The electric 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 correct) has been removed and switched upside-down. The grey band inside its cup is a long term magnet.
A brushless DC electrical motor (BLDC motor or BL engine), also known as electronically commutated engine (ECM or EC electric motor) and synchronous DC motors, are synchronous motors powered by DC electricity via an inverter or switching power which produces an AC electric current 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 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 can also be a switched reluctance engine, or an induction (asynchronous) motor.
The Drive Chain advantages of a brushless engine over brushed motors are high power to weight ratio, high speed, electronic control, and lower maintenance. Brushless motors discover applications in such locations as pc 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 term magnets on the outside and a spinning armature on the inside. The permanent magnets are stationary, so they are called 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. So the armature spins through 180 degrees. To keep it spinning, you have to change the poles of the electromagnet. The brushes manage this change 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 simple and cheap to manufacture, but it has a lot of problems:
The brushes eventually wear out.
Because the brushes are producing/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 utilization of brushes puts a limit about 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 remove the brushes. In a brushless DC engine (BLDC), you place the permanent magnets on the rotor and you move the electromagnets to the stator. Then you use a computer (connected 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 rather than mechanical brushes, it’s more precise. The computer may also factor the swiftness 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 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 drawback of a brushless engine is its higher initial cost, but you could recover that cost through the higher efficiency over the life span of the motor.