The Research of Traction Inverter Fault Diagnosis Based on the Analysis of Motor Vibration Signals

The main circuit simulation model of three-level traction inverter based on SVPWM strategy is established. Taking the power switch elements as the object, the structural fault modes of the inverter are simulated, and the analysis results show that the inverter faults have a great influence on the harmonic content of the output current of the AC side, the content 5, 7, 11 and 13 octave of the fundamental frequency of current increases greatly. After the current harmonic inputting the traction motor, 5, 7 octave and 11, 13 octave harmonics are converted into 6 octave and 12 octave ripple torque acting on the motor respectively, making the motor output vibration contain 6P(1 − s) and 12P(1 − s) current harmonic frequency, which is determined by the logarithm of the magnetic pole P and slip rate s. The vibration signals on the actual operation of the high-speed EMU traction motor were analyzed, and the results show that in the normal mode of inverter, the motor vibration contains current harmonic frequency not obviously, while in the fault mode, it is obviously. It is verified that the main influence of inverter fault on traction motor vibration is current harmonic frequency, therefore, the traction inverter can be fault diagnosed by monitoring and analyzing the motor vibration signal.