my inrunner build ? go ahead and laugh

[AussieJester]

You could always go 'ghetto' and get a tub of Devcon and spread this between the magnets would also help hold them in place...

KiM

[rhitee05]

9 magnets seem to be a recuring theam in the halbauch array. Are there any other configurations?
If I am interpreting the graphics correctly the 9 will unite to make 1 pole.

It's actually an 8-magnet cycle. I added the 9th magnet to make the model more accurate, since the real array would be a continuous circle.

I'm aware of 3 Halbach configurations. The first one I posted was a 45-degree configuration, where each magnet is rotated 45 degrees from the previous. This is similar to the LaunchPoint motor being discussed here. The second one I posted was a 30/60 configuration, which uses increments of 30 and 60 degrees. This is used in the CSIRO solar car motor. There is also a more simple 90-degree configuration, which only uses a 4-magnet cycle. At a low model resolution, all 3 configurations seem to show roughly the same flux densities. I assume that there are in fact some differences to justify different configurations being used in different applications.

it shows: having the magnets embedded in iron prevents the magnetic flux from crossing the airgap - this is where you want it as this is where your current conducting coils are!

We have to be a little careful here about interpretation. Steel between two opposing magnetic poles will cause a magnetic short circuit and divert flux away from the air gap. That's not what's happening in the round w/ steel model, however. In this case, the steel is linking the adjacent parts of the Halbach array (which are not opposing poles) to provide a low-reluctance path. Just like electricity, magnetic flux requires a complete circuit and more flux will flow with lower reluctance. Cylindrical magnets by themselves have basically a zero-area contact patch, so the flux is required to travel through the air and thus a high-reluctance path. Having the steel lowers the reluctance and increases the flux flowing through the airgap. Don't be fooled by the potential lines, the coloration is what indicates flux density. The flux density in the steel opposite the magnets is a good measure of how much flux is actually making the complete circuit and thus doing useful work in the motor.

Eric

[enoob]

You could always go 'ghetto' and get a tub of Devcon and spread this between the magnets would also help hold them in place...

KiM

well thank you . you just showed me my bonding agent for the magnets to the steel
this should make a great adhesive for this with the added bonus of some steel in any of the cavity's between the machined parts and the magnets. beeeeeautiful .
i was looking at adding some kind of ferro fluid to an apoxy for this but me likey your stuff better.

[Miles]

You'll still need a close fit............

[enoob]

and a wing with a prayer.

[AussieJester]

I have used Devcon in the past, for those that haven't i can best describe it as JB Weld on roids, the stuff is the shit, its also a lil pricey but well worth it, you can also get it in many guises ie. with different metal added to it, steel aluminium copper etc etc It will definately have no problem holding magnets in place can guarantee you that.

KiM

[rhitee05]

I think I have to eat my hat a little bit here. I just did some more modeling, trying to do a more quantitative analysis of the different scenarios. All of these look at a partial cycle (6 magnets) of the 30-degree configuration. I changed a few other things, so these results are not directly comparable to the previous models.

- Round magnets only (no steel)
- Round magnets with steel backing, but nothing in front
- Round magnets surrounded by steel level with the magnet faces
- Square magnets with no steel

These plots show flux density in the radial direction across the middle of the airgap (the useful flux). The important bit of data is basically the peak flux density (don't mind the negative sign). The magnets-only case actually shows the highest flux density of the round magnets, with the steel-surround case the lowest. It's worth pointing out that there's only about 10% difference here between best- and worst-case, but that's exactly opposite what I've been saying. Given the rough nature of these simulations, I'm going to call those all roughly equivalent.

But, note the plot for the square magnet array. Using square magnets gives you about a 27% increase in magnet volume over the round ones, but a 100% increase in the flux density.

So, a square-array is still more efficient, but it doesn't look like a round array is as bad as I thought it'd be without some steel. I'd say it's time for enoob to start making some metal shavings to see what happens in the real world.

[enoob]

wow i love the internet . this is to cool.

thanks alot for your time rhitee5 . much appreciated

ok i just shared a beer with my neighbor mechanical contractor who i helped with a french door install over summer and got him keyed up to do some metal machining for me tomorrow as payback.

if not steel back to derlin ? or is aluminum ok for this . got lots of that around that i could work myself as well.

[AussieJester]

or is aluminum ok for this

+1 for aluminium...lighter and easier to work with...

KiM

[paultrafalgar]

So, a square-array is still more efficient, but it doesn't look like a round array is as bad as I thought it'd be without some steel. I'd say it's time for enoob to start making some metal shavings to see what happens in the real world.

Don't want to distract you guys from your excellent thread, but take a moment to look at this video where Cedric Lynch (Godhead) explains why he uses rectangular magnets:
http://www.in.com/videos/watchvideo-ced ... 01603.html
Before you die of laughing at his manner, remember, he makes better electric motors and vehicles than anyone! Enjoy!

[Jonathan in Hiram]

Don't want to distract you guys from your excellent thread, but take a moment to look at this video where Cedric Lynch (Godhead) explains why he uses rectangular magnets:

I think he was talking more about the stator iron than the magnets, he mentioned having grain oriented transformer steel sliced into pieces.

Which reminded me of another possible inrunner topology that I saw on da tubez many years ago but am apparently unable to find now. I recall that the motor I saw was built for research purposes and was seven phase but I'm drawing a total Google blank on anything remotely like it.

I totally blow chunks at 3D modeling so please bear with me here.

This is one pole of one phase of an inrunner motor without the coil drawn in, the coil will be wrapped around the upper bar of the iron laminations.

The magnets will be attached to a rotor with the iron and coils arrayed around the outside.

This topology has Cedric's advantage of remarkably easy stator manufacture along with extremely easy coil winding and the air gap can be kept quite thin I think with rigid motor structure.

axial flux inrunner component.jpg (24.78 KiB) Viewed 509 times

[Thud]

here ya go enoob:
http://cgi.ebay.com/10-Neodymium-Magnet ... 53ddc19ad3

[rhitee05]

Jonathan,

That seems like a pretty workable axial flux design. That's very closely related to the two-stator/one-rotor design Thud was working on in another thread, except with only one set of coils instead of two. Having two coils would probably give higher power density, but your design is probably easier to DIY.

[Jonathan in Hiram]

Eric,

I recall reading about a motor somewhere that had the poles angled at 45 degrees, supposedly it increased torque, something to do with maximizing the area of the air gap..

Would something like this produce more torque than the first design I showed?

ETA: One advantage I can see is that it can be made thinner than a lot of the other axial flux designs since the width of the iron is only the same as the longest part of the magnet.

[enoob]

Cedric Lynch (Godhead) explains why he uses rectangular magnets:
http://www.in.com/videos/watchvideo-ced ... 01603.html
Before you die of laughing at his manner, remember, he makes better electric motors and vehicles than anyone! Enjoy!

so this has me a tad concerned . ive read a bit about Nicola tesla and well lets just say i suspect that cedric lynch IS nicola tesla .

OR spending to much time around electromagnetic fields makes you rather hhhmm lets say eccentric .

nice video . no distraction, i appreciate the relativity. dont let the direction i pursue with this build stop anyone from speaking up . im hoping to get this one together with what i can get off the shelf at minimal cost with minimal wait time.

at this point the round magnets and corless stator are just easier to play with, fibreglass and aluminium get the job done and i got that in spades stacked against the shop wall . if i see any measure of success ill step it up and see what can be milked out of it with grain oriented steel lams and custom magnets .

charging up the camera . i got me some photos to share

[enoob]

here ya go enoob:
http://cgi.ebay.com/10-Neodymium-Magnet ... 53ddc19ad3

) thanks my friend you know i already orderd the other ones you did the cad drawing to . be here monday so i got work to do on a rotor

may be wrong but i saw that those ones are n48 , while stronger the 42's apparently deal with heat a little better. so i took the bait.

if this one works out then ive already (in my head) worked out a water jacket wrapping the stator . im thinkin ill make this one spin and see what i get for rpm. go from there.

speaking of rpm its time to buy the wire . any suggestions ? i was going to go with 16 or 14 gauge with as many turns as i can fit into it.

[enoob]

Eric,

I recall reading about a motor somewhere that had the poles angled at 45 degrees, supposedly it increased torque, something to do with maximizing the area of the air gap..

Would something like this produce more torque than the first design I showed?

ETA: One advantage I can see is that it can be made thinner than a lot of the other axial flux designs since the width of the iron is only the same as the longest part of the magnet.

the first thing i see with that setup is a rather easy way to trap magnets to a rotor . and i cant remember the math but a 45 degree angle significantly increases surface area.
be fun to try.

[Thud]

ENOOB!
I seem to have missed a dimension on the dia. of the mags in that drawing.
They are in fact .5"dia.
this drawing represents .37"dia mags.


there ya go, let me know if i have something goofy.

[Miles]

may be wrong but i saw that those ones are n48 , while stronger the 42's apparently deal with heat a little better. so i took the bait.

That's often the case, but not necessarily so. You'd need to know the thermal rating, to be sure. Strictly, N48 and N42 have the same thermal rating:
http://www.kjmagnetics.com/specs.asp.

[enoob]

ENOOB!
I seem to have missed a dimension on the dia. of the ags in that drawing.
They are in fact .5"dia. i will repost a drawing with the 24 poles with 3/8"dia. in a moment.

no rush . till lunch im dad not chad the fabricator. (wifes sleeping off a night shift kids are at preshcool )

ive made the jig and its easy to adjust size . the only real important number i need is the radius to the center of the mags and in reality the test runs with the jig will flush out the correct measurements i need . nice to have a accurate starting point though.

late today or first thing in the morning ill get my aluminium disks in the jig and see what happens . so far im happy with how its working the mdf .

[Thud]

please see above edits. I thin i got mm

[enoob]

please see above edits. I thin i got mm

no problem . on the phone with mag4less right now . checking if my order is out yet, made it last night online so i doubt it.
be nice to have the stronger mags and the lower kv.

may be wrong but i saw that those ones are n48 , while stronger the 42's apparently deal with heat a little better. so i took the bait.

That's often the case, but not necessarily so. You'd need to know the thermal rating, to be sure. Strictly, N48 and N42 have the same thermal rating:
http://www.kjmagnetics.com/specs.asp.

thanks miles . took another look at what made me see that and im betting i was comparing nh or nm 42's to a n rated 48 . looks like n rated = 170f . i hope so cuz mags for less is out as of 1 min ago and emovendo is stepping in .found some n50s but what i read says they are relatively easy to demagnetize and will keep the beer fridge empty a little longer so ...... no.

[rhitee05]

I recall reading about a motor somewhere that had the poles angled at 45 degrees, supposedly it increased torque, something to do with maximizing the area of the air gap..

Would something like this produce more torque than the first design I showed?

ETA: One advantage I can see is that it can be made thinner than a lot of the other axial flux designs since the width of the iron is only the same as the longest part of the magnet.

I think you're correct, the increased airgap area should increase torque/power. Finding magnets with that shape seems tricky, though. Without modeling it, I'm not sure offhand if there's anything you'd need to tweak with the design to optimize the flux flow, but seems like a reasonable concept. The form factor would be attractive, as you mention.

[AussieJester]

Before you die of laughing at his manner, remember, he makes better electric motors and vehicles than anyone! Enjoy!

He does have uuuuhm..'interestinnnnnggggg' mannerismmmmmss doesn't heeeee, i'm guessing hes some what of an ecntric individual, he obvioulsy
knows his stuff though, some might impressive figures for his motorcycle!

KiM

[enoob]

cheduled Delivery Date:03/12/2009 Shipped To: LANGLEY, BC, CA Weight:1.90 Lbs
Need to send e-mail notifications?
Use UPS Quantum View Notify® to send delivery or exception notifications.
E-mail Notifications
To view additional tracking information, please log in to My UPS.


Location Date Local Time DescriptionWhat's this?
COMMERCE CITY, CO, US 25/11/2009 21:36 ARRIVAL SCAN
MESQUITE, TX, US 25/11/2009 0:56 DEPARTURE SCAN
RICHMOND, BC, CA 24/11/2009 22:43 PACKAGE DATA PROCESSED BY BROKERAGE. WAITING FOR CLEARANCE
MESQUITE, TX, US 24/11/2009 22:48 ORIGIN SCAN
24/11/2009 17:10 PICKUP SCAN
US 24/11/2009 14:46 BILLING INFORMATION RECEIVED







sigh . i new i shoulda got it sent to ship happens id have em by now .
bloody excruciating.