Rare-earth Permanent Magnet Brush Motors
In comparison to ferrite, rare earth magnets (Neo) have a significantly higher energy product which, when properly incorporated in a motor’s design, can provide the motor with an increased power output, an improved efficiency, or some combination of the two
Recent improvements in the magnetic, mechanical, and thermal properties of neodymium-iron-boron (“Neo”) magnetic materials, together with the evolution of low cost, high volume manufacturing processes, have made the replacement of traditional ferrite permanent magnets attractive in appliance applications. While the development of Neo magnets has had a significant technical and economic impact on the traditional electric motor industry, these advancements have been slow to gain acceptance from the appliance sector.
The reason for this has been the higher cost of Neo compared to ferrite, while ignoring the added value that Neo can provide to most applications. Continual price reductions in both Neo magnets and the powders from which they are made are finally enabling the replacement of ferrites in many battery-powered appliances. The cost difference between a Neo and ferrite magnet solution is narrowing, the value of which will be evident in improvements to motor production and performance.
Torque is increased by increasing airgap flux density, but this increases iron losses, cogging torques, etc and involves the magnet working well below its maximum energy product, which increases mass and magnet cost.
These advances led to the more demanding applications and, in these cases, the design of the machine is a very careful balance between conflicting requirements.
Custom Design Services - Many years of experience in analysing, designing, testing, and evaluating products has allowed us to accumulate a large bank of data that is particularly helpful in refining the optimum designs and enabled us to support our customers in developing innovative rare earth brushed motors across a wide range of applications.
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