Stator fault, rotor fault and other faults are likely to cause permanent magnet synchronous motor (PMSM)asymmetric operation, which results negative sequence component. In the existing literatures, they focus more on negative sequence current resulting from a certain fault of the conventional motor fault, and focus little on a comprehensive analysis of the negative sequence component. In this paper, the simulation model and experimental platform of the electric vehicle drive motor is established as the research object, in order to further study negative sequence current and negative sequence impedance under asymmetry operation condition caused by the stator windings of three phase unbalanced. The experimental and simulation results show that the angle between non-fault phase deviates more from 120 ° along with the increase of PMSM unbalanced degree; the negative sequence current under fault condition is far greater than the negative sequence current during normal operation; the negative sequence impedance under fault condition is far less than the normal operation and have more robustness. These conclusions provide the basis for the study of permanent magnet synchronous motor fault diagnosis based on negative sequence component.
