Permanent magnet selection in magnetic driving motors
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- publisher
- Gordon
- Issue Time
- Mar 5,2013
Summary
There are many choices of permanent magnet materials, and the performance varies greatly. Therefore, when designing a permanent magnet motor, it is necessary to choose a suitable type of permanent magnet material and specific performance indicators.
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
4)
Cost-effective
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
