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In the design,manufacture and application of Permanent Magnet Motor,it is necessary to pay attention

1. Magnetic circuit structure and design calculation.

In order to make full use of various magnetic permanent magnets, especially excellent magnetic properties of rare earth permanent magnet, you can not simply copy the structure and design of permanent magnet motor or electrical excitation motor the traditional calculation method, must establish a new design concept, re analysis and improvement of the magnetic structure.With the rapid development of computer hardware and software technology, calculation, and numerical optimization, modern design method and simulation technology continues to improve, through the joint efforts of the motor in the academic and engineering circles, is now in the permanent magnet motor design theory, calculation method, structure process and control technology has made a breakthrough, to form a set of numerical calculation of electromagnetic field and equivalent circuit analytical solution of combining analysis method and computer aided analysis and design software, and is constantly improving.

2. controlling problem

After the permanent magnet motor is made, the magnetic field can be maintained without external energy, but it also makes it difficult to control the magnetic field from outside.It is difficult for permanent magnet generator to adjust its output voltage and power factor from outside, and permanent magnet DC motor can not be changed again.These limits the range of applications of permanent magnet machines.However, with the rapid development of MOSFET, IGBT and other power electronic devices and control technology, most permanent magnet motors can be controlled only by armature without magnetic field control.When designing, it is necessary to combine three new technologies, rare earth permanent magnet material, power electronic device and microcomputer control, to make the permanent magnet motor run under the new working conditions.

3. Irreversible demagnetization problem

If the design or use is improper, permanent magnet motor in high (NdFeB permanent magnet) or low (ferrite permanent magnet) temperature, armature reaction in impact current, or in severe mechanical vibration may cause irreversible demagnetization or loss of excitation, the motor performance is reduced, can not even use. Therefore, it is necessary to study the design method and device for motor factory inspection of permanent magnetic materials of thermal stability, and analysis of various structural forms of resistance to magnetic ability, in order to design and manufacture, adopt corresponding measures to ensure the permanent magnet motor without demagnetization.

4. Cost Problem

The ferrite permanent magnet motor, especially the micro permanent magnet DC motor, is widely used because of its simple structure, low quality and lower total cost than that of the electric excitation motor.Since the price of rare earth permanent magnet is relatively expensive, the cost of rare earth permanent magnet motor is generally higher than that of electric excitation motor, which needs to be compensated by its high performance and operating cost savings.In some cases, for example, the voice coil motors of computer disk drives use NdFeB permanent magnets to improve the performance, reduce the volume quality significantly, and reduce the total cost.In the design, both the performance and the price are decided according to the specific use occasions and requirements. After the comparison of the prices, the decision is taken, and the innovation of the process and the optimization of the design are carried out to reduce the cost.

5. Development trend of rare earth permanent magnet motor

China is rich in rare earth resources, and the reserves of rare earth minerals are the first in the world.The research level of rare earth permanent magnet material and rare earth permanent magnet motor has reached the international advanced level,give full play to the advantages of rich rare earth resources in China, it is of great significance for us to study and popularize the various permanent magnet motors represented by rare earth permanent magnet motors, which speed up China's entry into a well-off society in an all-round way.

The rare earth permanent magnet motor is developing towards high power (high speed, high torque), high function and micro direction, and constantly expanding new motor varieties and application fields, and the application prospect is very optimistic.In order to meet the needs, the design and manufacturing process of rare earth permanent magnet motor need to be innovated constantly. The electromagnetic structure will be more complex, the calculation structure will be more accurate, and the manufacturing process will be more advanced and applicable.These complex problems need to be optimized by applying multidisciplinary theory and system engineering to improve the performance to price ratio and to promote the further development of disciplines and industries such as electrical machinery.

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