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Author Topic: Inductive Kickback  (Read 156559 times)

citfta

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Inductive Kickback
« on: November 20, 2015, 01:13:17 PM »
This thread is to discuss what direction the current flows during inductive kickback.  Or to put it another way, as the magnetic field collapses which way does the current flow?

The definition of an inductor is that an inductor opposes change in current flow.  This would imply that as voltage is removed from an inductor the inductor would then try to keep the current flowing in the same direction until the magnetic field is exhausted.  This can be proven with experimentation.

So let the discussion begin.  Do you agree or disagree with this description of how an inductor works?  Please explain why you agree or disagree.  Please keep your comments to a technical discussion and not get into name calling if you disagree with someone.

Respectfully,
Carroll

synchro1

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Re: Inductive Kickback
« Reply #1 on: November 20, 2015, 01:26:35 PM »
Can you supply me with any links to support your theory that current and voltage can share opposite polarities?

seychelles

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Re: Inductive Kickback
« Reply #2 on: November 20, 2015, 01:29:47 PM »
THE CURRENT REVERSE FROM ITS ORIGINAL DIRECTION.

seychelles

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Re: Inductive Kickback
« Reply #3 on: November 20, 2015, 01:34:07 PM »
THE THEORY OF MAGNETIC SPIN. SO IF THE SPIN IS CW WHEN THE
CURRENT IS APPLIED THE BEMF SPIN ANTICLOCKWISE VICE VERSA.
WHEN CURRENT IS APPLIED ETHER IS FORCE OUT AND WHEN CURRENT
IS OF ETHER SPRING BACK..THERE AMEN.

seychelles

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Re: Inductive Kickback
« Reply #4 on: November 20, 2015, 01:38:05 PM »
HE KNOWS WHAT HE IS TALKING ABOUT EVEN IF I DO NOT UNDERSTAND IT
100% HE IS A GENIUS..https://www.youtube.com/watch?v=KooPsEE7E-Q

seychelles

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Re: Inductive Kickback
« Reply #5 on: November 20, 2015, 01:41:38 PM »
So sooory i have been shouting haven't i..

tinman

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Re: Inductive Kickback
« Reply #6 on: November 20, 2015, 03:05:57 PM »
This thread is to discuss what direction the current flows during inductive kickback.  Or to put it another way, as the magnetic field collapses which way does the current flow?

The definition of an inductor is that an inductor opposes change in current flow.  This would imply that as voltage is removed from an inductor the inductor would then try to keep the current flowing in the same direction until the magnetic field is exhausted.  This can be proven with experimentation.

So let the discussion begin.  Do you agree or disagree with this description of how an inductor works?  Please explain why you agree or disagree.  Please keep your comments to a technical discussion and not get into name calling if you disagree with someone.

Respectfully,
Carroll

To make things clear,it should be said that when the current source is interrupted,the current will want to keep flowing through the inductor-not if the voltage is removed.

It is said that an inductor is a current source,but that has never sat well with me,and i consider an inductor and a capacitor as a means to store energy,which can deliver power-not just current or voltage.

The flyback from an inductor can deliver power to a load,and the value/resistance of that load will determine as to what the voltage and current values will be with a set inductor. E.G-if the resistance of the load is low,then the flyback voltage will be low,and the current high. If the resistance of the load is high,then the flyback voltage will be high ,and the current low.

It should also be noted that the lower the resistive value of the load being placed on the flyback,the longer the magnetic field takes to fully collapse around the inductor. This results in a higher current due to the slower collapsing field,but a lower voltage for the same reason-the slower changing magnetic field with time. The higher the value of the resistive load on the flyback,the quicker the magnetic field around the inductor will collapse. This results in a lower current but a higher voltage due to the faster changing magnetic field with time.

tinman

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Re: Inductive Kickback
« Reply #7 on: November 20, 2015, 03:25:40 PM »
2

When the current source to an inductor is interrupted, the current will continue to flow through the inductor in the same direction,but the voltage across that inductor will invert. This is how the simple circuit below is able to work,and the LED can be lit from the flyback<--im guessing you guys want to use the term !flyback! so as to keep it simple?.

Diagram 1 shows the switch closed,and current flows from the battery into the top of the inductor,and out the bottom of the inductor,and into the negative of the battery. At this point in time,i also assume that we will stick to conventional current flow throughout this thread-so as to keep it simple?.

Diagram 2 shows the current flow through the inductor,and voltage polarity across that inductor the moment the switch becomes open. This current flow,and voltage polarity will remain the same until such time as the magnetic field around the inductor has fully collapsed-all stored energy has been depleted. We know the current flowing through the inductor must be in the same direction,and the voltage must have inverted in order for the LED to light.

Jeg

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Re: Inductive Kickback
« Reply #8 on: November 20, 2015, 03:46:26 PM »
Hi guys

When the switch opens, inductor will try to keep its magnetic field alive, and to retain its magnetic poles at the same place as when the switch is closed. There is no other way for this to happen than the current to keep going on same direction as before. This is simple physics. What path it will take depends on the circuitry. In this example bemf  just can not return to the negative of the battery because the circuit is open!!! It will go through diode because the circuit closes through the capacitor back to the base of the inductor.
Sometimes our minds get stack in simple matters. It happens to all of us. :)

synchro1

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Re: Inductive Kickback
« Reply #9 on: November 20, 2015, 03:47:38 PM »
To make things clear,it should be said that when the current source is interrupted,the current will want to keep flowing through the inductor-not if the voltage is removed.

It is said that an inductor is a current source,but that has never sat well with me,and i consider an inductor and a capacitor as a means to store energy,which can deliver power-not just current or voltage.

The flyback from an inductor can deliver power to a load,and the value/resistance of that load will determine as to what the voltage and current values will be with a set inductor. E.G-if the resistance of the load is low,then the flyback voltage will be low,and the current high. If the resistance of the load is high,then the flyback voltage will be high ,and the current low.

It should also be noted that the lower the resistive value of the load being placed on the flyback,the longer the magnetic field takes to fully collapse around the inductor. This results in a higher current due to the slower collapsing field,but a lower voltage for the same reason-the slower changing magnetic field with time. The higher the value of the resistive load on the flyback,the quicker the magnetic field around the inductor will collapse. This results in a lower current but a higher voltage due to the faster changing magnetic field with time.

@Tinman,

 The speed that the Reed switch contacts separate determines the "Flyback Voltage".

synchro1

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Re: Inductive Kickback
« Reply #10 on: November 20, 2015, 03:51:08 PM »
Hi guys

When the switch opens, inductor will try to keep its magnetic field alive, and to retain its magnetic poles at the same place as when the switch is closed. There is no other way for this to happen than the current to keep going on same direction as before. This is simple physics. What path it will take depends on the circuitry. In this example bemf  just can not return to the negative of the battery because the circuit is open!!! It will go through diode because the circuit closes through the capacitor back to the base of the inductor.
Sometimes our minds get stack in simple matters. It happens to all of us. :)

@Jeg,

There's no longer any current flowing after the Reed switch is open. You maintain that the magnetic field is sustained by some imaginary current!

citfta

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Re: Inductive Kickback
« Reply #11 on: November 20, 2015, 03:56:25 PM »
A link to get you started:  https://en.wikipedia.org/wiki/Inductor


I had to leave for a while but now I am back.

To answer the question about current flow and opposite polarity,  answer my question about which direction does current flow inside a battery.  Does it flow from positive to negative or the other way round?  And which way does it flow outside the battery?  When you get the answer to that you will understand why polarity can switch on an inductor but the current still flows the same way.

Also do you have a way to conduct the test with a 2 channel scope?

Carroll

tinman

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Re: Inductive Kickback
« Reply #12 on: November 20, 2015, 04:00:08 PM »
A link to get you started:  https://en.wikipedia.org/wiki/Inductor


I had to leave for a while but now I am back.

To answer the question about current flow and opposite polarity,  answer my question about which direction does current flow inside a battery.  Does it flow from positive to negative or the other way round?  And which way does it flow outside the battery?  When you get the answer to that you will understand why polarity can switch on an inductor but the current still flows the same way.

Also do you have a way to conduct the test with a 2 channel scope?

Carroll

Yes i do,and will be doing that tomorrow by way of video-as it is late at night here in OZ ATM.

tinman

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Re: Inductive Kickback
« Reply #13 on: November 20, 2015, 04:03:31 PM »
@Jeg,

There's no longer any current flowing after the Reed switch is open. You maintain that the magnetic field is sustained by some imaginary current!
When the switch opens,the current continues to flow through the inductor--this is the flyback current we are talking about.
What do you think flyback is Synchro?-->it is the power produced by the collapsing magnetic field around the inductor when the switch is opened. It is how i have drawn it a few post back.
Current continues to flow through the inductor after the switch is open. The magnetic field is sustained some what due to the current loop through the inductor and LED.

Jeg

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Re: Inductive Kickback
« Reply #14 on: November 20, 2015, 04:03:50 PM »
Synchro,
The current that flows when the switch is open is not from the battery. Isn't an inductor an energy tank? How that energy manifests itself during a field collapsing?