In a normal DC motor, many permanent magnets are installed on its exterior and a spinning armature in the interior. The former are stationary and are referred to as the stator. The latter rotates, so it is referred to as the rotor. The armature bears an electromagnet. So, when electricity is run through it, it establishes a magnetic field in the armature that pulls and repels the magnets in the stator. In this way, the armature spins in 180 degrees. In order to keep the spinning continuous, the poles of the electromagnet are needed to be changed. The brushes manage all the changes in polarity. They are in touch with the two spinning electrodes which are attached to the armature and they tend to flip the magnetic polarity of the electromagnet when it is spinning.
This setup is simple and cost effective to manufacture, but it comes with loads of issues like:
- The brushes tend to wear out eventually.
- As the brushes are making or breaking the connection, sparking and electrical noise is generated.
- The brushes tend to limit the max speed of the motor.
- When you have the electromagnet in the center of the motor, it makes it really hard to cool.
- When you use brushes, it limits on the number of poles the armature can have.
Nowadays the computers and power transistors made it possible to turn the motor inside out and get rid of the brushes. When it comes to a brushless DC motor or BLDC or the 24V brushless motor, you put the permanent magnets on the rotor and move the electromagnetics to the stator. Then with the help of a computer connected to high power transistor, you can charge up the electromagnets as the shaft turns.
Advantages of brushless electric motor
- It is precise in nature because the computer has full control over the motor rather than the mechanical brushes. The computer also has the ability to factor the speed of the motor into the equation. Consequently, this makes the brushless motor more efficient in nature.
- There is no kind of sparking involved and there is much less electrical noise.
- There are no kind of brushes that can wear themselves out.
- With the presence of the electromagnets on the stator, they can be easily cooled down.
- There can be many electromagnets installed on the stator when rooting for more precise control.