Effect of permanent magnet materials on the performance of permanent magnet synchronous drive motor
In recent years, permanent magnet materials have developed rapidly and have a wide variety. The most commonly used types are: ferrite permanent magnet materials, aluminum-nickel-cobalt permanent magnet materials and neodymium-iron-boron rare earth permanent magnet materials.
The outstanding advantages of ferrite permanent magnet materials are that they do not contain rare earth elements and precious metals such as cobalt and nickel. The price is low, the manufacturing process is simple, the coercive force is large, the anti-demagnetization ability is strong, the density is small, and the quality is light. However, the ferrite permanent magnet material is hard and brittle, and cannot be electrically processed, and the produced motor has low power and low efficiency. The AlNiCo permanent magnet material is characterized by low temperature coefficient, high residual magnetic induction and low coercivity. Easy to magnetize and demagnetize, but contains precious metals such as cobalt, so the price is very high. NdFeB rare earth permanent magnet materials have become the main force of permanent magnet materials with their excellent magnetic properties, and their magnetic properties far exceed those of other magnetic materials such as ferrite and AlNiCo.
A new generation of NdFeB permanent magnet materials has been developed to date, and its residual magnetic induction strength at room temperature has reached 147T. The internal coercive force can be more than 1000kA/m, and the maximum magnetic energy product (BH) is up to 398kj/m, which is 5-12 times of ferrite permanent magnet material and 3-10 times of alumino-nickel-cobalt permanent magnet material. The shortcoming of NdFeB permanent magnet material is that the Curie temperature is low, the magnetic loss is large when used at high temperature, and the thermal stability, corrosion resistance and oxidation resistance are poor, so the surface should be based on the use environment of the magnet. Coating treatment. To meet the automotive environment requirements.
The magnetic properties and mechanical properties of NdFeB rare earth permanent magnet materials are significantly higher than those of ferrite and AlNiCo permanent magnet materials. The processing performance is good. China's rare earth production accounts for more than 80% of the world total. With unique natural resources, NdFeB rare earth permanent magnet materials are more suitable for new energy vehicles permanent magnet synchronous drive motors.
