How to prevent demagnetization of permanent magnet DC motors?

Permanent magnet motor demagnetization not only affects the use of the motor but also consumes maintenance costs.

Here is the answer to how to prevent demagnetization of permanent magnet DC motors.

1、Choose the right power of the permanent magnet DC motor

Demagnetization is related to the selection of permanent magnet DC motor power. Correct selection of permanent magnet DC motor power can prevent or delay demagnetization. High-temperature overload is the main factor causing the demagnetization of permanent magnet motors. Therefore, it is very important to have a certain safety factor when selecting the power of a permanent magnet motor. According to the actual load conditions, it is best to leave a margin of about 20%.

2、Prevent overload starting and repeated starting

The starting torque oscillates and the stator field demagnetizes the rotor poles during the starting torque trough. Therefore, do not let the permanent magnet DC motor start frequently or under a strong load.

3、Enhanced design

(1) Appropriately increase the thickness of the permanent magnet

From the perspective of permanent magnet DC motor design and production, the relationship between armature response, electromagnetic torque, and permanent magnet demagnetization should be considered. Permanent magnets are susceptible to demagnetization by the flux generated by the torque winding current as the rotor surface and the flux generated by the radial force winding. In a permanent magnet DC motor with a constant air gap, the best technique to prevent demagnetization of the permanent magnet is to sufficiently increase the thickness of the permanent magnet.

(2) Ventilation slot circuit inside the rotor to reduce rotor temperature rise

If the temperature rise of the rotor is too high, irreversible demagnetization of the permanent magnets will occur. The structural design allows for a built-in internal rotor ventilation circuit to directly cool the magnets. This not only improves efficiency, but also reduces the magnet temperature.

These are some of the ways to prevent demagnetization of permanent magnet motors.

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