Abstract
For the phenomenon of rotor demagnetization of Permanent Magnet Synchronous Motor(PMSM), studying the dynamic modeling and analysis of demagnetization rotor. Firstly, considering the unbalanced magnetic pulling (UMP) of the rotor under the demagnetization and the nonlinear Hertz contact generated by the rolling bearing, the double rectangular coordinate system of the stator and rotor is constructed, and the mathematical model of the unbalanced magnetic pull UMP is constructed with the rectangular coordinate as the variable. Then, the dynamics Jeffcott model of the bearing-rotor- magnetic fields coupling system in the condition of demagnetization is established. Based on this, the demagnetization status of permanent magnet in PMSM is described from three aspects: (1) rotor offset caused by demagnetization, (2) demagnetization angle, (3) decrease of air-gap MMF at the demagnetization angle. Through the analysis, it is found that there is a “saddle” point in the bifurcation plots of the rotor system with the change of demagnetization angle. The position of the “saddle” point in the bifurcation plots with the change of demagnetization angle is related to the speed. The research results of this paper provide a theoretical basis for demagnetization quantitative diagnosis and demagnetization vibration control of permanent magnet synchronous motor.
Highlights
With the wide application of permanent magnet synchronous motor(PMSM), the research on its specific fault has become a hot topic
Considering the unbalanced magnetic pulling (UMP) of the rotor under the demagnetization and the nonlinear Hertz contact generated by the rolling bearing, the double rectangular coordinate system of the stator and rotor is constructed, and the mathematical model of the unbalanced magnetic pull UMP is constructed with the rectangular coordinate as the variable, the dynamics Jeffcott model of the bearing-rotor- magnetic field coupling system in the condition of demagnetization rotor of the PMSM is established
The demagnetization status of permanent magnet in PMSM is described from three aspects: demagnetization angle, demagnetization amount of the demagnetization angle and rotor offset caused by demagnetization
Summary
With the wide application of permanent magnet synchronous motor(PMSM), the research on its specific fault (demagnetization) has become a hot topic. The demagnetization of the permanent magnet in the rotor of the permanent magnet synchronous motor (PMSM) results in an uneven air-gap flux density in the motor, resulting in unbalanced magnetic pull (UMP) acting on the rotor, and considering the influence of rotor gravity On this basis, the research on rotor system dynamics of PMSM can be transformed into the research on Jeffcott rotor system as shown in Figure 2 to simplify the research. If the permanent magnet of PMSM rotor is non-uniform demagnetization, the UMP produced by demagnetization is not acting on the center position of shaft, at this time, the actual rotor will be simplified as a Jeffcott rotor system in the disk offset state.
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