A smaller and cheaper open source brushless motor
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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
Open Source Files - https://github.com/CarlBugeja/PCB-Motor-v4
This video shows my attempt in trying to design a rotor-flux brushless pcb motor prototype:
How fast can my PCB Motor go?
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!
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.
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!
Its this simple:
Hi :) i will release open source parts very soon so you can build your own
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.
Good question, I mean air flow would be an obvious reason but at this stage I doubt that would be much of an issue.
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 :)
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.
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..
Would be cool to see this type of approach applied to creating a micro linear actuator
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.
I'll buy ten of them! That or make the cad files and bill of materials available, perhaps? Please?
Hi! Thanks for your kind comments :) I think I will eventually open source this design.. It just needs a little more testing
It almost needs another row of headers on the other side, just for support. It might be helpful
Hi 🙂 the headers are just a temporary solution. My plan is to put the stator on the esc pcb.
This would make the whole setup light and more compact
could you put the headers on the other side, then slide the esc under and solder it? that would be sweet
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 ?
Carl Bugeja
Jithin Sanal
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.