How Are Motors Classified?

1. By Type of Working Power Supply

Motors can be divided into DC motors and AC motors according to the type of working power supply. DC motors can be classified by structure and working principle into: brushless DC motors and brushed DC motors. Brushed DC motors can be further divided into: permanent magnet DC motors and electromagnetic DC motors. Electromagnetic DC motors are subdivided into series-excited DC motors, shunt-excited DC motors, separately excited DC motors and compound-excited DC motors. Permanent magnet DC motors are subdivided into rare earth permanent magnet DC motors, ferrite permanent magnet DC motors and AlNiCo permanent magnet DC motors. AC motors can also be divided into single-phase motors and three-phase motors.

2. By Structure and Working Principle

According to structure and working principle, motors can be divided into DC motors, asynchronous motors and synchronous motors. Synchronous motors can be classified into permanent magnet synchronous motors, reluctance synchronous motors and hysteresis synchronous motors. Asynchronous motors can be divided into induction motors and AC commutator motors. Induction motors can be subdivided into three-phase asynchronous motors, single-phase asynchronous motors and shaded-pole asynchronous motors, etc. AC commutator motors can be subdivided into single-phase series-excited motors, AC-DC dual-purpose motors and repulsion motors.

3. By Starting and Operation Mode

According to the starting and operation mode, motors can be divided into capacitor-start single-phase asynchronous motors, capacitor-run single-phase asynchronous motors, capacitor-start and run single-phase asynchronous motors and split-phase single-phase asynchronous motors.

4. By Application

According to application, motors can be divided into drive motors and control motors. Drive motors can be classified into motors for electric tools (including drilling, polishing, grinding, grooving, cutting, reaming and other tools), motors for household appliances (including washing machines, electric fans, refrigerators, air conditioners, tape recorders, video recorders, DVD players, vacuum cleaners, cameras, hair dryers, electric shavers, etc.) and motors for other general small mechanical equipment (including various small machine tools, small machinery, medical equipment, electronic instruments, etc.). Control motors can be further divided into stepping motors and servo motors, etc.

5. By Rotor Structure

According to the rotor structure, motors can be divided into squirrel-cage induction motors and wound-rotor induction motors.

6. By Rotational Speed

According to the operating speed, motors can be divided into high-speed motors, low-speed motors, constant-speed motors and variable-speed motors. Low-speed motors are further divided into gear reduction motors, electromagnetic reduction motors, torque motors and claw-pole synchronous motors, etc.

In addition to being divided into stepped constant-speed motors, stepless constant-speed motors, stepped variable-speed motors and stepless variable-speed motors, variable-speed motors can also be divided into electromagnetic variable-speed motors, DC variable-speed motors, PWM frequency conversion variable-speed motors and switched reluctance variable-speed motors.

The rotor speed of an asynchronous motor is always slightly lower than the synchronous speed of the rotating magnetic field. The rotor speed of a synchronous motor is always maintained at the synchronous speed regardless of the load size.