12 kw rc motor

Electric Motors and Controllers
markobetti   10 kW

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Re: 12 kw rc motor

Post by markobetti » Mar 21 2010 7:15am

sorry its 75 kv ..not 90 or 60 ... grrr ...

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liveforphysics   100 GW

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Re: 12 kw rc motor

Post by liveforphysics » Mar 21 2010 8:13am

nieles wrote:because the motors are not made yet, can we make a request that the shaft will exit the motor from the other side?

it is a bit hard for me to explain what i am trying to say, but i hope you understand.

Niels

On every RC motor I've worked with, its a fairly simple affair to loosen the grubs that lock the rotor to the shaft, and slide the shaft to be in whatever position you require, and re-lock it in place.

Also, being 1" means loads of high strength bar stock is available to make shafts in any legnth needed.

I'm thinkin some 1" shafts with a 10-11t sprocket for #219 chain milled right into the end of them would be the perfect combo of reliabilty, stregnth, and most compact size. :)
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Miles   100 GW

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Re: 12 kw rc motor

Post by Miles » Mar 21 2010 8:29am

The shaft reduces to 20mm diameter inside the motor, Luke.

It's possible you could reverse it.

Replacement 20mm shaft would be fine, if not preferable, though...

If you're ordering a batch, I would specify that you want a 20mm shaft exiting at the mount end.

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Jeremy Harris   10 GW

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Re: 12 kw rc motor

Post by Jeremy Harris » Mar 21 2010 9:32am

Luke,

There may not be any merit in strengthening the can, as that won't be anywhere near the most stressed component, I think. The rpm limitation will be set by the bearings, specifically the skirt bearing. This will be limited to around 6000 to 6500 rpm or so, judging from it's size. It may be possible to get a higher speed rated bearing, I've assumed that it's a standard metric deep groove ball bearing with a bore of 70mm and an OD of 90mm (just guesses from looking at the drawing). Still, 6500 rpm at 75Kv makes over 80V a possibility; upping the bearing spec to maybe something that might take 7500 rpm would get you up to around 100V. Exceeding the bearing speed limit will only result in a shorter bearing life and a bit of extra heat, so it may be acceptable for intermittent use, anyway.

Also, looking at the design, I don't think it's worth putting the shaft right through, particularly as the shaft is machined with a step (it's 1" at the bell end but smaller where it goes through the stator hub). The drive torque comes from the end of the bell, so fitting a sprocket directly to that would be the best bet and is probably the reason for that adapter shown on the first photo. It's always a challenge getting the shaft and bell to couple together well on outrunners, I've already had one of mine tear the nasty little grub screws around on the shaft. Taking the drive direct from the bell removes that hassle. Unlike baby outrunners, this motor looks to have really big support bearing and the outboard end bearings look to be well up to the task of taking the side loads from a chain or belt sprocket. The stator hub is similarly massive, so would likely be stiffer than any home brew bearing support. The only issue might be over the stiffness of the mounting base to take the cantilevered loads, but looking at the drawing and photos I think it'll probably be fine.

I've heard it said that bearings on RC motors need to be beefed up to take sprocket/belt side loads. In reality, a big propeller will put bigger side loads into the bearings than the modest tension from a chain or belt. The gyroscopic forces acting sideways on a prop hub are very high, particularly during extreme aerobatics, which is what a lot of these motors are used for. The rates of rotation in pitch and yaw of some of these powerful models are very fast, with rapid onset, so the motor bearings take a pounding, with high sideways shock loads. That's not to say that all outrunners have excellent bearings; my experience has been that most Chinese made motors have bearings that are just about adequate (in terms of quality). Virtually all can benefit from being re-built with decent quality bearings, in my opinion.

Jeremy
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Miles   100 GW

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Re: 12 kw rc motor

Post by Miles » Mar 21 2010 10:31am

Maybe they would do a shaft with a standard keyway?

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Re: 12 kw rc motor

Post by liveforphysics » Mar 21 2010 10:40am

Jeremy- Thank you for the excellent info and insight!
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markobetti   10 kW

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Re: 12 kw rc motor

Post by markobetti » Mar 21 2010 1:29pm

Hal , tell them what you think about the motor ,and if you wish to tell them what can they expect in the future from you :twisted:

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Re: 12 kw rc motor

Post by markobetti » Mar 21 2010 1:44pm

hal also said that the shaft could be on reverse , i will ask

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HAL9000v2.0   10 kW

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Re: 12 kw rc motor

Post by HAL9000v2.0 » Mar 21 2010 2:29pm

Motor is great, it is huge, I was suprised how small it looks on the Marko's picture, allmost twice as big as plattenberg . Very simmilar to hxt but better, it has big bearing, something like 70x90x10 mm bearing on fixed side. The axle is on wring side but it is no problem to make on both sides. Axle diameter is overkill but I see that they do that to make bearing choice easier. The only thing that can be better is wire dia. The exit wire is cca 6-8 mm^2. My guess it can do 4-5 KW continuusly without any problem. The stator is made around huge chunk of aluminium and I guess it can do few times more kW for few minutes...
Unfortunatly that is it from me because I manage to burn the only sensorless controller before we started it. In a week or two another high power sensorless controller will arive and more info then.

You can expect LC and hall added...

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12p3phPMDC   1 kW

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Re: 12 kw rc motor

Post by 12p3phPMDC » Mar 21 2010 4:11pm

MArkobetti/Hal

Do you know what the configuration of the motor is?

How many slots/poles on the stator and magnets on the rotor?

Thanks!

I wonder what the chances are of getting larger phase wires?
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Re: 12 kw rc motor

Post by markobetti » Mar 22 2010 4:10am

20 POLES, DON KNOW HOW MANY MAGS . I WILLL CHECK.

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Jeremy Harris   10 GW

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Re: 12 kw rc motor

Post by Jeremy Harris » Mar 22 2010 8:31am

Sounds very good, Marko. I'm seriously thinking about resurrecting my light motorcycle project. It's been on hold for several reasons, one being the problem of getting enough batteries in it with the big Mars motor and Alltrax controller. This motor looks to be the same, or maybe more, power than the Mars and I know I can make a controller much smaller than the Alltrax. I reckon I could lose about 20 - 25kg of weight off the bike by using this motor, even if I do need to add another reduction stage.

I'm looking forward to hearing how Hal gets on with it, if all looks OK I will PM you to add my name to the list. I may buy either one or two motors, depending on how they perform.

Jeremy
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markobetti   10 kW

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Re: 12 kw rc motor

Post by markobetti » Mar 22 2010 8:32am

only 5 orders motors on pm. with mine it is 7. Well guys i dont think we are going to make 30 pcs ..

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Re: 12 kw rc motor

Post by markobetti » Mar 22 2010 8:37am

yep , motorcycle coversion sounds great , and on one shaft and two controllers there should not be loss of efficiency , and hell ; they would look great if somebody likes eye candy like me :)

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Re: 12 kw rc motor

Post by markobetti » Mar 22 2010 8:39am

hals version will bring out the monster from the monster , i am seriously thinking about naming him hals HULK and making him with anonized green color :) :) how about it hal?

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12p3phPMDC   1 kW

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Re: 12 kw rc motor

Post by 12p3phPMDC » Mar 22 2010 10:20am

It's probably the lack of test data holding things up.

I've got a Turnigy 100A controller I'd be willing to help out with.

Freight to Europe would be expensive.

It wouldn't support this motor to full power though.

I'm thinking we need a 200A 100V controller for this beast.
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Re: 12 kw rc motor

Post by swbluto » Mar 22 2010 11:40am

Do you know where the technical specs are? Kv, no-load current at some mentioned voltage, and the motor's resistance would be nice. All but kv are easy to measure with a power supply and voltmeter, and I can explain it if you'd like.

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Re: 12 kw rc motor

Post by markobetti » Mar 22 2010 1:10pm

all right . This is all info i have : .the RPM of motor is 750. the idle current is 8.6A when we use the 12V voltage to test it - manufacturer

URL=http://img291.imageshack.us/i/infoo.jpg/]Image[/URL]

i cannot confirm anything except that the motor construction is great. Still waiting for sensorless controller for test

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Re: 12 kw rc motor

Post by markobetti » Mar 22 2010 1:15pm

Image

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Re: 12 kw rc motor

Post by markobetti » Mar 22 2010 1:25pm

Jeremy what is your conclusion based on parameters ?

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liveforphysics   100 GW

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Re: 12 kw rc motor

Post by liveforphysics » Mar 22 2010 1:37pm

You're not going to find a sensorless controller to do it any justice.

There isn't a sensorless controller available that can even do the 1/3rd the size HXT motor any justice.

Get one of those motors to Jeremy or Burtie, and they can figure out a sensor position/solution for it, and then it can be used properly.

RC controllers are for toy motors in 10lbs toys. This is not a toy motor.


As far as the people asking about bigger phase leads, that would just require doing a higher KV wind. They just pair the phase wires up in delta and run them out of the case on RC motors, so the wire size is determined by the winding dimensions, which are of course determined by the number of winds.
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Re: 12 kw rc motor

Post by swbluto » Mar 22 2010 1:50pm

The following quoted text might be wrong. I have a feeling I ignored the squared relationship between kv and resistance which may be applicable here...
The resistance looks pretty low for the kV. An HXT motor has a resistance of 27 mOhm at a kV of 130, so this motor would imply (130/75)*(27/10) = 4.68 times the copper fill of the HXT 130 kV motor. Must be hefty!
The graph was derived with 12 volts and no current limiting (Which would be unrealistic as you'd have to employ motor current limiting at the bottom end as the 3000+ amps as would be implied by 36 volts would be a little ridiculous.):
Untitled.gif
Untitled.gif (60.28 KiB) Viewed 2469 times
At 12 volts, the efficiency peaks at 85%. As with most motors, its efficiency will probably increase with higher voltages so based on comparisons to agni and hxt, I might expect its efficiency to peak at 92-95% at higher voltages like 60 volts.

As you notice, the amps with this "no limits" simulation is 1100, so motor current limiting would probably be used in real life and the bottom half of the graph would be kind of unrealistic. Looking at the graph, it looks like 300 motor amps would correspond to a starting torque of 39 N.M.; With an 8:1 reduction, you're looking at 312 N.M. at the wheel which is definitely appreciable.

As far as this goes, I definitely think a sensored controller would be realistic. The inherent error involved with sensorless is fine with lower powers, but it results in huge wasted power at higher power levels in a varying load application = needs a beefier controller. As far as I know, I haven't found true high power sensorless controllers other than RC controllers.

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Jeremy Harris   10 GW

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Re: 12 kw rc motor

Post by Jeremy Harris » Mar 22 2010 2:08pm

Marko,

Looking at those figures, Io (the motor no-load current) seems to be a little high at 8.6A. It may be that this is related to the way the test was done, or perhaps, just an error.

Is this data from Hal or is it from the manufacturer? My experience with Chinese motors is that the specifications are often a bit garbled, possibly as a result of language problems. For example, one motor I bought had a stated Io of 3.6 amps, yet when I put it on the bench and tested it I found that it varied between 0.8A and 2A over the full voltage range.

The winding resistance, Rm, looks pretty good at 0.01 ohms though, the motor looks able to handle the current OK for short periods, although the I²R losses at 200 amps will be around 400 watts, so it will need some cooling. At a guess I'd suggest that the continuous power rating should be around half this (maybe around 140 amps), but that's still pretty good and a lot better than the nearest big, cheap outrunner.

For comparison, the HXT 80-100 130Kv, 6500 watt motor has an Io of 2A, an Rm of 0.032 ohms. At it's maximum voltage of 48V and max power of 6500 watts it will draw 135 amps and have I²R losses of over 580 watts, so far less efficient. There's no way the HXT motor will sustain 135 amps, either, my guess is that it'd get pretty warm if run at more than about 50 amps continuously. On bikes it's hard to draw currents of over 100 amps for long, though, at least on the road, so the average current is likely to be a lot lower, which is why people aren't burning these motors out. This big motor will be even better, as it looks like it should be able to run at maybe three times the continuous power of the HXT.

As soon as we hear from Hal I'll PM you, Marko.

Jeremy
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markobetti   10 kW

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Re: 12 kw rc motor

Post by markobetti » Mar 22 2010 2:22pm

No ,this is manufacturers data. Hal and i didnt test it , because controller burned :) No problem , i think i will ask Hal to help with this order . Heat will be no problem since Hal has figured out a way to cool it if it will be needed . Jeremey thanks for reply and others. It looks as this motor is a real deal, also i have no doubt in Hals idea since the way he will cool it is very promising . One thing about this motor, it doesn't lack the space for modding unlike other outrunners . In two weeks i should get the sensored motor . For me the only thing that is bothering me is not the power of motor ,or cooling , but the direct drive . i am designing a frame for dd , and if it will not be possible dd i will have to redesign the frame ..

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Re: 12 kw rc motor

Post by markobetti » Mar 22 2010 2:27pm

the exact weight of the motor is 5.2kg

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