Rotating Magnetic Field's and Inductors.

[poynt99]

Well Poynt,we are awaiting for you to provide that proof,and show us that your simulation of my DUT can show what my DUT show's. Saying that you dont have the time to finish tweaking it,but to then propose another challenge(having time for another challenge) seems a bit Irish to me?.

I think you are the only one waiting for something to happen, that I have already said 2 or three times, is not going to happen. 

Listen up Mr., as long as I retain free will, neither you nor anyone else is going to dictate what I do with my free time! I don't have to justify bugger all to you, and its your problem if you can't see the sensibility in my decision to build rather than simulate. You should be bloody well more than satisfied that I am even willing to do that!

These claims i have made(an increase in inductance in the coil),are the very same one's that you !not so long ago! deemed may be possible. But here you are calling it a magic trick .

That is your over all claim of this thread? Is that so? No, You're moving the goal posts again.

I posted a quick video showing how having a rotor with alternating magnetic field passing a pulsed inductor can improve the efficiency of that inductor as far as the inductive kickback output go's.

My challenge is to that statement, not to whether the inductance is increasing or not.

Anyway Brad, I could have a field day with your recent posts, but alas I choose to do other things with my time, because it is not worth it. My past dealings with Rosemary Ainslie taught me a great deal about dealing with "difficult" people and when one's time is worth investing and when it is not, so I will remain reserved.

You would be wise to stop tirading about and instead do something extraordinarily productive with that magic ssg rotor of yours. But I wouldn't want to tell you what you should do with your time now, would I?

[Magluvin]

Ok. It seems we have some work to do. 

I just inserted a ferrite bead in my 1.65mh coil. It went up to 2.17mh. Then I added a 3/4 by 1/8 disk neo magnet, tried both ways. Got 2.15mh.

From what I had understood in the past before reading the power supply book was that adding a magnet to a coil would lower the inductance, from what were were discussing then was that the magnet sorta stiffens things up a bit.

But now I am at square 1.   Hopscotch anyone?

So when I get home I will reread the text to see if what I reread already was accurate.

Thinking about it before I posted this, there may be an issue with reading inductance of the coil being it is biased one way and not the other with the magnet. So the question for me is it possible that adding the magnet screws with the way the inductance meter reads the coil?.  Like I can understand that if the meter is putting and ac sig to the coil and sampling what it samples that the magnet biasing the coil might have an odd effect if the meter wants to see ac. Dunno yet.

Considering that the magnet instilled inductors the book was talking about were only for dc pulse efforts, then maybe we cannot look at the coil as being the same with magnetic biasing when were talk about inductance in general..     Like say if without the magnet on the coil being used in a dc-dc converter, dc pulsed, that the coil/core for the design has only so much in it before saturation, but when adding the magnet being biased against the coil field and our level of saturation becomes possibly near twice the level than without the magnet, could that increase be labeled as an increase in inductance? Larger core=higher inductance and larger core= higher saturation point. Being it is a dc pulsed inductor and not for ac(as in + and - from 0v), because if we reverse the magnet in that same situation, saturation levels would be down as compared to no magnet added because the coil would be adding to the mag field causing premature saturation, as the magnet has the core prefilled in a sense.  So maybe we cannot assume the henry meters are showing the real deal when looking at magnetically biased core/coils. What got me thinking these things with the meters is that fact that it didnt matter what polarity the magnet was, the meter read the same, so we have to assume the meter is not dc pulsing the coil the get samples, it is using ac.

So in our case here, we are using dc pulsing. So, can we consider if the magnetically biased core increases the level of saturation of the core, would that also be considered an increase of inductance of the coil?? In a dc pulsed situation of course.

Just did these things after work here at my shop. Put the motor together last night and messed around a bit. Cant use my adjustable supply to run it as the grounds of the scope and supply cause big issues. Ground isolation plug adapters will work?  Read in the past of someone cutting of the gnd post of the ac plug. Not doin that, yet.

Also had some settings on the scope messed up where my ac sig of the coil alone with rotor spinning was big on the plus side and little on the - side.  Still getting used to this thing. Finding on a new project just to hit default settings. Lots of menus to miss something maladjusted. Can make ya loony tunes.

Mags

[gotoluc]

I just inserted a ferrite bead in my 1.65mh coil. It went up to 2.17mh. Then I added a 3/4 by 1/8 disk neo magnet, tried both ways. Got 2.15mh.

Mags

Hey Mags, why are you using  Ferrite to test?... it's the worse core you can use to test this.
Use steel laminations, at least you won't have a drop in Inductance or next to none.

Again, the only core material I have ever seen increase Inductance by a magnet (without need of movement) is Finemet.
I suggest you get some toroids and test it out like I did in my demo video.

You can buy them here: http://www.elnamagnetics.com/catalogs 
If you have some kind of business you may be able to request a free sample.

I've attached some PDF's

Luc

[gotoluc]

Error

[gotoluc]

It would be interesting.
For starters these experiments should be repeated with the Finemet cores.

Thanks verpies, but that document is way too long for me.
If you want to go through it and chose the one you think is the most interesting and post a diagram of the test device, I'll see what I can do.

Thank for sharing

Luc