Demagnetization fault diagnosis of permanent magnet in synchronous motor

Yongming Yang, Yaqiang Li

COMPUTER MODELLING & NEW TECHNOLOGIES 2014 18(12D) 221-225

State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing, China

Permanent Magnet (PM) embedded in the rotor simplifies the mathematical model of Permanent Magnet Synchronous Motor (PMSM), making its control method simple and flexible, and improving its power factor. But in the actual operating environment, the biggest risk of PMSM lies in demagnetization of rotor permanent magnet material. High temperature would make PM in the rotor suffer demagnetization, which is irreversible. If it develops without sufficient attention, there will be a major accident. From the detection state of the rotor flux, the stator magnetic flux equation is analysed under the demagnetization and the flux observer system is reconstructed, in order to obtain a quantitative analysis of the d-q axis flux and the demagnetization flux angle. Finally, the respective simulations will be made from three perspectives, such as no demagnetization, amplitude demagnetization and angle demagnetization of PM in the motor. It turns out that the flux observer can be used to real-time monitor the demagnetization of PM in the PMSM and the similar case, and can timely make an accurate fault diagnosis.