Brushed V's Brushless Motors

[katch]

Has anyone done back to back testing of the two ?

Whats the physical construction difference internally ?

[R9000]

I don't know how much you know to start with, so I guess I'll start from basics? Brushed motors have two carbon brushes which contact a commutator. This commutator switches the direction of the current flow every part-turn so that the motor can be powered by DC and keeps rotating in the same direction. The brushes act as a way to transfer current from the stationary stator of the motor, to the rotating coil of the motor, which is connected to the output shaft. The electromagnetic field induced in the coil repels the permanent magnets in the stator and thus the shaft rotates.

Brushless motors however, do not have brushes contacting the rotor, therefore rotation is achieved by stationary electromagnetic coils repelling permanent magnets on the rotor. However, this means that, since there's no commutator, the polarity of these coils needs to be switched by some external device to keep the motor running in the same direction, and that's where a brushless ESC comes in, which powers each coil with a certain timing (not sure on the specifics of that, but some motors have rotational sensors to help out).

Power-wise, it seems the consensus that brushless motors are more powerful and require less maintenance than brushed motors, since they have no carbon brushes scraping against the commutator (which eventually erode away in brushed motors). However, brushed motors apparently have much better low-speed control, and have more consistent torque behaviour, whereas brushless depend a great deal on the ESC.
That's all I know from memory, hopefully it's accurate. :P

[shakesc]

A bit of testing on http://www.fightingrobots.co.uk/thre...highlight=olaf

Olaf was originally speed 900's

[katch]

That makes much more sense now, as i have never seen a brushless i was coming up with lots of ideas in my mind to see how it might work, but wasn't going to buy one to find out at this stage ! .. That explanation makes perfect sense, so thank you .

Looking at firmware for a motor is over my head, its very clever though !