1.1 Classification of motors 1.1 Divided by working power: DC motors and AC motors DC motors are divided by 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. Permanent magnet DC motor is divided into: rare earth permanent magnet DC motor, ferrite permanent magnet DC motor and AlNiCo permanent magnet DC motor. Electromagnetic DC motors can be divided into: series-excited DC motors, shunt-excited DC motors, separately-excited DC motors and compound-excited DC motors. AC motors can also be divided into: single-phase motors and three-phase motors. 1.2 According to the structure and working principle: it can be divided into DC motor, asynchronous motor, synchronous motor Synchronous motor can be divided into: permanent magnet synchronous motor, reluctance synchronous motor and hysteresis synchronous motor. 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 motors, AC and DC motors and repulsion motors. 1.3 Divided by starting and running mode: 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. Divided by use: drive motor and control motor. Motors for driving: motors for power tools (including tools for drilling, polishing, polishing, grooving, cutting, reaming, etc.), home appliances (including washing machines, electric fans, refrigerators, air conditioners, tape recorders, video recorders, and DVD players) , vacuum cleaners, cameras, hair dryers, electric shavers, etc.) and other general small mechanical equipment (including various small machine tools, small machinery, medical equipment, electronic instruments, etc.) with motors. Control motors are divided into: stepper motors and servo motors. According to the structure of the rotor: squirrel induction motor (the old standard is called squirrel cage asynchronous motor) and wound rotor induction motor (the old standard is called wound asynchronous motor). Divided by operating speed: high-speed motor, low-speed motor, constant-speed motor, speed-regulated motor. Low-speed motors are further divided into gear reduction motors, electromagnetic reduction motors, torque motors and claw-pole synchronous motors. In addition to the stepless constant speed motor, the stepless constant speed motor, the stepless variable speed motor and the stepless variable speed motor, the speed regulating motor can also be divided into the electromagnetic speed regulating motor, the DC speed regulating motor, the PWM variable frequency speed regulating motor and the Switched reluctance 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 a synchronous motor is always maintained at a synchronous speed irrespective of the size of the load. Note: 2-pole motor speed 3000 rpm 4-pole motor speed 1500 rpm/min 6-pole motor speed 1000 rpm/min 8-pole motor speed 750 rpm Most small and medium-sized motors with oil-impregnated bearings use rolling bearings. At present, large and medium-sized motors also use rolling bearings. Rolling bearings are divided into deep groove ball bearings, self-aligning ball bearings, cylindrical roller bearings, self-aligning roller bearings, helical roller bearings, angular contact ball bearings, tapered roller bearings, thrust ball bearings, thrust self-aligning roller bearings. Commonly used rolling bearings for motors are deep groove ball bearings, cylindrical roller bearings, spherical roller bearings, and angular contact ball bearings. The bearings at both ends of the small motor use SKF deep groove ball bearings, the medium motor uses roller bearings at the load end (generally used in high-load conditions), and the non-load end uses ball bearings (but there are opposite cases, such as 1050kW motors). There are also small motors that use angular contact ball bearings and large motors that use spherical roller bearings. Motor bearing classification NSK motor bearing performance requirements require no abnormal noise, low vibration, low noise and low temperature rise. No abnormal sound is the requirement that the bearing has no abnormal sound caused by sliding friction. Generally, after installation, no-load operation is required, and there is no abnormal sound outside the electromagnetic sound and wind sound. Vibration and noise are the requirements for the bearing itself. After installation, the vibration value of the whole machine should also be checked to meet the factory requirements. The vibration and noise values u200bu200bof the bearing itself are specified in national or industry standards. Vibration is divided into velocity vibration level V, acceleration vibration level Z (expressed in decibels).