Diagnosis method for open‐circuit faults of six‐phase permanent magnet synchronous motor drive system

This study proposes a diagnosis method for open‐circuit faults of six‐phase permanent magnet synchronous motor. When the open‐circuit fault occurs in the single‐bridge arm or the double‐bridge arm, wavelet transform extracts the trigger signal of fault, and the z 1 – z 2 plane current component is analysed. Seven kinds of fault modes are defined by analysing the characteristics of the scatter plot of the z 1 – z 2 plane current component. The fractal dimension of the z 1 – z 2 plane current component scatter plot is calculated to accurately quantify the fault modes. Moreover, 13 fault areas are defined by analysing the current centroid position of the z 1 – z 2 plane current component. First, the diagnosis of two particular kinds of fault modes is completed by selecting the fault area. Besides, the diagnosis of the remaining five kinds of fault modes is completed by combining the fault area and the fault mode. The conditions for judging all open‐circuit faults are summarised to establish a fault database. All the open faults can be diagnosed by searching the fault database by the proposed method. Finally, the effectiveness of the method is verified by experiments.