The motor from a 3.5″ floppy disk drive. The coils, arranged radially, are made from copper wire coated with blue insulation. The balanced rotor (upper right) has been taken out and switched upside-down. The grey ring inside its glass is a long lasting magnet.
A brushless DC electrical motor (BLDC motor or BL motor), also known as electronically commutated motor (ECM or EC engine) and synchronous DC motors, are synchronous motors powered by DC electrical power via an inverter or switching power which generates an AC electric current to drive each phase of the motor with a closed loop controller. The controller provides pulses of current to the motor windings that control the velocity and torque of the engine.
The construction of a brushless engine system is typically similar to a long term magnet synchronous electric motor (PMSM), but may also be a switched reluctance engine, or an induction (asynchronous) motor.
The benefits of a brushless electric motor over brushed motors are high power to weight ratio, high speed, electronic control, and lower maintenance. Brushless motors discover applications in such places as pc peripherals (disk drives, printers), hand-held power tools, and vehicles which range from model aircraft to automobiles.
In a typical DC motor, there are permanent magnets externally and a spinning armature on the inside. The long term magnets are stationary, so they are known as the stator. The armature rotates, so that it is named the rotor.
The armature contains an electromagnet. When you operate electricity into this electromagnet, it creates 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 change the poles of the electromagnet. The brushes deal with this alter in polarity. They make contact with two spinning electrodes attached to the armature and flip the magnetic polarity of the electromagnet since it spins.
his setup works and is simple and cheap to produce, 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 center of the motor makes it harder to cool.
The usage 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 engine (BLDC), you put the long lasting magnets on the rotor and you move the electromagnets to the stator. Then you use a computer (linked to high-power transistors) to replenish the electromagnets as the shaft turns. This system has all sorts of advantages:
Because a computer settings the motor instead of mechanical brushes, it’s more precise. The computer can also factor the acceleration of the motor in to the equation. This makes brushless motors more efficient.
There is no sparking and much less electrical noise.
There are no brushes to wear out.
With the electromagnets on the stator, they are extremely easy to cool.
You can have a whole lot of electromagnets on the stator for more precise control.
The only disadvantage of a brushless engine is its higher initial cost, nevertheless, you could recover that cost through the greater Conveyor Chain efficiency over the life of the motor.