10' axial flux home made windmill

ricielectric

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The reason for getting involved in building a wind generator is I'm building a cabin on some remote property and the power company wanted $84,000 to run the line. So, here I am.
And now for the monologue. It is mostly a Hugh Piggott machine with a little otherpower influence. It has coils: 75 turns, 2 in hand, #17 AWG, 9 coils on 12 inch 3/8 plate for 3 phase. Magnets are 2 inch x 1 inch x 1/2 inch, N40, supposedly for 24 volt.
The hub I used was from a small station wagon. I just walked around the junkyard till I found one I could use.

hub.JPG


I built a coilwinder as seen in the postings and books. Added a counter so the wind count would be on the mark.
coil_winder_counter.JPG


coils.JPG


Here's the coils after they were wound.

coil_layout.JPG


Here they are laid out.

coil_pasteup.JPG


Here they are pasted up with strips of fiberglass. All I could get was the none-woven fiberglass and it wasn't very strong and it came apart easily so if you have a choice, I would recommend getting the woven stuff.

waxed_mold.JPG


Here's the stater mold with 3 coats of wax on top of 2 coats of linseed oil.
stator_clamped.JPG


My mold was made out of 3/4 inch veneer covered chipboard and I was afraid it might flex or bow, so I put some heavy boards across to make sure it was flat and clamped it well.
 
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ricielectric

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Here is the casting ready to be popped out of the mold. It came out very easily. I was surprised. With a slight slap on the back with my hand and it came out.
staror_out_of_mold.JPG


I had some finning around the edges but it all came loose also, because I had waxed everything many times.
stator_cleanedup.JPG


The finning cut off quite easily so was not a big problem. When I got close to the casting, I just ground it away with a small die grinder.
bare_rotors_template.JPG


I had the rotor plates cut by a local welding shop being my hub had 5 holes, and also I wanted to have some holes cut that matched some holes in the hub for ventilation. I don't know if that will actually work, but I'll give it a try. On the indexing plate that I got from Otherpower, there was no allowance for other than a 4-hole spindle, so it took me awhile to figure out where to put some holes so I could key it to the rotors to make sure my north - south magnet match would be.
frame_start.JPG


welded_frame.JPG


These are a couple shots of the main frame. It's basically just pieces of iron from my scrap pile. Instead of welding two angle irons together as Hugh does, I used a piece of channel iron that was wide enough to accommodate my hub.
tail_brace.JPG


I put a small extra brace on the tail for a little more support and I just like the looks of it better.
back_rotors.JPG


This shows the one rotor that has the vent holes in it. This is the one that will bolt tight to the hub so they will be the only way in for extra air.
 

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painted_frame.JPG


frame_tail.JPG


A couple more shots of the main frame and the tail attached.
rotor_clean.JPG


This shows the rotor with the band. I cut the bands from a piece of sheet stainless steel that I had, as they don't use stainless steel banding around here. It wasn't exactly straight but I think it worked out okay. I cleaned the plates with lacquer thinner before I put the magnets on. I also had lightly sanded the plates hoping the resin would stick better.
rotor_cast_marked.JPG


rotor_cast_mess.JPG


The cast poured into the rotor. I think the stainless steel rim made it a lot easier than building a mold to hold it all, and, of course, I always make a mess, but I try to make it easy to clean up with the newspaper. After the casting had cured for several days, I painted the magnet side with the super duty epoxy paint hoping to keep the moisture away from the magnets.
rotor_on.JPG


The base rotor on with the vent holes lined up with the holes in the hub.

stator_on.JPG


Here's the first shot of the base rotor and the stator installed.
rotor_2_on.JPG


2_rotors_on.JPG


Here's the second rotor on and a view of the side showing that the magnets stick up above the rim slightly. I thought this might work like fan blades and help pull air through to keep things cool.
 

ricielectric

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I had two extra plates made to put on both sides of the blades to help support everything. I stuck one of these on the bolts just before I tightened everything for the last time to make sure that the bolts stayed in alignment.
posts_riped.JPG


blade_layout.JPG


No one carries cedar around here except for fencing material which was very poor quality. I finally found some posts that were approximately four inches square that I picked through and found fairly straight grained ones that I ripped in half, and then edge planed and glued back together. I found that I could get two five-foot blades out of three strips and I probably could have made longer blades if I had needed them without any more waste. After I glued them up, I ran them through my planer to make sure they were all the same thickness and flat.
blade_ruffout.JPG


blade_ruffout2.JPG


blade_front_edge.JPG


I did most of the main roughing out with a hand power planer. It worked quite well but you need to be careful on cutting too much off.
blade_fin.JPG


blade_fitcheck.JPG


It only took me a couple days to get the carved blades done, and then I fit checked the pieces to make sure everything fit together.
blade_ballance.JPG


After putting the front and rear ground plates on the blade, I had drilled a 1/8 inch hole in the exact center. I hung this from the rafters of my garage with a wire and used fishing weights to figure out where the balance weight needed to be. It all seemed to work out quite well. The blades that I carved ranged in weight from 3 pounds 7 oz., to 3 pounds 9 oz., so I didn't think this was too bad for seat of the pants hand planed work.
powerbox.JPG
 

ricielectric

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I was trying to figure out how to seal the top of the pivot and make a usable power splice box and this is what I came up with. So far, it looks like it's going to work okay.
blade_coate1.JPG


Well, a lot of people have written that linseed oil was the best coating so I put approximately 8 coats, maybe more, on them. They seem pretty good. Hopefully, they will last. I hadn't really thought about the cedar being very fragile but in just handling the blades and bumping the trailing edge on the workbench, I got a couple of dings in them.
blade_1_piece.JPG


I have built a temporary tower (about 20' tall) that I will be mounting the generator on for a test run in my back yard. Hope to have it up within a few days. Will post an update when I get it in the air.
 

ricielectric

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Here are some notes to aid in designing your blades…. .
Blade_design.jpg

Step 1: Mark out the stations
Step 2: mark width of each station cut out all unnecessary wood
Step 3: mark the drop of each station and draw a line
Blade_design2.jpg

Step 4 mark the thickness at each station ( both sides) then remove the excess material
Step 5. Mark each station at 38% of station width, draw a connecting line and carve the material to shape the wing. Make sure you don’t cut the line. This will be the thickest part of the blade.
If you don't want to go through all of that you can build a blade from station 4. Using the angle and width and make one straight blade from this. Once the blade is made you can glue angle blocks on the new blade at the angle it will be installed.​
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ricielectric

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Built Axial Field Alternator

Built Axial Field Alternator
.
My goal, once again, was to keep it as simple as possible so others could build one with basic tools and could be done relatively cheap. I believe what I have here accomplishes these goals.
Since Radial flux type units require specificaly sized parts I chose the Axial Flux type. One of the things in the back of my mind was the "cogging" effect created by most of the PM alternators and the amount of wind it takes to start it. During the thought process for acomplishing this project I needed to either make it an "air core" or come up with a way to hand build an iron core. The "air core" type isn't very efficient in the sense that the coils aren't saturated properly when the magnets pass the coil. In order to cure this problem you would need 2 disc's with magnets on them. This would complicate the design so I started looking for other ideas. On first thought I pulled out a roll of mig welding wire and thought about rolling a "core" from this. Unfortuneately, this would require a special jig and a way to separate the wires from each other. I started looking at laminations from motors, transformers or what ever I thought would transfere flux fairly well. It dawned on me that sheet metal could be used in this part of the project. I cut strips of sheet metal and strips of cardboard and coiled them up until I had a piece the size that I needed. I used Fiberglass Resin to "laminate" the coil together then glued it to a 9" disc made from 3/4" plywood. Below shows the disc and laminations glued in place.
AxialAlt1.jpg

The steel coil was glued to the wood with JB weld then the fiberglass Resin poured over the steel core. The outside diameter of the steel core is 8" and inside diameter is 5.5" . I marked the stator at 20 degree intervals so there would be 18 magnets used on the rotor. The coils had to fit over the 20 degree area and in a trianglular form so I made a jig to make the coils. There is 27 coils to fill the rotor for a 3 phase set up. Each coil was 30 turns of #20 wire, and all made in the same direction. Below shows the coils of each phase being placed on the stator.
AxialAlt2.jpg
AxialAlt3.jpg
AxialAlt4.jpg

The initial tests of the single coil showed 1.1V at 630 rpm which meant I should get 9.9 Volts from the series of 9 coils. Testing showed 13.5V AC and 22V rectified which was much better than I had anticipated. I laid in all the other sets and soldered up all the connections in series for the last 2 phases of the alternator. This leaves 6 wires loose - 3 starts and 3 finishes to be wired up later. I used a hot glue gun to place the coils before finishing the stator. I reinstalled it on the lathe and started testing it with all the phases in place. In a "star" wiring it made 38 volts at 630 rpm and in a "Delta" wiring it made 22 volts. "Star" gives you more volts but less amps and "Delta" gives you more amps but less volts. I'll talk about the different wiring of it later.
Below shows the Stator filled in with fiberglass resin. This seals the unit and holds the coils in place ... permanently! The other shows the steel disc the magnets are on for the rotor. None of them were glued on during the testing. They are quite strong and are very hard to move. The steel disc the magnets are on could be a disc cut out from plywood with a sheet metal disc laminated to the plywood disc. This would serve the same purpose. The steel behind the magnets intensifies the field going to the core and through the coils.
AxialAlt5.jpg
AxialAlt6.jpg

The magnet rotor will be mounted to the prop hub and the stator will be attatched to the bearing head. To complete the rotor the magnets are glued in place and resin will be poured onto the plate to lock them in forever then it will have to be balanced.
Now to the wiring.... Here lies a problem, you can wire the alternator in a star configuration or in a Delta. The star gives you much more voltage but less amps and the Delta gives you less voltage and more amps. Below shows the way each of the three phases would be wired....
3phase_wiring.jpg

If this alternator is wired in the star configuration it will produce 217 watts at its highest rpm. In Delta could deliver up to 400 watts. Unfortunately, the delta configuration won't allow charging until it reaches 500 rpm which means our windmill wont charge until around 14mph. On the other end the star will give us 76 watts at that speed. It would seem the best solution would be to use them both. I have yet to figure out exactly how to do this.... any electronic genious's out there? I thought of using a relay that would kick in at a certain voltage... but as soon as the relay changes the voltage drops. You could use power mosfets for controlling the wiring change but how to control the transition.... either by using a hall sensor to keep tabs on the rpm.... or build a separate mini generator on the outer rim of the stator for low voltage input to the gate of the FET's.... (See below on update for a wind driven relay system)
After exerting many brain cells on this situation ( at least several that I know still work ) I started thinking of different approaches to this Star/Delta delema... First was a thought on an aircraft ASI ( air speed indicator), this uses a diaphram to exert pressure on the needle drive system through the use of a "pitot tube". Assuming you could figure out the size of tube and diaphram to exert the right amount of pressure at a certain wind speed to move the relay, this could work. The drawbacks to this system is the fact the pitot tube could get plugged with ice, snow, bugs etc... not such a good idea. Then down to my last couple cells I thought of using the wind (like the tail) to exert pressure on the relay at a certain windspeed. This seems to be the best I've come up with so far so I decided to go with it ... unless someone comes up with something better... remember it must be simple! Below is a diagram of how the relay would be wired
Star-Delta_wiring.JPG

B,F,D are the moving contacts. A,C,E are the output lines. Once they are in contact with the red strip it would be in star configuration and when in contact with the blue strips its in Delta configuration. Make a mental note the 2nd phase of this alternator is reversed. This is because the phaseing is off when the coils are stacked in 3's. You still wind all the coils in the same direction and wire them all the same but the start and end wires are reversed. In any case... A small tail would (will) control the movement of the contacts. I haven't as yet built this unit and have no idea if it will even work as yet... its simply a plan... more on it later...
Below is a chart of the calculated performance of this alternator. You can see where the star and delta should interchange for better output.​
[FONT=Arial, Arial, Helvetica] [/FONT][FONT=Arial, Arial, Helvetica]Star wire configuration[/FONT][FONT=Arial, Arial, Helvetica] [/FONT][FONT=Arial, Arial, Helvetica] [/FONT][FONT=Arial, Arial, Helvetica]Delta wire configuration[/FONT][FONT=Arial, Arial, Helvetica] [/FONT][FONT=Arial, Arial, Helvetica] [/FONT][FONT=Arial, Arial, Helvetica]RPM[/FONT][FONT=Arial, Arial, Helvetica]Open V[/FONT][FONT=Arial, Arial, Helvetica][email protected][/FONT][FONT=Arial, Arial, Helvetica]Watts[/FONT][FONT=Arial, Arial, Helvetica]Open V[/FONT][FONT=Arial, Arial, Helvetica][email protected][/FONT][FONT=Arial, Arial, Helvetica]Watts[/FONT][FONT=Arial, Arial, Helvetica]200[/FONT][FONT=Arial, Arial, Helvetica]12[/FONT][FONT=Arial, Arial, Helvetica] [/FONT][FONT=Arial, Arial, Helvetica] [/FONT][FONT=Arial, Arial, Helvetica]7[/FONT][FONT=Arial, Arial, Helvetica] [/FONT][FONT=Arial, Arial, Helvetica] [/FONT][FONT=Arial, Arial, Helvetica]300[/FONT][FONT=Arial, Arial, Helvetica]18[/FONT][FONT=Arial, Arial, Helvetica]1.39[/FONT][FONT=Arial, Arial, Helvetica]19.5[/FONT][FONT=Arial, Arial, Helvetica]10[/FONT][FONT=Arial, Arial, Helvetica] [/FONT][FONT=Arial, Arial, Helvetica] [/FONT][FONT=Arial, Arial, Helvetica]400[/FONT][FONT=Arial, Arial, Helvetica]24[/FONT][FONT=Arial, Arial, Helvetica]3.41[/FONT][FONT=Arial, Arial, Helvetica]47.8[/FONT][FONT=Arial, Arial, Helvetica]14[/FONT][FONT=Arial, Arial, Helvetica] [/FONT][FONT=Arial, Arial, Helvetica] [/FONT][FONT=Arial, Arial, Helvetica]500[/FONT][FONT=Arial, Arial, Helvetica]30[/FONT][FONT=Arial, Arial, Helvetica]5.43[/FONT][FONT=Arial, Arial, Helvetica]76[/FONT][FONT=Arial, Arial, Helvetica]17[/FONT][FONT=Arial, Arial, Helvetica]4.64[/FONT][FONT=Arial, Arial, Helvetica]65[/FONT][FONT=Arial, Arial, Helvetica]600[/FONT][FONT=Arial, Arial, Helvetica]36[/FONT][FONT=Arial, Arial, Helvetica]7.45[/FONT][FONT=Arial, Arial, Helvetica]104[/FONT][FONT=Arial, Arial, Helvetica]21[/FONT][FONT=Arial, Arial, Helvetica]6.93[/FONT][FONT=Arial, Arial, Helvetica]97[/FONT][FONT=Arial, Arial, Helvetica]700[/FONT][FONT=Arial, Arial, Helvetica]42[/FONT][FONT=Arial, Arial, Helvetica]9.47[/FONT][FONT=Arial, Arial, Helvetica]132[/FONT][FONT=Arial, Arial, Helvetica]24[/FONT][FONT=Arial, Arial, Helvetica]13.96[/FONT][FONT=Arial, Arial, Helvetica]195[/FONT][FONT=Arial, Arial, Helvetica]800[/FONT][FONT=Arial, Arial, Helvetica]48[/FONT][FONT=Arial, Arial, Helvetica]11.49[/FONT][FONT=Arial, Arial, Helvetica]161[/FONT][FONT=Arial, Arial, Helvetica]27[/FONT][FONT=Arial, Arial, Helvetica]18.62[/FONT][FONT=Arial, Arial, Helvetica]260[/FONT][FONT=Arial, Arial, Helvetica]900[/FONT][FONT=Arial, Arial, Helvetica]54[/FONT][FONT=Arial, Arial, Helvetica]13.51[/FONT][FONT=Arial, Arial, Helvetica]189[/FONT][FONT=Arial, Arial, Helvetica]31[/FONT][FONT=Arial, Arial, Helvetica]23.29[/FONT][FONT=Arial, Arial, Helvetica]326[/FONT][FONT=Arial, Arial, Helvetica]1000[/FONT][FONT=Arial, Arial, Helvetica]60[/FONT][FONT=Arial, Arial, Helvetica]15.5[/FONT][FONT=Arial, Arial, Helvetica]217[/FONT][FONT=Arial, Arial, Helvetica]34[/FONT][FONT=Arial, Arial, Helvetica]27.91[/FONT][FONT=Arial, Arial, Helvetica]391[/FONT][FONT=Arial, Arial, Helvetica]
Below shows the magnet rotor after the Fiberglass resin was poured in around the magnets and the rotor mounted on the prop hub... The green is a rust resistant coating on all the steel parts that is exposed to the elements. The magnets are placed every 20 degrees and glued directly to the steel plate with aircraft epoxy. ( JB weld would work fine in this application). I used a coffee can lid (plastic) for the center and taped the outer edge of the steel plate to form a barrier to pour the Resin on. You want to make sure the rotor is level when you pour this or it will run to the low side.
rotor1.jpg
rotor_on_prop.jpg

Below shows the stator on the bearing head and the prop on the unit. I still have some finishing up to do before it goes on the pole but the project has come to its final stages. I used a 6 ft prop with a TSR of 8 for this one. Shouldn't be any reason this unit won't produce 400 watts. The prop, during testing in a 20mph wind, leaped to 1000 rpm with no problem ( no load on it ). Very Very quiet too ! Also should start in fairly low winds because there is no restriction (such as cogging) until it comes up to speed to start charging.
stator_on_bearing_head.jpg
prop_on_unit.jpg

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leomartin6

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Huy! I have found a lot of interesting stuff from here. Got a lot of help. The pictures are descriptive..
 
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