The rotor of a brushless DC motor is composed of a permanent magnet with a certain number of poles embedded in the surface of the core or embedded inside the core. The permanent magnets are mostly made of rare earth permanent magnet materials with high coercivity such as neodymium iron boron and high permeability magnetic induction density. The permanent magnet of this rotor acts similarly to the permanent magnet used in brushed motors, creating a sufficient magnetic field in the air gap of the motor, the difference being that the permanent magnet in the brushless DC motor is mounted on the rotor. Above, the magnetic steel of the brush motor is mounted on the stator. The rotor structure of the brushless DC motor mostly adopts a surface-adhesive magnetic pole, which is also called a tile-shaped magnetic pole. The surface-adhesive magnetic pole is a radial magnetized tile-type rare earth permanent magnet attached to the outer surface of the iron core, and the air gap magnetic flux density in the square wave form can be obtained by rational design.