liveforphysics
100 TW
Beautifully done my friend. 
When are you ordering lams?
When are you ordering lams?
Miles' 90mm inrunner build thread
- Thread starter Miles
- Start date
liveforphysics
100 TW
Miles said:Quite soon, now. I might order the wire first, just to be sure....liveforphysics said:
When I played a bit with attempting square wire motor winding a few years back, it was a demoralizing experience. I am 100% aware that it's humanly possible to do, and have seen beautiful examples of it being done successfully, but holy shit it's harder than you may think because of the work-hardening tendency making it very weird to bend after it's been bent once or twice. I've had the privileged of seeing the quality of work your hands are capable of producing, and have no doubt you will nail it, just offering my own limited experience as advise. Minimize the amount of bending in the wire as you're winding it. Protect all the edges from chaffing, maybe even have the whole length of wire in a fiberglass protective sleeve or something that you just slide back as you're winding but otherwise keeps it protected from banging off the vise and workbench and whatever else while winding. It's pretty rough.
Thanks, Luke. I've worked a bit with copper before, so I'm somewhat prewarned of what's in store.... :| It will help that each coil will be wound as a separate length. The worst bend, at the centre of the coil, can be done before insertion, so I'll be able to use a jig for that. Anyway, I'll definitely get the wire before I order the laminations.....
speedmd
10 MW
Beautiful work Miles. I hope to at some point master the solid modeling as you have shown here, but much to learn to get to your level. Impressive work and a Nice compact design.
In the local transformer plant they were fond of wrapping kapton tape on areas of the wire showing chafing issues. Lots of teflon tubing also used to ease stresses on wire when hand repairs were made. It was easy to slip out of the way and off when you had the wire near in place. Some of the jobs, only a few of the best could make it look good. You could always spot their work.
In the local transformer plant they were fond of wrapping kapton tape on areas of the wire showing chafing issues. Lots of teflon tubing also used to ease stresses on wire when hand repairs were made. It was easy to slip out of the way and off when you had the wire near in place. Some of the jobs, only a few of the best could make it look good. You could always spot their work.
Thanks speedmd. I've been using 3D CAD, of one sort or another, for 14 years, now. I'd recommend that you get a 3D controller such as the Space Navigator from the start.
I'm looking forward to learning about the practical aspects of motor building now. The winding is going to be a challenge.......
I'm looking forward to learning about the practical aspects of motor building now. The winding is going to be a challenge.......
It would be possible to have a mechanical switch for the fans. A latch could be moved by an actuator rod in the hollow axle....liveforphysics said:Those fans look extremely potent IMHO. You may find your no-load increases substantially driving them, but at least if anything is gonna raise no-load, you would want it to be cooling.
Lebowski
10 MW
Miles said:
Lots of plasters, buy lots of plasters... my most painful bike-building injury so far was a needle through the nail into my thumb
another one was, when you drill aluminium and the ensuring stuff gets wrapped around the drill and cuts open your hand... not as painful though as the nail thing
crossbreak
1 MW
got my finger skin clamped between magnet and stator of a 160mm outrunner 2 weeks ago. The skin is still black :x also buy some heavy leather gloves if you leave your house for buying plasters
speedmd
10 MW
Thanks Miles
I got a space navigator last year, and yes, agree, it rocks. Huge time saver. I am through my second year of self learning the system and feel better now knowing how long you have been at it.
The other thing the transformer winding repair men would use is these hand made plastic mostly wedge ended rods (crow bars). They would gang them up and wedge them into tight spots to help pack and shape the heavy rectangular wire. Some were soft(teflon or hdpe) and some were glass filled. They all had their private collection of them and held them under high security. It would have been impossible to do what they were doing anywhere near as well with just finger tips.
Watch out for those thin lams! Get a deburring wheel. Cheers.
I got a space navigator last year, and yes, agree, it rocks. Huge time saver. I am through my second year of self learning the system and feel better now knowing how long you have been at it.
The other thing the transformer winding repair men would use is these hand made plastic mostly wedge ended rods (crow bars). They would gang them up and wedge them into tight spots to help pack and shape the heavy rectangular wire. Some were soft(teflon or hdpe) and some were glass filled. They all had their private collection of them and held them under high security. It would have been impossible to do what they were doing anywhere near as well with just finger tips.
Watch out for those thin lams!
Get a deburring wheel. Cheers.
Wheazel
10 kW
Love to check in on this thread, following with pleasure!
I wanna wish good luck with the winding, i bet it can be done with the right tools.
A question:
Does it matter on some motorparameter how tight the winding turns around a statortooth?
And by that i mean compared to the theoretical scenario when the wire would wrap around the statorteeth with no radius, thus making the total wire slightly shorter.
I get that the resistance will be marginally higher from a slightlylonger wire but I am wondering if it affects the motor in some more ways?
I wanna wish good luck with the winding, i bet it can be done with the right tools.
A question:
Does it matter on some motorparameter how tight the winding turns around a statortooth?
And by that i mean compared to the theoretical scenario when the wire would wrap around the statorteeth with no radius, thus making the total wire slightly shorter.
I get that the resistance will be marginally higher from a slightlylonger wire but I am wondering if it affects the motor in some more ways?
Miles said:
If you intend to run proportionally lower battery voltage to reach the same speed, it's not going to be problematic at all, since everything stays the same, in proportion.
If you wind it with one turn, and get 3uH, it's still a non issue, if you drive it with a proportionally lower voltage.
You can not only look at the inductance number. You have to put it in the perspective of the voltage and current. If your motor had 1A peak current, 45 uH would be a disaster, but if it had 1000A peak current, the PWM-frequency would be smoothed out to where you couldn't even notice any ripple. And perhaps, 45uH would create too much phase lag to even reach peak efficiency at higher speeds, unless you increase battery voltage.
I think that a properly designed (iron based) motor (like yours) can never have too low inductance. It's only if you make the teeth too thin which makes them almost saturated by the magnets (which I think the case is with the colossus and maybe other RC-based motors). And perhaps if you have some strange proportions like very big diameter and very short stator.
speedmd
10 MW
Hi Miles
I still have much to learn on this topic and only partially through my reading list, but still not able to find much on why fill factor matters so much. Only hunch I can come up with and it is just a hunch at this point, is that a packed gap prevents flux from going stray. Would also love to see a thermal profile of the coil and see how tight vs loose wrap would compare and what exactly happens at the end turns with both current and heat profiles. This is the best thread I have followed on the sphere by far. Any additional reading lists you could share would be a great benefit to us motor maker wannabes.
cheers
Hi speedmd,
Fill factor is important because of the correlation to Rm. I guess the thermal significance of "packing" depends on whether the motor is vented, or not?
Here's a good paper. I must have posted it before, somewhere....?
Fill factor is important because of the correlation to Rm. I guess the thermal significance of "packing" depends on whether the motor is vented, or not?
Here's a good paper. I must have posted it before, somewhere....?
Miles said:
Ah, IC. FOC controllers needs to have pretty accurate motor parameters to work properly. If their software and/or firmware has a 100uH hard limit, then there is a problem, if your motor has 45uH phase to phase. That will probably not work very well.
It's strange that all their controller models seems to have the same inductance limit. It should change with the specs. Their 240A peak model should be able to drive motors with lower inductance, especially at a low voltage.
speedmd
10 MW
Miles said:
Thanks for the link Miles.
I could see that a tightly packed space may be better at conducting away heat and a looser one may be better with convective/ vented cooling.
Still not seeing the Rm relationship to fill factor/ eddy current losses. Great paper I am part way through has much to study on the topics.
http://www.academia.edu/1360191/Brushless_DC_Motor_Characterisation_and_Selection_for_a_Fixed_Wing_UAV
Rm = Combined winding and ESC resistance [Ω ]
I will need to look at this when a bit more fresh. Just not grasping it all just yet.
Thanks for the help with it.
Rm is directly proportional to the fill-factor (inversely!). You need the greatest aggregate conductive cross-sectional area possible, for the chosen number of turns.speedmd said:
Thanks for the link. I'll take a look at it later.
I woke up yesterday morning worrying about the inductance of my motor (as one does... ) Then it struck me that the value given in Emetor is probably for the induction of a single phase (I checked this with Stephan). So, to get the phase to phase induction figure, I'd need to double this............
90uH is a bit closer to 100uH than 45uH was...
) Then it struck me that the value given in Emetor is probably for the induction of a single phase (I checked this with Stephan). So, to get the phase to phase induction figure, I'd need to double this............90uH is a bit closer to 100uH than 45uH was...
This is for a wye termanated motor. Is that estimate with the coils in the magnetic field?Miles said:I woke up yesterday morning worrying about the inductance of my motor (as one does...
90uH is a bit closer to 100uH than 45uH was...
