
If the secondary and diode were perfect and the load was a short circuit, then this flux would be maintained indefinitely and the current in the primary could be interrupted instantaneously and without any back EMF across the opening switch.

[forest]

I think I didn't understood it : if the coil is replaced by transformer with primary and secondary then in the first stage of "flyback converter" in the secondary would flow induction current , right ? Why not divert this flow to the load having 2 impulses instead of 1 in normal flyback converter

[Verpies]

Because if you allow the current in the secondary to flow at the same time as in the primary, then less flux will be stored in the core/gap.
This happens because the flux generated by the current flowing in the secondary opposes the flux generated by the current flowing in the primary.

Therefore, when the primary current is interrupted later, there will not be much flux stored in the core/gap to create what you call a "flyback pulse".