source for tiny, brushless, low rpm motors with integrated commutation
- I am looking for a tiny, DC, brushless motor with integrated commutation (speed controller integrated, maybe with a PWM speed control signal to the controller) and good starting torque for low rpm.
I have played with a 15mm diameter, 5V brushless dc fan (made by ADDA but intended to cool electronics). The commutation is integrated but it is simple. I haven't torn it apart yet, but I suspect the windings are just one coil, with Y shaped metal yokes, like larger PC fans. It doesn't start very well at low voltage (2.8V) and high loads.
I know there are motors for RC helicopters about this size, with 3 pole windings, but I don't see one with integrated electronics, all requiring an ESC electronic speed control, and intended for higher voltages, say 6V, and higher rpm's. I know it is just a matter of packaging the two together, but is there one already out there? And will it have good starting torque?
Also, should I look for stepper motors, with many more poles? I suppose they might have higher starting torque. I am aware of the tiny stepper motors in DVD sled controls, but it seems like those also have one coil (with magnetic poles shaped by metal yokes) and thus not have much starting torque.
I am designing for solar power harvesting that can output a max of 5V, using super caps with a max of 5V. And I don't want to use gearing to lower the rpm's unless it is necessary. I'm looking for ultra reliability, and I don't think gears will have that.