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  1. #61
    Join Date
    Nov 2009
    Posts
    105
    Project update:

    I am able to fabricate the cogged pulleys that are required. Adding idler pulleys will be challenging. I have to order larger diameter timing belts so the pulleys can be a larger diameter to allow better bolt hole placement. Comments welcomes.
    Attached Thumbnails Attached Thumbnails 1.jpg   2.jpg  

  2. #62
    Join Date
    Nov 2004
    Posts
    202
    Have you considered poly-vee belts instead of cog belts?
    It might be easier to fabricate the pulleys.
    Nice work BTW

  3. #63
    Join Date
    Nov 2009
    Posts
    105

    VAWT belt drive

    Greetings, project update:
    Timing belts and pulleys are installed on a test rig. Because the pulleys are made using two pieces I was able to bevel each piece toward the center of the pulley. This forces the belts to track toward the center of the pulley so a lip is not required. I have to find the correct tool to bend the spring into the correct shape. This is a first attempt but it appears to be working. The spring pulls on the top and bottom of the movable shaft and all belts have tension. Again this is a experiment and a learning experience, I do not know how long the belts will last. The next step is to mount it on the PMA and perform a road test. The current configuration is a 1 : 6 ratio.
    Attached Thumbnails Attached Thumbnails side.jpg   spring.jpg   top.jpg  

  4. #64
    Join Date
    Mar 2007
    Posts
    217
    I have just found this thread today and read through it. I just want to make a few comments....

    Burnit0017,

    First, VERY impressive work on both the stacked design and the gearing; however, I think you will find you would be a lot better off concentrating your efforts on direct drive. You asked earlier in the thread about more coils/magnets VS Larger coils magnets....the answer is not completely straight-forward, but in your case you should increase the number of magnets/coils to achieve higher voltage.

    You should find a fairly linear relationship between No-Load voltage and RPM; taken to the simplest case it should be fairly obvious that the more times a coil changes from North to South, the higher the output. This being said, a typical DIY wind turbine has a rather wide RPM range. If your PMA is designed to cut-in @ say 200RPM and 6mph wind speeds, it is quite likely it will turn over 1000rpm at high wind speeds. This implies that you would have 70V No Load @ 1000RPM (0.07V/RPM). This is a VERY typical problem with PMAs for Wind Turbines.

    Believe it or not, you are 90% of the way to a solution with your stacked stator design. You should focus on achieving 1/3 of your cut in voltage at your target RPM PER stator (for a three stator design). You then wire your stators together via relays so that they are configured to all be in series until the output reaches a predetermined level, then you engage the relays and the stators are then configured in parallel. Your resistance will drop by 1/3 and your efficiency will increase. (Obviously the voltage will be clamped to your battery voltage, and the increase in current output will be the result decreased losses in the stator coils.)

    With a four stator design this idea can be expanded to: 1) All Series 2) Two Series in Parallel 3) All Parallel . This technique can also be used on single stator designs with 2 or more coils per phase. The simplest technique to engage the relays is separate coils of smaller wire and ~15% fewer turns on all of the coils in a particular phase group (ie one leg). This independent, single phase coil is then rectified and connected to the relay coils. For a "switch over" @ around 30V you would use a 24V relay. The additional coil wire should be at least 50% smaller than the primary wire (just large enough to handle the relay current) and can be wound in hand with the primary wires. For a three step process, simply reduce the relay turns to ~45% of the primary turns, and use 12V relays for the first stage and 24V relays for the second stage (it is important in this case to use a voltage regulator for the 12V relays, and it is not a bad idea to use a voltage regulator in all cases). You can use series resistance to fine tune your switch points.

    Anyway, I hate to see all the work you have done on your gearing go to waste, but gearing a VAWT really robs a lot of its potential power; solving the problem with relays wastes almost no power and actually gains back a lot of power that was being lost in heat. (If you are interested, here is a link to a thread where I first started thinking about "stacked stator" Axial FLux alternators: The Gotwind Forum • View topic - VAWT Water Pump Calculations skip down to the last few posts, the top part is all about water pumps).


    BJenkins earlier in the thread repeatedly mentioned designing a wind turbine for low wind speeds. This is problematic, though a very common goal. The problem is the physics of wind power. Betz's Law ( Betz' law - Wikipedia, the free encyclopedia ) places an upper limit on the amount of energy that can be extracted from wind @ ~59.3%. This is not an arbitrary limit, and more modern approaches have shown that the only way to achieve even this limit is by increasing the TSR (Tip-Speed-Ratio) to infinity, and this Coefficient does not include mechanical losses or energy conversion losses. But the biggest problem is the actual available energy in low speed winds which is defined by:

    Code:
    E = 1/2 * p * A * V^3 * Cp
    
    Where:
    E = Energy 
    p = Air Density
    A = Area 
    V = Wind Velocity
    Cp = Coefficient of Power (a derating factor that includes the Betz Limit and must be < 0.593, typically from 0.10 to 0.45)
    So, for a swept area of 100m^2 (1076.39ft^2) the total energy (Cp = 1) is as follows:

    Code:
    Area    Area    Speed   Speed   Power
    M^2     Sq Ft   MPH     m/s     Watts
                                            
    100.00  1076.4   5      2.2        684
    100.00  1076.4   6      2.7      1,181
    100.00  1076.4   7      3.1      1,876
    100.00  1076.4   8      3.6      2,800
    100.00  1076.4   9      4.0      3,986
    100.00  1076.4  10      4.5      5,468
    100.00  1076.4  11      4.9      7,278
    100.00  1076.4  12      5.4      9,449
    100.00  1076.4  13      5.8     12,013
    100.00  1076.4  14      6.3     15,004
    100.00  1076.4  15      6.7     18,455
    100.00  1076.4  16      7.2     22,397
    100.00  1076.4  17      7.6     26,865
    100.00  1076.4  18      8.0     31,890
    100.00  1076.4  19      8.5     37,505
    100.00  1076.4  20      8.9     43,744
    100.00  1076.4  25     11.2     85,438 
    100.00  1076.4  30     13.4    147,638
    A 100M^2 wind turbine has a diameter of 11.28M (37ft) which is very small for commercial, very large for DIY, but serves to illustrate how little power there is in light wind compared to how much power is in even moderate winds. Following are projections of power collected over 30 days for constant wind speeds from 5mph to 50mph (2.24m/s to 22.4m/s) and a Cp of 0.50:

    Code:
    formula ==>  kWh = Cp * kW Avail * 24 Hours * 30 days
    
    Wind               kW        #        kWh        Retail    
    Speed    Cp      Available  Days    Produced     Value
       5    0.50      0.684     30       246.24       $24.62
      10    0.50      5.468     30     1,968.50      $196.85
      15    0.50     18.455     30     6,643.69      $664.37 
      20    0.50     43.744     30    15,747.84    $1,574.78
      25    0.50     85.438     30    30,757.68    $3,075.77
      30    0.50    147.638     30    53,149.68    $5,314.97
      40    0.50    349.956     30   125,984.13   $12,598.41
      50    0.50    683.508     30   246,062.75   $24,606.28
    The point here is that 4 hours of 30mph wind can produce more power than 30 days of 5mph wind, and 50mph wind has 1000 times more energy in it than 5mph wind. There are several things that should be noted: 1) Choosing a windy site for a wind mill is VERY important 2) The entire wind turbine system should be maximized for efficiency near the high end of the anticipated wind speeds 3) Failing to capture 0-5mph wind is trivial if you consider that the example system would likely be designed to produce upwards of 500kW peak power (again small commercial HUGE DIY). 4) Wind Turbines are ONLY practical where there are fairly constant winds in excess of 10m/s (>20mph), these are typically remote, uninhabited areas because NO ONE wants to live where there is constantly 20mph+ winds. (see #1 ;-) )

    Building a DIY wind turbine can be a great experience and provide a tremendous sense of accomplishment, but anyone considering it should be realistic about the amount of power they will be able to produce and have an intimate knowledge of the wind patterns in the area the turbine will be located. I am fascinated with wind turbines in general, and I have a special love for VAWTs, I think they are majestically beautiful and the ultimate in simple elegance; however, VAWTs have proven to be stubbornly inefficient and expensive. Most DIY Wind Turbine builds ultimately fail because the site was chosen w/o regard to prevailing winds and the cost of maintenance eventually out weighs the energy savings. This DOES NOT mean that there are no DIY wind mills producing respectable amounts of power, there are plenty of them, it just means the success stories are generally the exception rather than the rule.

    I realize that my rather long post may appear to some to be disparaging of wind turbines, but this is NOT the case. I do think it is important to have a firm grasp on the real-world physics of them and design them with realistic goals in mind. A typical commercial wind turbine build begins with a 2 to 5 year site evaluation. The site evaluation is essentially 24/7 data logging of wind speed and direction. During this evaluation period the turbine design will be continually refined to maximize the output efficiency wrt the data and infrastructure costs will be calculated (things like distance to existing power lines, cost of roads, availability of local maintenance personnel, environmental impact, etc, etc). In contrast to this, most DIYers see a TV special or read an article and decide to put up a wind mill to lower their power bill.

    And (FINALLY) :-) to the topic of this thread, "An Open Source Wind Mill Design". I would suggest starting here: Hugh Piggott's home page . Hugh has been working on DIY wind turbines for a couple of decades. While he did not invent the axial flux alternator, he certainly adapted it for DIY wind turbine purposes. I would guess that he has introduced more people to 3 phase power generation than most EE professors. There are MANY, MANY "open source wind mill designs", the problem isn't really finding one, it is selecting the right one for a specific area (or, realizing that a particular area is simply NOT suitable for a wind mill).


    Cheers,

    Fish

    PS: For those interested in a very viable DIY VAWT design, google Ed Lenz VAWT, or visit his site @ VAWT he has a very cool design that is quite well-documented.

  5. #65
    Join Date
    Nov 2009
    Posts
    105
    Greetings, I finally found the correct timing belts. I had to make new pulleys. I purchased them for a auto parts store and the sales person told me they should be replaced every 60,000 miles. J The teeth are very large and the belts do not stretch. All the problems have been resolved and I do not for see any maintenance problems. Please disregard all earlier posts about timing belts. I am using a standard configuration for one direction operation. Enjoy the day.
    Attached Thumbnails Attached Thumbnails 3.jpg   side.jpg   tbelt.jpg  

  6. #66
    Join Date
    Nov 2004
    Posts
    202
    Good job! I'm guessing that those are camshaft timing belts??

  7. #67
    Join Date
    Nov 2009
    Posts
    105
    Hi, thank you, yes they are auto timing belts. I had to add a bearing within a bearing at the very top to stop the shaft from flexing. I am very happy with the results. I recently found out about the concept of MPPT. The core of the circuit is a Buck converter. The circuit in theory isolated the permanent magnet alternator for the battery allowing the turbine to spin more freely. Then the circuit converts the high voltage and low current to a low voltage and high current which is better for charging batteries. I will post result when available.
    Attached Thumbnails Attached Thumbnails 1.jpg   smallTestcircuitConceptDrawingCompInverter.jpg  

  8. #68
    Join Date
    Nov 2009
    Posts
    105

    Buck converter for small wind turbine project

    I am currently searching for away to supply the IC’s with Vcc. I am not sure if I should use a 12 volt linear regulator from the 12 volt battery bank or if there is a method to use the large input capacitor at Vin. The voltage at Vin can range form 0 to over 200 volts open circuit and I do not know how fast the buck converter will drain the cap at Vin when the mosfet is oscillating. Comments are welcome.
    Attached Thumbnails Attached Thumbnails 555output.jpg   VsMosFet.jpg   Vout.jpg   TestcircuitConceptVccVdrDrawing.jpg  


  9. #69
    good talk
    http://www.oreplant.com/products/centrifuge-machine.html

  10. #70
    Join Date
    Oct 2006
    Posts
    41
    hi
    good work from every one here .

    i have a question and i know that this will sound stupid but here we go.

    what about using a wind mill ( like the water pump one from old farms )
    and a small altornator with built in regualtor to charge batteries.

    the wind mill will have to be ratio up to make it spin fast enough.

    then on the bearing of the tower you could bild a comatator so the mill could spinn 360 deg all day

    this is just an idea ( might not be a good one )

    what thoughts are out there

  11. #71
    Join Date
    Nov 2009
    Posts
    105
    Hi, RPM may be a problem, what is the required RPM for the alternator to start charging? Would you have to supply a voltage to energize the alternator? I have a seen a company that uses that wind mill design and reports good numbers, but I think they are using a permanent magnet alternator because they operate at a lower RPM and do not need to supply a voltage to the alternator. I hope to see some photo’s of your project. My project is experimental and I am using a VAWT because it is the easiest to fabricate. The wind mill design you are suggesting does have a proven history. I think it is a good idea.

  12. #72
    Join Date
    Nov 2009
    Posts
    105

    Smile VAWT Project update using a buck converter

    [ame=http://www.youtube.com/watch?v=B3dLzZZ5jKQ]50wattLoad.AVI - YouTube[/ame]



    Hi, the video shows manual operation of PMA using a buck converter to drive a 12 volt 50 watt load. Without the buck converter I can not spin the PMA fast enough to illuminate the light because the faster you try to spin the PMA the more it acts like a electric brake. Adding the buck converter delivers more current to the load and the PMA is much easier to spin. The next phase of the project is to adapt the circuit to charge a 12 volt battery bank. Comments welcome and enjoy the day.


    Video showing VAWT operation with no load, just for fun, I am happy spring is here

    [ame="http://www.youtube.com/watch?v=EKH7DJKxryw&feature=related"]http://www.youtube.com/watch?v=EKH7DJKxryw&feature=related[/ame]

  13. #73
    Join Date
    Nov 2009
    Posts
    105

    VAWT Project update using a buck converter

    Greetings, using a isolated power supply and FOD3180 does work. I am using a blocking diode between the inductor output and the plus terminal of the 12 volt battery. The gate driver is triggering a N channel IRF540 in a Buck circuit configuration and is charging the battery, current about 1 amp. Then I replaced the battery with the 50 watt halogen light and the circuit was able to illuminate the light after I adjusted the duty cycle, current max about 4 amps. I was manually operating the PMA. So far this is a very happy day. The next step is to drive the PMA with the drill press to determine how the circuit behaves at a higher RPM.

    Chapter 4. page 69

    OhioLINK ETD: Taschner, Matthew

    Isolated power supply with FOD3180 gate driver. N channel Buck converter using a IRF540 mosfet. Bottom wave form is gate of mosfet, top wave form is source of mosfet.
    Input voltage max about 40 volts. Output current varies depending on duty cycle. Circuit still needs improvement but it is working. Input voltage is from a permanent magnet alternator and is being manually operated. Comments welcome.
    BuckConverterUsingIsolatedPS&FOD3180.AVI - YouTube

  14. #74
    Finally after all this time I am in a postion to contribute to the thread I started, lol.

    Im keen to build some windmill blades, using my router. Not sure if it will be vertical or classic windmill but I should hopefully be able to do some cutting this weekend if I can find some good cad/plans.

  15. #75
    Join Date
    Nov 2009
    Posts
    105

    Quote Originally Posted by gavztheouch View Post
    Finally after all this time I am in a postion to contribute to the thread I started, lol.

    Im keen to build some windmill blades, using my router. Not sure if it will be vertical or classic windmill but I should hopefully be able to do some cutting this weekend if I can find some good cad/plans.
    Hi, congratulations. I hope to see some photos of your project. If it is a HAWT or a VAWT I really believe that adding a MPPT to your project will make the greatest contribution for its ability to perform well.
    Recommended videos showing the benefits of adding a MPPT controller to a wind turbine.

    [ame=http://www.youtube.com/watch?v=0TE38SOdf64&feature=channel&list=UL]New MPPT Board Prototype - YouTube[/ame]


    [ame=http://www.youtube.com/watch?v=4JcC--1urUw&feature=player_embedded]MPPT Experiments - YouTube[/ame]

    Here are some forums where others have made similar projects and may be able to make some recommendations.
    windgen.org discussion - windgen.org discussion

    Fieldlines.com: The Otherpower discussion board - Index

    Anotherpower.com Information about solar wind and other DIY alternative energy

    The Back Shed: Started Buck c&#111;nverter project

    I hope this helps. Enjoy the day.

  16. #76
    Thanks for the links, looks like there are some great sites and plenty of projects to have a look at.

    I have started a forum to hopefully produce an opensource windmill with its members. I acknowledge the fact there are already some forums out there doing something similer, however just like the opensoure 3d printing scene (rep rap etc..) multiple similer projects and communities do not seem to be a bad thing, and contribute to a cross pollination of different ideas between groups.

    http://www.openwind.org

  17. #77
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    Apr 2006
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    3206

  18. #78
    Join Date
    Jan 2006
    Posts
    2985
    Quote Originally Posted by fizzissist View Post
    HA HA HA HA

    Why waste your time on a wind powered car when you could just run it on water?

    Now back to the real wind power.....

    Matt

  19. #79
    Join Date
    Mar 2006
    Posts
    16

    Wind turbine design

    All about wind statistics and wind turbine design you can find here:

    Applied Computational Fluid Dynamics (CFD)

  20. #80
    Join Date
    Sep 2007
    Posts
    8
    Quote Originally Posted by abbabba View Post
    The idea is quite clever. From the practical point of view however, I think the wear and tear will kill the idea. And there is the noise as well. I don't think the neighbours would approve. Good luck with your pursuits though. abbabba
    Also if the turbine is spinning at a high speed it seems it could fly apart from all the mechanical movement. I feel the best design is something along the lines of a barrel cut in half vertically. Of course the design would need to be refined. I want to do a design of such a vertical shaft WT down the road. I really like to use SketchUp Pro, anyone else have experience with this software?

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