Which type of magnets is used in motor?

Permanent magnet motors use permanent magnets as excitation sources. According to materials, permanent magnets usually are AlNiCo magnets, ferrite magnets, samarium cobalt magnets and neodymium magnets.

Neodymium Magnets

Neodymium magnets include sintered neodymium magnets and bonded neodymium magnets. Sintered neodymium magnets are normally designed as arc-shape, they are installed in alternate order of S/N pole. This structure allows those magnets to provide stable and strong magnetic fields. Ring motor magnets are generally bonded neodymium magnets, multiple pole magnetization is required is ring motor magnets. Although neodymium magnets generate strong magnetic force, the eddy current loss must be taken into consideration. High temperature caused by eddy current loss will cause irreversible demagnetization of neodymium magnets.

Samarium Cobalt Magnets

Sintered samarium cobalt magnets play an irreplaceable role in some specific motor applications. It has very great temperature stability, the influence of temperature changes on the magnetic properties of SmCo magnets is not as great as that of neodymium magnets. Samarium Cobalt magnets are usually used in high temperature motors like aviation motors.

AlNiCo Magnets

Alnico magnets are rarely used in motors because of their low magnetic properties compared with rare earth magnets. In some special conditions, motors need to work above 350℃, we can only choose alnico magnets because samarium cobalt magnets and neodymium magnets do not work anymore.

Ferrite Magnets

Ferrite magnets take a great market share of permanent magnet motors. In addition to low cost, corrosion resistance and wide operating temperature range, ferrite magnets are also free from eddy current loss due to their high resistivity. Due to relatively low magnetic energy, permanent magnet motors made of ferrite are generally larger in size

SmCo Arc Magnet for Motor

AlNiCo Arc Magnet for Motor

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