The armature contains an electromagnet. When you run electrical power into this electromagnet, it generates a magnetic field in the armature that draws in and repels the magnets in the stator. Therefore the armature spins through 180 degrees. To maintain it spinning, you have to alter the poles of the electromagnet. The brushes handle this modify in polarity. They speak to two spinning electrodes mounted on the armature and flip the magnetic polarity of the electromagnet since it spins.
his setup works and is simple and cheap to manufacture, but it has a lot of problems:
The brushes eventually wear out.
Because the brushes are making/breaking connections, you get sparking and electrical noi
The brushes limit the maximum speed of the motor.
Having the electromagnet in the heart of the motor helps it be harder to cool.
The usage of brushes puts a limit on how many poles the armature can have.
With the Auto Chain advent of cheap computers and power transistors, it became possible to “turn the engine inside out” and eliminate the brushes. In a brushless DC electric motor (BLDC), you put the long lasting magnets on the rotor and you move the electromagnets to the stator. You then use a computer (connected to high-power transistors) to charge up the electromagnets as the shaft turns. This technique has all sorts of advantages:
Because a computer regulates the motor rather than mechanical brushes, it’s more precise. The computer may also factor the speed of the motor into the equation. This makes brushless motors more efficient.
There is absolutely no sparking and much less electrical noise.
There are no brushes to degrade.
With the electromagnets on the stator, they are extremely easy to cool.
You can have a lot of electromagnets on the stator for more precise control.
The only disadvantage of a brushless engine is its higher initial cost, but you can often recover that cost through the higher efficiency over the life of the motor.