Joint Diagnosis And Performance Optimization Methods For Device Open-circuit And Sensor Faults In Traction Converter

The traction converter is an important part of high-speed train power system,and its reliability level is related to the safe operation of the train.Traction converters work in high temperature,high voltage,and high current condition for a long time,which is one of the high-frequency fault sources of trains.When a fault occurs,if it can not be dealt with timely and correctly,it will easily lead to cascading faults,which will bring huge security risks to the high-speed train.Therefore,it is of great theoretical significance and practical value to carry out research on fault diagnosis and performance optimization of traction converters to improve the safety level of the train.This paper takes the traction converter as the research object,and focuses on the fault modeling,fault diagnosis and performance optimization methods of the traction converter.The main innovative work of the paper is as follows:(1)In the process of fault modeling of traction converters,there are problems such as large amount of calculation,complex fault analysis,and different traction converter topology changes caused by different device open-circuit faults.These make the fault modeling difficult.Aiming at the problems,a uniform fault modeling method for traction converters based on the single leg model is proposed.The operating principle of the traction converter with device open-circuit fault is revealed.The open-circuit faults in different Insulated Gate Bipolar Transistors(IGBTs)and champing diodes are analyzed,and the effects on the inputs and outputs features of the single leg are obtained.The single leg modeling method of open-circuit faults in different devices is built.Based on the single leg model,a uniform model of the traction converter with open-circuit faults is constructed,which can describe the traction converter not only in normal condition but also the abnormal condition that the open-circuit fault occurs in any IGBT or clamping diode open-circuit fault on any leg of the traction converter.(2)There are many devices in the traction converter,the sensor faults,the open-circuit faults in different IGBTs and clamping diodes share overlapping fault characteristics.It brings difficulties on the fault location of device open-circuit faults and sensor faults in the traction converter.Aiming at the problems,a joint diagnosis method for open-circuit faults and sensor faults in traction converter is proposed.In-depth analysis of the influence of faults on the DC link voltage,based on the DC link voltage residuals,a fault detection method for device open-circuit faults and sensor faults is proposed 、 Based on the reconstructed voltage residual,a classification method for device open-circuit faults and sensor faults is proposed and the open-circuit faults are located、 Based on the differential of the voltage residual,a location and type identification method for sensor faults is proposed.The device open-circuit faults are located and the sensor faults are located and the types are identified in the traction converter without any additional sensors.(3)Since the single phase structure of the traction rectifier,the device open-circuit fault has noticeable impact on both legs.After the open-circuit fault occurs in different devices of the traction inverter,the voltage output capability of the traction inverter decreases in different degrees,which lead to different degrees of stator current distortion and output torque fluctuation.Different estimators need to be constructed for performance optimization after different sensor faults.Aiming at the problems,a fault performance optimization strategy for traction converters is proposed.The ability of the traction rectifier to adjust the grid-side current and DC-link voltage,the voltage output capacity of the traction inverter after the device open-circuit faults and the quantitative relationship between DC link voltage,its differential residual and fault information after sensor faults are analyzed.A performance optimization method based on residual adjustment capacity-finite control set-model predictive control(RACFCS-MPC)for the traction rectifier,a performance optimization method based on residual output capacity-finite control set-model predictive control(ROC-FCS-MPC)for traction inverter after device open-circuit faults are proposed.A performance optimization method for fault sensor based on signal reconstruction is also proposed.The control performance of the traction converter is imporved effectively after device open-circuit faults and sensor faults.In this paper,a controller hardware-in-the-loop test and verification platform for the fault simulation,diagnosis and performance optimization of the high-speed train traction drive control system is developed independently.After the real-time test of the platform.The effectiveness of the proposed method are verified by the hardware-in-the-loop tests.