(Wind Nerd alert) Mini Axial Flux Alternator Parts

Discussion in 'My Shapeways Order Arrived' started by samdekok, Feb 17, 2011.

  1. samdekok
    samdekok New Member
    My parts for a mini axial flux power generator (alternator really) arrived, and work great.

    The design is a new idea to make the winding of the coils simple and easy by making the bobbins a feature of the overall part, with a 4mm hex key fitting to wind the copper wire on easily.

    It worked great and I am really happy with the tolerances. The 10mm neodymium magnets also snap into place really well.

    Next step - to put it onto a magnetically levitating wind turbine and make a tiny bit of power from it.

    I have put this part into my shop in case schools or educational facilities would like to buy one, or someone wanting to make a large turbine but needing a small unit to build first.

    IMG_3087.JPG IMG_3085.JPG
    Last edited: Feb 17, 2011
  2. ana_xyz
    ana_xyz New Member
    Cool! Any chance we could see a video of it in action? :)
  3. dizingof
    dizingof New Member
    Very Cool !

    One of my favorite subjects - green power.

    I see you're using thick enamel wires - so you're going for more current then volt?
    How much volt /milli-amp does each coil produce? did you test them yet?

    One of my To-Do designs is a thin case for iPhone with tiny cylindrical neodymium magnets (bought few from a Swiss manufacturer) positioned inside uniquely shaped coils for maximum generated current with each tiny move of the iphone.
    Current then stored in a thin backup battery.

    Of course the i'm hoping the precision of the 3D printed design plus the right calculations can make it work or scraped.. :)

    Well Done !


  4. stop4stuff
    stop4stuff Well-Known Member
    Very neat!

    It would be interesting to see what power you get out of that little alt, and more interestingly how fast you need to make it spin (I'm guesstimating upwards of 400 rpm just to get enough volts to see DC after the rectifier)

    A few of my observations, and questions.

    Does it have a ferrous plate behind the magnets to maximixe the magnetic flux density? Are there two magnet rotors to concentrate the flux through the coil legs?

    8 coils and 6 magnets is an unorthodox layout, how does the phasing work out? Usual configurations are 10 or 5 coils with 12 or 6 magnets for 5 phase, 9 coils with 12 magnets for 3 phase, 12 or 6 magnets 6 or 3 coils for single phase.

    If you need any help planning the layout for your alternators, feel free to ask... small size alternators happen to be something I'm very keen on, as you can see from my LEGO weight driven generator

    @Dizingof... reverse engineering a 'Shaker Light' would help you out - but there's not much power to be had.

    p.s. have a search for MOSFET rectifier for the least voltage drop in converting to DC. Geranium diodes also have a very low voltage drop, but they do not have very good reverse voltage tolerance.

    Last edited: Feb 19, 2011
  5. samdekok
    samdekok New Member
    Hi Dizingof, yes I went for more turns in order to get the voltage up, in order to get past the diodes, and power loss increases with current.

    I didnt play with flux density yet - this wasnt about maximising power yet. It would be interesting to run it in alumide and let the induced current alter flux density. Perhaps.

    Yes it's an odd ratio of coils to magnets - it was an idea I had to gang each opposite set of coils together to get four coil phases being jumped in turn by 6 magnets. I havent hooked it up yet beyond a single coil, it made sense after a few beers but i think I will need to sit down with paper and some diodes and rethink it. Otherwise I will develop a new 3d model with the traditional recipe of ~1.34 magnets per coil. A quick open circuit test only went with millivolts. In hindsight I should have gone for 0.4mm wire or less.

    What I really wanted out of this was something people could buy, pop together and built their confidence, before scaling it up into something at least 10 times bigger. I'm not keen to get anything other than milliwatts out of it. Great idea on germanium diodes - I'll be checking that out. I'll post more soon...
    Last edited: Feb 20, 2011
  6. lensman
    lensman Well-Known Member
    Really neat and practical. Looks like something I could use in the time machine I'm making right now.... or will be making as I've been told by myself in the past :twisted:

  7. samdekok
    samdekok New Member
    Well I did think of calling it the flux capacitor, but I doubt I'll get 'one point twentyone gigawatts' from it as the Doc says on back to the future. Perhaps we could model a small delorean to mount it on....
    Last edited: Feb 21, 2011
  8. stop4stuff
    stop4stuff Well-Known Member
    Did you get any numbers out of that alt yet?

    I've had an idea for a stator planned out for a while, its based on Ed Lenz's 'Slotty Thing' alternator 'coil' former (dunno if you've seen his stuff - http://www.windstuffnow.com ), he used to post over on http://www.fieldlines.com too... anyways alts aren't a new idea, but combining 3D printing and alt manufacture are. Are you ok with me having a hit at designing an alt? (asking first so as not to tread on toes)

    Last edited: Feb 23, 2011
  9. samdekok
    samdekok New Member
    I'm hoping to get some time this saturday to wire it up, I've been trying to overlay the 8 coils into 4 pairs in inkscape , then overlay the 6 magnets to see what each phase is doing. Hmmmm.

    I'd love you to model it - if its good can I buy one? :p

    Ed's site is what inspired me to find a way to rapid wind the coils. So my idea was to build the bobbins in like I did so they could be wound quickly via a li-ion driver and a hex key. i therefore thought the extra expense of 3D manuf would be offset by the reduction in time costs. The other thing i have is a silicone and resin casting kit. If the first prototype was expensive it might still be a nice way to make a very precise silicone mould and cast heaps of them. I have been thinking of making a flat pack kit that could be sold into australia schools etc, with a lenzII vawt. You might want to check out my lenzII blade rethink on youtube: http://www.youtube.com/user/samdekok72

    I found that making the magnet holes 0.2mm smaller in dia than the magnets made them pop in nicely over a 10mm diameter. No glue needed.

    And I donloaded the drill plugin for sketchup (maybe you model in something else) and drilled the unit out quite a bit to save on volume costs. Just putting material where the strength is required...

    It'd be nice to have someone to collaborate on this stuff with! Perhaps we could design in parallel then compare ideas! i think my rotor plate would be cheaper to produce as a laser cut sheet thru other online sites if the diameter were to perhaps double. I have a large approx 300 watt unit made from a fisher and paykel washing machine motor that I have been working on, it's been taking priority to winding up the little sub-watt unit.
    Last edited: Feb 23, 2011
  10. stop4stuff
    stop4stuff Well-Known Member
    Upon seeing your alt, one of the first things I did was to replicate the layout in Corel Draw... you could series opposite coils for a four phase alt, I think the phases would be out enough that you'd need to rectify each phase individually.

    If I got your dimensions right, you may have enough spare room on the rotor to go to 8 magnets and series all the coils for a single phase unit. Without any kind of flux channeling (steel backing for the magnets, dual rotor etc), I'd guesstimate you'd need about 1200-1600 turns total (150-200 turns per coil) and have the rotor spinning at 300+rpm to make 4v after the rectifier.

    I see you have a hole in the stator casing below each bobbin... could the wire from the bobbin be fed out through this hole? If so, you would be able to get the magnets a little closer to the coils which would help things a bit.

    I'd be happy to colaborate in a design :)