A brushless DC motor   (BLDC) is an AC synchronous electric motor that from a modeling perspective looks very similar to a DC motor    . Sometimes the difference is explained as an electronically controlled commutation system, instead of a mechanical commutation system, although this is misleading, as physically the two motors are completely different. (The rest of this article assumes the reader is familiar with the principles of electrical motors.)

A BLDC motor   powering a micro remote-controlled airplane. The motor is connected to a microprocessor-controlled BLDC controller. This 5-gram motor produces more thrust than twice the weight of the entire plane. Being an outrunner, the rotor-can containing the magnets spins around the coil windings on the stator.Three subtypes exist:

The three-phase AC synchronous motor type has three electrical connections

The stepper motor type may have more poles on the stator.

The reluctance motor.

In a conventional (brushed) DC motor  , the brushes make mechanical contact with a set of electrical contacts on the rotor (called the commutator), forming an electrical circuit between the DC electrical source and the armature coil-windings. As the armature rotates on axis, the stationary brushes come into contact with different sections of the rotating commutator. The commutator and brush system form a set of electrical switches, each firing in sequence, such that electrical-power always flows through the armature coil closest to the stationary stator (permanent magnet).

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 intelligent electronic controller. The controller performs the same power distribution found in a brushed DC motor  , but using a solid-state circuit rather than a commutator/brush system.

Contents [hide]

1 Comparison with brushed DC motor  s

2 Controller implementations

3 Variations on construction

4 Applications

5 Power Supplies AC vs DC

6 Model aircraft scene

7 See also

8 External links