Turnigy CA120-70 8600W Brushless Outrunner (100c eq)

Miles said:
From the photo, it's either 28, 30, or 32 magnets. 30 isn't likely, I guess.... Come on Marko :mrgreen:
Click to expand...

If it's 28 magnets, it's going to be a sad day. :'(
 
is there a concensus that 32 poles would be the better senario for controlling this motor?
I would love to hear the reasons for the benifit of every one reading along.

I really think that the ABC senario is prolly not the "most" powerfull, but it is going to be increadbly flexible for tuning & reconfiguring.
I will leave all the ramifications of BEMF & re-circulating currents, harmonics, & all the other electricly generated nastys to the bigger brains available on the subject.

if there is a best case senario for a given parameter set Lets get a list together.

Example:
1) Low voltage(44.4) max-eficentcy= BLAH,BLAH,BLAH
2) Low voltage(44.4) Max power= Blah,-,-
continue up (or down) the voltage tree for builders to have a data base for makig the motor conform to their requirments.
Is this making it "too" easy for complete newcomers to the electric revolution on the horizon?

Edit: More senarios
Etard wrote:
Here's a thought... What about a manual clutch that would allow the motor to spin up to a decent rpm, just like an ICE motor and then dump the clutch for a decent launch? Would the controller survive much better in this kind of scenerio?
Click to expand...
In light of Matts experiments with a tourque limiting slipper clutch. I began to recall some small scale hydrolic units. Any one recall the Losi Hydro-drive?. I have no idea of the efficancy of a simple hydrolic clutch with a settable lock-up at 2500rpms....but a smaller version of a reckluse clutch would provide the same tuneability & any clutch would get us out of the "stalled"condition much sooner... I have always thought a centrifugal clutch was a mismatch in EV apps. Now it seems a resonable end run around start up issues.
Now I have to dig into machinerys handbook & calculate the weights & such for an 1/2 scale horstman style racing clutch...
 
I haven't been keeping up with all you motor nerds lately (still buried in BMS-related stuff... :roll: ), so can you explain what the difference is between LRK windings, vs. ABC? If not, is there a thread where you all are discussing it?

-- Gary
 
markobetti said:
it was hard to count it upwoards, i pulled the back plate down.. Sorry luke its 28
Click to expand...

Damn! That means we've gotta do the goofy winding patterns, and limits the possible configurations. :(
 
Gary,
As I understand the history, What is now called LRK, (an akronym for the 3 gentlmen who started winding thier airplane motors this way) was a comon wind for Hydro-electric power generators in Poland.
there is a long standing debate on the benifits of the winding senario regarding true performance output. I have concluded it is just another "variable" to make a motor perform for a particular set up.
There are many good technilogical discusion on the subject at RC groups.

When you have time these will explane far better than I could:
This is the basics of the design & a good description of the implied "electrical gearing effect" of LRK configured motors:
http://www.gobrushless.com/kb/index.php?title=Brushless_101_-_Chapter_3

some discusions at RC groups with good input from the GURU's:
http://www.rcgroups.com/forums/showthread.php?t=761336
http://www.rcgroups.com/forums/showthread.php?t=572191&page=2

My main focus has been relitive to the ever increasing scale of these motors & the changing effects of proportions on the dynamics.
I also suspect the reason we see so many of the LRK/DLRK in the rc wordl has to do with the economics of supplying 10 or 14 magnets over 16.
 
24 slot 28 magnet winding scheme from the Powercroco site:

http://translate.google.com/translate?u=http%3A%2F%2Fwww.powercroco.de%2F24N28P6530.html&sl=de&tl=en&hl=&ie=UTF-8
 
lfp wrote:
Damn! That means we've gotta do the goofy winding patterns, and limits the possible configurations.
Click to expand...
screw that! I am going 32 poles.....make it as easy as possible......but no easyer.

Tiberius: imagine the rpm potential of a mono pole motor!

Markobetti, how close is this to the motors your currently offering? You sound confident that the one in your hand is the same motor. If so can you tell me the Id of the magnet can? I can see if my magnets are going to fit in that can or if I need to fab a new one. Thanks Thud.
 
Thats the exact same motor .... the aluminium parts are the same etc.......
i am not offering them, hobby is ... Accountant must check if we can even sell them with lower price... but i personally think its impossible...
. id is diameter of can or ?
 
this is without aluminium part down there ... also the lenght of magnets is 5,5cm and they are 3,3 mm tick and 1cm wide...





 
Thank you Marcobetti,
tThat was my original suspicion, that the supplier was the same for some of the components. But it is very good news for the EV crowd just the same. Just need to figure out the proper controlling set up & every one wins. T
 
140 kv with hal sensors due to stator pair poles and 14x140x72=141 120 erpm , right miles ?
Thats why my is 70kv and i run it with kelly. But since infineon has 120 000 erpm its going to roll good on 24 fet 4110 controler...
 
I see the advantage of a clutch ( you don't have to rewind the motor), but if the motor has a Rd of 4,8mOhm in delta, it'd have ca. 15mOhm in wye. That's pretty close to the 17mOhm of the ( now to be called :wink: ) smaller brother 80-100.
There are several bikes out there with a rc-controller/80-100 combo able to handle this start-current.

You just need to have a wye/delta switch...
-Olaf
 
This seems like an interesting motor. The pole count is so high that I imagine it will have serious core loss issues at high speed (over 4000RPM), as well as high PWM frequencies and processing power for the u-controller.

If someone can tell me the mass (or a good estimate) of the stator iron, I could give you a curve showing the core loss vs. RPM.

Since the KV is 140, the kT would then be 0.07Nm/A. (Kt = 9.549/Kv), so at 250A (recommended controller spesification) that would only be 17Nm of torque, so the 1cm shaft should be able to handle that. I think that the motor spec they advertized is way off. Something with that diameter and length shold be able to handle much more torque than that. I think once you guys get this in and re-wind it and give it a proper controller, the real spesifications and capabilities will soon be determined.

-ryan
 
Actually Biff and others i think rating is right... Factory gave me rating of 60v 250amp for the motor ... thats 15kw ,and they are rating it much lower on hobby site..
 
markobetti said:
Actually Biff and others i think rating is right... Factory gave me rating of 60v 250amp for the motor ... thats 15kw ,and they are rating it much lower on hobby site..
Click to expand...

60V At 140RPM/V is 8400RPM with 28poles is 117000e-RPM or almost 2kHz electrical frequency. I imagine to make such a high frequency motor, the design has really short teeth to minimize core loss at such high frequencies, which means also very little space for copper and hence the low torque. With such a high KV and low resistance I think it will be a challenge to get a good controller on this guy. My first guess is for EV applications it would probably be best to rewind it with more turns to get a lower kv, and higher inductance / resistance and run it on a higher battery voltage, maybe 120V, but I could be wrong, I haven't really given the controll difficulty too much though.
 
I just had a closer look at the images, and it looks like the teeth ar about 3cm long, so my theory about short teeth in the previous post is probably wrong. I don't know why there is such a low limit on the current, I would expect a motor of that size to be able to deliver 50Nm (or 500A DC according to the advertized kv and calculated kt) at least for a couple minutes.

Also I expect at such high RPM the core loss will be significant. Core loss goes up with the square of frequency, and the Turnigy motor has about 150W at 800hz and the stator weights about 400g. So with an estimated 2x core mass, and just over 2x the frequency, I would expect 8x the core loss, or close to 1.6kW of core loss at 8400RPM.

-ryan
 
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