October 16, 2019

2. Increasing the Energy of Permanent Magnets

Permanent magnets, especially the rare-earth type, provide the fixed magnetic field for the most efficient motors in the world.  This high efficiency is expected since other types of motors require that the fixed field is “created” by the electrical input power to the motor. Therefore, other types of motors have an inherent loss associated with the need to provide the energy to create the fixed field. A greater fixed field can be created with higher energy magnets (for the same allotted volume). The magnets achieve higher and higher flux densities making smaller and more efficient motors. The magnet industry has pushed in this direction with rare-earth solutions for the past 40 years. A negative of this push is the high cost of rare-earth magnets.  These types of magnets are typically the most expensive part of the motor. Rare-earth motor grade permanent magnets are often 5 times higher per kg than any other motor material.