Definition and application fields of permanent magnet motor and NdFeB magnetic tile

The definitions and application areas of permanent magnet motors and NdFeB magnets are as follows:

1. Permanent magnet motors are divided into permanent magnet DC motors and permanent magnet AC motors.
   1.1. Permanent magnet AC motor refers to a polyphase synchronous motor with a permanent magnet rotor. In the past, ferrite and alnico magnetic tiles were mainly used. With the increasing power requirements, ferrite and alnico magnetic energy The product is low and cannot meet the requirements. Now NdFeB magnetic tiles are widely used in the field of high-power synchronous motors and generators. Of course, due to the precious rare earth resources, the price of raw materials for NdFeB magnetic tiles has doubled, and its manufacturing cost and production price will continue to increase in the future, affecting its many applications in some low-end fields. The negative temperature coefficient and low Curie temperature of NdFeB permanent magnets also restrict their use in high temperature applications.
   1.2. Permanent magnet DC motors are divided into brushless motors and general DC motors with commutators. The application occasions are judged from the shape of the magnet and the number of poles. In general DC motors, most of them are 2-pole and 4-pole, and magnetic tiles are basically used as motor stators. Most of the miniature DC motors use ferrite magnetic tiles, which are mainly used in toys, home appliances, and cars. When a brushless motor uses a magnetic tile as a stator, it generally exceeds 6 poles, so its central angle is much smaller than that of a general DC motor. However, when the magnetic tile is used as the rotor of the brushless motor, it can have more than 4 or 6 poles. For 4 poles, the outer surface of the rotor is magnetized, and because it has to be assembled into a circle, its central angle is close to 90°. One point can be different from the general DC motor.
2. The magnetic tile has different requirements for performance and magnetic field waveform depending on the application scope. As a rotor category, its outer arc surface field has high requirements, and the basic waveform requirement is sine wave. As a stator, it depends on the output requirements of the motor, spark and The magnetic tile used as the stator has a high inner arc surface field. Due to the shape and production characteristics of the magnetic tile itself, its waveform is mainly saddle-shaped. This type of waveform has a large output, but spark noise and no-load current. big. In order to improve vibration noise, commutation sparks, and reduce no-load current, the shape and size of magnetic steel and mold design must be carefully designed. Among them, magnetic tiles with different thicknesses have been widely used. The principle is to make the arc gas inside the magnetic tile. The waveform of the gap magnetic field tends to be flat-topped.