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In today’s DC motor, the excitation mode that generates the main pole magnetic field by DC current is called current excitation; If the current excitation is replaced by a permanent magnet to generate the main pole magnetic field, the motor is called a permanent magnet generator. The article aims at ferreting out some problems you might meet while you are operating the sophisticated machine and propose the corresponding solutions.
a.Control problem
Problem: permanent magnet generator can maintain its magnetic field without external energy after it is made, but it also makes it extremely difficult to adjust and control its magnetic field from the outside.
Solution: With the rapid development of control technology of power electronic devices such as MOSFET and IGBTT, permanent magnet generator does not need magnetic field control in application, but only motor output control. The design requires the combination of NdFeb materials, power electronic devices and microcomputer control three new technologies to make the permanent magnet generator operate under new conditions.
b.Irreversible demagnetization problem
Problem: If the design and use of improper, permanent magnet generator in the temperature is too high (NdFeb permanent magnet) or too low (ferrite permanent magnet), under the impact current generated by the armature reaction, or in the violent mechanical vibration may produce irreversible demagnetization, or loss of magnetism, so that the motor performance is reduced, or even can not be used.
Solution: It is necessary to research and develop methods and devices suitable for motor manufacturers to check the thermal stability of permanent magnet materials, and to analyze the anti-demagnetization ability of various structural forms, so as to adopt corresponding measures in the design and manufacturing to ensure that the permanent magnet generator will not lose magnetism.
c.Cost problem
Problem: Because the current price of rare earth permanent magnet materials is still relatively expensive, the cost of rare earth permanent magnet generators is generally higher than that of electric excitation generators.
Solution: With the advancement of technology and large-scale production, the cost of permanent magnet materials is gradually reduced, which will help reduce the cost of permanent magnet generators. At the same time, the performance and reliability of permanent magnet generators are constantly improved to improve their cost performance and expand their application in the market.
In a whole, permanent magnet generators may encounter some problems during operation, but with the continuous development and improvement of technology, these problems will be gradually solved.
