A brushless DC motor (BLDC) is a synchronous electric motor which is powered by direct-current electricity (DC) and which has an electronically controlled commutation system, instead of a mechanical commutation system comprisingbrushes and a commutator. In such motors, current and torque, voltage and rpm are linearly related.
Two types:

• The stepper motor type may have more poles on the stator (fixed permanent magnet).
• The reluctance motor. This may not have permanent magnets, just salient poles that are pulled into alignment by timed stator drive.

In a conventional (brushed) DC motor, brushes (usually made of graphite, but metal in some of the smallest motors) are under spring tension; they rest on the commutator), which is nearly always a cylindrical assembly of insulated copper bars parallel to the shaft. This is a long-life rotary switch; it connects the DC electrical source to the armature coil-windings. As the armature rotates on axis, the stationary brushes come into contact with different sections of the rotating commutator, thereby switching in different sections of the rotor winding. The part of the rotor winding that receives power at any given instant is always "misaligned" with the stator poles, and magnetic attraction makes the rotor turn. (These motors are also made to run on regular AC power, as well; such motors are found in vacuum cleaners or traditional electric handheld power tools and sewing machines, for instance. They are typically noisy and run faster than induction motors.)
In a BLDC motor, the electromagnets do not move; instead, the permanent magnets rotate and the armature remains static. This gets around the problem of how to transfer current to a moving armature. In order to do this, the brush-system/commutator assembly is replaced by an electronic controller. The controller performs the same timed power distribution found in a brushed DC motor, but using a solid-state circuit rather than a commutator/brush system.