many users may have a question, what to do with demagnetization of permanent magnet dc motors? how to deal with it? let's introduce the method.
1. the power selection of permanent magnet dc motor is correct
demagnetization is related to the power selection of permanent magnet dc motors. choosing the correct power of a permanent magnet dc motor can prevent or delay demagnetization. the main reason for demagnetization of permanent magnet synchronous motors is high temperature, and overload is the main reason for high temperature. therefore, when selecting the power of a permanent magnet motor, a certain margin should be left. according to the actual situation of the load, it is generally around 20%.
2. avoid overloading and frequent starts
the starting torque is oscillating. in the valley of starting torque, the stator magnetic field has a demagnetization effect on the rotor magnetic poles. therefore, try to avoid heavy loads and frequent starts of permanent magnet dc motors.
3. improving design
(1) increase the thickness of the permanent magnet appropriately
from the perspective of design and manufacturing of permanent magnet dc motors, the relationship between armature reaction, electromagnetic torque, and permanent magnet demagnetization should be considered. under the combined action of the magnetic flux generated by the torque winding current and the magnetic flux generated by the radial force winding, the permanent magnet on the rotor surface is prone to demagnetization. the most effective method is to increase the thickness of the permanent magnet appropriately when the gap of the permanent magnet dc motor remains unchanged.
(2) there is a ventilation slot circuit inside the rotor to reduce the temperature rise of the rotor
if the temperature rise of the rotor is too high, the permanent magnet will experience irreversible loss of excitation. in structural design, the internal ventilation circuit of the rotor can be designed to directly cool the magnetic steel. it not only reduces the temperature of the magnetic steel, but also improves efficiency.