How To Prevent Demagnetization Of Permanent Magnet DC Motors?

Demagnetization of permanent magnet motor not only affects the use of the motor, but also consumes maintenance costs. Here are some answers for you
1. Choose the right power of permanent magnet DC motor
Demagnetization is related to the selection of PMDC motor power. Proper selection of PMDC motor power can prevent or retard demagnetization. High temperature, i.e. overload, is the main factor that causes demagnetization of PM motors. Because of this, it is important to have a certain safety factor when selecting the power of a PM motor. Depending on the actual load, a margin of roughly 20% is preferable.

2. Prevent overload starting and repeated starting
The starting torque is oscillating, and the stator magnetic field is demagnetizing to the rotor pole during the starting torque trough. Therefore, let the PMDC motor not start frequently or under strong load.
3. Enhanced design
(1) Properly increase the thickness of permanent magnets
From the point of view of PMDC motor design and production, the relationship between armature response, electromagnetic torque and permanent magnet demagnetization should be considered. Permanent magnets are susceptible to demagnetization in the magnetic flux generated by the torque winding current as the rotor surface and the magnetic flux generated by the radial force winding. In a permanent magnet DC motor with constant air gap, the best technique to prevent demagnetization of the permanent magnet is to increase the thickness of the permanent magnet sufficiently.

(2) Rotor with internal ventilation slot circuit to reduce rotor temperature rise
If the rotor temperature rises too much, irreversible demagnetization of the permanent magnets will occur. The internal ventilation circuit of the rotor can be built into the structural design to cool the magnet directly. This increases the efficiency while reducing the magnet temperature.
These are some ways to prevent demagnetization of permanent magnet motors. For more information, please feel free to contact us!