Why Are Brushless Motors So Efficient?
In order to fully understand the functioning of a brushless motor, it may help to first examine a brushed motor. Most brushed motors are constructed with permanent magnets and an electromagnetic armature rotating within the permanent magnets. When supplied with direct current the electromagnets induce a magnetic field, which as a result, rotates the armature. With brushed motors, the brushes continuously alter the polarity of the armature causing rotation from the magnetic attraction and repulsion forces. The fundamental principles of a brushed DC motor and a brushless DC motor are very similar. Similar to a brushed motor, a brushless DC motor contains the two basic components - the rotor and the stator. But in the case of a brushless DC motor, the electromagnet portion is stationary, hence the name stator, whilst the permanent magnets are located on the rotor. Brushless DC motors (BLDC motors) when supplied with power also alternate the polarity but this time of the stationary stato