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Portal Point Generator

An efficient and compact generator that can be coupled with wind turbines or water wheels to produce upwards of 100W

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Originally designed and built to take on an expedition to Antarctica coupled with a wind turbine. Portal Point was one of the locations in Antarctica that this was set up to generate power to charge electronics, and hence named after it.

I was unable to find a cost-effective generator and using motors backward to generate power seemed too wasteful because of their inherent detent torque. I decided to go back to fundamentals and build a turbine would give the maximum possible output for its size.

This generator was used in Antarctica along with CFA2018 and the organization 2041 to generate power and power our electronics. It goes to show the resilience in 3D printed parts and what amazing things this technology can do in the future and play an important role in creating a sustainable future.

What is a Dual Axial Flux Generator?

A dual axial flux generator consists of powerful magnets placed on either side of a fixed stator winding, like a sandwich creating a very strong magnetic flux between them, and thus inducing a powerful EMF in the stator winding when in motion. Since the magnetic flux is axial to the output shaft, it is an axial flux generator, unlike a radial flux generator like that most commonly found in DC motors that are converted as dynamos.

I chose to build this kind of generator, since it creates a dense magnetic field and makes the most efficient use of the magnets. There is hardly any magnetic flux leakage outside the generator itself.

Another upside is that, it makes the generator flat, and is easy to construct, as well as integrate into power generation projects.


In the expedition to Antarctica,  I coupled this along with a Helical Wind Turbine Design (https://www.thingiverse.com/thing:99132) to create a Wind Turbine we could use to charge our electronics and equipment with.  In this documentation I shall also outline coupling the generator to the wind turbine project as well. 

Generator.rar

Full assembly

RAR Archive - 714.24 kB - 08/11/2018 at 06:32

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Standard Tesselated Geometry - 360.34 kB - 08/11/2018 at 06:19

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Standard Tesselated Geometry - 444.61 kB - 07/13/2018 at 10:47

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Standard Tesselated Geometry - 259.16 kB - 07/13/2018 at 10:47

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Standard Tesselated Geometry - 80.94 kB - 07/13/2018 at 10:47

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  • 16 × N52 Neodynium Magnets 40x20x5mm
  • 1 × 30 AWG Enamel insulated Copper Wire (M)
  • 250 × M4 Threaded Road (mm)
  • 1 × 1.2mm Mild Steel Sheet 200x400mm
  • 1 × 25A 50V Bridge Rectifier

View all 8 components

  • Generator Optimization

    Vijay08/23/2018 at 13:27 0 comments

    With the one version done and tested,  I wanted to address and fix some of the design and construction issues I faced while building and designing version one. The following are the list of changes I am aiming for:

    1) Rotor Assembly

    Assembling the rotor was literally a bloody nightmare resulting in cuts and bruises from shattered magnets flying all over the place.  The rotor will be modified to aid easier assembly

    2) Stator rigidity

    Owing to the weight of the stater assembly with the large number of magnets, the stater began to show signs of fatigue after a few days of continuous use ( When kept in vertical position). A large amount of weight from the heavy rotors were being concentrated at the center of the stator. I will be beefing up the stator with ribs, and redesigning the casing such that it takes away the loading from the stator as much as possible. 

    3) Coil Winding Rig

    A coil winding rig with a arduino and encoder which can repeatably reproduce the number of coils on the stator winding's

    4) Using a Wind Turbine Charge Controller 

    I had used a buck converter with a bridge rectifier initially which did the job of charging a phone, but I think its not the best way to do things. For one, there is no over-speed protection which shunts the output of the turbine to prevent it spinning wildly out of control in case of a storm or something.  Image result for wind turbine charge controller

    So I ordered this relatively cheap wind turbine charge controller. I'm still unsure what wizardry is going on inside it, but hope it does a better job than a buck regulator. 

  • Voltage Output

    Vijay08/06/2018 at 06:33 0 comments

    I peaked the voltage output at about 75V with a drilling machine before I screwed up my multi-meter, probably by going over its rated current, but it was producing a cool 24V from a ceiling fan.
    I was able to step down the voltage using a buck regulator and charge things, but think I would need to Charge Controller of sorts to better regulate the voltages and give a decent amount of current, especially if the voltages peaks go above 40V which would damage the buck converter. 

  • Rotors

    Vijay07/15/2018 at 15:43 0 comments

    The picture below shows of the rotor stacks up into an assembly. The magnets get embedded into the magnet housing, and is covered by a laser cut sheet metal cover. The sheet metal cover prevents magnetic flux of the powerful magnets from going out of the generator, and also makes the flux stronger on one side of the Magnets.

    The rotor brace prevents the powerful magnets from collapsing into each other ( THE MAGNETS ARE FREGGIN POWERFUL), as well as provides a way to mount the drive shaft. Use M3x16 CSK screws to mount everything together.


  • Star Topology Arrangement​

    Vijay07/15/2018 at 15:34 0 comments

    Connect the phases in a delta pattern. There are 2 Coils for each phase. The coil on the opposite sides are of a single phase.

    Connection coils of the same phase in series first, the "OUT" of the first coil with the "IN" of the second coil of the same phase.

    The above picture shows 9 coils, but its connected the similar way for 6 coils as well

    Then connect all the remaining "IN"s of the three phases together which would be the common ground. All the "OUT"s will be the three phase output.

    In the below images, I covered the coils with the stater cover, and marked the IN's and OUT's of the coils to aid wiring.

    Figure 24: Twisting joints of wire pairings (as per description)

    removed the enamel from the ends of the wires with sand paper:

    Figure 21: Stripping enamel off the copper wire with the help of sand paper

    (My desk is messy, i know)

    here im' soldering two coils of the same phase together. 
    Figure 23: Soldering pairings of copper wires

  • Stator Assembly

    Vijay07/14/2018 at 11:23 0 comments

    Coil Placement:

    Place the coils inside the Coil Holder/ Stator. There are three pins inside which the coils will sit.

    The "IN" and "OUT" of the coils where the winding started and ended need to the placed in the appropriate notches. These will help identify how the coils would be wound.

    Figure 15: Coils placed in coil housing

    Coil Housing Preparation:

    Glue gun the coils in place.

    Figure 16: Glue applied to raised edges of the coil housingApply glue to the edges of the coil housingFigure 18: Coil housing being coveredThe coil housing is covered with the 3DP Housing CoverFigure 19: Coil housing being covered

  • Assembly Process: Jig Preparation + Coiling

    Vijay07/13/2018 at 13:59 0 comments

    Jig Preparation:

    The winding jig is used to wind the coil. The Jig and the Jig holder are fastened together using M3 fasteners.

    Figure 1: Both jigs affixed together along their shape and their elevations facing each otherPrint 2 Jigs,  fix them along their shape, and elevations facing each other.

    Figure 2: Jig handle attached to the jigs on one faceAttach the 3DP Jig Holder on one of the faces. I recommend marking this face, and you should use the same convention when winding all the coils., and the winding direction should match. 

    Figure 3: Jig handle attached to the jigs on one faceFasten everything togehter

    Figure 4: Wire inserted through hole in the jig to help the wire sit in the grooveThere is a small hole in the jig through which you can slot the wire, to keep it in place while winding.  Put the 30 AWG wire into this from the inside of the jig, coming out.

    Figure 5: Attach kapton tape to the face of each edge in a reverse manner to help get the coil out of the grooveAttach kapton tape in the 3 slots . Once the coiling is done, the kapton will be folded onto the finished coil to hold its shape.

    Coil Preparation:

    The jig is mounted on a power screw driver/drilling machine using a HEX bit. There is a notch on the jig to indicate when the maximum number of coils are reached.

    Try and maintain a constant level of tension on the coils to get a roughly same number of coils. 6 coils will need to me made like this.

    Use kapton tape to keep the cool from unwinding. Keep the kapton in place on the inside of the coil, and wind on top of it.

    There is a hole on the jig where the start of the coil is placed. As long as you use the same convention for winding, and placing into the coil holder, you should be alright, only the polarity of the DC would change.

    To Do: Automate this process with a encoder and counter to be more accurate.

    Figure 7: Wire being wound around the jig with the help of a hand drill and drill bit

     If you have the patience, you can hold the handle and wind by hand, or use a drill/power driver to make this faster. You need 6 coils.

    Figure 8: Unscrewing the jig handle

    Fold the Kapton tape over the coil to hold it in place. Now work backwards to remove the coil.

    Figure 9: Removing the jig handle

  • Story

    Vijay07/13/2018 at 13:45 0 comments

    Mission:

    To make energy generation accessible with 3D printing.

    Story:

    I had been selected to join the International Antarctic Expedition (IAE), ClimateForce: Antarctica, that equips leaders with resources and actionable solutions to become a part of a global force of change.

    This expedition gave me the ability to learn from experts on the subject of climate change as well as equip myself to be in a position to create an impact back home.

    I wanted to use this opportunity as a platform to promote the use of 3D printing to give access to renewable energy to as many people as possible. Even though the maximum output if this generator is 50-100W, it can act as a blueprint for others to get into improving manufacturability of wind turbine or generator designs. Maybe this could inspire some college students who take up this project to pursue renewables as a career.

    This generator was used in Antarctica along with CFA2018 and the organisation 2041 to generate power and power our electronics. It goes to show the resilience in 3D printed parts and what amazing things this technology can do in the future and play and important role in creating a sustainable future.

                               Assembling the wind turbine in Antarctica proved to be quite a challenge with gloves on.


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Discussions

Shyam Parameswaran wrote 09/13/2018 at 08:28 point

Very nice Vijay and thanks for sharing. Any idea how much torque the generator generates (at a particular power input)?

Thanks

  Are you sure? yes | no

Adarsha wrote 08/09/2018 at 13:10 point

Very cool project Vijay. Wondering how the magnets are oriented? entire face of the rotor are all of same side (so one face is south pole and other is north pole)? or inside each rotor you will have balanced number of S and N poles?

  Are you sure? yes | no

Vijay wrote 08/11/2018 at 06:16 point

On each rotor face, N and S alternate, which get coupled to the opposite  pole on the other rotor.  There is a metal disk on the outer face of the rotors to prevent magnetic flux getting lost outside the motor and concentrates it inside and between the rotors only.
The magnetic forces are so strong, its impossible to get the rotors apart without tools once they are on the shaft, even with a significant gap in between.  
God save the person that would have got them stuck together :p

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TJ wrote 08/02/2018 at 01:11 point

I think there is a STL missing from the posted files. It seems to be listed as "Stator Brace/Shaft Clamp". Is it possible to make this available with the other files? Thanks in advance Love the project.

  Are you sure? yes | no

Vijay wrote 08/11/2018 at 06:06 point

Sure let me check this out.  I was planning on doing a once-over with the prints and designs and make sure everything is proper, I had to do some amount of filing and sliding to get everything to fit and not scrape parts inside the generator for this version, so I imagine it may be a little frustrating for people. 

  Are you sure? yes | no

Vijay wrote 08/11/2018 at 06:33 point

I've added Generator.rar to the files, it has the full assembly. 

  Are you sure? yes | no

Jeff Cooper wrote 07/31/2018 at 20:37 point

Thanks for sharing your project.  This should definitely spur some 3DP green energy projects as well as be a great teaching instrument.  Did you record the numbers of turns in the individual coils?  Thanks again!

  Are you sure? yes | no

Vijay wrote 08/11/2018 at 06:11 point

Almost everything was empirically determined. I chose the N52 grade magnets first, which were available locally, and just designed everything around that, right to the maximum number of coils that would fit. 
I plan to make a coil winding machine with an encoder and arduino to recreate this project in a more systematic manner than flying by the seat of my pants. 

You are very welcome!

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Tinkerloonllc wrote 07/15/2018 at 17:08 point

I love this!

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Carlos wrote 07/12/2018 at 00:04 point

Amazing. I can definitely use this on disaster relief deployments.

  Are you sure? yes | no

Vijay wrote 07/15/2018 at 15:57 point

I hope it comes of use to you!

  Are you sure? yes | no

Dennis wrote 07/11/2018 at 18:29 point

You had better weather in Portal Point than I did!

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earl wrote 07/11/2018 at 17:38 point

Are you going to make the plans available for others to print?

  Are you sure? yes | no

Vijay wrote 07/13/2018 at 10:52 point

They are up now,  will update process and procedure by today.

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Aayush Khanna wrote 07/11/2018 at 17:08 point

Pretty cool stuff ! 

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Vijay wrote 07/15/2018 at 15:57 point

Thankyou!

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Shah Selbe wrote 07/11/2018 at 17:02 point

Awesome project! I can see us using this in the field.

  Are you sure? yes | no

Vijay wrote 07/15/2018 at 15:57 point

Thankyou! I hope the design comes of use to you!

  Are you sure? yes | no

Mike Szczys wrote 07/09/2018 at 21:18 point

A very cool build, and amazing that you tested it out in Antarctica, wow!

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Vijay wrote 07/16/2018 at 06:44 point

Thankyou Mike!

  Are you sure? yes | no

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