Wind Turbine Transmission

[ChrisOlson]

.......and when it starts to fully furl, the blade slows done, amps drop from 50 to 10 amps. The blades then swing back into the wind, and the whole process starts all over again. It will keep doing this until the wind drops down to around 18 MPH

The furling system I use can be adjusted from being a breakaway type where the machine reaches max amps, then furls and basically shuts down and waits for much slower wind speeds - to being a governor that will take the machine to max amps and hold it there and immediately react and swing the rotor back into the wind.

I prefer somewhere in between those two extremes, because the first doesn't maximize kWh output and the latter is hard on generator stators.  So on the last few machines I've gone to setting the spring pressure and angle so the furling is progressive up to about 65% furled to act as a governor and maintain a high output level.  Then if it goes over that, the furling forces become linear and the machine folds up and stays folded up until the wind speed drops considerably.

The problem you describe is caused by too much offset of the rotor to the yaw axis.  A lot of these homebrew designs are using too much offset because people have had problems with burnouts, and they can't get the tail light enough to get that rotor closer to the yaw shaft, where it should be.
--
Chris

[Warrior]

Hello Chris,

I have been following your turbine construction with great interest and enthusiasm. Your work is excellent to say the least.

My first turbine was also chain driven step up, mostly due to cost of magnets. The machine did OK for what it was and for the money that was invested. I did leave the chain open to the elements and eventually got tired of hearing it. But you confirmed that encasing it with oil bath it's silent. So now I know how my next turbine will be built  

I find there's a lot of hype behind gear drive vs direct drive concerning the losses etc. And you have one more time, confirmed this is pretty much a myth.

Just a thought, instead cutting 5 or so pieces of 1/4 “ plate to make the case, what if you cut a piece of thick walled rectangular tube/pipe and just made top and bottom covers?

Keep up the great work!!

[ChrisOlson]

Just a thought, instead cutting 5 or so pieces of 1/4 “ plate to make the case, what if you cut a piece of thick walled rectangular tube/pipe and just made top and bottom covers?

That would definitely work.  The inside dimensions of my case are 10" high x 7" wide x 4" front to back.  If you could find a piece of rectangular tubing that size it would save a lot of work.

As far as "losses" in that drive - forget it.  The gains in the generator WAAAY outweigh any losses in the drive.  I made the mistake of building the generator rotors and putting magnets on them first, then started playing with winding combinations.  I had intended to use a delta winding but found out I couldn't because the resistance got so low it tried to push 200 amps.  I would've needed to go to 8" diameter rotors to use delta and get the coil spacing right.  And then I would've had to switch to using wedge magnets, or go to less poles, to do that.  So what I ended up with was a bit of a compromise.  But I know more now to build the next one, and that one will be a smaller diameter 8" unit with 8 poles and 24 coils laid out overlap.

That's what the first one is all about - learning how to do the next one better.
--
Chris

[poco dinero]

Hi Chris,

I'm interested in your opinion here.

Posted on: December 20, 2010, 03:01:21 PM                     Posted by: ChrisOlson 
 
Posted on: December 20, 2010, 03:01:21 PMPosted by: ChrisOlson 
 
To my way of thinking a brake is only useful on a turbine to keep it parked in high winds.

I have a 5 kw commercially-built direct-drive wind turbine.  It has a cable-activated drum brake; the drum is about 6 inches in diameter and two inches wide.  I haven't flown it yet, but I plan to soon.

The rotor is 16.5 feet in diameter, and although the machine is rated 5 kw at 22 mph, it could put out up to about 8 kw in a 44 mph wind, then it's supposed to yaw out of the wind.

What is your opinion of what would happen if I lost the generator in a 60 mph wind, the rotor experienced runaway, and I went out and tried to brake it to a stop.  This brake looks pretty robust.

What'dya think?

poco

[fabricator]

Hi Jerry, i'm not Chris nor do I play him on TV, but I did stay at a Holiday Inn Express last night
I've happen to have had pretty much this same conversation with Chris and I'm pretty confident his reply would be "No chance in hell".
When you figure the power that is being output at that rotor speed by that size rotor, and the size of that band there really aint much chance it's gonna stop it, it might slow it down some but by the time it does any brake linings will have burned away and the band will be red hot and will just stretch at that point.

[smidy]

I was just reading on a motorforum about a breakbench for power mesuring a volvo 2.3l standard engine in a homebuilt breackbench, it was breaking with a disk brake from a car, the standard 2.3 litre engine is about 90kw and the bench was able to stop the engine from any rpm full trottle. its a swedish forum but if it is in any intrest it is here:  http://forum.savarturbo.se/viewtopic.php?t=42360&postdays=0&postorder=asc&start=0   and oh yes all the pictures is translated to english  and if you are intrested use google translater, it will be goofy but better than my english i think 

[watermanhfl]

Chris,
You have me thinking again about my next wind turbine.  A 90 degree transmission so that;
1) a car disc brake is easy, I have had a run away and do not want again.
2) No twisting wires, just changed them out after 4 years of up time.
3) high rpm gains you are experiencing
4)reuse some of my 10' parts on a 13'
Old Jakes did it on some models.
I know that normal bevel gears will have some losses but maybe there is something more effective out there.

Ant

[jimovonz]

poco,

I suspect the brake would manage - you would like to think that it has been designed to be useful! Unlike many braking situations, the brake only has to slow the blades down enough to get them out of their power band and after that there is only the momentum to dissipate. If you compare this to the brakes on a car (with brakes not too different to yours), a quick calculation shows that a 2000kg car stopping completely from 100km/h in 5 seconds dissipates energy (~heat) at an average of 155kW or close to 40kW per brake unit (assuming 1 brake per wheel sharing the load evenly). In addition, the limiting factor with a car is traction, I dare say that the brake unit itself is capable of significantly more - especially for short durations as would be the case when shutting down a wind turbine. A quick Google search reveals a couple of references to braking in high performance racing cars where the peak dissipation is well over 2000kW!

[clintonbriley]

On the 6 inch brake drum...... I think Fabricator is on the mark here.  If comparing the application to that of an automobile, it is
something akin to stepping on the brakes while also stepping on the accelerator at the same time.  In a slow wind it would probably
stop it, but in a fast wind I think not.
Clint

[12AX7]

Any idea what is the total number of hours and how much pocket change ?

Well, the transmission has about $65 worth of extra parts in it that a direct drive don't have - namely an extra shaft, two extra bearings, two sprockets and the drive chain.  The rest of it is pretty much a wash because you still have to have one set of bearings, stator support and on and on to build a turbine anyway.

Being the case is integral with the yaw tube and tail mount, it's just basically 5 pieces of sheet steel torched out of a sheet of 1/4" and all welded together to make the case.  The cover is made out of a piece of 3/16" sheet steel.

The generator has roughly half the wire in it that a direct drive would have, and 24 2 x 1 x .5 N42 bar magnets instead of 32 2 x .5 disc magnets.  I figured the savings in magnets alone at about $175, depending on where you get them from.  The generator rotors are 10" diameter instead of 16".  And the stator is 14" OD instead of 20", and only .450" thick instead of 5/8".  You can get away with the very thin stator because the diameter is small enough that it won't warp and come into contact with the rotating assembly when you start applying serious torque to the mount.

It cools better because it has less wire mass to retain heat, is thinner, and because the generator rotors are spinning at such high speed without the magnets being encased in resin, the rotors become centrifugal fans.  Those rotors move a LOT of air over that stator at 600 rpm.  I had absolutely no overheat problems testing on the stand at 80 amps for an hour because if you tape a piece of paper to the outside perimeter of the stator that paper stands right out on end from the air blowing over the stator.

So there's a number of advantages that I see here.

I never figured any of the costs to the penny, but it was cheaper to build this geared unit than it would have been to build a direct drive, with most of that cost being in the generator.  The downside is that it takes more work and some basic machining to build it.  At the minimum, unless you get your parts waterjet or plaz cut, you'll need a lathe, vertical mill and drill press to build one.  I have all that stuff, but if you had to hire it done, then the cost would go up because machine work does not come cheap.
--
Chris

Hi..

So,  I guess the next question is...   where do we send the checks,  and whats the current back log time?


ax7
Mark

[defed]

after reading your progress on this machine, i am quite interested in it.  you should write a small pamphlet on the design w/ some extra instructions/dimensions...sell them for $5-10.  i am less than an hour away from Royal Wind and Solar, so that makes the design even more intriguing to me!

[ChrisOlson]

after reading your progress on this machine, i am quite interested in it.  you should write a small pamphlet on the design w/ some extra instructions/dimensions...sell them for $5-10.  i am less than an hour away from Royal Wind and Solar, so that makes the design even more intriguing to me!

I may perhaps do that.  It might take me a bit to put together clear, concise instructions and a parts list on how to build one.  I do have the second one built now and I made a little video of it explaining some of the improvements and changes I made in the second one:
http://www.youtube.com/user/OlsonFarms#p/u/6/MzO1ZHML6wQ

--
Chris

[defed]

I may perhaps do that.  It might take me a bit to put together clear, concise instructions and a parts list on how to build one.  I do have the second one built now and I made a little video of it explaining some of the improvements and changes I made in the second one:
http://www.youtube.com/user/OlsonFarms#p/u/6/MzO1ZHML6wQ

--
Chris

that's pretty sweet.  at what wind speed do you expect it to reach 260rpm?

do you have any detailed threads on the tail/furling systems that you are currently using?

[ChrisOlson]

that's pretty sweet.  at what wind speed do you expect it to reach 260rpm?
do you have any detailed threads on the tail/furling systems that you are currently using?

On my 12 volt it's hitting 260 at 24 mph.  But it's too much for the 12 volt.  It's got the ammeter so far laid into the peg at that speed that it'll eventually burn the shunt out in the ammeter.  I didn't really want the 12 volt putting out more than 80 amps, but it's peaked at 106.73 amps today.  I have to adjust the furling on it when I can lower the tower.  We've had ice storms and stuff and right now it would be just about impossible to let the tower down to adjust it because everything here is coated with ice.

I don't have any detailed instructions on the furling system, but it's pretty simple.  When I get around to putting together an instruction book that part will be included in it.
--
Chris

[artv]

Chris your the type of guy that just "does it",the best kind there is,...I envy your knowledge......try reversing the process, try to create as much heat as you can,....heat and presssure are the same thing..............just had to say it........artv

[fabricator]

Heat and pressure are NOT the same thing.

[zvizdic]

I like that idea with the transmission.

 Especially because the chain is used.
 Now imagine a higher RPM on the alternator and large truck alternator rotor with the PM.
 Perhaps this could be the next project.

 Just wondering how they will react to short-circuit switch.

 Sure I like your way of designing and thinking outside the box.
 I also do not like to copi everything I do has my touch a little bit.

 Very good job

[ChrisOlson]

Now imagine a higher RPM on the alternator and large truck alternator rotor with the PM.
 Perhaps this could be the next project.

Just the core charge on a worn out 200 amp 24 volt 4000-series Leece-Neville (Prestolite) HD truck or coach alternator is usually more than it costs to build your own permanent magnet generator.  The rectifier assy alone in those alternators is $600.  By the time you got one modified with a permanent magnet rotor I suspect you'd be able to build about five axials for the same cost.  And those 24 volt alternators only have 7 turns of 13 AWG wire in them in delta, meaning they have to run at 3,000 rpm before they reach 75% of their rated output, and 6,000 rpm for full output.  Their output below 3,000 rpm is basically pathetic, with a very steep power curve from zero to 75%, and the 24 volt 200 amp one has to be spinning at 1,400 rpm to even put out one amp.

I have my doubts it would be practical unless you happen to just have one laying around.  I got a 320 amp 28 volt brushless one that I stole the rectifier out of but it would take one dang big wind turbine to drive that thing.  And then what the hell would you do with 320 amps down the tower?

I guess one possibility I could think of is to move all your heavy welding operations to the base of the tower.  Lug a set of jumper cables out there, hook the positive to your work, clamp a 7018 in the negative, wait until a big gust hits and voila!  DC reverse polarity  - don't even need a Lincoln 225.
--
Chris

[fabricator]

Now imagine a higher RPM on the alternator and large truck alternator rotor with the PM.
 Perhaps this could be the next project.

  And then what the hell would you do with 320 amps down the tower?


--
Chris

Personally I'd stay as far away from it as possible.

[zvizdic]

OK  you mist my point.

You know if you disconnect regulator and rectifiers  from alternator and go directly to the battery to excite rotor coils

and rewed engine til you rich 120vac you can connect welder to 1 phase and do some short welding .

So 40$ magnet insted of rotor coils 1:8 transmition 10' turbine = 1200 rpm 48 vdc cut in.

I am not a Windblue seals person using a chart as a reference.




If you need to rewind stator no need for 10 pound of cooper.

[redtick]

Chris,
Would you give a finial run down of your setup?
During the build you played with a lot of combinations. Did you keep an oversized blank disk to shape the flux? How many wraps and what gage?

[ChrisOlson]

Would you give a finial run down of your setup?
During the build you played with a lot of combinations. Did you keep an oversized blank disk to shape the flux? How many wraps and what gage?

I eventually ended up going with two mag rotors with 2 x 1 x .5 N42 bars.  The original was 12 volt but put out too many amps.  Over 120 at times.  I've since changed both my machines to 24 volt to get the amps down.  50 turns of 13 AWG in delta.  It still hits 80 amps at times.
--
Chris

[defed]

i thought the 24v ones were wired star?

[ChrisOlson]

i thought the 24v ones were wired star?

Not any more.  They push too many amps for a wye winding.  I experimented with two different generator stators and the delta one won out on the tower.  The delta one lets the rotor run a bit faster, which doesn't seem to hurt anything, and it can be used for 12 volt by running the rotor a lot slower.  But it'll still push over 100 amps pretty easy on 12 volt and 80 on 24.

The wye-wired stator just won't stand up in sustained high wind speeds so a few days ago I decided to not mess with wye stator windings anymore in this machine.
--
Chris

[defed]

ok, guess i have to refresh myself on how to wire delta before i build one (if i ever get my paperwork filed to the town!).

[ChrisOlson]

ok, guess i have to refresh myself on how to wire delta before i build one (if i ever get my paperwork filed to the town!).

Just get a piece of paper and draw a triangle on it.  Each side of the triangle represents one phase.  If you go around the triangle clockwise, the end of phase 1 is hooked to the start of phase 2, the end of phase 2 is hooked to the start of phase 3 and the end of phase 3 is hooked to the start of phase 1.  The three legs down the tower are hooked to the corners of the triangle.

In delta two phases are connected parallel and each phase delivers half the total amount of power flowing in the leg down the tower.  In wye the power in the leg has to flow thru two coil groups in series.  It's just like hooking batteries in series or parallel - in parallel each battery has to deliver half the total current of the load and you get no voltage boost.  In series each battery has to deliver the full amount of current flowing to the load and you get a voltage boost.

For that reason, a delta winding has double the amp capacity of the same winding in wye.

In delta, being you have phases connected in parallel it's important that the sine waves of those phases match.  If they don't you'll get what some people describe here as the dreaded delta circulating currents.  It has nothing to do with circulating currents just because it looks like everything is hooked in a loop - it's merely a mismatch between phases.  As long as you pay attention to coil layout and magnet spacing you'll have no problems with a delta generator and it'll just run.  You also can't generate big hairy-a$$ed sine waves by using big wide magnets that overlap adjacent phases and excite them when it's got the previous phase still fully excited.  If you do that you won't get a delta generator to work at all and it'll actually "cog" just turning it by hand with no load on it.
--
Chris

[ChrisOlson]

Over several weeks of gathering and recording data points and entering them in a spreadsheet to figure out power curves for this geared turbine, the below graph is what I've come up with on it.  This is at 24 volt - this machine ultimately proved to be too much for 12 volt.  The stator will take it in 12 volt in really cold weather, but once the weather warms up I suspect the stator would have a hard time staying cool enough to last on 12 volt.

I tested two different stators and the wye one shows a distinct advantage at lower wind speeds.  Like at 7 mph the wye stator is putting out 15 watts more than the delta one.  At 9-10 mph it's down to 4-5 watts difference.  The delta one closes the gap and pulls ahead at about 12 mph and never looks back.

After adjusting the furling on the machine, it starts to fold up at about 24 mph but it continues to keep putting out more power the faster the wind blows even though it's running furled.  I really haven't 100% figured that out yet.  For some reason these GOE222 blades just do not seem to want to back down their power output with the swept area reduced by furling it.  They just keep right on crankin' and I've got some theories as to why they do this but the bottom line is that I've still seen it put out over 80 amps running at 30 volts and I really don't know what the ultimate top end is.  And that's why I don't think the wye stator is the way to go in this machine - I think you'd be looking at a burnout in 60-70 mph winds with a wye stator.  Delta windings have proven to me to be able to pack more ampacity into the same copper mass and they'll take higher peak outputs without heating up as fast, and retaining coil heat, as an equivalent wye unit.

The numbers I've used to develop the power curve for this machine were gathered on a real tower, in real wind, in real world conditions over several weeks and using some extrapolation to fill in gaps in between data points. No theoretical bench testing stuff here.



--
Chris

[bvan1941]

Very nice report Chris on the geared transmission- Wye/Delta stator combination. Don't forget to give some periodic updates and thoughts on your creation.
Bill

[kevbo]

For that reason, a delta winding has double the amp capacity of the same winding in wye.

That is not a bad explanation for getting a feel for what is going on, but because the windings have a 120 degree phase difference,  the current increase is  X 1.73 (square root of three) rather than X 2.

If you went north 10 miles then north another 10 miles, you'd be 20 miles from where you started. 

If you went north 10 miles, then turned 60 degrees toward the east and went another 10 miles (so the two legs of your path were at a 120 degree angle) then you would end up only 17.3 miles as the crow flies from where you started out.   

[ChrisOlson]

That is not a bad explanation for getting a feel for what is going on, but because the windings have a 120 degree phase difference,  the current increase is  X 1.73 (square root of three) rather than X 2.

Well, I was referring to ampacity of the winding, not current increase in delta vs wye.  The resistance of a given winding in delta is typically 1/3 of wye and power flows thru two coils groups in parallel instead of two groups in series.  So if a given winding has a maximum capacity of 10 amps in wye, that same winding has a maximum capacity of 20 amps in delta.
--
Chris

[Dave B]

"For some reason these GOE222 blades just do not seem to want to back down their power output with the swept area reduced by furling it.  They just keep right on crankin'"

Hi Chris,

  Thank you for posting your data on your 12G machine, this looks super for a 12' machine. We can relate to your statement above for sure about the 222 blades, they just do not want to stop pulling after a certain speed and load even if like you say they are turned out of the wind. Seems I remember the Dan's had an issue with this with a set we sent them to test quite a while back as well. I think they took drastic measures and cut them off shorter to get them under control with the machine they had.

  Very interesting to see your results and hear your comments on the 12G. I know there are many out there including myself who watch for your posts mainly because you do things. Although entertaining at times the chatter about shoulda, coulda, woulda gets old fast compared to seeing projects bulit and tested. Way back at the start of this board you saw the hands on all the time, it really wasn't such a chat room.

  Thanks again Chris for posting, very interesting information and kudos on your transmission 12G turbine !   Dave B.

  

[ChrisOlson]

 Thank you for posting your data on your 12G machine, this looks super for a 12' machine. We can relate to your statement above for sure about the 222 blades, they just do not want to stop pulling after a certain speed and load even if like you say they are turned out of the wind.

Thanks Dave.  Those blades refuse to stall.  The tips stay flying even at very low TSR and they put tremendous twist to the shaft unlike anything I've ever really seen.  In really high winds with the rotor turning at decent rpm, but low TSR, this equates to gobs of power when a "normal" airfoil would be stalled and slack off.  That's my theory, anyway, on why the power continues to increase even after the machine furls.

Furling it definitely reduces the amount of power but I have yet to see those blades just give up and flat out stall.  You take a 60 mph wind speed at 2 TSR and that 12 foot rotor is still running at 280 rpm and it just doesn't give up.  And you take the amount of total energy flowing the reduced swept area with it furled at 60 mph, minus the efficiency of the airfoil, and you still get 3 kW easily.

So my advice to anybody building a turbine with GOE222's is that you'd better not scrimp on the generator because these blades will burn it up if you run it in high winds.  Saying simply that they're a "high torque" profile is probably the gross understatement of the century.  And as testament to that fact, I changed my power bus for 12/24 volt (I made a post on this here http://fieldlines.com/board/index.php/topic,144888.0.html ) so I could run incoming power at 24 volt and switch it to 12 volt to balance the banks and cut the turbine power during bank balancing.  Well, that was a good theory, but I found out that if the turbine is running at 40 amps when the bus switches there's a momentary ~250 amp surge of power as it brakes the turbine and the ammeter will settle in at 75-80 amps @ 12 volt instead of 40 amps @ 24 volt with the rotor running half the rpm that it was in 24 volt.  I ain't never seen any other turbine rotor ever do that.  Near as I can figure, being the blades have no twist or taper, at a given rpm the station along the airfoil that's operating at optimum angle of attack simply moves further out towards the tip of the blade at slower rpm and they just continue to pull.

They're a really fun blade to fly because they start up at about 3-4 mph and at 6-7 mph you can lean into them pretty hard with the generator and they really don't care.
--
Chris

[Dave B]

"Near as I can figure, being the blades have no twist or taper, at a given rpm the station along the airfoil that's operating at optimum angle of attack simply moves further out towards the tip of the blade at slower rpm and they just continue to pull."

Chris,

  I think this is a very good explanation, it sure makes sense to me that that is what must be happening. This along with the same chord width to the tip keeps that curve pretty darn flat. Slower wind, still great torque because it's still the same profile and continues to fly at the ideal station like you said rather than needing to run faster as with a tapered / twisted blade further out. They must speed limit some where because of their unique profile but going back in time to the Winchargers they certainly knew what they had and one of their solutions was the centrifigal air brake arrangement.

  Thanks for the tip to others who may want to use these blades, build a very stiff alternator or a very wishy washy furling or both. I would also highly suggest a mechanical means of shutdown in addition to the shorting switch. Thankfully no physical scars from learning this several times over but we have some interesting wall art and stories from along the way.

  Dave B.