1) permanent magnet motors are divided into permanent magnet dc motors and permanent magnet ac motors.
1.1 permanent magnet ac motor refers to the multiphase synchronous motor with permanent magnet rotor. In the past, ferrite and al-ni-co magnetic tile were mainly used. With increasingly high power requirements, ferrite and al-ni-co cannot meet the requirements due to low magnetic energy accumulation.Of course neodymium iron boron magnetic tile, because rare earth resources precious, raw material prices rise exponentially, its manufacturing costs and production prices will continue to increase in the future, affecting its use in a number of low-end fields.The negative temperature coefficient of ndfeb itself, low Curie temperature, also limits its high temperature applications.
1.2 permanent magnet dc motor is divided into brushless motor and ordinary dc motor with commutator. Its application is judged from the shape and number of poles of the magnet.In the ordinary dc motor, 2 pole and 4 pole in the majority, and the magnetic tile is basically used as the motor stator, most of the micro dc motor use is ferrite magnetic tile, mainly used in toys, home appliances, automotive fields.When brushless motor USES magnetic tile as stator, it usually exceeds 6 poles, so its central Angle is much smaller than that of ordinary dc motor.But the magnetic tile as a brushless motor rotor, can have more than 4, 6 pole number, for the 4 pole, the rotor is magnetized on the outer surface, and because to be assembled into a circle, its central Angle is close to 90°, this can be different from ordinary dc motor.
2), magnetic tile according to different application fields, have different requirements for performance and magnetic field wave form, as the rotor field, its outer surface table field requirement is high, the basic requirements for sine wave waveform, the stator, then according to the requirements of the motor output, select the requirement of the spark and noise, as the stator magnetic tile, tile arc high table field, because of magnetic tile itself shape and nature of production, the main waveform as saddle, the waveform output is big, but the spark noise, no-load current.In order to improve vibration noise, commutation spark, reduce no-load current, the shape and size of magnetic steel, mold design, etc., have to be carefully designed, among which unequal thickness magnetic tile has been widely used, the principle is to make the magnetic field waveform in the arc air gap inside the magnetic tile trend to the flat top wave.