Research on the Mechanism of Demagnetization Limitation in Permanent Magnet Servo Motors

Background: Demagnetization limitation of permanent magnets is the maximum demagnetization rate, and it is not only influenced by motor overload capacity, but also influenced by winding limit temperature and permanent magnet limit temperature. It has important significance to study the influence of demagnetization limitation on motor whole life cycle management. Methods: In this paper, the finite element method, the analytical algorithm and the equivalent thermal network method were adopted. Aiming at the mechanism research on the demagnetization limitation of permanent magnet servo motors (PMSM), the demagnetization factor is proposed, which can reflect the relationship between the demagnetization and electromagnetic performance of PMSMs, and it can also indicate the influence of overload capacity on demagnetization limitation. Based on the calculation of motor losses, the temperature variation of the motor was studied in depth. Considering the temperature rise caused by heat accumulation effect, the demagnetization limitation of permanent magnets was obtained. Combined with the constraint of the winding insulation grade and limit temperature of permanent magnets on demagnetization limitation, the optimal combination of armature windings and permanent magnets was determined. Results: The accuracy of calculation results was verified by experiment to prove the correctness of the research on demagnetization limitation. Conclusion: The research on motor demagnetization can provide some useful reference for motor design and maintenance.