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Permanent Magnets Effects on the Electric Machines

New energy concepts are required for the future of our industrial society. In this context, the materials are constantly changing and their industrial applications are diversifying. In the last decades, there has been a revolution in the development of the magnetic materials. The last is the creation of the high performance magnetic materials such as “Samarium-Cobalt” and “Neodyme-Fer-Bore”. There are two types of the materials:

  • Soft magnetic material – Soft magnetic composite materials are used to produce magnetic circuits. They are used in electric machines for channelling and concentrating the magnetic flux.
  • Hard magnetic material – Hard magnetic materials retain their state initial magnetization even when applying a relatively high magnetic field. They are used as a magnetic field source.

But today I would like to bring out more information about permanent magnets. They are part of the family of the hard magnetic material. This gives it special properties related to the existence of the magnetic field. There are four main classes of permanent magnets: ferrite; alnico; samarium Cobalt (SmCo); neodyme-fer-bore (NdFeB)
A permanent magnet is characterized by its hysteresis cycle; more particularly the second quadrant of the cycle. This quadrant shows the demagnetization curve which gives all of the characteristics of the magnet: remanent induction (Br); the coercive field (Hc)(1) ;  energy density (BH)max (see the figure bellow); curie temperature(2)

Magnets Proprieties
Y axis is the magnetic field (A/m)
X axis is the remanent flux density (T)
X axis is the remanent flux density (T)







Permanent magnets have a wide range of applications. Among these applications are electric machines; particularly synchronous machines. To accompany the progress and change in magnetic materials, Flux 2D/3D software by CEDRAT has developed several models (linear, non-linear, spatial…) which allow taking into account different types of permanent magnets. The last one is the demagnetization (3) of the permanent magnets.

Read more in the following article: Taking Demagnetization into Account in Permanent Magnets Using Flux

  1. Remanent induction of the permanent magnet: measuring the induction or persistent flux density in a permanent magnet after magnetization.
  2. Coercive field of the permanent magnet: temperature at which the magnet will become demagnetized.
  3. Demagnetization of the permanent magnet: Demagnetization of the permanent magnet means that the magnet loss its magnetic proprieties. The demagnetization of the magnets leads to decrease the performances of the machine.