Electric motor (English: Electricmachinery, commonly known as " motor ") refers to an electromagnetic device that realizes electrical energy conversion or transmission according to the law of electromagnetic induction.

The motor is represented by the letter M (D in the old standard) in the circuit . Its main function is to generate driving torque as a power source for electrical appliances or various machines. The generator is represented by the letter G in the circuit. Its main function is to convert mechanical energy into electrical energy.

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 into brushless DC motors and brushed DC motors according to their structure and working principle.

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

2. 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.

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 and running single-phase asynchronous motor and split-phase single-phase asynchronous motor.

4. According to the purpose, it can be divided into: drive motors and control motors.

1) Driving motors can be divided into: power tools (including drilling, polishing, grinding, grooving, cutting, reaming and other tools); household appliances (including washing machines, electric fans, refrigerators, air conditioners, tape recorders, video recorders, DVD players, vacuum cleaners, cameras, hair dryers, electric shavers, etc.); other general small mechanical equipment (including various small machine tools, small machinery, medical equipment, electronic instruments, etc.) motors.

2) Control motors are further divided into: stepper motors and servo motors, etc.

5. According to the structure of the rotor, it can be divided into: cage induction motor (called squirrel cage asynchronous motor in the old standard) and wound rotor induction motor (called wound rotor asynchronous motor in the old standard).

6. According to the running speed, it can be divided into: high-speed motor, low-speed motor, constant-speed motor, speed-regulating motor. Low-speed motor can be further divided into gear reduction motor, electromagnetic reduction motor, torque motor and claw-pole synchronous motor.

A DC motor is an electric motor that runs on a DC working voltage and is widely used in radio recorders, video recorders, DVD players, electric shavers, hair dryers, electronic watches, toys, etc.

When the power supply line is not very long, the relationship between power and wire diameter (national standard copper wire)