using a brushless motor for a project

Projects General Guidance
1

hello

I am currently planning a 3d POV display.
At the moment I am stuck at what motor I should use. I need at least 1800rpm - but not more than 2500 because of instability.
I need a powerfull enough motor that has the correct torque at the same time.
So far I havnt found any matching brushed dc motor - some are spinning to fast - ohters are too weak. (need good bearings bulid in)

My other solution would be a brushless motor. I would control it with an rc ESC together with an 555 or an Arduino (would be no problem).
But my main conecrn is, that allmost all brushless motors need ALOT of current - I dont need more than 50W of constant power.
My Power supply will be 9V.
I am afraid that the brushless motor will have too less torque when running at 2000rpm.

Are there any brushless motors which are suitable for me? I have looked almost everywhere and all these brushless rc motors take 20A and up

  • I dont want to lift my 3dpov up - it just needs to spin fast enough.

I have also found out that the "kv" rating belongs to RPMs per Volt so woth a 9V power supply I need a small 200kv brushless motor with not more than 70W power output.
If you know a place where I can gat something like that or any alternative - I would be really happy!

By the way:
An Atmega328 is sitting in the spinning 3DPOV. It uses a hall effect sensor to sync.
It has build in different features, which i want to switch while running.
As far I am planning to vary the RPMs to tell the arduino which programm he has to run.

Best regards,
Max

2

The R/C world of brushless DC motors come in all sizes, current ratings, speed (Kv (rpm/v)) ratings and can be controlled easily with a matching ESC which will emulate a servo input.

3

Have you thought about using a gearbox to drop one of the available cheap motors into your speed/torque range?

4

thx great links
but I still cant find any 200kv motor that is not above 50A peak current.
Almost all small motors have 1000 and above kv rating
and the bigger and stronger the kv sinks whilte the current rises.

5

mzure:
thx great links
but I still cant find any 200kv motor that is not above 50A peak current.
Almost all small motors have 1000 and above kv rating
and the bigger and stronger the kv sinks whilte the current rises.

Many R/C applications requiring gearing or belt drive pully (helicopers for one) to better match load to avalible motors, perhaps you also need to consider that. Does complicate the task that is for sure.

6

Another option is to wind your own motor, there are some great guides on rcgroups on how to do that and calculators to work out the final result specs...

I recently re-wound two 370 size brushless motors to make them suit my needs... intimidating at first, but you can't argue with the results...