Demagnetization of Rare Earth Magnetic Steel in Permanent Magnet Motors
In fact, the most important part of the permanent magnet brushless DC motor is the rare earth magnet of the permanent magnet motor, and the rare earth magnet of the permanent magnet motor is most afraid of high temperature. At high temperatures, it will gradually demagnetize over a long period of time. The higher the temperature, the greater the risk of demagnetization.
Once the demagnetization speed is amazing, but after partial demagnetization, the current of the permanent magnet brushless DC motor will continue to increase, and the energy consumption will also increase, which will increase the user's electricity cost. At the same time, a motor strike may occur at any time. Once the permanent magnet brushless DC motor loses its magnetism, the only option is to replace the motor, and the maintenance cost is huge.
How to judge the loss of magnetism of the permanent magnet motor rare earth magnet of the permanent magnet DC brushless motor? The reason for the demagnetization of the permanent magnet brushless DC motor is that the high temperature resistance level is an important indicator to measure the performance of the permanent magnet brushless DC motor.
If the permanent magnet motor rare earth magnet exceeds the temperature resistance level, its magnetic flux density will drop sharply. High temperature resistance grades can be divided into: N series, resistant to 80 degrees; H series, resistant to 120 degrees; SH series, resistant to more than 150 degrees.
① Correctly select the power of the permanent magnet DC brushless motor; the demagnetization of the tile type magnet is related to the power selection of the permanent magnet motor. Correct selection of the power of a permanent magnet brushless DC motor can prevent or delay demagnetization. The main reason for the demagnetization of the tile-type magnetic steel in the permanent magnet synchronous motor is that the temperature is too high, and the overload is the main reason for the high temperature.
Therefore, a certain margin should be left when selecting the power of the permanent magnet motor. According to the actual situation of the load, generally about 20% is more appropriate.
② Avoid heavy load starting and frequent starting.