The development of the magnetic tile is based on the needs of the permanent magnet motor itself.
1) Permanent magnet motor is divided into permanent magnet DC motor and permanent magnet AC motor.
1.1 Permanent magnet AC motor means a multiphase synchronous motor with a permanent magnet rotor. Previously, ferrite and aluminum nickel cobalt magnetic tiles were mainly used. As the power requirements become higher, ferrite and aluminum nickel cobalt can not meet the requirements due to low magnetic energy accumulation. Now neodymium ferroboron is widely used in the field of high-power synchronous motors and generators. Of course, neodymium ferroboron tile, because rare earth resources are precious, the price of raw materials has doubled, and its manufacturing costs and production prices will continue to increase in the future, affecting its large use in some low-end areas. The negative temperature coefficient and low Curie temperature of neodymium iron boron permanent magnet itself also limit its operation at high temperatures.
1.2 The permanent magnet DC motor is divided into brushless motor and ordinary DC motor with a commutator. Its application is judged from the shape and pole number of the magnet.
In ordinary DC motors, most of the 2 and 4 poles are used, and the tiles are basically used as motor stators. Most of the miniature DC motors use ferrite tiles, which are mainly used in the fields of toys, home appliances, and automobiles. When a brushless motor uses a tile as a stator, it generally exceeds 6 poles, so its center angle is much smaller than that of an ordinary DC motor. However, when the magnetic tile is used as a rotor of a brushless motor, it can have more than 4 or 6 poles. For 4 poles, the rotor is a magnetic charge on the outer surface, and because it is to be assembled into a circle, its center angle is close to 90 °. This point can be distinguished from ordinary DC motors.
2) According to the application field, the magnetic tiles have different requirements for performance and magnetic field waveforms. As the rotor field, the outer arc surface surface field requires high requirements, and the waveform basic requirements are sine waves. As the stator, according to the output requirements of the motor, The different requirements of sparks and noise are selected. The stator's magnetic tile has a high internal arc surface field. Due to the shape and production characteristics of the magnetic tile itself, the waveform is mainly saddle-shaped. This type of waveform has a large output, but the spark noise and empty load. Current is large. In order to improve vibration noise, change spark, reduce empty load current, shape size of magnetic steel, mold design, etc. must be carefully designed, among which unequal thick magnetic tiles have been widely used. The principle is to make the magnetic field waveform of the arc gap in the magnetic tile tends to flat. Top wave.