Brushless DC motors (BLDC motors) are electronically commutated motors. They have synchronous operation, their rotational velocity being aligned with the frequency of the drive current. Although called DC, the motor is powered by an integrated inverting power supply that generates AC waveforms to energize the motor windings. These waveforms steer current with the correct timing so as to cause commutation. Rotational velocity of the motor is an integer proportionate to the AC frequency presented to the motor windings. Feedback sensors control the power supply drive current in order to set the motor speed under varying torque conditions. Contactless operation provides brushless DC motors longer mean time to breakdown and failure (MTBF) over brushed alternatives.  They are quieter and use less power.

Brushless DC motors are typically configured to have two coils energized at any particular time, one repulsing and the other attracting. Hall effect sensors or rotary encoders are usually used to determine which coils need to be energized at any particular time to generate motion. Back electromagnetic force (BEMF) can be monitored on the non-energized coils to sense rotor position with additional complexity in the control circuit to handle starting and stall conditions. BEMF voltage levels are proportional to the rate of change of the magnetic field. Low levels on startup and stalling conditions can lead to control errors. If this is not handled the motor can commence spinning in the wrong direction.

Three Phase (6 step) Brushless DC Motors are common type of BLDC Motor. They are controlled in 60 degrees steps around a full circle with waveforms that can be generated by simple logic circuits. Two out of three windings are energized at any one time to create motion. Motor Windings are configured in either star or delta topology. Star or Delta describes how the windings connect.