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niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331
Posted: 06:22pm 01 Oct 2009
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hello all
i,m waiting on a small cheap ebay 12v winch to come..it should have a fairly high ratio ..so hopefully i can play with it a bit as the basis for a yaw motor ,im not sure how suitable it,ll be .....(the yaw motion should,nt be a very big load maybe an amp or 2...i think..which might help..)
the supply battery however is 48v...(the mill system voltage )
would a pwm speed controll cct allow me to step down the the 48v and not ultimately fry something ?
Edited by niall1 2009-10-03niall
RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495
Posted: 10:12pm 01 Oct 2009
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I have a couple of these. I was planning to use one for my traxle. I too, thought that I could get one to just "tick over" with light loads and modest current draw - however they won't even tick over at 6 amps on a 12V supply, which surprised me.
Not sure quite how much they will need to operate even unloaded, because at 6A and not going, I ceased to be interested.
My "plan" had been to use a power fet and PWM to provide a low "average" voltage/current to the motor, but the current required just made it impractical.
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 11:14pm 01 Oct 2009
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Hi Niall,
The intended winch purpose has no regard for electrical efficiency.
Gordon.
Edited by GWatPE 2009-10-03become more energy aware
niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331
Posted: 12:31pm 02 Oct 2009
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nuts...
i suppose i can test it out as a regular winch...niall
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 02:54pm 02 Oct 2009
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Perhaps you could try a windscreen wiper motor? The one I use on my 2x 210W panel solar tracker has a 55:1 worm drive, it draws about 2A on 12V. Edited by Tinker 2009-10-04Klaus
niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331
Posted: 03:40pm 02 Oct 2009
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hi Klaus
the windscreen motor could do it...plus the heavy duty ones i think can be 24v and should turn up in the scrap yard
the only reason i thought about the "thing" from ebay was the 150:1 ratio
if the wiper motor used a simple chain drive to the yaw pipe there might be another 3:1 ratio to be gained ?
i,m guessing a huge amount about all this and dont know what an ideal yaw speed would be....(too fast sounds bad)
your motor drive sounds interesting .......
can i ask how it connects to the moving section ?
the natural yaw action of the mill should (i hope) work with the motor ...maybe this,ll helpEdited by niall1 2009-10-04niall
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 09:01pm 02 Oct 2009
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Niall,
I would use the winch motor as it will have the strength to carry the whole show off.
Dont underestimate the forces at work on the blades working against the yaw holding parts.
The forces can be very severe (torque wise with wind shift) and perpetual.... they don't stop.... They will wiggle and wrench at the pivot assembly trying to find a weak spot.... the gears will be well tested. Make sure they are big enough to stand up to this behavior.
Perhaps use relays and micro switches to control the thing... with some serious hysteresis built in.... yes low tech I know, but that is also roughly how we do it on the biggies over here (hydraulic motors though).
I would use a tl494 to do the pwm, and control it via current rather than voltage. This will give you soft start, and will let the fets have an easier life.... or lots of meters of fencing wire in the wiring to act as a decent resistor.... or even use your dump load as the dropping resistor.
.............oztules
Edited by oztules 2009-10-04Village idiot...or... just another hack out of his depth
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 01:54pm 03 Oct 2009
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Hi Niall, actually I was not telling the whole story, the wiper motor drives a worm gearbox so its a 55:1 reduction driving another 50:1 . Nice and slow for what I wanted, about 3 seconds to turn the panels 15 degrees.
Oztules has a good point, the wiper motor has a plastic gear and would not be up to the yawing load directly. But for driving another gear box its great. I'll attach a picture how I connected mine - it was a bit fiddly due having to modify the wiper arm on the motor shaft.
Klaus
niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331
Posted: 05:31pm 04 Oct 2009
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i like the independant gearbox Klaus...their not that easy to come across .... combining both seems a much bigger ratio than 150:1 (what i was thinking of using )...thanks for the pic .......lots to think about
oz ..., i havent tried the current mode control before ,(voltage only) but i,ll read up on it and have some 494,s lying around
Edited by niall1 2009-10-06niall
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333
Posted: 07:55am 05 Oct 2009
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Hi niall1
On a different thought that i have toyed with, is to mount the whole tower on top of a car diff or a drive shaft up the centre of the tower and rotate it from the ground.
The diff ratio is not great enough without a second gearbox between the diff and the motor.
A car diff is strong and easy to adapt.
I built a solar tracker from a car diff standing vertical with a axle and its housing removed from one side.
The spider gears was welded to create a locker diff.
Some time soon i will post an article on the building of the diff solar tracker.
There is some back lash in the diff but this might work to ones advantage and allow for a little floating of the mill head (2-4 degrees floating)
The motor driving the solar tracker is no bigger than a wiper motor (1-2amp)driving through a 200:1 gearbox with a further @ 4:1 diff ratio.
The location of this is in a very high wind area and with stands gail force winds.
The panels create a large sail area of over 5m2 and do not track the wind but the sun and can cop a lot of wind forces.
I only have a poor photo at present but here is a photo of the drive basics.
One advantage in using something like a diff is its strong and it reduces the force applied to 1/4 before it reaches the gearbox.
Food for thought?
Pete (Downwind)
Sometimes it just works
niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331
Posted: 09:25pm 05 Oct 2009
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very interesting looking at both systems ....physical strength seems obvious in both .. you guys have a lot of know how here already ,thanks for posting ....
the winch motor should be here soon ..then i,ll do some tests on it (exacting revenge on it with an autopsy might be part of it)
i do have one other 12v winch (not the planetary type and not as compact)....it can raise the mill... but i dont really trust it that much for that purpose ..
so one or other can be tried out...definately food for thought Edited by niall1 2009-10-07niall
niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331
Posted: 09:20pm 12 Oct 2009
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well the winch arrived
the aluminum (or something similar) drum (i took it apart) dosent seem to have a very tight fit to the main drive ,the mesh is only half an inch long,...any yawing wiggle would make short work of the aluminum ...
the main drive seems pretty good though , i should be able to remove the drum and add a permanent sprocket instead and take it from there
it pulls about 1 amp at idle , but seems to need a bigger kick to get started , driving a separate gearbox (its pretty compact) seems doable..
they have a bit of grunt, but are noisy inefficient things alright
Edited by niall1 2009-10-14niall
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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. Nice and slow for what I wanted, about 3 seconds to turn the panels 15 degrees.
