Motor (English: Electric machinery, commonly known as “motor”) refers to an electromagnetic device that realizes the conversion or transmission of electrical energy according to the law of electromagnetic induction. The motor is represented by the letter M (D in the old standard) in the circuit, and its main function is to generate driving torque. As the power source of electrical appliances or various machines, the motor is represented by the letter G in the circuit, and its main function is to convert mechanical energy into electrical energy. How to divide the motor: 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. Brushed DC motors can be divided into permanent magnet DC motors and electromagnetic DC motors. Electromagnetic division: series excitation DC motor, parallel excitation DC motor, shunt excitation DC motor, compound excitation DC motor. DC motor permanent magnets are divided into rare earth permanent magnet DC motors, ferrite permanent magnet DC motors, and AlNiCo permanent magnet DC motors. 2) AC motors can 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. 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 excitation motors, AC-DC dual-purpose motors and repulsion motors. 3. According to the starting and running mode, it can be divided into capacitor-started single-phase asynchronous motor, capacitor-run single-phase asynchronous motor, capacitor-started single-phase asynchronous motor and split-phase single-phase asynchronous motor. 4. According to the application, it can be divided into drive motor and control motor. 1) Drive motors can be divided into: motors for power tools (including drilling, polishing, 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.) with motors. ) and other general small mechanical equipment (including various small machine tools, small machines, etc.) 2) The control motor is divided into stepper motor and servo motor. 5. According to the rotor structure, it can be divided into cage induction motor (the old standard called squirrel cage induction motor) and wound rotor induction motor (the old standard called wound asynchronous motor). 6. According to the running speed, it can be divided into high-speed motor, low-speed motor, constant-speed motor and speed-regulating motor. Low-speed motors are divided into gear reduction motors, electromagnetic reduction motors, torque motors and claw-pole synchronous motors. In addition to the stepped fixed speed motor, the stepless fixed speed motor, the stepped variable speed motor, and the continuously variable speed motor, the speed regulating motor can also be divided into electromagnetic speed regulating motor, DC speed regulating motor, PWM variable frequency speed regulating motor, switched reluctance motor. Speed ​​motor. The rotor speed of an asynchronous motor is always slightly lower than the synchronous speed of the rotating magnetic field. The rotor speed of the synchronous motor is independent of the load and always maintains the synchronous speed.