Research On Observer-based Fault Diagnosis For Traction Motors Of High-Speed Trains

As an important component of the traction system,the traction motor provides power to high-speed trains.Once the faults of the traction motor occur,the consequences would be destructive.In this paper,considering the load disturbance and parameter uncertainty,the observer-based robust fault diagnosis is carried out for the rotor broken-bar fault,the speed sensor incipient fault and the inverter IGBT open-switch fault of traction motors.Finally,the simulation results on the MATLAB/SIMULINK platform show the effectiveness of the proposed methods.This paper starts with the research background and significance,meanwhile,the research status of the traction motor fault diagnosis and observer-based fault diagnosis is given.Then the structure of the traction system is briefly introduced,the dynamic model of the traction motor is established,and two coordinate transformations as well as control strategies are given.Finally,the traction motor under the vector control is simulated on the MATLAB/SIMULINK platform.In order to detect the fault of broken rotor bars,the faulty mathematical model is established,and considering the variation of load torque,which is treated as a disturbance signal,the faulty model of traction motors with disturbance is obtained.Then,the original system is decoupled into two subsystems,a synthetical sliding mode-Luenberger observer is proposed to detect the fault of broken rotor bars,which is also effective for the incipient fault of smaller number of broken bars.Considering the speed sensor incipient fault of the traction motor of high speed trains and the uncertainty of rotor resistance because of the temperature varying,the faulty motor model with the parameter uncertainty is established.Then,the original faulty system is decoupled into two subsystems,and an unknown input observer is designed for the subsystem with parameter uncertainty.More importantly,an adaptive unknown input observer is proposed to estimate the incipient fault,which can solve the problem of unknown disturbance amplitude and make it easy to solve the unknown input observer gain matrix.For the inverter IGBT open-switch fault of the traction motor drive system,a pseudo actuator faulty model with the load disturbance and the uncertainty of the rotor resistance is established,and the robust fault diagnosis of the traction motor is carried out.According to the H_?theory,an unknown input observer with the bounded real lemma is put forward.In order to determine the fault location,a fault isolation strategy is proposed,which is also effective for simultaneous open-switch faults.At the end of this paper,the contents of the research are summarized,and the drawbacks are put forward.Furthermore,the research prospect is presented for the future research.