12 kw rc motor

bearing said:
Pole count will not increase velocity. Magnetic field (in air gap, I assume) should not change. Length does not change. So the induced voltage/kv should not change. But this formula is maybe only for coreless motors?

-it doesnt change velocity, but more magnets mean a faster rate of change of flux in the teeth, and a higher number of cycles per rotation.

arlo that new controller you speak of runs just 10kpwm etc and may not even run hubbies to enough speed.

you can buy a controller for $489 that will get you well over 11kw shaft output from, it just not that much of a drama, accept for sevcons that have no speed. and arlo i thought your controller was meant to be cheaper alternative to an equivalent kw kelly?
 
Here's someone who did a test: http://www.helifreak.com/showthread.php?t=475358

Aslo, see Bruce Abbott's reply in this thread at RC Groups:
http://www.rcgroups.com/forums/showthread.php?t=1377493
 
toolman2 said:
you can buy a controller for $489 that will get you well over 11kw shaft output from, it just not that much of a drama, accept for sevcons that have no speed. and arlo i thought your controller was meant to be cheaper alternative to an equivalent kw kelly?
What controller is it for 489? 11 kw is not bad. Is this the one Splinter got 7hp at the wheel from?
Mine is better with more fetures and in the future more power but I can not make it cheaper yet.
 
Has anyone played with GM controllers yet? http://www.goldenmotor.com/
 
Haha called golden motor canada and he doesnt even know what PWM frequency meens.
 
toolman2 said:
...you can buy a controller for $489 that will get you well over 11kw shaft output from...

Why spend so much? I can get more than 11kw out with less than $200 in controller cost, and I tested it for 9 months to prove durability. You can't go to the extremes of low cost, because most around here aren't comfortable without spending more money.
 
John in CR said:
toolman2 said:
...you can buy a controller for $489 that will get you well over 11kw shaft output from...

Why spend so much? I can get more than 11kw out with less than $200 in controller cost, and I tested it for 9 months to prove durability. You can't go to the extremes of low cost, because most around here aren't comfortable without spending more money.

no john, you are confusing your peak power consumption figure from the ca into massive heavy hub motor, with actual measured output at the tire using a dyno, they are different. :wink:
please dont bother reminding us that its verified cos you checked the motors side plate temp, with your finger. :roll:

but to answer your question anyway, its worth it for us to have good smooth torque throttle, 33khz pwm, super high erpm, heaps of pages of settings to tune and get good behavior from a very light and wound up rc motor. -i used a 24fet for a bit and it worked but was not very useable, im not keen for a greentime $58 special for this motor, but sure give it a try it may work.
 
Attached are two sets of simulations. First set is Colossus with 16p and 32p in no load and load simulations (free materials). They both show about the same torque. But the teeth have very high flux density with 16p, so it would never work in reality.

Second set is a 12t 8p/16p machine I made with really thick teeth, just to be able to run with true materials without getting into saturation with 8p. I ran no load and load simulations with free materials, and then load simulations with true materials (all I could afford, now I'm out of credits, lol). They all show about the same torque, although the 12t8p shows a little bit less, which I think is because there are some spots of saturation. But it may simply be in the margin of errors.

My results shows that pole count does not change kt. However, if the iron is close to saturation, then you may gain some kt by increasing pole count, I think.
 

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  • colossus-16p-100a-free.pdf
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  • colossus-32p-100a-free.pdf
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  • outrun-127mm-12t8p-6000rpm-100a-free.pdf
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  • outrun-127mm-12t16p-6000rpm-100a-free.pdf
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  • outrun-127mm-12t8p-6000rpm-100a.pdf
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  • outrun-127mm-12t16p-6000rpm-100a.pdf
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Yes, that's right. But what I meant is that I think that if you do that, reduce tooth width, then you will get a smaller "working range" of the motor. It will become more of a low rpm, low torque motor, low loss motor.
 
bearing said:
My results shows that pole count does not change kt. However, if the iron is close to saturation, then you may gain some kt by increasing pole count, I think.

thanks bearing,
so wouldn't that mean theres no or very little torque advantage from higher pole count?
that seems at odds with even the rc groups findings and the hacker f3A motors change from 28 mag to 20 reducing max prop driving ability.
that would mean kv does not change either? -dunno.
 
Miles said:
It's really difficult to get a meaningful comparison by changing the pole count whilst keeping everything else the same. I think we've learnt that much!

Ah, OK, now I see what you were saying before. More poles doesn't mean higher kt by itself. But it means that you can change the stator to get a lower weight, or smaller dimensions, or a higher proportion of copper, and so on. Which means you can get a higher kt with the same copper losses, if you wish. Yes thats true.

The start of this discussion however, was that I thought that changing to a rotor with more poles would create proportionally higher kt. And that is false. That was also what we thought in another thread prior to that, if I remember correct.
 
toolman2 said:
so wouldn't that mean theres no or very little torque advantage from higher pole count?
that seems at odds with even the rc groups findings and the hacker f3A motors change from 28 mag to 20 reducing max prop driving ability.
that would mean kv does not change either? -dunno.

I'm not sure, but I think that if the stator was designed for 28p, the teeth will get closer to saturation with 20p, which probably changes kt/kv for the worse.
 
bearing said:
Miles said:
It's really difficult to get a meaningful comparison by changing the pole count whilst keeping everything else the same. I think we've learnt that much!

Ah, OK, now I see what you were saying before. More poles doesn't mean higher kt by itself. But it means that you can change the stator to get a lower weight, or smaller dimensions, or a higher proportion of copper, and so on. Which means you can get a higher kt with the same copper losses, if you wish. Yes thats true.

gotcha, thanks that answers my question too.
just be careful guys, one of you is going to OD real bad on Emetor. :)
 
Miles said:
Playing with Emetor is really addicitve :shock: I've been doing some loaded sims with 24t 28p. It works ok in linear mode.

Oh, It works now?

I noticed this morning that the "help pictures" when choosing parallel tooth, parallel slots etc are gone, so maybe the code was updated tonight.
 
The reason I bought credits in the first place was that I thought that I needed them to be able to run the load sim on the Colossus. But it failed with true materials as well.
 
The 24t28p load simulation seems to be very heavy though. Mine has been running for over 10 minutes now. We are going to overload his machine :( :D
 
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