Sharing ideas on how to make a more efficent motor using Flyback (MODERATED)

[Magluvin]

From what I have just 'reread' in the book "Regulated Power Supplies" 4th edition  Irving M Gottlieb in the chapter  Devices and Components,  the magnetically biased inductor is meant for dc pulsing operations. So say we have a rod core with a coil and we apply an ac current to it we should be able to measure the cores magnetization curve from one magnetic polarity to the other, NS to SN etc.
So when we pulse a coil on the rod core with dc, we are only able to use half of the magnetization curve of the core. But when we bias the core with a magnet, with biasing in the opposite polarity of what the coil produces when pulsed, we now have access to the full magnetization curve of the core. By doing so we get almost twice as much ampere turns capability from the same coil/core with magnet bias vs without the magnet.

And it also increases inductance..  Its in the book.

Mags

[Magluvin]

Also, there is nothing said about core material affecting the outcome of core biasing. Most power supplies use ferrite cores, and that is what the book is all about.

Mags

[gotoluc]

Yes,i just found that out with my ferrite toroid. How ever,i also tried a metglass tape wound toroid core from an old toroid transformer,and it showed an increase in inductance when a magnet was bought close to it.

Seems ferrite is not all it's cracked up to be in this situation.

Brad

Are you sure on the metglas? because where I am at this time they have large metglas cores and I tested them with a magnet before posting.
The inductance goes up when approaching the magnet but once the magnet comes to rest the inductance goes back down. So to me that's not the same and more of an effect of induction taking place and affecting the Inductance meter rather then a permanent boost of inductance.
With the Finemet the boost in inductance did not come down once the magnet stopped moving or came to rest.

If you don't mind rechecking this it could be helpful as I'm hoping verpies can find a use for this effect.

Thanks mate

Luc

[gotoluc]

From what I have just 'reread' in the book "Regulated Power Supplies" 4th edition  Irving M Gottlieb in the chapter  Devices and Components,  the magnetically biased inductor is meant for dc pulsing operations. So say we have a rod core with a coil and we apply an ac current to it we should be able to measure the cores magnetization curve from one magnetic polarity to the other, NS to SN etc.
So when we pulse a coil on the rod core with dc, we are only able to use half of the magnetization curve of the core. But when we bias the core with a magnet, with biasing in the opposite polarity of what the coil produces when pulsed, we now have access to the full magnetization curve of the core. By doing so we get almost twice as much ampere turns capability from the same coil/core with magnet bias vs without the magnet.

And it also increases inductance..  Its in the book.

Mags

This is good information Mags!

If I remember correctly a few years back MH was going on and on about how magnets have zero effect or practical use on cored coils.

Thanks for sharing and get your gears in motion on how we can use this effect to our advantage.

Luc

[MileHigh]

This is still a similar pattern.   Take the example of screw threads.  When you turn a screw or bolt clockwise it tightens.  But you can shout, "On my bicycle there is one screw thread that tightens when you turn it counter-clockwise so what you are saying is not true!  Screw threads turn counter-clockwise to tighten!"  It's not a valid argument.

Yes, Magluvin has a book on designing power supplies and what he quoted from the book is 100% true.  Is anybody around here designing regulated switching power supplies?  Finemet is used for common mode chokes for EMI filters, beads, high-frequency power transformers, pulsed power cores, and presumably many other applications in magnetics.  Is anybody around here designing high-frequency power transformers?  Do I hear the sound of one hand clapping?

I thought that we were trying to understand the energy dynamics of pulsing a coil to do some work like driving a pulse motor.  I think several people have made some good comments about that issue but I am not sure the message is getting through.  Or should we talk about the counter-clockwise screw thread industry instead?

In the past year on this forum I have seen perhaps 20 magnetic circuits in diagrams that include odd arrangements with biasing magnets in various places.  My gut feel is telling me that none of them used biasing magnets with a definite useful purpose like Magluvin quoted from his power supply design book.  They were mostly put in the circuits out of blind belief and if you asked the people to explain why they added the biasing magnets you would most likely get a useless answer that doesn't make sense and can't be justified.  That's the state of the art.  So yes, in general, using "biasing magnets" in AC or pulse magnetic circuits will have no affect because magnets produce a DC bias and magnetic circuits are AC-based.  All of you should reject electronics quackery if it is introduced into something you are following.

Getting back to the dynamics of a pulsing coil - the power consumption will go down and the current will rise more slowly when it pushes on a rotor or exports power to the outside world.  This is something that pulse motor designers need to understand and appreciate.

MileHigh