All motors are composed of stator and rotor. In order to make the rotor rotate, it is necessary to constantly change the current direction, otherwise the rotor can only rotate half a turn, which is like a bicycle pedal. Therefore, DC motor needs commutator. The generalized DC motor includes brushless motor and brushless motor. Brush motor is also known as DC motor or carbon brush motor. The often said DC motor refers to DC brush motor. It adopts mechanical commutation. The external magnetic pole does not move, the internal coil (armature) moves, the commutator and rotor coil rotate together, and the brush and magnet do not move. Therefore, the commutator rubs and completes the switching of current direction.

Brushless motor is also called DC variable frequency motor (BLDC) in some fields. It adopts motor commutator, the coil (armature) does not move, and the magnetic pole moves. At this time, the permanent magnet can be outside or inside the coil. Therefore, there are outer rotor brushless motor and inner rotor brushless motor. However, a brushless motor is not a complete power system. The brushless motor can operate continuously only through the brushless controller, that is, the control of electric regulation. It is the brushless electronic governor that really determines its performance.

There are two kinds of general brushless motor drive motors, one is square wave, the other is sine wave. Sometimes the former is called a brushless DC motor, and the latter is called an AC servo motor, which is exactly a kind of AC servo motor. Brushless motor has different operation modes, which can be divided into inner rotor brushless motor and outer rotor brushless motor. The inner rotor is three-phase and the price is expensive. The outer rotor is usually single-phase and the price is close to the people. The mass production has been close to the carbon brush motor. Therefore, it has been widely used in recent years. The price of the three-phase of the outer rotor is close to the price of the wind rotor.