Why do you call it an AC Brushless motor and not a DC Brushless ?

 

 

 

An AC brushless motor is giving a sinusoidal EMF when turned around and we control it by sending a sinusoidal current waveform to the motor.

A DC brushless is a brushless motor optimized for "6 step control" which means that you only apply either 100% positive, 0% or 100% negative current to each phase. This will give 6 steps per revolution if it is a 2 pole motor. The EMF from such a motor is close to a square wave.