China's rare earth reserves account for about 23% of the world's total, and production accounts for 80% of the world. Rare earth elements are very important strategic resources. They are widely used in information, energy, materials, environmental protection, national defense and other fields. Among them, the application of new materials accounts for 62%, while the amount of rare earth permanent magnets accounts for 63% of new materials. At the 2017 Annual Meeting of the China Rare Earth Society held recently, the academicians of the Chinese Academy of Engineering all said that due to the special electronic structure of rare earth elements, and the high spin magnetic moment, large orbital moment, strong spin-orbit coupling, The application in materials occupies an irreplaceable important position, and its application needs to be continuously innovated and developed.
Recently, the "New Materials Industry Development Guide" jointly issued by the Ministry of Industry and Information Technology, the National Development and Reform Commission, the Ministry of Science and Technology and the Ministry of Finance clearly pointed out that "accelerating the realization of the industrialization of rare earth magnetic materials and application devices" and "developing rare earth permanent magnet energy-saving motors and supporting rare earths" Permanent magnet materials, high-temperature porous materials, intermetallic compound film materials, and high-efficiency thermoelectric materials are being promoted in key projects for energy conservation and environmental protection.
The rare earth permanent magnet motor is a new type of permanent magnet motor that appeared in the early 1970s. Tang Renyuan, an academician of the Chinese Academy of Engineering, pointed out that rare earth permanent magnet motor applications include computers, engineering equipment, transportation, wind power, wind turbines, pumps, petrochemicals, mining, household appliances, medical equipment, aviation, navigation, aerospace, weapons, etc. field. Seven of the ten key areas listed in "Made in China 2025" put forward requirements for rare earth permanent magnet motors. One of the focuses of "Energy Conservation Engineering" is to promote the application of rare earth permanent magnet motors. An important position in the national economy.
Tang Renyuan said that rare earth permanent magnet motors have many advantages. For example, the magnetic field is generated by permanent magnets, and the magnetic field does not require energy. Therefore, the motor has high efficiency and high power factor. The rare earth permanent magnet motor has low loss and low heat generation, which can improve the electromagnetic load. Power electronics technology, modern control technology and other advanced technologies combine to simplify or even remove the intermediate transmission mechanism, direct drive, can be further integrated with technical equipment; can achieve excellent control performance, is conducive to the intelligent development of the motor; motor structure Diversification is no longer limited to the traditional radial flux structure, and there are many new structures such as ironless core, axial magnetic flux, transverse magnetic flux, linear, double stator, double rotor, and stator permanent magnet.
At the same time, rare earth permanent magnet motors also have their drawbacks. Tang Renyuan introduced that, first of all, the price of rare earth permanent magnet materials is high, which affects the promotion and application of permanent magnet motors. The basic material of the motor is a few hundred yuan or tens of yuan per kilogram of silicon steel sheet and copper wire, and a permanent magnet requires several hundred yuan per kilogram. Secondly, the permanent magnet material is relatively brittle and the processing process is complicated. Its magnetic force is relatively strong, small motors can be assembled first and then fully magnetized, while high-power motors need to be magnetized and assembled first, which makes the process more difficult. Again, if the design calculation is incorrect, the permanent magnet material fails to guarantee high temperature performance, which may cause the motor to irreversibly demagnetize.
For the prospect of rare earth permanent magnet motor, Tang Renyuan put forward a few points of view: First, to improve quality and create a Chinese brand. Increase the synergy between research institutes and enterprises, gradually improve the engineering, maturity and matching of permanent magnet motor products, improve quality and reliability, create Chinese brands, and strive to export some products overseas. The second is to improve the cost performance, expand the scope of application, meet the needs of the rise of new industries and the upgrading of traditional industries. The third is to develop in the direction of high-end high-performance, such as new energy vehicle drive motors, high-end CNC machine tools and robots.