would this make an acceptable generator head for a wind turbine?

[xymox]

http://www.ebay.com/itm/ETEL-TML-permanent-magnet-torque-motor-generator-210mm-/250762996036?_trksid=p2992.m185&_trkparms=algo%3DSIC.OPJS%26its%3DI%26itu%3DUA%26otn%3D20%26pmod%3D250763342391%26ps%3D63%26clkid%3D4539949636827806377

Its swiss design so Im having a little trouble figuring out how many watts I could push out with this thing, looks very well made and compact, and 44 poles should give it really low rpm performance.

Thanks in advance.

[DanG]

My take on TMA0210-070-3SA decoded from the handbook & ad specs:

210mm (9") stator outside diameter, 5-1/2 inches internal opening - rotor 5-1/4" x 3-1/2"; 300VDC design voltage; .71mm / 21AWG windings, 200RPM maximum service speed; 50w heat dissipation in the windings at normal service levels, 225 ft-lbs peak torque...

It's designed for robotic arms for parts bin pickers or assembly line 'arm' positioning - huge start up torque. with no/lo RPMs..

The housing and bearings would weigh 3x or more than the claimed 50~ pound stator & rotor combined weight.

If they were asking 1/10th that price it might make a fun toy for something, say maybe a scale model of a Star Wars Imperial Walker or somesuch. As is its untouchable for windpower unless you print your own money and would use it for a VAWT...

[CaptainPatent]

Yeah - just to clear up mathematically why this motor is probably bad - While it is low RPM, it also looks to be a very high-torque machine.

If I'm doing my math correctly given the specs, at only 200 RPM (peak) while using 300V @ 23.1 Amps (nearly 7KW Peak) you couldn't possibly do a TSR 7 @ 12.5 machine which is the norm because the blades would need to be about 6 feet long (12 foot diameter machine) which would probably be fairly firmly cogged from the lack of wattage in the wind at corresponding levels - only about 650 watts (and about 250 that is able to be harvested.)

To get closer to the wattage needed, you'd probably need 10' blades or bigger (20' + machine) to have enough torque to get close to a match with the gen, but getting even somewhat close to 200 RPM at that size requires a tip speed that will destroy most blades:

If we aim even for 150RPM on a 20' machine the tip will travel at 20*pi*150*60/5280 or 107MPH so we'll have significant edge erosion without coming close to peak wattage for the gen.

That is on top of the weight as Dan discussed which will require one hell of a tower, some serious barrings and some decent overspeed protections.

I wouldn't go as far as saying it's untouchable for wind, but given the severe mismatch, it's just way off of ideal. If you shoot for a 15 or 16 foot machine with a 5 or 6 blade rotor, you may find a rotor 'near match' that will let it run at 150 RPM or so without significant tip erosion, but you're still looking at an absolute maximum of 75% of that generator's peak power in the best case at the cost of weight, extra blades, structure and money and that's only if you can overcome that gen's cogging.

[CaptainPatent]

Woah - I just looked back at this and realized I was a bit wrong. The mismatch is a bit smaller than I thought.

For some reason I was thinking the TS goal should be 80mph not m/s

With that being said though, even if you make a 20' machine out of it, you'll need winds on the high end to get it to spin and it looks like the 'ideal' blades for that gen would be roughly 15 feet long for a whopping 30 foot machine!

[xymox]

Thanks for comments.

So because of the high number of polls we have a llot of cogging that will need to be overcome. This I understand. larger blades would be in order. I had figured a pair of 8 foot blades.

As far as the bearing and housing needed, and associated weight:
bearing house could be made from thick aluminum plate, that would not weigh so much.

This can be bought for 400 bucks based on the recent buys on this auction.

[CaptainPatent]

I still think you're going to have some serious cogging problems even at 8' blades.

While I can't be sure without actually having access to that stator / rotor, I'm pretty sure the blade match range is going to be somewhere between 15' and 20' blades. You MAY be able to get by in the 12-15' range if they have a very fat profile or you have more blades for additional torque. That stator / rotor looks like it would make a MONSTER machine.

Between the motor, the housing, the bearings and the blades, the tower will probably need to hold 500+ pounds and be able to absorb almost 35K Joules of force at the top in order to stand up to even 30MPH winds. And that's if you have a solid furling system. Just for comparison - a 20 foot machine only requires 15K Joules of absorption at the top so this is more than double the strength needed.

At that size it also gets shakier as to whether or not you should build you blades out of wood too. Go too big and they'll rip themselves apart under their own weight and torque.

You'd probably have to go with Aluminum, fiberglass or carbon fiber to get to that size of blade and it would have to be reasonably thick aluminum.

Basically – if you want to get it to screw around and don't mind shelling out the cash for something that may not go anywhere, go for it. We'd love to see the results.

Just don't expect that it'll work unless you're willing to extend to the 30' diameter + range and take on all the additional expenditures that go with a project of that size (i.e. much stronger tower, bigger battery bank, very little DIY forum support as a 30 footer would be new ground, certifications for the high wattage you'll be dealing with, etc.)

[DanG]

I'd think there would have to be a MPPT buffer on the output to even allow it to start turning with any current flow at zero RPM. Huge motor start up torque means huge brake force.

They've now listed another unit about 10 times the power, 110kg weight at 31A continuous power.... http://search.ebay.com/250763342391

[joestue]

From the datasheet:

The values of the continuous torque in the data-sheet are given for an ambient (or water) temperature of 20°C
and a coil temperature of 130°C

ETEL's torque motors require a maximum concentricity between 0.2 mm for the TM#0140 motor series and 0.8
mm for the TM#1221 motor series.

and they go on to list the newtons/mm for any offset, which range from 750n/mm to 33,000n/mm for the xx1221

The data-sheet does specifically state that the magnets are bonded neodymium's, and i could speculate that the reason is to mitigate the eddy current generated in the magnets at high speed operation, so we're not talking 1.4T magnetic fields and halback arrays but its uh, "up there" and probably higher than one tesla. you would need to "short out" the rotor with a piece of sheet metal to allow you to insert it into the core, and you would still need a machine to lower it into the core for you.

Although it has 44 magnets, that doesn't mean it has 44 poles and the data-sheet doesn't mention the winding configuration.
The datasheet mentions the detent torque, and lists it as 1.5Nm average to peak for the TML -210-070, which is 1/34th of its continuous torque specification. This is actually really good, and that means it has a torque ripple of ~3%. This isn't as good as you can get with an iron core motor (less than 1% is possible) but its very low for a motor designed for high torque.

[xymox]

yeah the bigger one is quite freightening. For 2900 bucks Im sure I could find something more practical.

What would be the issue inserting the core into the stator?

[joestue]

go to youtube and search MRI + oxygen bottle.

[xymox]

dang, ok, I understand now...................