Theorectical benefit of ferro magnet holder for generator

[joestue]

arranging the magnets in such a way that they want to demagnetize themselves is not good. however, if you can fit triangular pole pieces between each magnet so that there is no wasted air gap, then your design can work efficiently.

the radial equivalent is (b)
https://www.researchgate.net/figure/Rotor-constructions-of-buried-permanent-magnet-motors-with-a-tangential-magnets-b_fig14_3270752

[brandnewb]

it looks to me that your magnet layout is unconventional.  it appears that you are placing the magnets on their edge. it appears the poles of the magnets are facing each other

indeed, they are arranged to repel each other.
If my Tesla measurements and applied formulas have any trustworthiness then having a repelling arrangement increases the amount of flux we get to play with close to the magnets.

If having a magnetically conductive housing for the magnets is also a benefit than a repelling arrangement increases the volume for the magnetically conductive material that can be used as opposed to a traditional arrangement. This is the original question I had.

[brandnewb]

arranging the magnets in such a way that they want to demagnetize themselves is not good. however, if you can fit triangular pole pieces between each magnet so that there is no wasted air gap, then your design can work efficiently.

the radial equivalent is (b)
https://www.researchgate.net/figure/Rotor-constructions-of-buried-permanent-magnet-motors-with-a-tangential-magnets-b_fig14_3270752

yes, I used to worry about this as well. But they seller of the magnets assures me that the amount of tesla needed to demagnetize is far greater than the strength of the magnets them self. The highest i've measured on one of the magnets was 480 milli Tesla. So this worry I no longer have.

[brandnewb]

I'll grant that you can aleays try something different and see what happens.

Using what you have now, you can try this:

___________ steel disk

O  O  O  O  O stator coil disk

#  #  #  #  #  magnet disk

O  O  O  O  O stator coil disk

___________ steel disk

The axle must make the two steel disks turn with the mag disk, i.e. 3 disks turning on the same hub.  The 2 stators remain still.

The size of coils in the stator should match the magnet spacing as exactly as possible.  The densest flux lines are Between magnets, now, which is a little counterintuitive to me.  I just drew a flux line circuit through these parts and the loops close.  So you'll get something.  Can't say how much though.

Thank you alot for your effort making this text diagram.

What I think I gather from it is that you have the outer steel disks rotate along with the magnets as to avoid a changing magnetic field in the outer steel disks to minimize eddy currents yes?

It would increase the complexity of the generator though but I do see where you are heading with your suggestion if my assumption of your intend is correct.
Also, I had planned to have the stator coil disks fully engulfed in the same CUT 150 um iron powder I have been mentioning in this thread before. And since it is not electro conductive I had hoped minimizing eddy currents that way.
Would this approach make sense as far as everyone here is concerned?

[electrondady1]

when i first got started building alternators i did an experiment similar to yours using iron filings. I placed  a completed mag rotor  on an axle, bagged it with clear plastic film an then started sprinkling lots of  iron filings on it.  It was easy to tell the strength and direction of the  magnetic flux as it lay down horizontally  from one mag to the next.  I then lowered a second mag rotor down (also bagged in clear plastic)  As the distance from one mag rotor to the other decreased the horizontal  iron filings began moving  from adjacent magnet  to the descending mag rotor and formed a vertical bridge between the two rotors          i for one would like to see a repeat  of you experiment  using iron filings so that it could illustrate the flux path in your rotor.  every thing i have read with regards to  inducing current in  a conductor points to the idea that moving the copper through the flux path at 90 degrees is optimum.
i can't see that happening with your arrangement

[MattM]

You can try it BUT you will not improve on his suggestion for two magnet disks sandwiching a single stator.  He's not going to tell you not to try something.  Enough people have tried it AND I'm confident that he knows what he suggested was better.  I'm a big believer in trusting experts.  It's not always easy to decypher the wisdom they provide.

[brandnewb]

It could well be my am wasting time here. I'll admit that. But there is also some joy in running experiments for me as I am really new to the field.

So given that we have no real clear definitive consensus yet on whether or not having a mag conductive housing for the magnets is beneficial or not perhaps I can try to run some experiments on how to find out.

My Tesla meter (which also has a Gauss setting btw) seems to be working again after having replaced the battery.

So if anyone can think of a way to measure something please let me know and I'll get on it.

[brandnewb]

You can try it BUT you will not improve on his suggestion for two magnet disks sandwiching a single stator.  He's not going to tell you not to try something.  Enough people have tried it AND I'm confident that he knows what he suggested was better.  I'm a big believer in trusting experts.  It's not always easy to decypher the wisdom they provide.

I am not sure what you mean, I had interpreted 'his' suggestion as 2 steel disks on the outsides rotating along the single magnet rotor in the middle that has a stator coil disk on each side.

[brandnewb]

You can try it BUT you will not improve on his suggestion for two magnet disks sandwiching a single stator.  He's not going to tell you not to try something.  Enough people have tried it AND I'm confident that he knows what he suggested was better.  I'm a big believer in trusting experts.  It's not always easy to decypher the wisdom they provide.

You are probably correct. My reasoning is to cut down on the expensive elements which are the magnets. Having 'only' 96 magnets is less expensive than having 192 magnets I figured.
Using both sides for coils feels like making most of the available flux as coils are in relative terms quite cheap.

So sure I am not looking for the strongest output possible. I am looking for a sensible high power output generator at low rpm.

I hope I am not deluded ;(

[brandnewb]

I'll grant that you can aleays try something different and see what happens.

Using what you have now, you can try this:

___________ steel disk

O  O  O  O  O stator coil disk

#  #  #  #  #  magnet disk

O  O  O  O  O stator coil disk

___________ steel disk

The axle must make the two steel disks turn with the mag disk, i.e. 3 disks turning on the same hub.  The 2 stators remain still.

The size of coils in the stator should match the magnet spacing as exactly as possible.  The densest flux lines are Between magnets, now, which is a little counterintuitive to me.  I just drew a flux line circuit through these parts and the loops close.  So you'll get something.  Can't say how much though.

the more I think of this suggestion the more it becomes less complicated to construct. I might well end up with this route.

[brandnewb]

The densest flux lines are Between magnets, now, which is a little counterintuitive to me.

As far I was able to deduce based on my flux readings the densest flux lines are for a traditional arrangement on the center of a magnet, not in between 2 adjacent magnets where the value is a theoretical 0.

For repelling the strongest flux lines are at the edge of a magnet.

So your intuition might well still be valid.

[brandnewb]

So given that we have no real clear definitive consensus yet on whether or not having a mag conductive housing for the magnets is beneficial or not perhaps I can try to run some experiments on how to find out.
So if anyone can think of a way to measure something please let me know and I'll get on it.

Perhaps if we turn it around the conundrum. Will there be a decrement in output potential if the magnet disk is ferro mag conductive?
If not I might as well do it anyway whether or not it really helps or not. I mean I have the ferro filament anyway to print. It would go to waste otherwise.

[MattM]

I believe Adriaan Kragten more or less answered your question.  It is just not often easy to digest what he says.

If you want to get both sides of the magnet then you're probably better off building coils to fold over your stator on the outside edge, so each leg of the coil is impacted by both poles.  Maybe you can build a clamshell with your 3D printer to make the coils removable.  You will use more copper, but more or less hit your goal without needing to worry about iron filings.

[brandnewb]

I believe Adriaan Kragten more or less answered your question.  It is just not often easy to digest what he says.

Agreed, I lack the knowledge and experience to be able to translate what he says.

So I'll try once again getting an answer in a simple yes or no format.

Will there be a decrement in output potential if the magnet disk is ferro mag conductive? Yet not electro conductive

[Bruce S]

brandnewb;
Since this is an unusual arrangement for a 'Mill.
Perhaps after you have the numbers from this build you can take the time to build a more traditional one (Magnets laid out in the standard N-S-N sense) and post those number side by side with your current build.

This way WE too get the benefit of the knowledge gained.

I continue to follow this thread for the shear knowledge .

Cheers
Bruce S

[electrondady1]

i am curious as well . having the mags placed on edge with like poles facing each other is unique .

[brandnewb]

brandnewb;
Since this is an unusual arrangement for a 'Mill.
Perhaps after you have the numbers from this build you can take the time to build a more traditional one (Magnets laid out in the standard N-S-N sense) and post those number side by side with your current build.

This way WE too get the benefit of the knowledge gained.

I continue to follow this thread for the shear knowledge .

Cheers
Bruce S

Understood Bruce,

I will continue then with a ferro mag holder unless someone stops the press.

In case I am disappointed with the actual output I might even try traditional, since at that stage in time there is nothing to loose anyway.

In case I do also go traditional I will be sure to share all data I can gather.

[Mary B]

So given that we have no real clear definitive consensus yet on whether or not having a mag conductive housing for the magnets is beneficial or not perhaps I can try to run some experiments on how to find out.
So if anyone can think of a way to measure something please let me know and I'll get on it.

Perhaps if we turn it around the conundrum. Will there be a decrement in output potential if the magnet disk is ferro mag conductive?
If not I might as well do it anyway whether or not it really helps or not. I mean I have the ferro filament anyway to print. It would go to waste otherwise.

If you make the magnet disc c magnetically conductive the magnetic field line will be focused on one side only if I understand your question. Put your magnets on a thin piece of steel and see how much magnetism you measure on the side opposite the magnets...

[SparWeb]

Brandnewb,
I trimmed off that last comment you made, since it was not appropriate. 

We're here to help, but only if it's fun for us.
I'm giving you a chance to rephrase your thoughts.

[brandnewb]

I am lost for words at the moment. Nothing I said was ill intended and I actually meant it being grateful

I apologize if I accidentally offended anyone.

English is not my native language. I guess sometimes I choose my words poorly then. Always unintended though

[MattM]

I'll just say that there is a lot of high functioning autism in this website.  I do not believe it is easy to communicate if you have autism.  Many times the words come out in our head much differently than how they appear typed, especially how English in written word can have so many dual meanings.  /speaking from personal experience

I guess his message went past me without sounding pointed.  Then again I try to read things in multiple viewpoints to try to understand messages, and this makes me semi-numb to commentary that upsets most people.  So no offense taken here.  I'm curious where your journey is taking you.

[brandnewb]

I'll try formulating it differently then in more broader terms.

I really value it if people want to contribute. I am really grateful for all efforts.

If the thread is poorly constructed due to me not being clear enough please ask questions so that I can try and better formulate what the intend is as to be able to help people more easily understand it and thus also help better.

I hope this clears up any misunderstandings that I have caused. Once again my apologies.

[brandnewb]

I forgot to mention btw that how ever far I'll get. All my plans, models and what have we will be available open source as a resource upon completion.
Or if one asks I can share my current status no problem.

I am just hoping to bring urban wind turbines in a positive spotlight again.

[joestue]

I posted the radial equivalent of what you are doing. If you get rid of all the wasted air gap space between the magnets then the flux will have to travel through your coils and the design will work.


Now I don't see the point of doing it this way but it does solve the problem of how to get pie shaped magnet poles from rectangular magnets.

[brandnewb]

I posted the radial equivalent of what you are doing. If you get rid of all the wasted air gap space between the magnets then the flux will have to travel through your coils and the design will work.


Now I don't see the point of doing it this way but it does solve the problem of how to get pie shaped magnet poles from rectangular magnets.

I have taken a look at your earlier link. I must admit that I found nothing to relate to.

What do you mean by 'wasted air gap'?
As far as I have gotten to understand PM generators all of them have an air gap between magnets. And also an air gap between magnets and coils. One way of reducing the air gap between magnets is if we go the Hallbach array route but then we'll loose a side of the magnet flux to play with.

So may I please ask you to try and make your point again coming from a different angle?

I really would like to understand your point to make sure I am not going to cast it aside as non relevant.

[joestue]

The triangular air gap where the magnet field makes a 90 degree turn to exit the magnet disk is wasted.


In a normal magnet disk with axially oriented magnets, the air gap between the magnets on the same disk is not wasted, very little magnetic flux takes that path to the other magnet. Most of it flows through the stator coils and through the other magnet on the other disk.




With regard to the link I posted, you looked at figure B correct?  If you remove all of the iron of the rotor, you would still have flux lines that reach out of the rotor and flow through the coils... It would just be less than half of what you would have if you had filled up the wasted volume of space with iron.


This is how I would do it.
https://imgur.com/a/MHJEySA

Take a disk and machine out the trapezoidal pole pieces you want and then insert the 4 magnets surrounding the trapezoid.

[brandnewb]

The triangular air gap where the magnet field makes a 90 degree turn to exit the magnet disk is wasted.

Ahh I think I am beginning to follow finally.

Are you referring to the middle of the middle in between 2 repelling magnets? there where 2 N's or 2 S's meet?
Although I would not call that shape triangular it is close enough that it made me latch on to what, I think, you are taking about.

Is that the area we are talking about at the moment?

[brandnewb]

diamond shape comes to mind as best to reflect the area I think you are heading

[joestue]

His diagram almost shows the magnets touching each other on the inner diameter, which is why I called it triangular.


Anyhow, any time magnetic flux has to flow through air and it can't do work on the copper conductors in the stator, it is costing you an equivalent volume of magnet.

I added a drawing to my prior post of how I would use radially oriented magnets to create an axially oriented magnet disk.

Only problem with this is you need a coil on both sides and a core for those coils. (Or use this magnet disk in-between two axially oriented traditional magnet disks and two stator coils.

[brandnewb]

If you remove all of the iron of the rotor, you would still have flux lines that reach out of the rotor and flow through the coils... It would just be less than half of what you would have if you had filled up the wasted volume of space with iron.

If you mean that having a rotor filled with iron powder is better than having one without then I think I finally found the answer I have been asking about all this time.

Either way, Thank you so much for contributing.!! I am going the iron powder route until someone stops the press.

[SparWeb]

I think the confusion is that we don't know what to make of the assembly you've made or drawn. 

Rather than push everyone to teach every detail, here's a short-cut.
Attached below is a white-paper that I wrote many years ago but it seems to capture the typical construction and principles that an axial-flux alternator uses to work.
I really want you to read it through because I spent a lot of time making it as readable and useful as possible for folks in EXACTLY your situation.
You're creative and motivated.  You just need some direction to make the physics come to life in your mind.

Second point: this is a DIY site.  That means do-it-yourself.  I'm telling you that this project needs some effort on your part to figure stuff out before insisting that others guide your hand.  That's no fun for us.

 AXIAL_FLUX_HowItWorks_V4.pdf (1232.26 kB - downloaded 28 times.)

[brandnewb]

For those interested in continued data.

My hypothesis still seems confirmed. It's the quality of the Tesla meter and of course my consistency of measuring I am worried about.

But I for one will trust my own data for now by lack of anything better. Repelling seems like a fruitful endeavor.

[brandnewb]

I only wish I could have supported having a ferro holder for the mags is beneficial. I failed with an earlier attempt to demonstrate that so if anyone can think of an experiment to run I am more than glad to do it.