Farfle
100 kW
Miles said:
If I had room for bigger fins, I'd rather use the space for a bigger motor
Very true... still hate to see it with weenie little fins though
Miles' 90mm inrunner build thread
- Thread starter Miles
- Start date
Very true... still hate to see it with weenie little fins though
Farfle
100 kW
Miles said:If I made them narrower, they might look taller?Farfle said:
More thinner fins works better generally, there's a modeling software for this...
Farfle
100 kW
Miles said:
Yeah, there's a lot of nitpicking to be done, I said Fawk it on my motor, but at 29 pounds it's definitely the "fill the space with motor" theory. It could be at least 4 pounds lighter, there's a chunk of 40mm solid steel rod that's almost 100mms long left in there because I didn't have a long enough drill to hollow it out, and the yolks between the teeth and the iron around them "not back iron? Front iron?" Lol, is way to thick. at almost 13mm.
Farfle
100 kW
I wish I could have spent as much time as I wanted on this guy, it really deserved better than it got. but there was a deadline to hit, and start to finish in one month and under 500 bucks was the big accomplishment with this motor, not necessarily it's power/weight or power/m3 .
Farfle
100 kW
Not sure, I have always wanted to convert a Klx650/Ktm 990 adventure or similar to electric, and it would need some serious poop to be sporty, so when I have the cash to do it, I'll be building a monster outrunner, probably 30t 32mag wound AaAaA BbBbB CcCcC then DdDdD EeEeE FfFfF and run two independent controllers and hall sets. Essentially two separate 15t16p motors sharing the same magnet ring.
crossbreak
1 MW
The EMP N6354 outrunner would also be a nice competitor:
weight: ~650g
actual over all length: 58mm
stator dia: 52mm
stator thickness: 23.5mm
lamination thickness: ~0.35mm
pole pairs: 14p 12n
wire turns per tooth: 15
rated KV: 200 in delta, 116 in star
field changing frequency: ~815 @7000rpm or 420Hz@3600rpm [edited]
looks like this one is a perfect candidate for speeding it down. Unlike the turnigy and aeolian outrunners, this one has a single piece stator carrier, which should make it possible to better cool it when running it enclosed. Copper fill could be better, doesn't come even close to the tongxin (which has awful copper fill, never seen any better yet).
weight: ~650g
actual over all length: 58mm
stator dia: 52mm
stator thickness: 23.5mm
lamination thickness: ~0.35mm
pole pairs: 14p 12n
wire turns per tooth: 15
rated KV: 200 in delta, 116 in star
field changing frequency: ~815 @7000rpm or 420Hz@3600rpm [edited]
looks like this one is a perfect candidate for speeding it down. Unlike the turnigy and aeolian outrunners, this one has a single piece stator carrier, which should make it possible to better cool it when running it enclosed. Copper fill could be better, doesn't come even close to the tongxin (which has awful copper fill, never seen any better yet).
crossbreak
1 MW
I just counted the laminations of an N6354 again. Seems to be 67 or 68. I calced 0.35mm sheet thickness, the stator is 23.5mm thick.
Hi Miles, sorry for the slow reply regarding magnet eddy current losses. The links you put up were very very helpful in coming to terms with loses involved (why do engineers use greek letters, what did the ancients know about PM motors?). It seems the heat generated in the magnets is very real and another huge % of the heatload at such high frequencies. The lam thickness didn't have any effect as the motor was being driven from a lathe and losses measured. Motor was a CA120, old high pole version .35mm lams. It seems that at these higher frequencies, eddy currents in the magnets may be able to be reduced by maybe up to a factor a 1/2 using 4 magnets per pole radially as this seems the most beneficial layout. But i,m a bit to tight to buy the magnets and prove that. But power stops here because of the internal magnets heat generated.
Regarding magnet choice. Why would you skimp on magnet strength for your motor? It seems such a sweet little design deserves the best.
Zappy
Regarding magnet choice. Why would you skimp on magnet strength for your motor? It seems such a sweet little design deserves the best.
Zappy
Hi Zappy,
I'm glad that helped.
Regarding magnet strength, you can either use a thicker magnet or a higher grade one. It's much cheaper increasing strength by using a thicker magnet. For the current design I can load the magnetic circuit enough using low grade 3mm thick magnets which makes going with a higher temperature rating less expensive.
For an inrunner, the only downside to thicker magnets is greater mass on the wrong side of the glue joint.
For an outrunner, the thinner the magnets, the greater the air gap diameter. So, higher grade magnets have a performance advantage to balance their extra expense.
In the latest iteration, I've reduced the airgap to 0.6mm and increased the magnet strength to N35. I adjusted the teeth section to match. So, I'm loading the magnetic circuit a bit more.
I'm glad that helped.
Regarding magnet strength, you can either use a thicker magnet or a higher grade one. It's much cheaper increasing strength by using a thicker magnet. For the current design I can load the magnetic circuit enough using low grade 3mm thick magnets which makes going with a higher temperature rating less expensive.
For an inrunner, the only downside to thicker magnets is greater mass on the wrong side of the glue joint.
For an outrunner, the thinner the magnets, the greater the air gap diameter. So, higher grade magnets have a performance advantage to balance their extra expense.
In the latest iteration, I've reduced the airgap to 0.6mm and increased the magnet strength to N35. I adjusted the teeth section to match. So, I'm loading the magnetic circuit a bit more.
Hi Miles, regarding air gap, Just for an example I have an 80 series turnigy out-runner motor, and with feeler gauges the air gap measures .9mm. The can is also very thin with a fair bit of magnetism on the outside of the can (enough to make a screw stick vertically out off the can by its head). If i made a can with a 1mm smaller inside diameter, closing the air gap to .4mm what benefits could be expected ?? and what benefits from upping the thickness of the flux ring?
With winding the kevlar, everything said is correct. I have a lot of filament winding composite experience. I used do do R&D for these guy's
http://www.cstcomposites.com/
The kevlar thread/filament is very waxy so is hard to bond well so epoxy with a higher enough glass transitional temp for max expected magnet temp will be needed and may be hard to find in the tiny amounts needed. I have a patch of kevlar off cut if you need a few threads for a couple of motors or some 24k carbon filament i can send you for free if you want. These fibers are very strong and you could tease out the filament to be very very thin (for min air gap interference) and it would make it bomb proof especially at such low rpm.
Zappy
With winding the kevlar, everything said is correct. I have a lot of filament winding composite experience. I used do do R&D for these guy's
http://www.cstcomposites.com/
The kevlar thread/filament is very waxy so is hard to bond well so epoxy with a higher enough glass transitional temp for max expected magnet temp will be needed and may be hard to find in the tiny amounts needed. I have a patch of kevlar off cut if you need a few threads for a couple of motors or some 24k carbon filament i can send you for free if you want. These fibers are very strong and you could tease out the filament to be very very thin (for min air gap interference) and it would make it bomb proof especially at such low rpm.
Zappy
mdd0127
100 kW
- Joined
- Sep 30, 2008
- Messages
- 1,084
Your motor looks beautiful Miles!
While the electrical/magnetic stuff is over my head, I do have one tiny suggestion. Would it be possible to make the cooling fins form a spiral? If so, a thin can could be slid over the motor, sealed at the ends and make for a very low profile liquid cooling option.
I'll be shopping for a motor for my next build soon and the one you're working looks perfect.
While the electrical/magnetic stuff is over my head, I do have one tiny suggestion. Would it be possible to make the cooling fins form a spiral? If so, a thin can could be slid over the motor, sealed at the ends and make for a very low profile liquid cooling option.
I'll be shopping for a motor for my next build soon and the one you're working looks perfect.
Does it have a ring bearing?zappy said:
You really need to do an analysis of the stator to see what the new flux densities are. You'd need to determine what strength the magnets are for that. If any parts of the circuit become saturated, you may not gain much.
Perhaps experiment with a steel band on the outside of the present can first? Taking that part of the circuit out of saturation will help.
Increasing flux will reduce Kv and increase Kt. Iron losses will increase, of course.
8) It's great to have someone with expertise in composites! Thanks for the offer!zappy said:
I was thinking I might get away without having to reinforce with filament - hence the airgap reduction. I've increased the height of the magnet separator upstands on the core to 2mm and I can wedge the 2 magnets apart against these as I bond.
Need to give this some more thought...
Attachments
mdd0127 said:
Thanks mdd!
It's certainly possible. It might make more sense to have a different can for liquid cooling with the fins running axially, though?
At the back of my mind, is the possibility of producing these as a kit. Have to see how tricky they are to wind first, though... Different motor lengths would be no problem.
I've adjusted my 125mm inrunner design to use the same 5mm x 3mm magnets as this one does.
Attachments
Lebowski
10 MW
in this last design the stator teeth are so wide that they overlap 2 sets of magnets... is that smart ?
gut feeling would say that this effectively reduces magnet strength (as you're cancelling one with the
other) plus it gives you an unnecessarely high commutation frequency...
gut feeling would say that this effectively reduces magnet strength (as you're cancelling one with the
other) plus it gives you an unnecessarely high commutation frequency...
