The electric motor from a 3.5″ floppy disk drive. The coils, arranged radially, are manufactured from copper wire covered with blue insulation. The well balanced rotor (upper correct) has been removed and turned upside-down. The grey band inside its glass is a long lasting magnet.
A brushless DC electric motor (BLDC engine or BL engine), also referred to as electronically commutated electric motor (ECM or EC engine) and synchronous DC motors, are synchronous motors powered by DC electrical power via an inverter or switching power supply which produces an AC electric current to drive each stage of the motor with a closed loop controller. The controller provides Drive Chain pulses of current to the engine windings that control the acceleration 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 can also be a switched reluctance engine, or an induction (asynchronous) motor.
The benefits of a brushless engine over brushed motors are high capacity to weight ratio, high speed, electronic control, and lower maintenance. Brushless motors find applications in such areas as computer peripherals (disk drives, printers), hand-held power tools, and vehicles ranging from model aircraft to automobiles.
In an average DC engine, there are long lasting magnets externally and a spinning armature on the inside. The long lasting magnets are stationary, therefore they are known as the stator. The armature rotates, so that it is called the rotor.
The armature contains an electromagnet. When you run electrical power into this electromagnet, it creates a magnetic field in the armature that attracts and repels the magnets in the stator. Therefore the armature spins through 180 degrees. To keep it spinning, you need to change the poles of the electromagnet. The brushes manage this alter in polarity. They speak to two spinning electrodes mounted on the armature and flip the magnetic polarity of the electromagnet as it spins.
his setup works and is easy and cheap to produce, but it has a lot of problems:
The brushes eventually degrade.
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 heart 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 possible to “turn the electric motor inside out” and get rid of 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. Then you use a computer (connected to high-power transistors) to replenish the electromagnets as the shaft turns. This system has a variety of advantages:
Because a computer handles the motor rather than mechanical brushes, it’s more precise. The computer may also factor the quickness of the motor in to the equation. This makes brushless motors better.
There is absolutely no sparking and much less electrical noise.
There are no brushes to degrade.
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 drawback of a brushless electric motor is its higher initial cost, nevertheless, you can often recover that cost through the higher efficiency over the life of the motor.