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PCB Motor

A smaller and cheaper open source brushless motor.

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My open source PCB motor is an 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.

The current prototype has a 3d printed rotor with a 16mm diameter.

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

PCB Motor V1.rar

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

  • PCB Motor with integrated ESC!

    Carl Bugeja3 days ago 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 Bugeja4 days ago 0 comments

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

    This is how it cimpares 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. 

  • PCB Motors HackChat

    Carl Bugeja08/09/2018 at 00:19 0 comments

    Next Friday there's going to be a HackChat on my PCB Motor! Join the event to ask me any questions on the project! 

    https://hackaday.io/event/160136-pcb-motors-hack-chat

  • How i came up with the idea?

    Carl Bugeja07/15/2018 at 06:23 0 comments

    This is the drone concept that gave me the idea of trying to create the PCB motor and spherical folding propeller! Both of these projects need a lot more work and improvement to make this drone feasible but at least now I have a starting point :)

  • New PCB Motor with Driver

    Carl Bugeja07/12/2018 at 23:24 1 comment

    I finally ordered a new PCB motor with an integrated ESC. I have managed to package the circuit in a very small space,  30x16mm including the stator. For now I have ordered the same star winding configuration that i've used in the first prototype. I'll be ordering more configurations soon.

    The circuit basically consists from:

     Hall Sensor (US1881) to detect the magnets inside the rotor.

    • MCU (PIC16F1503) - I have shifted from the DSPIC33EP128 to the PIC16F1503. This MCU has less computational power (not much is required since I am no longer considering sensorless control) but is packaged in 3x3mm chip and is around $2 cheaper
    • 3-Phase Motor Driver (STSPIN230) - which is rated at 1.3Arms, and has several types of fault protection build-in.
    • A filtering circuit to supply the micro.

    I will upload all the source code and gerber files once the PCB arrives and verify its functionality. Keep tuned! 

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Discussions

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

  Are you sure? yes | no

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

  Are you sure? yes | no

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).

  Are you sure? yes | no

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.

  Are you sure? yes | no

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,  

  Are you sure? yes | no

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..

  Are you sure? yes | no

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.

  Are you sure? yes | no

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.

  Are you sure? yes | no

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.

  Are you sure? yes | no

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 :)

  Are you sure? yes | no

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. 

  Are you sure? yes | no

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.. 

  Are you sure? yes | no

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

  Are you sure? yes | no

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.

  Are you sure? yes | no

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?

  Are you sure? yes | no

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

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

  Are you sure? yes | no

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

  Are you sure? yes | no

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. 

  Are you sure? yes | no

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

This would make the whole setup light and more compact

  Are you sure? yes | no

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?

  Are you sure? yes | no

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

Sure :) 

  Are you sure? yes | no

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