Research On Fault Diagnosis Method Of Power Tube Of Power Electronic Converter

With the development of the power electronic industry,the structure of power electronic converters has become more complex and the scale of application has become larger.At the same time,its stability and reliability have attracted more and more attention in recent years.In order to ensure the stable and reliable operation of the system and prevent the failure of the whole system caused by the failure of one of the devices,the fault detection and positioning should be carried out in time to complete fault isolation and fault tolerant control.Power components are the most vulnerable parts of power electronic converters whose reliability directly affects the safe and stable operation of the whole system.This paper focuses on the research of two-level three-phase rectifier and three-phase voltage source inverter in power electronic converter,and carries out in-depth research on their working principle,modulation strategy and fault diagnosis of power tube.Firstly,the development of fault diagnosis technology and the current research status of fault diagnosis of power electronic converters are introduced.For the internal fault diagnosis of power electronic converters,the advantages and disadvantages of different methods are compared.This paper uses a more mainstream method to analyze the current signal as the research object,and introduces various indicators that affect the efficiency of fault diagnosis..Secondly,the three-phase PWM rectifier system and its working principle are analyzed and explained,and its common faults are explained based on this system.On the basis of in-depth analysis of the working status,by comparing the current flow in the rectifier under the health status and the power tube open-circuit fault,the open-circuit fault mechanism of the power tube is analyzed and studied,and the fault characteristic quantity is extracted.The fault detection is based on the symmetry of the rectifier topology,the current data reconstruction method is used to compare the difference between the positive and negative half-wave lengths of the grid-side current after the fault,and the fault diagnosis simulation model is built in combination with multi-scale entropy.Finally,21 kinds of power tube IGBT open-circuit fault detection and location can be quickly completed,which verifies the effectiveness of the scheme.Then,in order to better study the principle analysis of the open-circuit of the three-phase inverter power tube,the induction motor drive system simulation platform built in this paper.The simulation platform includes three parts: the control module,the inverter module and the motor load.Different types of open-circuit faults are simulated by turning off the driving signals of different power tubes.Use the similarity of the current time series to detect faults.On the basis of fault current flow trajectory,fault detection is carried out by using the similarity of current time series,and a fault diagnosis method based on phase current half wave being zero is proposed,which can quickly complete fault detection and location.Finally,through hardware and software design,a physical experiment platform was built,and the fault diagnosis scheme was verified by physical experiments,which verified the rapidity and effectiveness of the method.There are 50 figures,4 tables and 89 references in this thesis.