When we speak of magnet, there is the possibility of choosing two materials: Ferrite and NdFeB. Ferrite magnets and rare earth magnets available today have high coercivity so that demagnetization is not a big problem, and magnets can act on small values of permeability coefficients 1 1/2 hp 56c motors. This allows the use, for example, of the configuration of buried magnets that would be impossible with the low coercivity alnico magnets. As one of the project’s goals is to reduce cost, the ferrite was chosen for the development of the engines.
For the configuration of buried magnets, they can be naturally magnetized after assembly. Due to the precision of the intermediate steel between the magnets, there is no need for machining or grinding after final assembly of the rotor. Mechanical retention methods are safer than glue-based methods, and another advantage is the likelihood of using low-cost magnets, low magnet machining cost, and high air-gap flux density. The iron part of the pole can be designed to reduce cogging torque. Typical Br values of NdFeB magnets are around 1.05 T, while the ferrites have a Br about 40% of this value, ie, 0.405T.