The motor from a 3.5″ floppy disk drive. The coils, arranged radially, are made from copper wire covered with blue insulation. The well balanced rotor (upper right) has been eliminated and switched upside-down. The grey band inside its glass is a long term magnet.
A brushless DC electrical motor (BLDC engine or BL motor), also known as electronically commutated engine (ECM or EC engine) and synchronous DC motors, are synchronous motors powered by DC electrical power via an inverter or Stainless Steel Chain switching power which creates an AC electric energy to drive each stage of the motor via a closed loop controller. The controller provides pulses of current to the engine windings that control the rate and torque of the electric motor.
The construction of a brushless electric motor system is typically similar to a long term magnet synchronous motor (PMSM), but may also be a switched reluctance electric motor, 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 find applications in such places as pc peripherals (disk drives, printers), hand-held power equipment, and vehicles which range from model aircraft to automobiles.
In an average DC engine, there are long term magnets on the outside and a spinning armature on the inside. The long lasting magnets are stationary, so they are called the stator. The armature rotates, so it is named the rotor.
The armature contains an electromagnet. When you operate electricity into this electromagnet, it generates a magnetic field in the armature that attracts and repels the magnets in the stator. So the armature spins through 180 degrees. To maintain it spinning, you need to modify the poles of the electromagnet. The brushes deal with this alter 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 produce, but it has a lot of problems:
The brushes eventually wear out.
As 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 use of brushes puts a limit on how many poles the armature can have.
With the advent of cheap computers and power transistors, it became feasible to “turn the engine inside out” and get rid of the brushes. In a brushless DC engine (BLDC), you place 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 charge up the electromagnets as the shaft turns. This system has all sorts of advantages:
Because a computer regulates the motor instead of 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 wear out.
With the electromagnets on the stator, they are very 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, but you can often recover that cost through the higher efficiency over the life span of the motor.