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PCB Motor

A smaller and cheaper open source brushless motor

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My open source PCB motor is my attempt to build a smaller, cheaper and easier to assemble micro brushless motor.

What unique about this motor design is that the stator is printed on a 4-layer PCB board. The six stator poles are spiral traces wounded in a star configuration. Although these coils produce less torque compared to an iron core stator, the motor is still suitable for high-speed applications.

It also has a 16mm diameter, 1.7mm thin 3d printed 4-pole rotor. So the total thickness of this axial flux motor adds up to 5mm (excluding the shaft) and weighs 1.5 grams.

The inspiration for this idea came from trying to build smaller and cheaper drone. Making the motor onto the PCB itself will reduce the overall price of any tiny robot, allowing swarm robotics to become more affordable.

My PCB-Motor is made from a 6-pole stator printed on a 4-layer PCB and a 4-pole 3d printed rotor. Its has an outer diameter of 16mm and is rated at 1 watt. 

I had this idea when I was trying to design a small compact drone. The PCB motor is much cheaper than other micro brushless motors and also easier to assemble. My goal is to make the rotor part of the BOM and mounted just like any other component on a PCB. 

VIDEO

HACKADAY SUPERCON DEMO

6-layer PCB Motor Gerber Files.rar

Gerber files for my 11mm diameter 6-layer PCB Motor

RAR Archive - 46.53 kB - 11/07/2018 at 16:52

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ESC BOM.JPG

BOM for my PCB motor brushless ESC with Hall sensor feedback

JPEG Image - 59.80 kB - 10/22/2018 at 04:42

Preview
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PCB Motor ESC Gerber Files.rar

Open Source Gerber Files for my PCB motor brushless ESC with Hall sensor feedback

RAR Archive - 171.61 kB - 10/20/2018 at 17:47

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PCB Motor ESC Schematics.JPG

Open Source Schematics for my PCB motor brushless ESC with Hall sensor feedback

JPEG Image - 61.15 kB - 10/20/2018 at 17:45

Preview
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PCB Motor V1.rar

Open Source Gerber Files and STL file of the first PCB-Motor prototype.

RAR Archive - 194.17 kB - 02/07/2018 at 22:54

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  • 1 × 3D Printed Rotor
  • 1 × PCB Stator
  • 4 × Magnets (5mm diameter x 1mm thick)
  • 1 × Shaft (1.5mm diameter)
  • 1 × SMF681X-ZZ Bearing

  • CORE PCB Motor

    Carl Bugeja01/07/2019 at 19:06 0 comments

    Check out this teardown of the CORE-PCBMotor!! I came across this motor a few months ago, after a few people who saw my design sent me their website's link. There's not much information on it and its also patented but this guy managed to take it apart and review it.

    http://build-its-inprogress.blogspot.com/2018/12/core-outdoor-power-pcb-motor-teardown.html

    I have no idea why they decided to use it for a lawn trimmer (there's much more interesting applications) but its very interesting to see how it was designed, the way the windings are connected and that it has sufficient torque to rotate a blade!

  • Smallest PCB Motor

    Carl Bugeja10/31/2018 at 00:11 0 comments

    My SUPER tiny 6-layer PCB Motor is spinning! Here's the full video describing how I designed it:

    My original 4-layer PCB motor had a 16mm diameter. By adding two extra layers I was able reduce the number of turns per layer and get it to 11mm. The total height of the motor is 3.6mm and its weight is 0.5 grams.

    No space is lost in this pcb! Each coils have 3 vias to connect the in-between layers. These forced a triangular shaped stator poles, which utilize the magnetic field area more efficiently.

    The tiny rotor design has four press-fit 2mm n52 magnets and a 3mm bearing. This new design has the shaft soldered onto the stator, so it is fixed and don't rotate with the rotor.

    I had chosen to go with this design because of two things:

    1. I couldn't find a bearing small enough to fit in the middle of the stator.
    2.I'm not planning to use a shaft. Customized 3d-printed rotors makes much more sense. 


    The phase resistance of this motor was measured to be 15ohmsand its getting to 85℃ with a 4V supply, so it should be perfect for a 1s lipo.

  • ESC details

    Carl Bugeja10/20/2018 at 17:52 0 comments

    This video shows how i designed my PCB Motor's ESC and what where the challenges involved in getting my speed controller to work.



    This is its schematics:


    It has a PIC16F1503 as the main controller and a triple half bridge driver STSPIN230, to control the three phases of the motor. These are both powered from the same supply, to avoid having an extra power wire or on-board regulator, reducing the cost even further. I filtered the digital circuitry supply from an LC filter to attenuate any noise the motor can generate. It can operate from a 5V to 2.6V supply and draws around 220mA in total.

    As i explained in my previous project logs, the back emf generated from my pcb motor was too weak to implemented a sensorless speed controller. So i decided to use a hall sensor to provide feedback to the microcontroller and then implemented a speed closed loop speed controller. 

    The open source gerber files and schematics for this PCB are available for download. 

    In the beginning of November I will be giving a demo of this project at the Hackaday Superconference so see you there! 

  • PCB Motor with integrated ESC!

    Carl Bugeja10/14/2018 at 14:36 0 comments

    I have finally finish my PCB Motor with the integrated ESC! Made this quick video showcasing it:

    The PCB was hand soldered. It took me a little while to get it to work because I had some soldering flux residue on one of the motor driver chip that was acting as impedance. This was triggering the driver's on-board protection circuit. But after removing the chip and clean its pads, it was up and running.

    I have managed to fit the ESC in such a small area by soldering parts on both sides of the PCB and using the smallest footprints I could find! Both the MCU and motor driver have a 3x3mm qfn package and most of the other discrete components are 0201s! 

    I'm currently making another video explaining how i design this driver and what were the challenges involved! So I will be releasing its schematics and gerber files in the next few days :)

  • SUPER tiny 6-layer PCB Motor

    Carl Bugeja10/12/2018 at 21:22 1 comment

    Today I have received my super tiny 6-layer PCB stator measuring 11mm in diameter. 

    This is how it compares to my 4-layer prototype. 

    I'm super excited to test this thing out and see it run, but unfortunately the magnets still haven't arrived yet :/ stay tuned for more updates!

    JLCPCB was cool enough to sponsor and manufacture this tiny 6-layer PCB Motor! I highly recommend them if your looking for super cheap pcb prototypes. 

  • 6-layers

    Carl Bugeja10/02/2018 at 19:46 3 comments

    I love designing electronics that fit in very tiny space. My 4-layer brushless PCB Motor is currently 16mm in diameter. So how can I make it smaller?

    This 16mm design is already pushing the limits by having 4mils (0.1mm) track width and clearance. Using thinner pcb traces is possible, but would make its price (for prototyping) explode. My intent is to make this open source motor accessible to others, so it doesn't makes much sens to go in this direction. So I'm sticking to 4/4mil traces.

    My motor has around 40 turns, so going much lower than that would make the coils too inefficient and the pcb would heat up way to much. Based on a my pcb coils tests the minimum number of turns for 4mil should be 40 turns and for 5mil it should be 60 turns, not to exceed 70°C with a constant (100% duty cycle) supply. 

    The only remaining option to try and make it smaller, is to increase the number of layers to decrease the number of turns per layer. The current design has 10 turns per layer, so for this tiny 6-layer motor I  decided to go for 6 turns per layer, having a total of 36 turns. Setting a tight clearance of 4mil, the total diameter of the motor end up being 11mm.

    The extra two layer, increased the number of vias in the middle of each coil to three. This naturally formed the spiral to have a triangular shape which use the area of the magnetic field more efficiently.

    Another natural advantage of using a 6-layer pcb, is that the thickness between each layer is much smaller which increases the magnetic field strength.

    For this design I had to make some changes on the rotor, because I couldn't find a bearing small enough to fit at the center of the pcb (smallest bearing available is 2mm). So what i decided to do is extended a stationary-shaft from the pcb, and connect the bearing on the rotor. I'm still designing the 3d-printed part, so I will post more info on that soon.

    I have just ordered this 6-layer pcb motor from JLCPCB which were kind enough to sponsor this design. 

    We'll see how it goes!

  • Project Update

    Carl Bugeja10/02/2018 at 17:07 0 comments

    Here's a quick update video on my brushless PCB Motor project, with a list of things I was working on and what I plan to do next.

  • IEEE Spectrum - “The Printable Motor.”​

    Carl Bugeja08/29/2018 at 18:09 0 comments

    My PCB Motor got featured on IEEE Spectrum! Check out their article bellow :)

    https://spectrum.ieee.org/geek-life/hands-on/how-to-print-an-electric-motor

    It will also appear in the September print issue as “The Printable Motor.” 

  • New PCB Soldering

    Carl Bugeja08/22/2018 at 22:05 0 comments

    Soldering of the new pcb is done! I still have to test all the components though 


  • New PCBs

    Carl Bugeja08/09/2018 at 20:06 0 comments

    The new PCBs have arrived! The rest of the components should be delivered by next week 

    The silkscreen on the coil traces looks a little crappy but its my fault for not checking the manufacturer's print resolution. 

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Discussions

Moldovanu Ionut wrote 01/26/2018 at 10:22 point

Hello , can you please release the pcb design files , or just draw a schematic of the coils and all the details?

  Are you sure? yes | no

Carl Bugeja wrote 02/07/2018 at 22:56 point

Hi! The files are now available for download

  Are you sure? yes | no

oshpark wrote 01/26/2018 at 05:38 point

great idea!

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Carl Bugeja wrote 01/27/2018 at 06:59 point

Thanks :)

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Robert Mateja wrote 01/25/2018 at 09:04 point

I that HP MultiJet material or your own print for black rotor ?

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Carl Bugeja wrote 01/25/2018 at 11:26 point

Hi i have 3d printed from shapeways

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agarner3 wrote 01/25/2018 at 07:37 point

This is such a great idea. I agree it would work better with a different stator/magnet configuration. It would be interesting to see how torque and kv would be affected with different thickness traces. And how much more output and balance you could achieve with two magnet sets sandwiching the stator. 

I can see a revolution in quad copters coming on. It would be amazing to see this on the crazyflie (open source)  quad

  Are you sure? yes | no

Carl Bugeja wrote 01/25/2018 at 11:30 point

Sure :) a rotor combined with propeller is coming soon

  Are you sure? yes | no

Thomas Daede wrote 01/25/2018 at 04:07 point

This is neat! I would like to try to build my own, and also have some things I'd like to try to improve the design:
Most axial flux motors have magnets on both sides of the stator. The purpose of this is to not just to fit in more magnet, but to make sure all of the magnetic flux passes perpendicularly through the stator - with your current design, some of it wraps around the magnets and doesn't even make it through the PCB. Likewise, on the rotors behind the magnets is iron, to complete the magnetic circuit and get better utilization of the magnets. Iron-filled plastic could substitute here, though it's less important and just using beefier magnets might also be OK.

The downside of facing rotors is there is a huge amount of force between them. You'll either need strong 3D printed parts, or attach them on the outer diameter, running the wires through a non-rotating axle.
For bigger motors, you can get a better winding factor with an 8/9 or 10/12 arrangement. If you don't already know about it, there's a nice winding calculator here: https://www.emetor.com/edit/windings/

Note that coreless axial flux motors like this can be quite efficient. You might find some inspiration from the CSIRO design often used by solar cars. http://www.ata.org.au/wp-content/uploads/marand_high_efficiency_motor.pdf

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Carl Bugeja wrote 01/25/2018 at 17:42 point

Hi Thomas! Thanks for the tips! For the second prototype I have order semicircular magnets so that all magnetic flux pass through the stator, just like you suggested :) stay tuned for the update

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adria.junyent-ferre wrote 01/29/2018 at 09:02 point

Excellent feedback. Btw, I tried the iron-filled plastic myself  some time ago when I wanted to make a linear actuator with 3d-printed parts and the results were quite disappointing. The effective permeability one gets ends up being around 2, which is quite disappointing (https://hackaday.io/project/11082-measuring-blackmagic3ds-ferromagnetic-filament).

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Daren Schwenke wrote 01/24/2018 at 21:57 point

Thin out your rotor and add a second stator above.  Gives you your second bearing mount, doubles your output torque, and will probably be more stable as both sides will push/pull the rotor at the same time.

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Carl Bugeja wrote 01/25/2018 at 17:36 point

Hi Daren cool idea! I would consider adding another rotor to have magnets on both sides rather than adding another stator. This will definitely help increase the torque,  

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Daren Schwenke wrote 01/25/2018 at 18:11 point

Torque comes from flux density.  There are a couple ways to increase that. 

Simplest way is to use a core material.  This compresses your field lines for your electromagnet yielding higher flux density, at the expense of additional inductance.  But that doesn't really fit here.

Next simplest would be to compress/redirect the field lines from your permanent magnets back towards your electromagnets.  This is usually accomplished by backing them with iron. A washer or the bell from a fridge magnet might do it.

So where I was going with the second stator is related to the latter.  Besides doubling the flux density of the electromagnets, you are also confining the stray back field lines from your rotor magnets.  Of course I could be full of it, but it works in my head..

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CWC wrote 01/24/2018 at 21:42 point

Hello Carl. Congratulations on your excellent work! Please let us know if you plan to sell your motors. I like the idea of putting the stator on the ESC PCB.

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Carl Bugeja wrote 01/25/2018 at 11:32 point

Hi :) i will release open source parts very soon so you can build your own

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spillikinaerospace wrote 01/24/2018 at 21:26 point

Hi Carl excellent work! one question: why didn't you make the rotor from a PCB? it seems to me that would be better than 3d printing.

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Prof. Fartsparkle wrote 01/24/2018 at 21:30 point

Good question, I mean air flow would be an obvious reason but at this stage I doubt that would be much of an issue.

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Carl Bugeja wrote 01/24/2018 at 21:33 point

Hi! the rotor needs to hold the magnets in place that's why its 3d-printed. But make a pcb on top of the rotor is certainly possible. The only problem would be passing signals and giving power to that board.. But with a little imagination I think it can be solved :)

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alexwhittemore wrote 01/24/2018 at 22:53 point

This was my question as well. I think what he means is to pocket-mill recesses in a similarly sized PCB to fit the magnets, making a roughly equivalent structure from FR4 instead of plastic. An FR4 magnet carrier would ultimately be stronger than the plastic version, and practical to fabricate since it doesn't require any complicated 3D geometry, only standard controlled-depth milling. And really, you wouldn't necessarily need that either - you could use through-routes on one PCB and leave it at that with the magnets glued in by the sides, or glue the milled PCB to a flat one of the same diameter to make fake pocket mills. Making such a through-milled magnet carrier would also enable Daren's idea above of adding a second stator to double torque. 

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Carl Bugeja wrote 01/25/2018 at 17:29 point

The problem with a pcb rotor is actually keeping the magnets in place .. its certainly possible to have them press fitted inside but having the rotor spinning at high speed it would be safer to have a cover over them.. 

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Sean Weppner wrote 01/24/2018 at 21:13 point

Would be cool to see this type of approach applied to creating a micro linear actuator

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Carl Bugeja wrote 01/24/2018 at 21:38 point

Hi Sean a micro linear actuator seems feasible with this technology.. However it would have a weak torque since it don't have a metalic core.

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eekster wrote 01/24/2018 at 19:08 point

I'll buy ten of them! That or make the cad files and bill of materials available, perhaps? Please?

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openube wrote 01/24/2018 at 21:23 point

I second this. I'll buy or BOM please?

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Carl Bugeja wrote 01/24/2018 at 21:41 point

Hi! Thanks for your kind comments :)  I think I will eventually open source this design.. It just needs a little more testing

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ActualDragon wrote 01/23/2018 at 23:32 point

It almost needs another row of headers on the other side, just for support. It might be helpful

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Carl Bugeja wrote 01/24/2018 at 06:59 point

Hi 🙂 the headers are just a temporary solution. My plan is to put the stator on the esc pcb. 

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Carl Bugeja wrote 01/24/2018 at 07:02 point

This would make the whole setup light and more compact

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ActualDragon wrote 01/24/2018 at 10:50 point

could you put the headers on the other side, then slide the esc under and solder it? that would be sweet

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malvasio.christophe wrote 01/23/2018 at 09:44 point

can you make a coil that the rotor will rotate in the opposite direction with gears

to generate electricity from interaction of rotors : how much ? how far can you go if you add it to the pcb ?

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Jarrett wrote 01/22/2018 at 22:06 point

Woah. Do you have more pictures of the PCB?

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Carl Bugeja wrote 01/22/2018 at 22:10 point

Sure :) 

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