Author Topic: Active Pitchcontrol  (Read 331871 times)

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SparWeb

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Re: Active Pitchcontrol
« Reply #693 on: May 23, 2017, 10:19:15 PM »
Going right down to basics...  very basic...

You need to maximize "Electromotive force" and minimize the resistance.  I think the need to reduce resistance in the coils of wire is obvious, but there's a trade-off when going to larger wire, which you're aware of.  There are things you can do to make it work out.  It is a balancing act. 

If you haven't dealt with the expression EMF, Electromotive force (or its equivalent in Dutch "Elektromotorische kracht" ) then take a moment to read up on it, because it will help you balance the need for a strong magnetic field with your budget to spend on magnets.  I'm really not the best person to explain it, but I was exposed to the concept in college, and it has helped me a lot when I was building my own generators.

I think I can also point you to some online calculator webpages that will help you try various combinations of magnet size.  That may help you see what thickness of magnet you really need.  I stated my guess earlier (about 10 mm) but you could find a combination of 8mm magnets or maybe thinner, depending on what you want to do.

Gearing a turbine adds cost and complexity, so the money saved on magnets at the cost of gearing can easily be penny-wise-and-pound-foolish.
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
System spec: 135w BP multicrystalline panels, Xantrex C40, DIY 10ft (3m) diameter wind turbine, Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024
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joestue

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Re: Active Pitchcontrol
« Reply #694 on: May 24, 2017, 01:44:42 AM »
In this case the magnet width is greater than the gap so the situation is reasonable.

In this particular case i would configure the magnets for 32 poles so that the cross sectional area of the magnet appears to be a 1:1 ratio, but this could be argued later.
My wife says I'm not just a different colored rubik's cube, i am a rubik's knot in a cage.

mbouwer

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Re: Active Pitchcontrol
« Reply #695 on: May 24, 2017, 04:45:36 AM »
At professional wind turbine manufacturiers many disciplines work together. There is a continuous development.
That's also what homebuilders need. We can make it happen on a forum like this.


hiker

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Re: Active Pitchcontrol
« Reply #696 on: May 24, 2017, 09:00:47 PM »
missed out...back in 04  it was a everyday new build dam near...tons of picts and talk of builds.....guess i better hit the shop !!
WILD in ALASKA

SparWeb

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Re: Active Pitchcontrol
« Reply #697 on: May 24, 2017, 11:25:10 PM »
Hiker,
Many of us have noticed.
Popularity and dropping cost of solar is one factor, but I am not sure what is really behind it.
Maybe it is just that Facebook sucked most of our supply of new members away.
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
System spec: 135w BP multicrystalline panels, Xantrex C40, DIY 10ft (3m) diameter wind turbine, Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024
www.sparweb.ca

mbouwer

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Re: Active Pitchcontrol
« Reply #698 on: May 25, 2017, 04:46:36 AM »
We are talking about generating energy. A big advantage is that solar and wind energy can complement each other.
But it is not that easy to get a good and safe and reliable device on your yard.
« Last Edit: May 25, 2017, 04:54:05 AM by mbouwer »

electrondady1

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Re: Active Pitchcontrol
« Reply #699 on: May 25, 2017, 07:30:58 AM »
but now, at least you can talk about a vertical mill without being insulted called a Charlatan  or insane.
 

mbouwer

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Re: Active Pitchcontrol
« Reply #700 on: May 28, 2017, 02:42:44 PM »
After rereading lots of information on this and other topics it seems to me it's better to focus on radial+lamination core.

Found: Outer diam. 364 mm / inner diam. 234 mm / 48 slots

hiker

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Re: Active Pitchcontrol
« Reply #701 on: May 28, 2017, 06:40:24 PM »
Nice find....
WILD in ALASKA

joestue

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Re: Active Pitchcontrol
« Reply #702 on: May 28, 2017, 07:05:08 PM »
do you have the rest of it?
My wife says I'm not just a different colored rubik's cube, i am a rubik's knot in a cage.

mbouwer

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Re: Active Pitchcontrol
« Reply #703 on: May 29, 2017, 04:46:41 AM »
This is what I have. It is a good starting point?

mbouwer

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Re: Active Pitchcontrol
« Reply #704 on: May 30, 2017, 06:03:22 AM »
Then I guess: internal size of the coil about 40 mm

                     inner width of the coil 14 mm + what is needed to bend out the coil heads

                     magnets 40 x 15 mm
« Last Edit: May 30, 2017, 06:09:39 AM by mbouwer »

hiker

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Re: Active Pitchcontrol
« Reply #705 on: May 30, 2017, 11:31:59 PM »
I just put a couple of pegs in the middle slots...that stick out aways...wind the coils right on the stator..wave wind or separate coils..or make a jig..then transfer the coils to the slots..
WILD in ALASKA

mbouwer

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Re: Active Pitchcontrol
« Reply #706 on: May 31, 2017, 09:16:01 AM »
Adapter kit to slide in the two middle slots to wind the coils on the stator. Both sides extend 21 mm from the lamination core.

Next item:  wire thickness.
« Last Edit: May 31, 2017, 09:26:28 AM by mbouwer »

joestue

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Re: Active Pitchcontrol
« Reply #707 on: May 31, 2017, 08:26:49 PM »
you can use a concentrated pole design that uses your existing 10 wide magnets.

every other tooth gets its own coil. no overlapping coils, rather high pole count, nearly no cogging, etc.
My wife says I'm not just a different colored rubik's cube, i am a rubik's knot in a cage.

mbouwer

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Re: Active Pitchcontrol
« Reply #708 on: June 01, 2017, 04:26:28 AM »
But does'nt it bring many advantages applying overlapping coils?
I also want to buy new magnet sizes.

Today I would like to get started with the suspension of the lamination core.

mbouwer

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Re: Active Pitchcontrol
« Reply #709 on: June 02, 2017, 04:15:16 AM »
Supporting ring of the lamination core.

mbouwer

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Re: Active Pitchcontrol
« Reply #710 on: June 03, 2017, 08:33:50 AM »
Beside the core I took a space of 14 mm for the bent out coilheads.

joestue

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Re: Active Pitchcontrol
« Reply #711 on: June 03, 2017, 05:40:27 PM »
But does'nt it bring many advantages applying overlapping coils?
I also want to buy new magnet sizes.

All that matters is that the coils be electrically useful. for air core coils, as i have explained, you need to overlap the coils and by doing so you can fit basically twice as much copper in your machine.

once you add a magnetic core, all that matters is that the coils be electrically useful and you fit as much copper as possible in the core.

anyhow, due to the aspect ratio of your core i think a concentrated pole design will be more efficient, due to the reduced end turn length.
if you go with the regular 3 tooth 1 magnet ratio, your end turns are three times the length of the active winding. basically 75% of the copper is wasted.

with a concentrated pole design, only half of the copper isn't doing anything, if you wind every other tooth.
if you wind every tooth, your end turn length will be somewhat but you'll have twice as many coils to wind.

(that's why i asked what did you do with the rest of the core)
My wife says I'm not just a different colored rubik's cube, i am a rubik's knot in a cage.

mbouwer

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Re: Active Pitchcontrol
« Reply #712 on: June 04, 2017, 09:17:53 AM »
It is clear that the dimensions of the core are not really suitable. But I think the material is o.k.
So what about adjusting the core.
Like cutting the teeth and in the remaining bridge 144 new slots.

joestue

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Re: Active Pitchcontrol
« Reply #713 on: June 04, 2017, 03:44:34 PM »
i don't know why you want to stick with the traditional three slots for every magnet (pole)

there really isn't any reason to do so in my opinion. it cogs badly unless the magnets are skewed across two teeth, which reduces the voltage.

anyhow the core you have is fine for a concentrated flux machine, given the 10mm wide magnets you already have. the number of magnets isn't critical, but there are combinations that are much better than others, such as two less or two more magnets than the number of slots. for some combinations of magnets and teeth, winding every tooth is about 5% better than winding every other tooth, but for some of them its electrically the same so do whatever is convenient.


cutting any laminate core destroys the baked on insulation and iron oxide coating and leaves a burr that cuts through to the other plate which makes an electrical path for eddy currents to flow through. eddy current is approximately proportional to the square of the thickness of the steel, that's why it makes a big difference.
« Last Edit: June 04, 2017, 06:01:17 PM by joestue »
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mbouwer

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Re: Active Pitchcontrol
« Reply #714 on: June 05, 2017, 07:12:07 AM »
Spokes 14 x 4 mm. Heads of the spokes 14 x 12 mm.

Slots 8 - 10 mm wide. Depth 30 mm.
« Last Edit: June 05, 2017, 07:16:22 AM by mbouwer »

Adriaan Kragten

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Re: Active Pitchcontrol
« Reply #715 on: June 05, 2017, 01:36:32 PM »
I don't see the logic of a coil around each stator pole. This only works for a 1-phase winding if the number of armature poles is identical to the number of stator poles but in this case the winding direction must alternate from left hand to right hand and you will get an extremely high peak on the clogging torque.

In my multi-pole generators, I have a coil around half of the stator poles but all grooves are completely filled with copper. All coils of the 3-phase winding have the same winding direction. The number of armature poles must be two more or two less than the number of stator poles and this neutralises almost all fluctuation of the clogging torque. There are several public reports on my website www.kdwindturbines.nl about multi-pole PM-generators with different pole numbers of which the most recent is KD 632 for a 26-pole generator. But there are also reports about a 34-pole generator (KD 622, KD 580 and KD 560) and about a 46-pole generator (KD 624). It depends on the number of grooves (or poles) of the stator stamping which you have chosen, which of my reports is most relevant to you.

joestue

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Re: Active Pitchcontrol
« Reply #716 on: June 05, 2017, 10:08:46 PM »
For some combinations of teeth and pole count winding each or half of the teeth is slightly more efficient than the other, and the end turn length is slightly reduced. And more surface area for cooling.

Anyhow you can find the winding factors and wiring diagrams on the emetor website.

30 poles 36 slots works good as well, you don't have to stick to the +/-2 rule, but below a ratio of 5 poles for 6 slots the winding factor drops off and copper losses skyrocket

My wife says I'm not just a different colored rubik's cube, i am a rubik's knot in a cage.

Adriaan Kragten

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Re: Active Pitchcontrol
« Reply #717 on: June 06, 2017, 05:29:54 AM »
What is said about a coil around each stator pole is right but I think that lying the double amount of coils is more work and you must be very alert that the winding direction of adjacent coils alternate. The advantage of a slightly shorter length of the coil heads is only relevant if the length of the stator stamping is short.

If you have 34 armature poles and 36 stator poles, the number of preference positions per revolution is 34 * 36 / 2 = 612. If you have 32 armature poles and 36 stator poles, the number of preference positions per revolution is 32 * 36 / 4 = 288 which is much smaller. The fluctuation of the clogging torque increases for decreasing number of preference positions per revolution, so I think that taking a difference of only 2 in between the number of armature pooles and stator poles is the best option.

Another point is the configuration of the coils. If you have 36 stator poles and 34 armature poles you can lay 18 full coils, so 6 full coils per phase. The coil sequence is: three coils U1, three coils V1, three coils W1, three coils U2, three coils V2 and three coils W2. If the north poles are about opposite to coils U1, the south poles will be about opposite to coils U2. So the three coils U1 must be connected such to the three coils U2 that the voltage of both coil bundles are strengthening each other.

If you have 32 armature poles and 36 stator poles you will get four coil bundles of each 1 1/2 full coils per phase positioned under 90 degrees. In this case you are forced to use three half coils per coil bundle. It is possible but I prefere the option with three full coils per coil bundel.

mbouwer

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Re: Active Pitchcontrol
« Reply #718 on: June 06, 2017, 08:50:28 AM »
Lamination cores in the professional turbines have another shape.
If I cut my 28 laminations like that, polish them and give them a new insulation layer.
Would'nt that bring me advantages?

Adriaan Kragten

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Re: Active Pitchcontrol
« Reply #719 on: June 06, 2017, 01:18:52 PM »
For big direct drive professional turbines, the rotational speed is very low. To generate a sufficient high frequency, therefore one needs a stator stamping with much more slots than for a normal asynchronous motor. For a small wind turbine the rotational speed is much higher and therefore you can use a stamping with 24, 36 or 48 grooves and stil have a sufficiently high frequency.

mbouwer

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Re: Active Pitchcontrol
« Reply #720 on: June 06, 2017, 02:34:13 PM »
Thinking of a safe quiet spinning workpiece in my garden.
With somewhat larger diameter.
Already full power at low wind speed.

Bruce S

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Re: Active Pitchcontrol
« Reply #721 on: June 06, 2017, 02:51:51 PM »
mbouwer;
As many before me have said, you'll need to decide what "low wind speed" you're trying to work with.
Most notably anything below 7 mph (3.12 m/s?) does not have nearly enough usable energy.

Others have designed their mills down in the 5 mph (2.23 m/s?) , however I couldn't find anything posted that had usable results. The VAWTs regularly shoot for lower speeds because of their wonderful ability to be self-limiting.

Hope this helps
Bruce S
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mbouwer

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Re: Active Pitchcontrol
« Reply #722 on: June 06, 2017, 03:33:00 PM »
Imagine a direct-drive generator of max. power 500 Watt
Diameter of the blades 5 m ( active pitch)

mbouwer

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Re: Active Pitchcontrol
« Reply #723 on: June 07, 2017, 08:34:59 AM »
It just depends on what you like you have on your yard: a high speed nervous propeller or quiet turning somewhat larger blades.

The suspension ring for the lamination core.

mbouwer

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Re: Active Pitchcontrol
« Reply #724 on: June 08, 2017, 06:04:05 AM »
There must be more people on this forum who are inspired by the energy-generating professional wind turbines around.

Ajustable suspension bracket. Now working on axle and hub.

mbouwer

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Re: Active Pitchcontrol
« Reply #725 on: June 09, 2017, 07:58:27 AM »
Suppose  I cut off the teeth and enlarge the inside diameter I get a nice backing ring for the coils.

Assembly: