1. The actual magnetic properties of permanent magnetic material are linked to the specific manufacturing process of the manufacturer, and there are always some deviations between its values and the data specified in the standard. There are certain differences in magnetic properties between different factories or batches of the same brand of permanent magnetic material. For the actual shape and size of the permanent magnet used in motor, there are some differences between its magnetic properties and standard data.
2. The magnetic properties of permanent magnetic material are related not only to alloy composition and manufacturing process, but also to the magnetic field heat treatment process. The so-called magnetic field heat treatment is the application of an external magnetic field in the decomposition reaction process of permanent magnetic material. After magnetic field heat treatment, the magnetic properties of permanent magnetic material are improved with directionality. The direction of paramagnetic field is the largest and the direction of the vertical magnetic field is the smallest. This is called anisotropy. For permanent magnetic materials without magnetic field heat treatment, magnetic properties have no directionality, which is called isotropy. It should be pointed out that for anisotropic permanent magnets, the direction of magnetic field during magnetization should be the same as that during magnetic heat treatment, otherwise the magnetic properties will be reduced.
3. Permanent magnetic material
rises from room temperature to the highest working temperature and then cools to room temperature after holding for a certain time. Its open-circuit flux permits no irreversible loss of more than 5%. Therefore, in order to ensure stable performance of permanent magnet motor in operation and avoid obvious irreversible demagnetization, magnetic stabilization treatment should be carried out before use. The method is to raise the temperature of permanent magnet material after magnetization to the expected maximum working temperature and keep it warm for 2 to 4 hours in order to eliminate this part of the irreversible loss in advance.