The electric motor from a 3.5″ floppy disk drive. The coils, arranged Conveyor Chain radially, are made from copper wire covered with blue insulation. The well balanced rotor (upper correct) has been removed and switched upside-down. The grey ring inside its cup is a long lasting magnet.
A brushless DC electrical motor (BLDC motor or BL electric motor), also referred to as electronically commutated motor (ECM or EC motor) and synchronous DC motors, are synchronous motors powered by DC electrical power via an inverter or switching power which generates an AC electric energy to drive each phase of the motor via a closed loop controller. The controller provides pulses of current to the engine windings that control the speed and torque of the engine.
The construction of a brushless motor system is normally similar to a long lasting magnet synchronous motor (PMSM), but may also be a switched reluctance electric motor, or an induction (asynchronous) motor.
The benefits of a brushless motor over brushed motors are high power to weight ratio, high speed, electronic control, and lower maintenance. Brushless motors find applications in such places as computer peripherals (disk drives, printers), hand-held power tools, and vehicles ranging from model aircraft to automobiles.
In an average DC electric motor, there are long lasting magnets on the outside and a spinning armature on the inside. The long term magnets are stationary, so they are known as the stator. The armature rotates, so it is named the rotor.
The armature contains an electromagnet. When you run electricity 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 keep it spinning, you have to change the poles of the electromagnet. The brushes handle this change 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 easy and cheap to manufacture, but it includes 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 engine.
Having the electromagnet in the center of the motor helps it be harder to cool.
The utilization of brushes puts a limit on how many poles the armature can have.
With the advent of cheap computers and power transistors, it became possible to “turn the engine inside out” and eliminate the brushes. In a brushless DC motor (BLDC), you put the long term magnets on the rotor and you move the electromagnets to the stator. Then you use a computer (connected to high-power transistors) to replenish the electromagnets as the shaft turns. This technique has all sorts of advantages:
Because a computer settings the motor rather than mechanical brushes, it’s more precise. The computer can also factor the swiftness of the motor into the equation. This makes brushless motors better.
There is absolutely no sparking and much less electrical noise.
There are no brushes to wear out.
With the electromagnets on the stator, they are very 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, nevertheless, you can often recover that cost through the higher efficiency over the life span of the motor.