Principle of Permanent Magnet Selection
1) It should be able to ensure a large enough gap magnetic field in the motor and meet the specified motor performance.
2) The magnetic performance should be stable under the specified environmental conditions, working temperature and use conditions
3) Has good mechanical properties to facilitate processing and assembly
According to the performance of existing materials and the performance requirements of the motor, generally speaking：
1) With the continuous improvement of performance and the gradual reduction of relative prices, the application of NdFeB permanent magnets in motors will become more and more extensive. It is not only possible to replace other permanent magnet materials in some applications, but also part of electric excitation motors
2) For occasions where the performance and reliability requirements are high and the price is not the main factor, the high coercivity 2:17 rare earth cobalt permanent magnet is preferred. The application occasions of 1:5 type rare earth cobalt permanent magnet will be reduced, mainly used in high temperature situations and occasions with large demagnetization field.
3) The performance requirements are not high, the dimension and quality are not strictly limited, and the price is the main factor to consider, then low-cost ferrite is preferred
4) In occasions where the operating temperature exceeds 300°C or where temperature stability is strictly required, such as motors for various measuring instruments, the AlNiCo permanent magnets with low temperature coefficient are preferred. The proportion of AlNiCo permanent magnets in the total amount of permanent magnet materials is gradually decreasing
5) Where mass production is large and the shape of the magnetic poles is complex, bonding permanent magnet materials are preferred