Micro sized Axial Flux 3 Phase Star or Delta wiring

Discussion in 'Wiring Methods' started by timber, Apr 29, 2013.

  1. timber

    timber WindyNation Engineer

    Hi All,

    It's been eons since I last posted here but I'm working on a fun little project that I thought I'd share with my old friends here. I'll post a few details and some wiring diagrams in case anyone is interested.
    Don't have any pictures yet but I'll try to capture some of the process for later posting.
    I've started winding the coils (10 of 15 so far) and have one rotor with magnets epoxied but still have a long way to go.

    As the title suggests, my project is building a scaled down version of the old standard, dual rotor, 3 phase axial flux alternator but instead of using 2-3" diameter x 1" thick neodymium, hand smashing, flux monsters I am using some tiny 3/4" x 1/4" thick, disc neos that were on sale.
    No great expectations using such small magnets; it's more a labor of love and the process of going through the steps of creating my first axial flux alternator, albeit a smaller version than most.
    (I think of it being in the range of somewhere between a standard axial flux build and a stepper motor). :D

    Note: Years ago I made a "conversion" alternator from a 120V induction motor, rewiring it to produce 2 phases, one from the stator windings and one from the start windings. There I ground down the rotor making it 4 sided and epoxied 7ea. 1/2" dia. x 1/2" thick cylinder neos in a group on each of the 4 sides. 28 neos total.
    It did OK and would generate ~14V @ ~3.5A in relatively low winds, enough to keep a couple of deep cycles topped off when not in use.
    (It died a couple of years ago when a magnet flew loose and it came to a grinding halt).
    Since that time I purchased a 500 Watt from WindyNation which does nicely and is built to last.

    On this little project I'm pretty much designing as I go. I know the basics of building an axial flux so I'm just using stuff I have around the shop, where possible, to fabricate.
    Each rotor will have 20 magnets (20 polls) and the stator will have 15 coils (5 coils per each of the 3 phases).
    The basic design is similar to the old standard, with a cast resin stator sandwiched between two rotors.
    I'll make sure I can adjust the stator location relative to rotors and distance between rotors to control the air gap.
    My rotor backing plates are go-kart sprockets (60 tooth I think) so are about 7.25" dia. This places the neos centered on a ~6.5" circle on each rotor.
    Stator will be ~5/16" thick and 8" diameter with ears for drilled holes which will allow me to adjust it's position using threaded rod and nuts.
    Coils will be trapezoidal with an average I.D. of 3/4" and an O.D. of 1-1/2" (width and height), 20AWG@70 turns each. (That's the max. I have room for).
    Rotors will also be tied together via threaded rod placed toward the center of the rotors. Nuts will allow for adjustment.
    My blades will be some Ametek type blades that Murray2paddles gave me years ago. I'll try 3 blades first but have 3 more if I want to add them later to capture low winds.
    My Yaw bearing will be a piece of greased pipe over pipe pole. If all goes well, I'll likely make another tilt-up pipe tower using 21' length of pipe.
    I doubt I'll go with a furling tail (but possibly), we'll just have to see what transpires.

    My goal is to use this and a 5 watt solar panel to trickle charge a 12V gel cell (I'm thinking 9Ah) to power some LED's for deck perimeter lighting. As of now, I'm not worried about a controller but if miracles happen maybe I'll need one. Whether I can achieve 14V with this little alternator is the $100000 question.
    Haven't tested a coil yet (only one rotor so far) but as I get things assembled I'll test one coil and extrapolate to see if I possibly have a chance or if I'm shootin' blanks.

    Below are diagrams of my stator wiring. (Star, Star Wiring Connections, Delta and Delta Wiring Connections)
    I will have 6 connection points, each an end of coils in series per phase.
    This will allow me to play with Star vs. Delta configuration and test each phase for resistance, voltage etc.

    Star - Phase1, Phase2 and Phase3 w/Connection Points

    Star Wiring Connections

    Delta - Phase1, Phase2 and Phase3 w/Connection Points

    Delta Wiring Connections

    Please let me know if you see any errors or problems and feel free to comment ... bad or good.

    timber out
  2. Looks like you are playing around with the same thing. My VAWT project needs a custom alternator. The cogging with these commercial PMA's wont let my low power lawn ornament spin. After lots of reading, I'm going with a air core stator, and starting smaller yet. 12 magnets and 9 coils.
    I have a couple of 60 tooth go cart sprockets I'm using too. From what I have read, the secret is the air gap between the magnets. So the coils need to be thin as possible with the smaller magnets.



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