Brushless DC motor switches the stator and rotor of an ordinary DC motor. Its rotor produces air gap flux for permanent magnet. And the stator is an armature composed of multiphase winding. Brushless DC motor has similar structure with the permanent magnet synchronous motor.

The stator of a brushless DC motor has the same structure with a synchronous motor or induction motor. After multiple phase winding such as three-phase, four-phase, five-phase winding is embedded into the iron core, the winding can be shaped into a star or triangle, and separately connects with each power tube of the inverter so as to make reasonable commutation.

Rotor is mostly made by samarium,cobalt, neodymium, iron, boron or other rare earth materials with high coercivity and high remanence. The magnetic pole be divided into surface magnetic pole, the embedded pole and the annular magnetic poles due to the different placement of the magnetic materials in the magnetic poles. Because the motor body is a permanent magnet motor, brushless DC motor is also called permanent magnet brushless DC motor.