[amit.som]

Hi All, It is general query. Is there any reason why single phase BLDC motor is not used for quadcopter ?

[crof2003]

Ive been watching this topic to see what the answer is.

My question to you: why would you want to use a single phase motor?

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[amit.som]

I think my answer would be I can manage to run BLDC motor with simple ESC, I do not need to switch on and off 6 switches (for three phase BLDC motor) and at same time I get efficient motor.

[crof2003]

I think the real answer is we dont use single phase motors is because none of the available motors are single phase.

I had looked this up after my first post and it really looks like generally single phase motors are heavier due to their need for more copper and are less efficient overall - both characteristics we dont want in quad motors.

This conclusion came from just a little bit of internet research, so i very well could be wrong about this.

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[TheOtherCliff]

Well for one thing, with less than three phases you (the ESC firmware) can't tell if it is running forward or backwards. 

Also, if it stops in the wrong place, you can't start it, or have a harder time starting it at least.

Also, just like an 8 cylinder automobile motor gives power throughout the cycle and doesn't require as much flywheel to keep it moving, a multi-phase BLDC motor gives power throughout the cycle rather than all here and then coast a while.