Online Degradation Monitoring Method of PMSM Based on Stator Current

The failure of driving motor can affect the safety of electric vehicles. This paper proposed a method on how to monitor health state based on the changes in stator current. A simulation model of permanent magnet synchronous motor (PMSM) was developed, which can simulate performance degradation. The stator current data were obtained through simulation by using fault injection under different states. The three indexes e.g. peak-to-peak, crest factor, and margin factor, of stator current were extracted, and the tolerance interval under the normal state was calculated. The simulation results show that the three indexes are all within the tolerance interval under normal condition. The degree of the monitoring indexes deviation from the tolerance interval is positively correlated with the degradation degree of motor. When the monitoring indexes are seriously deviated from the tolerance interval, fault warning should be given to avoid motor failures, and thus ensure safety of the electric vehicle.