MULE1.2 Axial flux test motor/bicycle specific
- Thread starter Thud
- Start date
Thud
1 MW
Alright,
Progress is continuing, I need a bit of help on the Hall sensors. Any one care to spec out a proven sensor.
Perferably one in the Newark catolog.
how's this one?
http://www.newark.com/allegro-microsystems/a1221lua-t/hall-effect-latch-ic/dp/57P7567?MER=NPI67_N_C_Sensors_AllegroMicrosystems_57P7567
I also have one of the new 200amp turnigy sensorless units to test with.
I ordered an Laser tachometer Last night & did some research on the induction brake dyno. looks like we are going to be having all kinds of fun in the next few weeks
I also recived the new chain breaker & started cutting a sprocket addapter to mount the 219 chain on the BMXer (I haven't forgotten I promised a video)
I am stoping tonight to see if I still have the powderd metal flyback cores in storage. I may get time to model some stator configurations to show this weekend, We need to get some consensus regarding a starting point.
Progress is continuing, I need a bit of help on the Hall sensors. Any one care to spec out a proven sensor.
Perferably one in the Newark catolog.
how's this one?
http://www.newark.com/allegro-microsystems/a1221lua-t/hall-effect-latch-ic/dp/57P7567?MER=NPI67_N_C_Sensors_AllegroMicrosystems_57P7567
I also have one of the new 200amp turnigy sensorless units to test with.
I ordered an Laser tachometer Last night & did some research on the induction brake dyno. looks like we are going to be having all kinds of fun in the next few weeks
I also recived the new chain breaker & started cutting a sprocket addapter to mount the 219 chain on the BMXer (I haven't forgotten I promised a video)
I am stoping tonight to see if I still have the powderd metal flyback cores in storage. I may get time to model some stator configurations to show this weekend, We need to get some consensus regarding a starting point.
MitchJi
10 MW
Thud
1 MW
Thanks Mitch,
Those are the best looking possibilities yet.
I stoped & picked up a couple rolls of the stained glass copper tape tonight to experiment with. It is as a suspected 1.25 mills. very frail. I am contemplating tripling the layers & testing the flat coil concept.
Those are the best looking possibilities yet.
I stoped & picked up a couple rolls of the stained glass copper tape tonight to experiment with. It is as a suspected 1.25 mills. very frail. I am contemplating tripling the layers & testing the flat coil concept.
John in CR
100 TW
I wonder if any of the stuff they use for flat wind inductors for speakers is thick enough to work. They're too pricey, but maybe the supplier of the ribbon copper already varnished has something thick enough.
How do we go about estimating the turns we need? Is it based on a target inductance, so we can use one of those online inductor calculators and see the diff between air core and iron core?
John
How do we go about estimating the turns we need? Is it based on a target inductance, so we can use one of those online inductor calculators and see the diff between air core and iron core?
John
Thud
1 MW
Here is what I am looking for.
http://cgi.ebay.com/Rotary-Sheet-Metal-Rolling-Shear-PLATE-CUTTER-Bench-Top_W0QQitemZ220506402030QQcmdZViewItemQQimsxZ20091106?IMSfp=TL0911061710007r12167
All the copper supliers I found are not the manufactures of their product listed on the web sites. They Have shown no interest in cutting the thicker copper to the widths Ive requested for quote. That last link Mitch posted, I had high hopes for but they only sell the catolog products on the site.
I have 2 rolls .0025"t foil tape I picked up last night to play with. I dont think it going to be any use in a motor though.
How thin can you get Kapton tape? I am wondering if a simple heavy paper would be addiquet as an insulator.
http://cgi.ebay.com/Rotary-Sheet-Metal-Rolling-Shear-PLATE-CUTTER-Bench-Top_W0QQitemZ220506402030QQcmdZViewItemQQimsxZ20091106?IMSfp=TL0911061710007r12167
All the copper supliers I found are not the manufactures of their product listed on the web sites. They Have shown no interest in cutting the thicker copper to the widths Ive requested for quote. That last link Mitch posted, I had high hopes for but they only sell the catolog products on the site.
I have 2 rolls .0025"t foil tape I picked up last night to play with. I dont think it going to be any use in a motor though.
How thin can you get Kapton tape? I am wondering if a simple heavy paper would be addiquet as an insulator.
Thud
1 MW
John,
If you can find a calculator & get some input regarding winds, go for it. I havn't found anything close to applicable in my searches.
The first shot is going to be blind I am afraid.
"Looks about right" is all I have to go on at the moment.
Miles,
Quit teasing & show us a photo
If you can find a calculator & get some input regarding winds, go for it. I havn't found anything close to applicable in my searches.
The first shot is going to be blind I am afraid.
"Looks about right" is all I have to go on at the moment.
Miles,
Quit teasing & show us a photo
Thud
1 MW
I want the coils to be almost stator thickness. Minimum air gap on all attempts.
On the smaller units I am shooting for a stator thickness in the 10-12 mm range.
On the larger motor that Luke is sending magnets for I am guessing 12-18mm.
I will make the molds specific to the final coil dimensions in hopes for a winning runner out of the gate.
I need to draw some coil grouping senarios & get some feedback regarding the layouts.
I can fit 12 coils into the smaller motor fairly easily'
The big motor looks like 15 right now. that will get a bunch of copper in there.
I will model a few of them for a vote tomorrow morning Before meeting the family for dinner.
On the smaller units I am shooting for a stator thickness in the 10-12 mm range.
On the larger motor that Luke is sending magnets for I am guessing 12-18mm.
I will make the molds specific to the final coil dimensions in hopes for a winning runner out of the gate.
I need to draw some coil grouping senarios & get some feedback regarding the layouts.
I can fit 12 coils into the smaller motor fairly easily'
The big motor looks like 15 right now. that will get a bunch of copper in there.
I will model a few of them for a vote tomorrow morning Before meeting the family for dinner.
MitchJi
10 MW
Hi,
?
A logical upgrade from square wireMiles said:
?
bigmoose
1 MW
If they won't slit the copper without you buying a mile of it; what about going back to the idea of running some 10 gauge copper thru a jewelers roller to flatten it? That way you could flatten a coils worth, and it would be a continuous strand. The thing about kapton as an interlayer insulator is it's incredible temperature capability. If you can believe it, I have used plain scotch magic mending tape for inter-layer separations when I ran out of the good yellow transformer tape. It has great dielectric properties; but isn't too temperature capable! Ought to consider dipping a completed coil in varnish also.
Thud
1 MW
Bigmoose,
That seems a viable option. I have one Jewler friend. I have no idea if he has a rolling mill or not.
I posted a link to a rolling shear on e-bay, looks quite questionable to me. & a new jewlers mill is a bit out of my budget.
I thought about buying it & a stock roll of the .020 copper from Mitches link at 1 or 2 " wide & cutting it what ever width.
I didnt call around yet to my machinst friends to find a local rolling shear. Has to be several around.
That seems a viable option. I have one Jewler friend. I have no idea if he has a rolling mill or not.
I posted a link to a rolling shear on e-bay, looks quite questionable to me. & a new jewlers mill is a bit out of my budget.
I thought about buying it & a stock roll of the .020 copper from Mitches link at 1 or 2 " wide & cutting it what ever width.
I didnt call around yet to my machinst friends to find a local rolling shear. Has to be several around.
MitchJi
10 MW
Hi,
Probably worth getting a quote for a custom size:
http://store.electrical-insulators-and-copper-ground-bars.com/copper-foil.html
If that doesn't work out is 10 mil x 1/4" wide ok?
http://store.electrical-insulators-and-copper-ground-bars.com/0th30gaxwi1.html
bigmoose said:
Probably worth getting a quote for a custom size:
http://store.electrical-insulators-and-copper-ground-bars.com/copper-foil.html
If that doesn't work out is 10 mil x 1/4" wide ok?
http://store.electrical-insulators-and-copper-ground-bars.com/0th30gaxwi1.html
RWP
1 kW
I have learned so much from this wonderful community it's my pleasure to share in whatever way I can.
Roy
it's my pleasure to share in whatever way I can.Roy
John in CR
100 TW
Thud said:
The coil calculators I've used have inductance as a target with these coils to be used in crossover networks for speakers. Here's one http://www.diyaudioandvideo.com/Calculator/Inductor/ I'm sure I've seen them for ferrite core inductors too. Can we use inductance as a target? Please forgive my ignorance.
John
rhitee05
10 kW
Thud said:
Thud, since you're building an iron-core motor, you can make the coils wide without penalty to your air gap. The core iron doesn't count towards the air gap length (reluctance much, much higher than air), so the air gap length is only the magnet-core spacing on each side. You could have a stator 2" wide with only a 1/4" airgap, no problem. It does become important if you're building a coreless motor, in which stator width does count as air gap.
Thud said:
John in CR said:
Thud, John, et al,
I agree that the initial try is probably just a guess. I think actual modeling and/or calculations using target specifications would be difficult. I would suggest using a couple parameters to help shape the guess. Since you're going for relatively low Kv, you probably can't go too far wrong using the maximum number of turns and coils that will fit in your desired form factor.
Coil inductance is somewhat important. This usually isn't an issue with iron-core motors, but there's a minimum inductance required for the given PWM frequency used in the controller. If you consider the controller-motor combination as a sort of DC-DC buck converter, where the motor serves as the inductor, there's a minimum inductor value required to keep current continuously flowing. If the inductor is too small, the converter will operate in "discontinuous" mode and the current can reach zero during the PWM cycle. Keeping the inductor large will reduce current ripple. As I said, this shouldn't be an issue for an iron-core motor, but some calculations could be done to verify.
Second, you should consider what the total per-phase winding resistance will be. That will determine the startup (stalled-motor) current, and the theoretical maximum power. Simple Ohm's law calculation based on the supply voltage and twice the phase resistance.
liveforphysics
100 TW
We will have something between 12-18 poles, which should give us quite a bit of flexibility in phase resistance depending on how we group them.
Just as a random example if each coil is 10mOhm, and we have 12 poles, we can group those 4 poles per phase to give us equilivant single coil resistance values between 40mOhm to 2.5mOhm.
It's nice that the number of coils gives us a lot of freedom to wind the coils with whatever materials are available that ensure best copper fill for us, and then dial things in to best suit our needs in the way we choose to wire them up. With conventional motor designs and winding, you have to choose very well on the first shot, because your only post-wind changes available are delta or wye.
BTW- rhitee05, how many poles would you recomend to work best for our magnet ring? Each magnet section is a 22.5deg trunkated slice of pie, but we can of course space them out, or run them rotated 90deg, or whatever best suits our application. I had 40 of them sent in total. Do you have an ideal recomendation for magnet-stator pairing?
Just as a random example if each coil is 10mOhm, and we have 12 poles, we can group those 4 poles per phase to give us equilivant single coil resistance values between 40mOhm to 2.5mOhm.
It's nice that the number of coils gives us a lot of freedom to wind the coils with whatever materials are available that ensure best copper fill for us, and then dial things in to best suit our needs in the way we choose to wire them up. With conventional motor designs and winding, you have to choose very well on the first shot, because your only post-wind changes available are delta or wye.
BTW- rhitee05, how many poles would you recomend to work best for our magnet ring? Each magnet section is a 22.5deg trunkated slice of pie, but we can of course space them out, or run them rotated 90deg, or whatever best suits our application. I had 40 of them sent in total. Do you have an ideal recomendation for magnet-stator pairing?
John in CR
100 TW
Thanks rhitee,
It seems that the route to greater power as well as torque using a single stator is to increase the diameter, because it allows for more and thicker copper. Being a noob to this, I don't want to focus on torque or power density other than to avoid iron in the structure except the axle. I do want to shoot for efficient as possible.
Since the losses are all in the copper, then it seems they would take the form of either/both:
1. Current flowing through the copper and is lost to resistance as heat without creating the maximum field.
2. Field gets created but not used due to misalignment with the magnetic flux, or field is lost to interference from the field of a neighboring coil.
Are there optimums to shoot for, or is design a balancing act in trying to minimize losses 1 and 2 ? I love Google and use it daily, but it doesn't have all the world's information organized and available quite yet, so I'm coming up empty. Imagine Googling 20 years from now though.
John
It seems that the route to greater power as well as torque using a single stator is to increase the diameter, because it allows for more and thicker copper. Being a noob to this, I don't want to focus on torque or power density other than to avoid iron in the structure except the axle. I do want to shoot for efficient as possible.
Since the losses are all in the copper, then it seems they would take the form of either/both:
1. Current flowing through the copper and is lost to resistance as heat without creating the maximum field.
2. Field gets created but not used due to misalignment with the magnetic flux, or field is lost to interference from the field of a neighboring coil.
Are there optimums to shoot for, or is design a balancing act in trying to minimize losses 1 and 2 ? I love Google and use it daily, but it doesn't have all the world's information organized and available quite yet, so I'm coming up empty. Imagine Googling 20 years from now though.
John
John in CR
100 TW
Miles said:
Does that mean the ribbon type coils will have increased losses from eddy currents, but it's a sacrifice you guys are accepting in pursuit of maximum torque density, since it permits maximum copper density?
John
The design we've been discussing here, is a cored one.
For coreless, the fact that the copper strips run away from the magnets (depthwise) and keeping the magnets inside the end turns of the coil, all helps. Please, someone correct me if I've got this wrong.
For coreless, the fact that the copper strips run away from the magnets (depthwise) and keeping the magnets inside the end turns of the coil, all helps. Please, someone correct me if I've got this wrong.
rhitee05
10 kW
You'd definitely want to space the magnets out. Those magnets are 1/8 arcs each, so if you made the rotor the same OD as the magnets you'd probably want to use 4 or 6 to leave some open space. 4 might be a bit sparse, so 6 seems like a good place to start.
Assuming the design goal is still relatively low Kv, you'd want a fairly high coil/magnet ratio, maybe 2, 3, or even 4x as many coils as magnets. So, 18 as LFP suggests might be good. At this point you've pretty much defined what the size of the coil is, so I'd put as much copper in there as you can fit. That'll give you coils that are pretty tall and narrow, which should be fairly optimal. You can connect the coils in any of several arrangements to get the desired phase resistance.
Assuming the design goal is still relatively low Kv, you'd want a fairly high coil/magnet ratio, maybe 2, 3, or even 4x as many coils as magnets. So, 18 as LFP suggests might be good. At this point you've pretty much defined what the size of the coil is, so I'd put as much copper in there as you can fit. That'll give you coils that are pretty tall and narrow, which should be fairly optimal. You can connect the coils in any of several arrangements to get the desired phase resistance.
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