Research on fault diagnosis of EMU traction inverter based on motor vibration
The safety and reliability of traction inverters are critical for the stable operation of high-speed EMU vehicles.To identi-fy the operating status of the inverter,this paper proposed a fault diagnosis method based on the analysis of motor vibration signals com-bined with the vehicle system dynamics.In this method,the motor vibration signal is taken as the monitoring object,and the characteris-tic signal of abnormal motor vibration caused by current distortion during inverter failure is detected for judgement.Taking the traction transmission system of CRH2 EMU as an example,a simulation model of a three-level traction inverter circuit based on space vector pulse width modulation strategy was established to simulate the structural fault modes of the inverter.The simulation results indicate that inverter faults significantly affect the harmonic content of the output current on the AC side,especially the 5th,7th,11th,and 13th har-monic currents.These harmonics currents are converted into pulsating torques at frequencies of 6P(1-s)and 12P(1-s)after input to the traction motor,acting on the motor and causing corresponding harmonic components in its output vibration.Analysis of vibration signals of the traction motor during the actual operation of high-speed EMU reveals that under normal circumstances,the vibration signals do not contain obvious harmonic frequency components,while the presence of inverter faults leads to a very significant content of this fre-quency in vibration signals.Therefore,the vibration signal analysis method proposed in this paper can effectively monitor and diagnose the operating status of the traction inverter and has a certain engineering application value.
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