Online Rotor Fault Diagnosis of Permanent Magnet Synchronous Motors Based on Stator Tooth Flux

Demagnetization and eccentricity are unique and common rotor faults of permanent magnet synchronous motors, respectively. These important factors affect reliability and security of motor drive systems. Online monitoring and real-time diagnosis are typically required in highly reliable application scenarios. The influence of demagnetization and eccentricity faults on spatiotemporal distribution of stator tooth flux based on a stator magnetic flux detection device with multiple search coils is analyzed in this article by establishing a mathematical model of stator tooth flux with corresponding faults. Moreover, a method for extracting rotor fault features and formulating the corresponding fault diagnosis is proposed. Simulations and experiments showed that the proposed diagnosis method can effectively identify the corresponding fault type and diagnose the number of demagnetization poles, degree of demagnetization, and magnitude and orientation of eccentricity ratio. The proposed method can provide an important basis for the operation and maintenance of the motor, help reduce losses due to faults, and improve reliability of the motor and the entire system.