1. Advantages of BLDC:
BLDC does not use the commutation brush of the mechanical structure but directly uses the electronic commutator. In use, BLDC has many advantages compared with the brushed motor, such as:

Can obtain better torque and speed characteristics; high-speed dynamic response; high efficiency; long life; low noise; high speed.

In addition, BLDC's better torque and size ratio makes it more suitable for applications that are sensitive to the weight and size of the motor. In this application note, a series of discussions will be made on the structure, basic principles, characteristics and applications of BLDC. The terms that may be used in the discussion can be explained in Appendix B "Glossary".

2. BLDC structure and basic working principle:
BLDC is a kind of synchronous motor, which means that the magnetic field generated by its stator and the magnetic field generated by the rotor are at the same frequency, so BLDC does not produce the frequency difference phenomenon of ordinary induction motors. In BLDC, there are differences between single-phase, 2-phase and 3-phase motors. The difference in phase type determines the number of stator coil windings. Here we will focus on the most widely used 3-phase BLDC.

2.1 Stator:
The BLDC stator is made by laminating and axially stamping many silicon steel sheets. In each slot, there are certain coils to form the windings, as shown in the figure below. In the traditional sense, the BLDC stator and induction motor stator are somewhat similar, but there are certain differences in the distribution of the stator windings. Most BLDC stators have 3 windings arranged in a star row, and each winding is composed of many internally combined steel sheets in a certain way. Even number of windings are distributed around the stator to form an even number of magnetic poles.