1. Electric motor classification

　　1. According to the type of working power supply : it can be divided into DC motor and AC motor.

　　1) DC motors can be divided according to their structure and working principle: brushless DC motors and brushed DC motors.

　　Brushed DC motors can be divided into: permanent magnet DC motors and electromagnetic DC motors.

　　Electromagnetic DC motor division: series excited DC motor, shunt excited DC motor, separately excited DC motor and compound excited DC motor.

　　Permanent magnet DC motor division: rare earth permanent magnet DC motor, ferrite permanent magnet DC motor and alnico permanent magnet DC motor.

　　2) AC motors can also be divided into: single-phase motors and three-phase motors.

　　2. It can be divided according to the structure and working principle: it can be divided into DC motor, asynchronous motor and synchronous motor.

　　1) Synchronous motors can be divided into: permanent magnet synchronous motors, reluctance synchronous motors and hysteresis synchronous motors.

　　2) Asynchronous motors can be divided into: induction motors and AC commutator motors.

　　Induction motors can be divided into three-phase asynchronous motors, single-phase asynchronous motors and shaded pole asynchronous motors.

　　AC commutator motors can be divided into: single-phase series-excited motors, AC-DC dual-purpose motors and repulsion motors.

　　3. According to the starting and running mode, it can be divided into: capacitor starting single-phase asynchronous motor, capacitor running single-phase asynchronous motor, capacitor starting running single-phase asynchronous motor and split-phase single-phase asynchronous motor.

　　2. Carbon brush motor

　　Motor carbon brushes are collectively referred to as carbon brushes of motors and carbon brushes of generators. The motor carbon brush looks a bit like the rubber strip of a pencil, with wires leading out from the top, and the size is different.

　　The role in the motor is to change the direction of the current, divided into DC motors and AC motors. The DC motor is used to change the conductive coil of the rotor, thereby changing the rotor magnetic poles, and then changing the motion of the motor. The carbon brush is used on the commutator or slip ring of the motor. As a sliding contact body that leads and imports current, it has good electrical conductivity, thermal conductivity and lubricating performance, and has a certain mechanical strength and the instinct of commutation sparks. Almost all brushed motors use carbon brushes, which are an important component of brushed motors.

　　Motor carbon brushes are suitable for all kinds of motors, generators, and axle machines. It has good reversing performance and long service life. The motor carbon brush is used on the commutator or slip ring of the motor, as a sliding contact body that leads and imports current. It has good electrical conductivity, thermal conductivity and lubricating performance, and has a certain mechanical strength and the instinct of commutation sparks. Almost all motors use carbon brushes, which are an important part of the motor. Widely used in various AC and DC generators, synchronous motors, battery DC motors, crane motor collector rings, various types of welding machines and so on. With the development of science and technology, the types of motors and the working conditions of use are becoming more and more diverse, so brushes of various grades are required to meet these requirements, so the types of brushes also change with the development of the motor industry. more and more.

　　The functions of carbon brush motors include:

　　1. Add the external current (excitation current) to the rotating rotor (input current) through the carbon brush;

　　2. Introduce the static charge on the large shaft to the ground (grounded carbon brush) through the carbon brush (output current);

　　3. Change the direction of the current (in the commutator motor, the brush also plays the role of commutation);

　　4. Lead the large shaft (ground) to the protective device for rotor grounding protection and measure the positive and negative ground voltage of the rotor.

　　The commutator is composed of brushes and commutation rings, and carbon brushes are one type of brushes. Due to the rotation of the rotor, the brushes always rub against the commutation ring, and spark erosion occurs at the moment of commutation, so the brushes are vulnerable parts in the DC motor. In order to improve the service life and operation stability of DC motors and reduce the noise and electromagnetic interference of DC motors, brushless DC motors tend to gradually replace brushed motors. Generally, AC motors do not need a constant magnetic field, so there is no need for a commutator, and there is no need for brushes; but the volume of AC motors is generally relatively large. The motors used in household appliances are generally AC motors, such as electric fans, washing machines, refrigerators, air conditioners, etc. do not have carbon brushes, but some use DC motors, such as many electric shavers, small kitchen appliances, electric bicycles, etc. have carbon brushes. Brushes are DC motors (excluding brushless ones). Motors that use dry batteries are all DC motors.